NCKRI Symposium 8 : Proceedings of the 16th Multidisciplinary Conference on Sinkholes and the Engineering and Environmedntal Impacts of Karst

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NCKRI Symposium 8 : Proceedings of the 16th Multidisciplinary Conference on Sinkholes and the Engineering and Environmedntal Impacts of Karst

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NCKRI Symposium 8 : Proceedings of the 16th Multidisciplinary Conference on Sinkholes and the Engineering and Environmedntal Impacts of Karst
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National Cave and Karst Reseaarch Institute Symposium 8 [web format]
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Land, Lewis (editor)
Kromhout, Clint (editor)
Byle, Michael J. (editor)
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The 16th Sinkhole Conference scheduled for 2020 was rescheduled to 2021. This is the first edition of the proceedings, containing papers already submitted. A second edition with additional papers will be available at the rescheduled 2021 conference.

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NCKRI SYMPOSIUM 8 Proceedings of the 16th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst Edited by: Lewis Land, Clint Kromhout, and Michael J. Byle www.nckri.org

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NATIOþnNAL CAVE AþnND KARST þRRESEARþcCH þIIþnNSTITUTEþSSYMPOSIUM 8 PROCEEDINGS OF THE 16th MULTIDISCIPLINARY CONFERENCE ON þSSIþnkNKHOLES AþnND THE þEEþnNGIþnNEERIþnNG AþnND þEEþnNVIROþnNMEþnNTAL þIIMPAþcCTS OF KARST First Edition E þditors DITORS :Lewis LandNational Cave and Karst Research Institute Carlsbad, New Mexico, USAClint KromhoutFlorida Geological Survey Tallahassee, Florida, USAMichael J. Byle Tetra Tech, Inc. Langhorne, Pennsylvania, USA Organized by:

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Published and distributed by National Cave and Karst Research InstituteDr. George Veni, Executive Director 400-1 Cascades Ave. Carlsbad, NM 88220 USA www.nckri.org Peer-review: Editors and associate editors of the Proceedings of the Sixteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst. The citation information: Land L, Kromhout C, Byle M, editors. 2020. Proceedings of the Sixteenth Multidisciplinary Conference on ASSOCIATE EDITORS Daniel H. Doctor U.S. Geological Survey Reston, Virginia Peter Hutchinson THG Geophysics Murrysville, Pennsylvania National Park Service Fort Collins, Colorado Simeon Suter Pennsylvania Bureau of Geological Survey Middletown, Pennsylvania Tetra Tech, Inc. Philadelphia, Pennsylvania Cover Photo:

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16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8III CONTENTSOrganizing Committee ........................................................................................ VIII Foreword .................................................................................................................. X Keynote Speaker Much to win, even more to lose: Assessing karst water availability in times of environmental change Andreas Hartmann ................................................................................................... 1 Banquet speaker Puerto Rico karst water resources and climate change: What’s at stake? Abel Vale ................................................................................................................... 2 Resource monitoring and management Combining high resolution spring monitoring, dye tracing, and outcrop and borehole observations to characterize the Galena Karst, southeast Minnesota, USA John D. Barry, Anthony C. Runkel, Julia R. Steenberg, Kevin J. Kuehner, Thomas P. Miller, and E. Calvin Alexander Jr. ........................................................ 3 Karst water resource management and sustainable educational practices in nine Yucatec Maya communities Khristin Landry-Montes ............................................................................................ 18 Temperature: an easy, inexpensive, but useful tool for mapping karst spring habitats Joe Yelderman and Stephanie S. Wong ............................................................. 30 The relationship between cave temperature and local atmospheric mean temperature in China Binggui Cai and Miaofa Li ..................................................................................... 36 Legal implications of large dairy farms in karst regions in the United States Jesse Richardson .................................................................................................... 40 Environment monitoring in Shengqi Cave, southwest China Tan Liang Cheng .................................................................................................... 48

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NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE IV Time series hydrologic monitoring within karst aquifers of Key Cave and Cathedral Caverns, Alabama Gheorghe M. Ponta, Stuart W. McGregor, and Randall Blackwood ............... 53 Geophysics/Remote sensing Capabilities, limitations, and opportunities for studying sinkholes using synthetic aperture radar interferometry (InSAR) Cathleen Jones ....................................................................................................... 68 Spatial and temporal imaging of a cover-collapse sinkhole in west-central Florida through high resolution remote sensing and geophysical techniques Christine Downs, Tonian Robinson, Garrett Speed, Jorge Gonzlez Garca, Noelia Garca Asenjo, Lori Collins, Travis Doering, Shawn Landry, David Eilers, .......................... 75 Geophysics of a doline shaft system Peter Hutchinson, Alexander Balog, and Danika R. Pils ..................................... 85 Using electrical resistivity methods to map cave passages and conduits in the San Solomon Springs karstic aquifer system, West Texas, USA Lewis Land, Michael Jones and George Veni .................................................... 93 Relationships between sinkhole-related features and activity and InSARdetected subsidence points in west central Florida Tonian Robinson, Christine Downs, Talib Oliver-Cabrera, Boya Zhang, Sarah Kruse Kruse, and Shimon Wdowinski ........................................................ 105 Integrating monitoring techniques for buried sinkhole monitoring in an urban environment Gabriella G. Williams, Vanessa J. Banks Dr, Elisabeth Bowman, Anthony H. Cooper, Lee d. Jones, Matthew P. Kirkham, David J R Morgan, and Paul Shepley .......................................................................................................... 110 Crosshole mapping of a subsurface void Peter Hutchinson and Maggie H. Tsai ................................................................ 119 Characterizing near-surface karst system under three stormwater retention basins in Silver Springs, Florida Mohammad Shokri, Yuan Gao, Kelly M. Kibler, Dingbao Wang, and Ni-Bin Chang ......................................................................................................... 127

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16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 V Engineering/Geotechnical Comparison of investigation methods at a karst site Mike Byle ................................................................................................................ 137 central Florida Yong Je Kim, Boo Hyun Nam, and Qipeng Phil Zheng .................................... 145 Sinkhole investigation after Hurricane Irma Ryan Shamet, Moataz Soliman, Yong Je Kim, Timothy Copeland, and Boo Hyun Nam ...................................................................................................... 155 Planning and construction control of expressways crossing karst in Slovenia Martin Knez and Tadej Slabe .............................................................................. 165 Hydrology Response of groundwater levels to hydrologic events in a karst aquifer system of northern Puerto Rico Norma I. Torres, Ingrid Y. Padilla, and Raul E. Macchiavelli ............................. 171 Are groundwater levels rising in Puerto Rico: The north coast limestone versus the rest of the island Ronald Richards .................................................................................................... 181 Characterizing fate and transport properties in karst aquifers under different hydrologic conditions Elienisse Rodriguez-Medina, Ingrid Y. Padilla, Fernando Pantoja, and Kateleen Vargas ................................................................................................... 192 The hydrochemical response of Heilongtan springs to the 2010-2012 droughts of Yunnan Province, Kunming, China Liu Hong M, Huacheng Huang, and Yinghua Zhang F .................................... 200 Assessment of submarine groundwater discharge in the coastal zone of Yucatan State, Mexico Dorina Murgulet, Ismael Mario Tapia, Jorge Alfredo Herrera Silveira, and Arnoldo Valle-Levinson ........................................................................................ 206

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NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE VI Using soil moisture observations to characterize groundwater recharge Romane Berthelin, Mirjam Scheller, Justine Berg, and Andreas Hartmann ............................................................................................... 220 Blanco County, Texas Robert Salinas, Yongli Gao, Lijun Tian, and Yunxia Li ........................................ 230 Environmental forensic investigation of mystery sediment plumes at Barton Springs, Texas Lindsey Sydow, David Johns, Saj Zappitello and Thain Maurer ...................... 236 Eliza Springs, Texas S.J. Zappitello, David Johns, and Lindsey Sydow .............................................. 246 Springshed delineation in a karst aquifer in Hays County, central Texas Brian A. Smith, Brian B. Hunt, Marcus O. Gary, Douglas A. Wierman, and Jeff Watson ............................................................................................................ 255 Geochemical evaluation of hydrogeologic interaction between the Edwards and Trinity Aquifers based on BSEACD multiport well results Lijun Tian, Brian Smith, Brian Hunt, James Doster, and Yongli Gao ................. 269 Geomorphology/Formation of karst and sinkholes Sinkholes and karst in Puerto Rico; picturesque and problematic Pat Kambesis and Ira D. Sasowsky ...................................................................... 278 Karst and sinkholes at Nash Draw, southeastern New Mexico (USA) Andrea K. Goodbar, Dennis W. Powers, James R. Goodbar, and Robert M. Holt ....................................................................................................... 287 Sinkhole formation mechanisms in James Bay lowland, northern Ontario, Canada Wanfang Zhou, Mingtang Lei, James W. LaMoreaux, and Dan Green ............................................................................................................. 299 Sinkholes developed in sandstone Ira Sasowsky ........................................................................................................... 307

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16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 VII GIS/Mapping and management Progress toward a preliminary karst depression density map for the coterminous United States Daniel H. Doctor, Jeanne Jones, Nathan Wood, Jeff Falgout, and Natalya I. Rapstine ............................................................................................... 315 Employing GIS techniques and machine learning for delineating groundwater recharge potential: A case study in the karst region of northern Puerto Rico Ingrid Y. Padilla-Cestero, Luisa Feliciano-Cruz, and Sarah J. Becker .............. 327 Sinkhole susceptibility mapping in Kuala Lumpur and the need for a buried karst database Vanessa J. Banks, Elanni Affandi, Ng Tham Fatt, and Christian Arnhardt ................................................................................................. 336 Development of karst landscape unit maps in southeastern Minnesota, USA Jeff Green and John Barry* ................................................................................. 344 A methodology for evaluating land disturbances at the site-level on the temperate forested karst of British Columbia, Canada Tim Stokes ............................................................................................................... 354 GIS-based spatial analysis of sinkholes in Cebu City, Philippines: insights on sinkhole occurrence and development Regina Martha Lumongsod, Noelynna Tuazon Ramos, and Roseanne Villanueva Ramos .............................................................................. 362

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NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE VIIIORGANIZING COMMITTEE Conference Co-Chairs Jim LaMoreaux, P.E. LaMoreaux & Associates, Inc., Tuscaloosa, AL Aquifer Conservation District, Austin, TX Program Chair Proceedings editors Survey, Tallahassee, FL Michael J. Byle, Tetra Tech Inc., Langhorne, PA Proceedings associate editors Murrysville, PA Collins, CO Simeon Suter, Pennsylvania Bureau of Philadelphia, PA Proceedings Layout Julie Fielding, University of Michigan, Program with Abstracts Aquifer Conservation District, Austin, TX Aquifer Conservation District, Austin, TX Field Trips Co-chairs Aquifer Conservation District, Austin, TX Short Courses Invited Speakers Antonio, San Antonio, TX Beck Scholarship and auction E. Calvin Alexander, Jr., University of Dorothy Vesper, West Virginia University, Morgantown, WV Circulars Educational accreditation Exhibitors and sponsors

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16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 IXWebsite Registration Treasurer Symbolic sale items Hotel/conference facilities Banquet and food Public relations Social media Engineering Services LLC, Longwood, FL Professional organization liaisons Engineering Services LLC, Longwood, FL Jim LaMoreaux, P.E. LaMoreaux & Associates, Inc., Tuscaloosa, AL Michael J. Byle, Tetra Tech Inc., Langhorne, PA Members at Large Jim Berglund, Temple University, Philadelphia, PA Bashir Memon, P.E. LaMoreaux & Associates, Inc., Tuscaloosa, AL Florida, Orlando, FL Brad Stephenson, Tennessee Dept. of Environment and Conservation, Oak Tallahassee, FL

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NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE XFOREWORD conferences and cultural events worldwide. This is unfortunately also true of the sixteenth Sinkhole Conference, organizing committee has chosen to reschedule the conference for the following year. The Sixteenth Multidisciplinary Sinkhole Conferences, and we look forward to supporting and hosting future meetings in other areas of the United As senior editor of the Proceedings Volume, I would like to thank all of those on the Organizing Committee who have Lewis Land, Proceedings Editor

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EDITED BY: Lewis Land National Cave and Karst Research Institute 400-1 Cascades Ave. Carlsbad, NM 88220 USA Phone: 575-932-9912 E-mail: lland@nckri.org Clint Kromhout Florida Geological Survey Florida Dept. of Environmental Protection 3000 Commonwealth Blvd, Suite 1 Tallahassee, FL 32303 USA Phone: 850-617-0332 Michael J. Byle Tetra Tech, Inc. One Oxford Valley, Suite 200 Langhorne, PA 19047 USA Phone: 215-702-4113 Michael.byle@tetratech.com16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 XI

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Many regions across the world are dependent on quarter of the world population completely or partially depends on karst water resources. Karst develops in karst regions, in particular at times of environmental change. environmental change on karst water resources. A walk across scales from the scale of individual caves scale studies, I will contrast the opportunities and climatic regions. The former will demonstrate that, presently and in the future, disproportionally large compared to non-karstic areas. The latter will quantify the contamination risk of karst water resources that can go along with inadequate management and how this risk for future research in karst hydrology.Biography water resources and their water quality. Andreas Hartmann‘s research focuses on the assessment of water resources in karst regions at various scales using KEYNOTE SPEAKERMUCH TO WIN, EVEN MORE TO LOSE: ASSESSING KARST WATER AVAILABILITY IN TIMES OF ENVIRONMENTAL CHANGEDr. Andreas HartmannUniversity of Freiburg, Andreas.hartmann@hydmod.uni-freiburg.de novel simulation approaches and model evaluation hydrological and hydrochemical information into his modeling approaches to achieve a high degree of process he and a team of four researchers are estimating the under changing environmental conditions. Apart from karst monitoring program with study sites in Australia, NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE 1

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BANQUET SPEAKERPUERTO RICO KARST WATER RESOURCES AND CLIMATE CHANGE: WHAT’S AT STAKE?Abel ValeCiudadanos Del Karso, avn@cdk-pr.org higher sea levels due to the melting of glaciers and polar ice shields, changes in rainfall either with extreme since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia. Biography market. An encounter with the karst and caves of Mona recognitions, locally and internationally, for its work to law to protect the karst landscape and that gave special the future, CDK is now in the process of creating the school.NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE 2

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3 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8COMBINING HIGH RESOLUTION SPRING MONITORING, DYE TRACING, WATERSHED ANALYSIS, AND OUTCROP AND BOREHOLE OBSERVATIONS TO CHARACTERIZE THE GALENA KARST, SOUTHEAST MINNESOTA, USAAbstractlineation using dye tracing and hydrograph separation methods has elucidated aquifer characteristics of the It underlies eleven counties in southeastern Minnesota and is used as a source of water for domestic and agricultural use. In two counties, Fillmore and Olmsted, it is a thinly covered well-developed karst that supplies to measure aquifer properties and recharge response following precipitation and snowmelt events. Data and transport of nitrate-nitrogen and other pollutants within springsheds. Dye tracing and hydrograph analtion and time of travel and to assist in determining the size and areal extent of the springsheds that supply perennial discharge to springs. Discharge, water temperature, and nitrate concentration are the emphasis of monitoring at several of the springs where data are paired with additional small watershed-scale hydrotershed in-stream locations. This allows an estimate of annual nitrate loading and assessment of agricultemperature cycles that are out-of-phase with average air temperature to nearly constant temperature inter the springs show characteristic multi-fold increases in discharge with rapid initial dilution of nitrate-nitrogen idly emerging via conduits at the springs. Following in the soil and in aquifer storage in the Bear Spring Springshed frequently increases nitrate-nitrogen conJohn D. BarryMinnesota Department of Natural Resources, Division of Ecological & Water Resources, 500 Lafayette Road, St. Paul, MN 55155, john.barry@state.mn.usTom P. MillerWestwood Professional Services, 12701 Whitewater Drive, Suite 300, Minnetonka, MN 55343, thomas.miller@westwoodps.comJulia R. SteenbergMinnesota Geological Survey, 2609 Territorial Road, St. Paul, MN 55114, jsteenb@umn.eduAnthony C. RunkelMinnesota Geological Survey, 2609 Territorial Road, St. Paul, MN 55114, runke001@umn.eduKevin J. KuehnerMinnesota Department of Agriculture, Pesticide and Fertilizer Management, Preston, MN 55965, kevin.kuehner@state.mn.usE. Calvin Alexander, Jr.University of Minnesota, Department of Earth & Environmental Sciences, John T. Tate Hall, Room 150, 116 Church Street SE, Minneapolis, MN 55455, alexa00l@umn.edu

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4NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE tions have routinely mapped sinkholes, sinking streams, Dye tracing to delineate springsheds and characterize aquifer properties has occurred in Minnesota for decades duit networks associated with well-developed karst are have opened up into large cave passages (Martin Larsen, try has occurred over the last two decades, ranging from ment of Agriculture. Springshed delineation and spring east Minnesota was investigated as a proxy for determinThis paper summarizes the results of our recent research shed analysis of two springsheds, Bear Spring and Pond Spring.Geologic and Hydrogeologic SettingIn Fillmore and Olmsted counties, unconsolidated sedilies Upper Ordovician and Devonian aged sedimentary posed in scattered outcrops across the two counties.Introduction southwest as part of the regional structural trend. As a structural features such as folds and faults are superimresistant to weathering and cover a greater extent of land surface than the softer sandstone and shale formations which crop out within the walls of valleys and along plarocks of southeastern Minnesota are predominately car University of Minnesota and the Minnesota Speleologi Figure 1. Springshed study areas superimposed on regional geologic setting of Paleozoic rocks in southeast Minnesota. Upper Devonian units are depicted with pink hues, Ordovician units are depicted with light green and blue hues, and Cambrian units are depicted with yellow, dark green, and light brown hues (See Figure 2). Geologic map from Runkel et al., 2013. Inset depicts mapped Niagara Cave passage in yellow.

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516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 instrumented near their resurgence points with pressure cord water level and temperature [Bear Spring, Engle Spring, Stagecoach Spring] or using an area-velocity inch smooth-walled pipe [Pond Spring]. The accuracy mented with pressure transducers, level was converted to discharge for each spring using equations developed through regression analysis of stage-discharge monitoring data. A geologic column for southeastern Minnesota (Figalized hydrostratigraphic properties of Ordovician and eralized into either aquifer or aquitard using relative assigned as aquifers easily transmit water through conexception of the St. Peter Sandstone, shallow aquifers ing groundwater from contamination. These rocks are shown on the column where descriptions from the hycommon. tropic groundwater system, limiting the volume and veenough to yield large quantities of water to wells. Many springs in Minnesota also emanate from units designat partings at discrete stratigraphic intervals apparently resistant to the development of through-going vertical fractures. These springs supply cool isothermal water that form the headwaters of many of the trout streams of the region.MethodsThe springs characterized in this investigation each Their stratigraphic positions were determined using a Figure 2. Geologic and generalized hydrogeologic attributes of Ordovician and Devonian rocks in southeast Minnesota. karst systems described in Runkel et al., 2013.

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6NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE station for a variety of rainfall conditions. southwest were used in the watershed analysis. To utilize values. The radar-estimated precipitation yielded very greater at the same location over the period of complete mated precipitation at the Bear Creek monitoring site was Water yield data from similar watersheds in southeast Continuous nitrate-nitrogen was monitored using Hach 2 concentrations were determined using ion chromatogra the Pond Spring investigation and for samples collected typically analyzed within a day of sample collection. samples. Passive charcoal receptors were deployed prior to quencies following dye introduction. Flow of dye through and where dyes were recovered from passive detectors and direct water samples. Fluorometric analysis was performed at the University of Minnesota Earth and Environmental tion analysis. Annual monitored volumes were compared were compared to calculated potential springshed areas. gime were summarized from the recorded timestep and annual volumes from each source were calculated. Figure 3. Contributing surface runoff watershed to the Bear Spring monitoring location.

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716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 individual sinkholes and time of travel were used to esin the upper Prosser Formation and an estimated vertical easily accessed via hyperlinks in the application. The current estimated springshed for Bear Spring, delin2 *Geospatial data for dye traces, including the locations of karst features and springs, are stored in parallel databases that share a relatable unique identifier. This unique identifier is used in the Minnesota Karst Feature Database (KFD), the Minnesota Spring Inventory (MSI), and the Minnesota Groundwater Tracing Database (MGTD). The unique identifier is a ten character alpha-numeric field, but has been abbreviated for this report (e.g., 55D0001312 is abbreviated to 55D1312). comparison when reviewing monitored volumes. To estimate springshed size, annual monitored volumes were compared to local precipitation records and estimated As Vma where: lithology, fracture density, fracture termination horizons, and cave passages and geometry. Borehole geophysical These datasets coupled with detailed geologic mapping of the area are critical to understanding groundwater Bear Spring Dye Tracing ResultsBear Spring is located west-southwest of Eyota, Minnesota at the stratigraphic position of the Prosser and Cummingsestimated minimum peak groundwater time of travel for the holes located closer to Bear Spring. The two closer sink-

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8NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE ary and showed two characteristic dilution events during curred during frozen ground conditions when meltwa to sinkholes connected to the spring. Starting in March tion pattern evident in an increasing stair-step pattern following dilution events is likely related to antecedent moisture conditions from a wet precipitation year and fertilizer application timing within the watershed. The wet climate. To date, the Bear Spring area has received Separation Results is grassed, with only minor impervious area. The over the period of record and an annual precipitation over that Bear Spring Intensive Spring Monitoring ResultsBear Spring shows an annual sinusoidal temperature cywith average air temperature. Within the seasonal cycle, winter precipitation and snowmelt recharge events produce rapid, short term decreases in spring water temperature to temperature. A warm summer precipitation event recorded nitrate concentration started around 20 ppm in June at the to their pre-precipitation levels, until the next precipitacipitation event level. These instantaneous increases in nitrate without a preceding dilution event are likely related to fertilizer application timing within the watershed, antenitrate-nitrogen stored in the soil column. occurred over the next two months, with nitrate slowly

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916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 most of the rapid movement of water through the aquifer occurs through the fracture networks. Examination of Outcrop and Borehole ObservationsFigure 4. July 2019. Precipitation exceeded the 30 year Normal for twenty of the thirty months monitored.

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10NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 5. July 31, 2019. Continuous nitrate data from early February through mid-March is missing due to equipment failure. Table 1. represent partial monitoring years. Total Monitored

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1116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Discussion with the results of springshed delineation determined shed analysis provides us with an improved understandillustrated in continuous high resolution hydrographs, thermographs, and chemographs, we present a holistic Prior to integrating chemograph and thermograph reMinnesota, the use of agricultural fertilizers, the appli cation of road salts for wintertime deicing, and water and chloride in surface water and groundwater systems. and researchers in this region. The Federal drinking waElevated nitrate is commonly found in the shallow karst pled that were completed in shallow Devonian and Or of cave drips and cave stream passages sampled from other than the commercial cave entrance area, is row crop where mixing lowers concentrations through dilution. video and gamma logs within Fillmore and Olmsted counlel partings within the Spillville Formation and along the tact strata. Examination of large outcrops and quarries has shown individual vertical fractures with apertures of a few centimeters are known locally to span entire outcrops that are tens of feet in height. Vertical fractures preferentially terminate near the uppermost part of the Cummingsville Stratigraphic locations of karst features (springs, seeps, sted counties show springs primarily occur in the lower Prosser and Cummingsville formations, corresponding lel fracture networks are preferentially located and verti lower Cummingsville and Decorah formations where partings are less common. Sinking streams and sinkholes Stewartville formations. Prominent vertical fractures are typically through-going across the Stewartville FormaFigure 6. Bear Spring Springshed areas determined through dye tracing and watershed analysis superimposed on bedrock geology. Geologic map from Steenberg, in progress.

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12NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE at Bear Spring revealed isotopically light snowmeltladen water rapidly arriving at the spring, documenting duits. However, partitioning of the snowmelt portion of discharge following the snowmelt recharge event was made up of isotopically heavier water consistent with groundwater released from aquifer storage (Barry et al., pically light snowmelt-laden water coincides with nitrate dilution events. The isotopically heavier water that made to the elevated nitrate-nitrogen released from soil losses and aquifer storage following recharge events. acterized at Bear Spring is similar to continuous data sites, Engle Spring and Stagecoach Spring, in Fillmore At an additional site, Pond Spring, dye tracing and continuous spring monitoring is used to estimate annual nitrate loading in a small watershed and to assess agricul moving more slowly through matrix or the smallest, poor ly connected fracture networks. Land use, and in particular crop rotation, within a springnitrate-nitrogen concentrations collected from a suite trate concentrations exceed soy rotation concentrations corn rotation average nitrate concentration is nearly douSpring Springshed has not occurred to date. However, in with typical agricultural usage trends for the area, as clothianidin is used as a pre-planting seed coating for corn precipitation and snowmelt recharge events. The initial pulse of recharge reaches the spring on time scales of several hours, similar to the results of the dye tracpulses. However, the out-of-phase sinusoidal temper southern Minnesota.

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1316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 concentrations at Pond Spring during non-storm-event, cant rainfall occurred during non-frozen soil conditions, The springshed area of Pond Spring, delineated via dye Estimates of the springshed area determined from spring and precipitation monitoring and watershed yield estiarea delineated via dye tracing. high-resolution monitoring at these springshed locations has shown elements of each porosity type conceptual ized in the triple-porosity model and is useful when transport through the aquifer. water that are large enough to crawl and walk through in Fillmore County, rapid dye trace velocities from dye tracing, rapid changes in spring discharge and tempera ture following recharge events, and the pulses of isotopitematic and nonsystematic fractures that are developed holes. to sinkholes during recharge events, the temperature of a longer residence time. Pond Spring emanates from the Decorah Shale. recorded in the dataset does not have the same resolution Figure 7. and nitrate grab sample concentrations. Precipitation and snow depth from edge of (1 mile) from spring.

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14NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEapparently is poorly connected to higher conductivity fracture networks and open conduits. is warranted.Conclusion terizing the conduit systems underlying the local landscape and providing insight into aquifer recharge and the The springshed size estimates presented here using traditional surface water modeling techniques show that ies. Other ongoing studies also tend to indicate that the proximated using the techniques outlined in this report, in response to changes in groundwater levels. The nitrate results collected using high frequency monilations, and to assist in understanding long-term trends. This work has shown that using a multi-tiered approach for springshed delineation can help improve nitratenitrogen yield loss computations and computer models tools in nitrogen BMP discussions with area farmers and through the fracture network is more rapid than through hydrograph separation analysis. The dimensions and An example toward the lower end of the continuum, televising, and pumping found no fractures, conduits, or open hole portion of matrix rock at this well was low, lel parting in the uppermost part of the open hole that Figure 8. Galena Group, Prosser Formation quarry located roughly 9.7 kilometers (6 miles) west-northwest of Harmony, Minnesota in Crystal Creek Watershed. Figure illustrates triple-porosity aquifer concepts (Worthington, 1999). Number 1 denotes mechanical fractures and dissolution conduits that allow Person in image is roughly 1.8 meters (6 feet) tall.

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1516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Digital Conservancy. . from the University of Minnesota Digital Conservancy. . the University of Minnesota Digital Conservancy. . Barry JD. In progress. Stagecoach Spring Monitoring . chemdataaccess.html . ing nitrate-nitrogen losses from agricultural activities AcknowledgmentsThe work presented in this report could not have occurred without the permission of landowners and spring owners who graciously allowed access to their property. Much appreciation is given to Martin Larsen for arranging access to Bear Spring. Partial funding for this work Legacy Amendment and the Minnesota Environment the initial supporters of the development of a spring monitoring network. Equal appreciation is given to appreciation is also given to Jen Ender and Joe Magee of the MPCA for their skillful installation and upkeep of the continuous nitrate monitoring equipment. Special thanks is given to Holly Johnson for her technical and graphical editing assistance.References caves and sinkholes, Text supplement to the geologic atlas, Fillmore County, Minnesota. atlas of Fillmore County, Minnesota. Minnesota

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16NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Luhmann AJ, Covington MD, Peters AJ, Alexander S, County, Minnesota, revisited [thesis]. Minneapolis groundwater. Minnesota Department of Health, in a southeastern Minnesota karst drainage . . atlas of Olmsted County, Minnesota. Minnesota SC. 2002. Karst hydrogeomorphic units, Plate of karst springs to high rainfall events. Hydrology Kuehner KJ. In progress. Characterizing nitrate fate and transport in Crystal Creek watershed. Minnesota Department of Agriculture. BJ, Kasahara SM, Luhman AJ, Alexander EC Jr. from the University of Minnesota Digital Conservancy. . University of Minnesota Digital Conservancy. . utilizing cover crops to reduce nitrate leaching, increase nitrogen retention and protect water Minnesota Digital Conservancy. .

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1716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of springs in southeast Minnesota. Minnesota southeastern Minnesota and its impact on nitrate . editors. Karst modeling. Karst Waters Institute Metropolitan area, Minnesota. Minnesota of intergranular and secondary porosity in part of Hydrogeology and mapping investigation of the St. Lawrence Formation in the Twin Cities its impact on nitrate concentrations in streams. prediction of aquitard integrity. Hydrogeology insights on aquifer nitrogen storage and delivery. Hydrogeology Journal.

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18 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8KARST WATER RESOURCE MANAGEMENT AND SUSTAINABLE EDUCATIONAL PRACTICES IN NINE YUCATEC MAYA COMMUNITIESAbstractThe karst landscape of Yucatn, Mexico is dotted with thousands of sinkholes that provide access to fresh water. These features, called cenotes in Spanish and ts’ono’ot in Yucatec Maya, range from subterranean caverns with well-developed speleothems to open-air sinkholes. While there are a variety of cenote types, all are connected to the subterranean freshwater aquifer. The inter sources, cenotes were conceived by ancestral Maya peoples as portals to supernatural forces and guardians of rain. Today, cenotes remain culturally important and are located near the center of most Maya communities, although wells have replaced them as sources of potable water. Many are now developed for tourism and serve as important economic resources. Despite their cultural and economic importance, cenotes are increasingly endangered by contamination caused by industrial and contamination, and unsustainable recreational use. One approach to mitigating these threats is through community-driven educational programming aimed at mobilizing youth to study and conserve cenotes in their communities. In 2018, InHerit: Indigenous Heritage Passed to Present, at the University of North Carolina at Chapel Hill, collaborated with students and faculty at the Universidad de Oriente in Valladolid, Yucatn, along with teachers at nine public secondary schools in Maya communities, to develop sustainable experiential education curricula related to sinkhole conservation, water quality monitoring, and cultural heritage. Supported by funding from a National Geographic Society grant, students and teachers at nine middle schools participated in this project. Here we discuss the goals and methods employed, as well as how this project is transforming students’ ideas about water conservation, and the application of Indigenous knowledge for cenote conservation.Cenotes and the Yucatan Peninsula AquiferThe Yucatn Peninsula, traditional homeland of Mayan-speaking peoples, is a karst plain. This 300,000 square kilometer region includes the Mexican states of Campeche, Yucatn, and Quintana Roo, as well as Belize and northern Guatemala. The porous limestone shelf system partly fed by seasonal rains that are quickly absorbed into groundwater. Limestone solution sinkholes, known as ts’ono’oto’ob (singular: ts’ono’ot) in the indigenous Yucatec Mayan language and cenotes in Spanish, form when the surface limestone erodes and dissolves, exposing the freshwater beneath that has, over time, carved out channels within the layers of limestone bedrock and sediment that make up the peninsula. subterranean caverns with well-developed speleothems to open-air sinkholes that appear more like lakes, and even Khristin Nicole Landry MontesDepartment of Art and Art History, Cornell College, 600 First Street SW, Mount Vernon, Iowa, 52134, USA, klandrymontes@cornellcollege.eduPatricia A. McAnanyDepartment of Anthropology, InHerit: Indigenous Heritage Passed to Present, University of North Carolina at Cha pel Hill, 301 Alumni Building CB#3115, Chapel Hill, North Carolina, 27599, USA, mcanany@email.unc.eduDylan J. ClarkInHerit: Indigenous Heritage Passed to Present, Research Laboratories of Archaeology, University of North Carolina at Chapel Hill, 108 Alumni Building CB#3120, Chapel Hill, North Carolina, 27599, USA, dylanc@email.unc.eduIvn Batn AlpucheProfessor and Researcher, Universidad de Oriente, Av. Chanyokdzonot, Valladolid, Yucatn, 97780, Mexico, Canek25@hotmail.com

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19NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEthroughout the Americas. In 2018, we began a collab orative cultural heritage education and conservation project with nine Yucatec Maya communities and middle schools, along with the Universidad de Oriente in Valladolid, Yucatn. Sponsored by an educational grant from the National Geographic Society, our project was designed to promote conservation of cenotes as unique natural and cultural resources by harnessing the energy and excitement of students aged 11 to 14 through experiential education activities designed around cenotes in their communities. Using a biocultural approach (Gavin et al., 2015) and methods from community-based par ticipatory research (CBPR) we sought to inspire youth to action in order to protect their cenotes for the future. This age group is entering a period of emerging social consciousness, and by engaging them at this time, we believe some will develop a strong conservation ethic around cenotes and carry their knowledge and passion forward. Integrating Indigenous knowledge and tradi tional appreciation for cenotes with hands-on education was key to our strategy.Cenotes as Biocultural PatrimonySince at least 1000 BCE, Maya populations have lived in complex urban settlements across the lowlands of the Yucatn Peninsula. Some of the more famous ar chaeological sites in the north include the ancient city of Chichn Itz that reached its height as a major polity between 950 and 1100 CE, ancient T’ho (whose ruins underlie the state capital of Mrida), and the Postclassic Period (1200–late 15th century) city of Mayapn. Smaller cities, such as Tulum on the eastern Caribbean coast, were ports of trade in ancient times and are today major tourist destinations. These ancient cities depended “dry” cenotes, known as rejolladas, in which the surface limestone bedrock collapses but does not reach the aquifer. Soils then accumulate in these spaces over time. There are an estimated 2,000 cenotes in the state of Yucatn alone, and perhaps over 7,000 in the region (Beddows et al., 2007, 33; Lpez-Maldonado and Berkes, 2017, 10). The Ring of Cenotes, a unique geohydrological reserve within Yucatn with a high concentration of cenotes and Chicxulub meteor some 65 million years ago and today is included on the tentative list of UNESCO World Heritage sites (Batllori Sampedro, 2017). Cenotes provide a continual source of freshwater and deeper, more fertile soils in both rainy and dry seasons, and are critical ecosystems that support regional biodiversity and the recharging of the Yucatn Peninsula Aquifer. All cenotes are connected, in the sense that they are or were linked to the aquifer. The Great Maya Aquifer (GAM) research project, also funded by National Geographic, has spent the last decade mapping underwater cave systems in this region and identifying tem now forms the largest submerged cave known on the planet (Coke, 2019). Moreover, underwater surveys within the aquifer continue to document paleontological including extinct megafauna and some of the oldest biological remains of Native Americans in the New World tropics, dating to c.13,000 BP (Anda Alans, 2010; Chatters et al., 2014). Considering the geohydrological and climatic character istics of this environment, it is not surprising that cenotes have been central to Yucatec Maya communities for thousands of years and are still found in or nearby most cities and towns (Figure 1). Also, cenotes always have been important to the cultural and religious life of people in Yucatn. Unfortunately, cenotes and the greater aquipollution, waste disposal contamination, unsustainable tourism development, and climate change. InHerit: Indigenous Heritage Passed to Present is a university program housed in the Research Labs of Ar chaeology at the University of North Carolina-Chapel Hill that is dedicated to building grassroots collabora tions in archaeology and cultural heritage conservation and education programs with descendent communities Figure 1. Cenote Yax Ek’ in Kaua, Yucatan.

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2016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8end of the dry season. One such ritual, referred to as a Ch’a Chak (or “rain calling”) ceremony is particularly important. trees, small plants, and objects associated with cenotes are placed on the altar as the embodiments of powers of the natural world. At each of the four corners of the altar, four young boys croak, playing the role of supernatural “frogs” in order to call the rain forth from cenotes to the sky and back to earth. This ceremony resembles what we understand from the prehispanic codices in which cenotes—rather than altars—served as the center of the ritual. Frogs and deities are pictured surrounding the cenote and connected to particular dates within the ritual calendar. Traditional Maya knowledge and cosmovision, like the 2 million or more people who now live in southeastern but these examples show us that cenote ecosystems continue to be a complex interweaving of natural and cultur al resources—at once essential sources of biodiversity, community history, and cultural identity. These sinkholes are irreplaceable elements of Yucatec Maya biocultural patrimony—a term that refers to their simultaneous biofor Indigenous people who have lived in this landscape for millennia. These biocultural resources, however, are increasingly threatened on a number of fronts that include both environmental degradation and a lack of interest (or perceived inability to implement conservation) at the community level (Figure 2). The latter may be the result of on-going distancing of young Yucatecos from traditional knowledge emphasizing the cultural value of cenotes and the interconnectedness of people and nature (Lpez-Maldonado and Berkes, 2017, 15). As archaeologists and art historians, we have observed that in Mexico, as elsewhere in Latin America, the Indigenous past and perceptions of cultural heritage are entangled with identity politics, nationalism, and economic development in complicated ways that can result in a form of heritage alienation for some communities (McAnany and Parks, 2012). This is an ideological distancing between the archaeological past and Indigenous present, between ancestors and descendants, caused by centuries of reframing heritage discourse in terms of a on cenotes as natural springs to provide potable water in lieu of rivers and instead of the brackish lagoons along the coast. At the same time, these watery caves were also celebrated as sacred spaces in the cultural and cosmological landscape. Strong evidence exists, for example, that the ancient Maya conceptualized cenotes as places that connected the realms of sky, earth, and underworld. At this nexus, supernatural forces and deities could transcend domains and humans could communicate with these forces. Evidence for these associations comes from the many offerings of precious objects as well as human and animal tes. For example, Chichn Itz’s large “Sacred Cenote,” which was described in historic records from the 16th century as a major pilgrimage site, contains thousands of high value objects made of jadeite, gold, ceramics, wood, and textiles, along with human bones, dating back to at least the 7th century CE (Coggins, 1984;1992). The urban plan of this ancient city and its massive civic-cere monial center also was guided by the location of cenotes that formed the spatial axes along which the community was organized (Guillermoprieto, 2013). The earliest Maya codices—books written in the centu ries before the Spanish invasion of Yucatn—also provide us with glimpses into the Indigenous worldview surrounding cenotes. These painted books, only four show cenotes with patron deities associated with water, rain, and fertility— including the rain god Chak. As anthropologists Christine Hernndez and Gabrielle Vail (2013, 14) have demonstrated, cenotes appear frequently in these ancient Maya almanacs because they were associated with agricultural abundance, places of origin and creation, powerful animals like serpents, and rain as a source of sustenance and life (2013, 38). Today, Yucatec Maya people occupy the same landscape and many speak the ancestral language. Some people also practice traditional religious traditions blended with those of Catholicism, especially in relation to agricul ture and rain. Cenotes continue to be an important part of these rituals and these features often loom large in traditional stories associated with community origins. Anthropologist Bruce Love (2012) has extensively documented traditional Maya religious practices aimed at bringing water and ensuring agricultural fertility at the

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21NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEfreshwater and saltwater above and below the halocline layer of the aquifer. Coastal storm surges also increase the likelihood of chemical contaminants entering the groundwater, creating additional stress on this vital resource. Furthermore, the increasingly important role that cenotes are playing in cultural tourism development in the region is a double-edged sword. On the one hand, tourist interest in visiting and swimming in cenotes has provided strong impetus for cleaning them up, passing legislation to protect and manage them through state agencies, and generating employment opportunities for communities. On the other hand, this also results in more cenotes being purchased by private individuals and corporations, reduction in access for local people, and destructive alteration of the physical structure of the cave or cenote to accommodate tourism infrastructure or change visual aesthetics. Cenote ecosystems have also been negatively impacted by the chemicals visitors wear into the water and the materials they leave behind. Mitigating these threats requires both top-down policy changes and grassroots, community-driven initiatives. In 2018 InHerit began a cultural heritage education initia tive called Cultural Heritage, Ecology, and Conservation of Yucatec Cenotes, known by its Spanish acronym PACECCY, in order to increase community interest and engagement with cenotes and water conservation at the local level, building on Indigenous knowledge and cultural appreciation to strengthen educational intervention through participatory science, history, and art. We agree with Lpez-Maldonado and Berkes (2017, 11) that conand intergenerational bridging of youth with elders and teachers will lead to more sustainable positive outcomes. Our objectives were to collaborate with middle school unifying national narrative of racial and ethnic identity countries (Clark and Anderson, 2015, 2). One of the legacies of colonialism and, later, nationalism is that people who speak Mayan languages today do not always identify as descendants of the people who built able cultural tourism attractions nearby (Arden, 2004; McAnany, 2016, 71). Local knowledge about natural and cultural patrimony—and the connections between these and the current inhabitants of the landscape and scieneducational curricula. Likewise, cultural anthropologists conducting ethnographic studies of local beliefs and values associated with cenotes have documented a decline, or at least lack of consensus, in speaking about cenotes as sacred or protected by “guardians,” or spiritually powerful animals, humans, or deities (Lpez-Maldonado and Berkes, 2017, 12).Current Challenges and the PACECCY Projecttn Peninsula aquifer are industrial farming, pesticide pollution, waste contamination, climate change, and unsustainable tourism development. Environmental impact studies have shown that there is a correlation between the location of large, industrial pig farms and the hydrogeological units at risk for aquifer contamination through the water table (Lpez-Maldonado and Berkes, 2017). In more rural areas, cenotes and the aquifer are where pesticides are utilized. Based on our initial obser vations this year, many cenotes located in both small villages and cities have become dumping grounds for trash, including empty pesticide bottles and lithium batteries. In some localities, domestic wastewater is routed direct ly into cenotes that are no longer used (or perceived not to be used) for freshwater (this was also observed during the initial phases of our project). As the resident population continues to rise in the Yucatn Peninsula, both permanently and seasonally with weather events that impact the region due to global cli mate change—whether droughts or hurricanes—also Figure 2. Trash in Cenote Yax Ek’, Kaua, Yucatan.

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2216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8rians, archivists, art historians, middle school educators and directors, and university and middle school students. We chose the nine schools selected for the PACECCY project based on the presence of a cenote in each community, proximity to Valladolid where UNO is located, and interest in participating on the part of the commu nity (Figure 3). Early in the project, we worked with 1 teachers and the director (principal) from each school to gauge students’ existing knowledge and interest in cenotes. We then collaborated with community teachers and directors to create and implement curriculum resources, but also by the interests of the students. After one round of in-school implementation, we designed workbooks that incorporate many of the activities we created and the teachers implemented in 2018, as well as background information on cenotes. These processes are discussed more fully below. Following Atalay’s (2012, 3) central tenant to “value information and ways of knowing contributed from diverse knowledge systems,” our methods focused on creating sustainable and equal partnerships between communities and outside scholars that were steered by the communities and what mattered to them. With these goals in mind, our team organized the overall project into these six stages: 1. A planning stage through March of 2018 during which time which we created an advisory board of teachers and directors from participating communities. 2. A pre-project assessment stage using surveys and photovoice in a sample of schools to understand students’ perspectives on community cenotes. teachers in nine Yucatec Maya communities to create innovative, experiential education curriculum materials designed to raise awareness of the ecological and cultural importance and vulnerability of cenotes, including their role in Maya history and literature. This methodology involves a form of braiding knowledge, an approach advocated by archaeologist Sonya and methods with local knowledge and experience, in this case to work synergistically toward shared goals of resource protection and management. Drawing upon the multiple complementary elements of Indigenous and Western knowledge systems, this approach gives Indigenous communities agency to interpret, monitor, and conserve sinkhole ecosystems. An equally important outcome we sought through this program with teach ers and students was “repatrimonialization,” in which people reconnect with their local cenotes as part of their biocultural heritage, that is integral to their communities and their stories—past, present, and future.Project Methods and ResultsIn both collaborative archaeology and this multi-compo nent educational and environmental conservation project, we incorporate methods from CBPR that emphasize breaking down colonial power structures when it comes to exploring and assigning meaning to the past. This process encourages dialogue and engagement between different participants at discrete stages of the investigation, creating points of intersection for bi-directional knowledge exchange (McAnany, 2016, 132). A communitybased cultural heritage project brings descendent communities’ voices into the process at the level of research design—from decisions about what research questions and interpretative strategies to pursue to the method ological approaches and kinds of evidence used to address these questions. This framework has guided our approach with the PACECCY project. PACECCY is especially focused on creating experiential learning opportunities through the study of oral history and folklore, science and safety, and the archaeology and among Inherit, Universidad de Oriente (UNO) in Valladolid, Yucatn, and the communities and secondary er, the team is composed of archaeologists, oral histoFigure 3. The edge of a centrally located cenote in Cuncunul, Yucatan.

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23NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCENine undergraduate public administration student ambassadors were selected as student ambassadors from UNO for this project. Several of these students speak Mayan in addition to Spanish and English and all grew up in eastern Yucatan. They served as points of contact and facilitated ongoing communication with communities’ teachers and the nine community schools. Their roles were to facilitate conversation between teachers and the rest of the PACECCY team, to help support the implementation of activities in the schools, and to attend and aid in the teachers’ workshops (Figure 4). These students also helped with translation from Yucatec Mayan to Spanish, as well as from Spanish to English. As young adults from Yucatn, several of whom are Maya themselves, the most important and overarching role of the UNO ambassadors was to support and carry forward the energy of the project into the future. collaborated to design survey questions for students in order to gauge their baseline knowledge of cenotes, the aquifer system, and what these biocultural resources meant to them and their communities. This was an impor tant component of the pre-project assessment that guided subsequent components. For some survey questions, students were also asked to draw what they knew or thought about cenotes. These surveys were given to students with instructions that we wanted to see what they knew about the cenotes in their own communities and what they wanted to learn more about. In addition to the survey, we employed an assessment technique from CBPR called photovoice in four of the nine communities. 3. A workshop stage in which three professional development events—designed and carried out for teachers and university students—took place and were based on topics related to cenotes as biocultural resources. 4. A stage during which we worked with teachers and researchers to design experiential education activities related to cenotes and the topics discussed in the educator workshops. This was followed by the implementation of those activities in participating schools. 5. A post-implementation stage during which time we designed assessment surveys and concluded activities in the schools. 6. A writing stage to create and publish workbooks containing background, teaching modules, and experiential education activities related to cenotes. Each of these stages allowed for the interchange of ideas and practices among project participants. They also offered opportunities for the project team to obtain ideas from middle school students both before and after experiential learning activities were implemented. Such information was invaluable throughout the course of our time in the schools, as well as during the creation of the workbooks. In the following sections, we discuss a selection of these stages more fully. Planning, Photovoice, and Pre-Project Assess ment Planning for PACECCY began in January 2018 and was Carolina, as well as by faculty and students from the Universidad de Oriente in Valladolid, Yucatn. Dr. Patricia at the University of North Carolina, served as Principal Investigator for the project with Dr. Dylan Clark, InHerit Program Director, serving as one of the project’s co-coordinators. The project’s Mexico-based coordinator was tin Landry Montes, assistant professor of art history at Cornell College, served as Project Facilitator and was a Yucatnand U.S.-based teams. The Project Facilitator also developed connections with school teachers and directors in Yucatn and coordinated the implementation of experiential learning in the schools. Figure 4. UNO Ambassador Yaremi Tuz May leading a water quality testing activity with students in Cuncunul, Yucatan.

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2416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8about. The image-based activities, including the survey drawings and photovoice images, showed us what students were focusing on in relationship to their commu nity cenotes and what they viewed as important. Many of the photos that were taken, for example, were of trash in and around the cenotes. From these photos and the discussions that followed, we found that contamination and pollution were of central concern to students. From the many images of stalactites and stalagmites, as well as plants and animals, it also was clear that students were with life. Surveys echoed these interests, and students often wrote about wanting to know more about cenote formation, the kinds of plants and animals that live inside cenotes, how cenotes related to stories they had heard and how cenothis activity re-ignited students’ interest in traditional knowledge related to the oral history of cenotes before any classroom curriculum materials were even fully Photovoice involves distributing cameras to members of the community—in our case middle school students— and asking them to take pictures of their cenote(s). Students then reconvened and discussed their photographs as a group. A major strength of this technique is that it gives agency to community members to explore local ized strengths and concerns, while also promoting dialogue between the various project participants. Beyond our own project, photovoice has been used successfully in other applied anthropology projects (Dedrick, 2018), as well as in public health research (Wang and Burris, 1997; Thelen and Morgan, 2015). In our photovoice activities, students, together with projthe community to take pictures (Figure 5). Students were given digital cameras and instructed to take photos of anything they wanted, as long as photos could be linked we downloaded the pictures into computers and printed the photos for the discussion session that followed. were provided with their printed photographs and asked to select two photos to write about and discuss. They had roughly 8 minutes to write freely and then they presented their photographs with their written thoughts to the rest of the group. They were asked what had inspired them to photo-document a particular aspect of a cenote in the manner they did. Researchers then engaged with students by asking openended questions to facilitate discussion of photographs. We found that certain themes naturally came to the forefront during these discussions and so—together with the next photo session that emphasized these themes of interest. We then went back to the cenote for Photo Session #2. For this session, students were asked to focus their in the discussion of photographs in the previous session. After this photo session was completed, we followed a similar process to Photo Session #1 and met students for the photos that were produced from the second photo session. Both surveys and photovoice activities allowed our team and teachers to understand what students already knew about cenotes and also what they wanted to know more Figure 5. Students from Yalcoba, Yucatan taking pictures of their cenote for photovoice.

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25NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEto cenotes). The workshop was led by experts in the Maya literature. As a way to encourage Indigenous stocards were bilingual in both Yucatec Mayan and Spanish and included vocabulary for various things associated with cenotes (animals, plants, rock formations, etc.), as well as helpful prompts for asking questions in an oral history interview. At the end of the workshop, teachers were given two backpacks to take back to their schools for use during the subsequent implementation phase, as well as in the future. For Workshop 2: Science and Safety, teacher training cenotes, water conservation and aquifer hydrology, and the safety and legal protection for cenotes at the state sessions. Also, teachers were introduced to educational water-quality test kits provided by the NGO EarthEcho International. Together with two OpenROV submersible drones, the test kits were used by classes to conduct citi zenscience projects involving water quality monitoring and underwater exploration of their community cenotes. cused on cenotes as important and irreplaceable cultural resources as well as part of an inherited Maya past. Invited speakers from both Mexico and the U.S. discussed as well as their presence and meaning in the ancestral Maya codices (Figure 6). The workshop also discussed cenotes as important elements in Maya cosmovision and as parts of sacred landscapes both in the past and today. In the spirit of Paolo Freire’s (1970) critical pedagogy, secondary school teachers and directors discussed both theoretical and historical perspectives on pedagogical approaches to biocultural patrimony in Yucatn’s secondary schools today. Invited guest speakers, each an expert on a given topical area, were invited to attend and lead and/or facilitate the workshops. Each of the workshops were attended by dents and encouraged dialogue about mechanisms for integrating these topics and curriculum resources into classroom activities. These workshops helped the group decide which experiential activities would be most usedesigned, bringing local cultural knowledge and ethnographic approaches directly into the planning phase of the project. generations within the same community, as students were more motivated to speak with elders and to compare diverse explanations for the hydrology and plant life of cenotes. Surveys and photovoice also served to reshape the direction of educator workshops and the curriculum materials we designed with an eye to the interests and viewpoints of young community members. Some of the topics that resonated most with students became central themes around which we built the educator workshops, especially oral history and traditions, chemistry, plant and animal biology, and ancient Maya painted manuscripts, or codices. Advisory Board Meetings and Teachers’ Work shops During and after photovoice activities, the community directors and 1-2 teachers from each school, met to discuss project assessment and plans for the next stages. Together, with the results from student surveys and photovoice in mind, the advisory board helped design three educational and interactive workshops for teach ers and student ambassadors that would take place at UNO. Each of these capacity-building workshops were and themes. The overall goal of the workshops was to bring teachers and researchers together to share knowledge and generate curriculum activities for students that were focused on cenote conservation and aligned with student interests and curiosities. The three workshop themes included (1) oral history and folklore, (2) science and safety, and (3) archaeology and heritage of cenotes. The workshops created transcultural spaces with oppor tunities for knowledge sharing in multiple directions between university students and researchers and secondary school teachers. The workshops are more fully described below. For Workshop 1: Oral History and Folklore, we incorporated training and use of oral history backpacks that contained voice recorders, notebooks and pencils, as well as students in conducting oral histories with members of their communities (especially as those histories related

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2616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8oral and literary traditions, and how to conduct oral history interviews. Then, they conducted their own inter views with family members and elders in their commu nities, using the oral history backpacks. Many students chose to interview family members with digital voice recorders about their experiences with local cenotes and the stories surrounding them. Students reported to their class about what they discovered through the interview process. Other classes preferred conducting interviews as a group. In one case, students interviewed a local j’men—traditional Maya healer—about his knowledge of and experiences with a local cenote. The entire class attended this event. One student asked questions (in the cards while another took notes on the conversation. Other students translated the Maya conversation into Spanish as part of their class project. Science and Safety Concentration : Students from each of the nine schools had class periods in which they were trained in the importance of testing for water quality in the cenotes. They used EarthEcho and LaMotte educational water quality testing kits to study the water quality cally, students tested for pH, dissolved oxygen, tempera ture, and turbidity (Figure 7). As part of this exercise, students participated in EarthEcho’s online Water Challenge by uploading data from their water quality tests to the EarthEcho International website and comparing them with information from students participating in the same citizen-science activity across the globe. In some cases, and if safety permitted, students were also able to submerge and drive underwater drones that were obtained for our project from OpenROV. The drones took video, as well as depth and temperature readings. The students could see underwater animals and geomorphic ful to implement with middle school students in the subsequent implementation phase. Implementation The implementation phase of the project began in late gether to schedule meetings with classes in order to undertake experiential learning activities. The learning activities implemented during this phase were largely based on the training teachers had received in the three educator workshops. Teachers worked with the Project and the nine UNO student ambassadors to schedule times and days for students to engage in activities. By encouraging UNO students to lead activities, we created an opportunity for local young adults to take the lead in sharing knowledge and inspiring a new generation of Maya students. In our work together with middle school teachers, we facilitated the following programming involving experiential learning that grew from the teach ers’ workshops: Oral History and Folklore Concentration: Students from each of the nine schools learned about oral history, Maya Figure 6. Teachers working with facsimiles of the ancient Maya codices in Workshop 3. Figure 7. Students perform water quality tests from their community cenote in Cuncunul, Yucatan.

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27NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEtime to plan the workbooks that would be created in the coming months. The Workbooks The workbooks created from this project are organized around the experiential learning activities that were undertaken throughout the year, as well as new activities that were inspired by those implemented in the pilot year of this initiative. The workbook units and their contents follow the main themes and concentration areas of the project, including: Geology and Hydrology, Oral Histories, Plants and Animals, the Maya Codices, Traditions and Sacred Landscapes, Archaeology and Biocultural Patrimony, and Caring for our Cenotes. Each unit includes background information on the topic, along with relevant lesson plans for the experiential learning activities that students took part in during implementation. Additional resources and ways to order more supplies (e.g., water quality test kits) are given at the end of each chapter.ConclusionsWe found that the steps and processes laid out above crebers of our team—from students to teachers to university ences together through the common goal of energizing secondary school students to be thoughtful and proactive stewards for their communities’ cenotes. Initial planning students at UNO provided opportunities for community collaboration early on in the process. Teacher workshops and advisory board meetings involving middle school vironments for capacity building and new opportunities for everyone involved to be active leaders and contribu tors in shaping an educational approach to sustainable conservation. These workshops and meetings, as well as active engagement in the classroom during the implementation phase, formation and ways of knowing. Much of the education al content produced was community driven and shaped by the students themselves. For example, early surveys and the use of photovoice allowed us to obtain, in both written and visual form, the perspectives of Maya youth on cenotes. These perspectives guided much of the organization and selection of activities that followed. Simifeatures inside the cenotes, and participated in recording and archiving the video along with measures of depth and temperature. In this manner, students not only obtained and compared water quality data, they also got a glimpse of what cenotes look like from within, including the life they contain, and the unfortunate truth that many also contain trash and other contaminants. Archaeology and Folklore Concentration : Students from each of the nine schools also had classes that focused on the history of cenotes in relation to the cultural traditions of ancestral Maya peoples. We concentrated especially on how cenote imagery and cultural value are manifested in ancient Maya books and as part of a cosmovision that includes sacred landscapes. For these sessions, students worked with facsimiles of two of the four existing prehispanic Maya codices—the Dresden Codex notes and deities related to cenotes in these manuscripts, and also learned to read simple hieroglyphic structures and dates. Additionally, students learned about the history of the codices and why cenotes often are depicted in them. Such curriculum emphasized what the codices can tell us about how important cenotes were in ancient Maya religion and the sacred landscapes they occupy today. As part of their experiential learning activities, students made their own cenote-focused codices in the ancient Maya style complete with patron deities, dates, and names written in Maya hieroglyphs (Figure 8).Post-Implementation Assessment, Workbooks, and ConclusionsPost-Implementation Assessment The implementation stage was completed in mid-December of 2018, at which point our team initiated a post-project assessment stage. At this point we provided surveys to students to assess what they had learned. Some questions were open-ended and focused on what they might do to improve education in their communi ties about cenote history and conservation. Teachers also were provided with a questionnaire that requested feedback and asked them to identify and elaborate on the middle school classes as well as the strengths and weakon the project once more and think about how programming could be improved to be even more useful and integrated into curricula at a greater number of schools in the region. The project team and teachers also used this

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2816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8with local biocultural resources and cenotes as important elements of Maya sacred landscapes. Ultimately, we believe the project promotes intercon nectivity. It recognizes multivocality, while simultane ously the intentionality of collaborators in selecting the strands—data, methods, and epistemologies—that they work to weave together. Through InHerit we strive to promote conversations that support a paradigm shift in academia toward community-based participatory research as a way of transforming and decolonizing the social sciences in order to make the results more applica ble to addressing the needs of the communities—in this case, conservation of the aquifer and cenotes. We antici pate that the Cultural Heritage, Ecology, and Conservation of Yucatec Cenotes project will serve as a model for future cultural heritage education projects aimed at supporting and mobilizing indigenous heritage for positive and sustainable change.AcknowledgementsWe would like to thank the National Geographic Society for the substantial funding they provided in support of this project, as well as the many private donors and supporters who contributed to the success of PACECCY. These include the Southern Historical Collection at the Wilson Library at UNC-Chapel Hill, EarthEcho Inter national, OpenROV, the Ministry of Urban Development and Environment of Yucatn, Mexico (SEDUMA), the Secretary of Public Education of Yucatn, Mexico (SEGEY), faculty and students at the Universidad de Oriente, our invited team of content experts from both Mexico and the U.S., and, of course, the directors, teach ers, and students and their families from the secondary cob, Tikuch, Calotmul, Tahcabo, Cuncunul, Xocen, and Referencesde Anda Alans G. 2010. En los profundos dominios de los dioses: arqueologa subacutica en Yucatn. In En los antiguos reinos del juagar, edited by Lilia Fernndez Souza, 133. Mrida: Secretaria de Educacin del Gobierno de Yucatn. Ardren T. 2004. Where are the Maya in Ancient Maya Archaeological Tourism? Advertising and the Appropriation of Culture. In Marketing Heritage: Archaeology and the Consumption of the Past, larly, listening to what the teachers wanted and needed for their classrooms helped to make the development and sustainability of a new cenotes-centered, biocultural patrimony curriculum a success. During the workshops and especially in their classrooms, teachers were active An unexpected outcome of the project was that some students were highly motivated to design and implement their own cenote conservation and clean-up projects, along with Maya codices workshops, as extracurricular small indication that students and teachers are embracing patrimonialization and driving forward on re-connecting Figure 8. Students from Ticuch, Yucatan made their own codices to highlight the story of their community’s cenote.

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29NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEUniversity; distributed by Harvard University Press. ISBN: 0-87365-694-6. OCLC: 26913402. Dedrick M. 2018. Photovoice as a method for the development of collaborative archaeological practice. Journal of Community Archaeology and Heritage 5 (2): 85. Freire P. 1970. Pedagogy of the oppressed, Trans. by M.B. Ramos. New York: Continuum. Gavin MC, McCarter J, Mead A, Berkes F, Stepp JR, Evolution 30: 140. https://doi.org/10.1016/j. tree.2014.12.005. Guillermoprieto A. 2013. Secrets of the Maya Otherworld. National Geographic 224 (2): 99. Hernandez C, Vail G. 2013. The Role of Caves and Cenotes in Late Postclassic Maya Ritual and Worldview. Acta Americana 18: 13. Lpez-Maldonado Y, Berkes F. 2017. Restoring the environment, revitalizing the culture: cenote conservation in Yucatn, Mexico. Ecology and Society 22 (4): 7. https://doi.org/10.5751/ES09648-220407. Love B. 2012. Maya Shamanism Today: Connecting with the Cosmos in Rural Yucatan. Precolumbia Mesoweb Press. McAnany PA. 2016. Maya Cultural Heritage: How Archeologists and Indigenous Communities Engage the Past. Lanham, MD: Rowman and McAnany PA, Parks S. 2012. Casualties of Heritage Distancing: Children, Ch’orti’ Indigeneity, and the Copan Archaeoscape. Current Anthropology 53 (1): 80. Africa: One Conversation at a Time. Bloomington and Indianapolis: Indiana University Press. Wang C, Burris MA. 1997. Photovoice: Concept, Methodology, and Use for Participatory Needs 369. edited by Yorke Rowan and Uzi Baram, 103. Walnut Creek, CA: Altamira Press. Future Challenges in Transforming Scholarship. Submission date for external review: December 1, 2015. Atalay S. 2012. Community-Based Archaeology: Research with, by and for Indigenous and Local Communities. Berkeley, CA: University of California Press. Batllori Sampedro E. 2017. Reserva geohidrolgica del anillo de los cenotes. In Cenotes y Grutas de Yucatn, edited by Wendy Pia Garca y Flix Ucn Salazar, 229. Mrida: Compaa Editorial de la Pennsula, SEDUMA. Beddows P, Blanchon P, Escobar E, Torres-Talamante O. 2007. Los cenotes de la pennsula de Yucatn. Arqeuologa Mexicana 14 (83) :32. Polyak V, Nava Blank A, Beddows PA, Reinhardt E, Arroyo-Cabrales J, Bolnick DA, Malhi RS, Culleton BJ, Luna Erreguerena P, Rissolo D, Pleistocene Human Skeleton and mtDNA Link Paleoamericans and Modern Native Americans. Science 344 (6185): 750. Clark DJ, Anderson DS. 2015. Past is Present: The Production and Consumption of Archaeological Legacies in Mexico. In Constructing Legacies of Mesoamerica: Archaeological Legacies and the Politics of Heritage in and Beyond Contemporary Mexico, Archeological Papers of the American Anthropological Association 25 (1): 1. Coke JG. 2019. Underwater caves of the Yucatan peninsula. In Encyclopedia of Caves, 1089. Cambridge: Academic Press. from the Sacred Well at Chichen Itza. Austin, TX: University of Texas Press. ISBN: 0-292-71098-4. Coggins CC. 1992. Artifacts from the Cenote of Basketry, Stone, Bone, Shell, Ceramics, Wood, Copal, Rubber, Other Organic Materials, and Mammalian Remains. Cambridge, MA: Peabody Museum of Archaeology and Ethnology, Harvard

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30 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8lated to the widening of fractures resulting from dissolusame dissolution process also produces karst features such as caves and sinkholes. The large openings char acteristic of karst also allows a variety of aquatic organisms including isopods, gastropods, and salamanders to live in portions of the aquifer. Opportunistic organisms can enter the aquifer through the large openings and take advantage of the nearly constant groundwater tempera ture insulated from climatic extremes. Such is the case of the federally threatened Salado salamander Eurycea chisolmensis. The Salado salamander occurs in several task in preserving the threatened Salado Salamander is increase. The Clearwater Underground Water Conservation District currently manages the Edwards aquifer in Bell County and has approved a Desired Future Condiarea. The second concern for the salamander is maintain related with the standard deviation of water temperature Eurycea tonkawae of the Edwards Balcones Fault Zone aquifer. This study focuses on water temperature associated with Big Boiltat provides an example of how temperature measure SettingSalado Creek is a shallow perennial stream approxiTEMPERATURE: AN EASY, INEXPENSIVE, BUT USEFUL TOOL FOR MAPPING KARST SPRING HABITATSJoe C. Yelderman Jr.Baylor University, One Bear Place 97354, Waco, Texas 76798, USA, joe_yelderman@baylor.eduStephanie S. WongBaylor University, One Bear Place 97354, Waco, Texas 76798, USA, stephanie_wong@baylor.eduAbstract diversity of specially-adapted, unusual, or rare aquatic pared to discharge from granular sand aquifers. Mapping areas associated with spring-dependent organisms. The Edwards Balcones Fault Zone aquifer in central Texas is home to several spring-dependent organisms including an endemic salamander, Eurycea chisolmensis, that is feder with a Solinst TLC meter and with a hand-held infrared camera. The Solinst TLC meter measured temperature visual images while documenting dynamics associated with spring discharge temperatures. The temperature data chemistry changes in local systems. Aquatic plant assemperature gradients. Overall, temperatures in Salado Creek dependent organisms, low cost, and ease of collection.Introduction high capacity to transmit water and its rapid recharge. The latter characteristic is due to thin soils over fractured

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31NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE MethodsCross Sections endpoint for aquifer groundwater temperature and then across the widths of Salado Creek at regular intervals low nature of the stream results in seasonal temperature discharge points and extends until surface exposure mixes with the groundwater and changes the tempera ture through dilution. Figure 1. Map of the study setting showing key locations. The study is focused on Big Boiling and Side springs in the downtown Salado spring complex. The spring complex is located in the Northern Segment of the Edwards Balcones Fault Zone aquifer.

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3216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8The three cross-sections were located in Salado Creek Imagery era was hand-held and the settings that did not vary inthe lock mode for the temperature scale was used on ocit provided the greatest contrast. The Hot Spot or Cold Spot settings were used for direct temperature readings from the hand-held camera. The camera was set to take a digital photo and a thermal image simultaneously. The Thermal MSX image mode.ResultsCross Sections nature of the Big Boiling Spring pool and channel due to the discharge volume and its regional nature. in karst springs in southeastern Minnesota may vary conductance values are similar to those measured at the Stagecoach Inn Cave, located to the south and upSpring and the Stagecoach Inn Cave are part of the same groundwater system. across the creek using stadia rod or reel tape laid across the channel width. Depth was measured using a metal and the discharge for each cross section was determined using the following equations: where and is equal to the sum of each of the partial discharges (qxx is the measured x is the measured depth in feet, and wx is the width of inter the natural water environment without the use of a stilling Figure 2. Diagram of Salado Creek showing key features. Cross-section locations are indicated by the red lines and labelled 1, 2, and 3.The green areas represent aquatic vegetation; primarily watercress.

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33NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCECross-section two is located in the natural channel of Salado Creek. The cross-section is consistently shallow, consistent across the section. The variation in tempera from groundwater, a low-water dam immediately upCross-section three is located in the natural channel of this location are intermediate values of those measured on the north side of the channel at the end of cross-secImagery April. A digital photograph of Side Spring discharge to discern the groundwater impact on the stream (Figratio when compared to Salado Creek. Discharge from The thermal infrared camera documented the impact of Side Spring and when compared to the digital photo the impact appears greater than the area of the small delta temperature. The temperature measured in the spring Figure 3. conductance data for cross sections 1 at two time periods. Note the consistency of the conductance, and the effect of the spring water on the downstream temperatures and conductivity in the creek. The cross section is oriented looking upstream and left to right is south to north.

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3416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8August. ent scale, and using the Cold Spot feature show a Spring discharge shows a slightly larger delta and a cern the groundwater impact on the stream (Figure red camera documented the impact of Side Spring the cooler water from the spring is skewed slightly of the camera. Discussion actions relies on contrasts. Therefore, seasons and diel temperature data and were helpful when temperature were generally greater in the groundwater than the sur face water and therefore correlated with the groundwater of Jollyville Plateau salamanders (Eurycea tonkawae values in their study were similar to the higher specific conductance values in this study. The Bowles et al. Figure 4. Images of Side Spring April 2, 2016, 8:33 a.m. The top image is a digital photo of Side Spring discharge into Salado Creek and the bottom image is the thermal image of Side Spring showing warmer groundwater (red colors) entering Salado Creek and continuing downstream along the bank. Figure 5. Images of Side Spring August 10, 2016, 4:57 p.m. The top image is a digital photo of Side Spring discharge into Salado Creek and the bottom image is the thermal image of Side Spring showing cooler groundwater (blue colors) entering Salado Creek and continuing downstream along the bank.

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35NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEdeveloped springsheds while this study compared spring to the receiving stream values. terial is important when using the Infrared imagery and can determine optimum time to collect thermal images or take stream measurements. Although the camera data recreational use allows human induced changes and the ing from the warm groundwater more quickly. The shallow nature of the spring runs and the creek camera would only sense the surface temperatures and necessary.Conclusions dependent aquatic organisms. Measurements from tem for aquatic organisms that prefer constant temperatures. The use of the thermal imagery is also helpful in under namics and appear useful in communicating information for management decisions or strategies.References of the Jollyville Plateau Salamander (Eurycea Devitt TJ, Wright AM, Cannatella DC, Hillis DM. groundwater salamanders: Implications for aquifer management and Biodiversity conservation. Luhmann AJ, Covington MD, Peters AJ, Alexander SC, and Monitoring Lakes and Streams. Washington State Department of Ecology, Olympia, WA. implementation and application. Clearwater Underground Water Conservation District. Segment of the Edwards Aquifer, Bell County,

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36 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8perature reconstruction assumes that cave temperature annual temperature of outside atmosphere. However, our monitoring data of a cave located in northeastern China higher than mean annual temperature of outside atmo of this research is to investigate the extent and magni Data Source and Analysis Each dataset represents one cave with parameters including cave air temperature, mean annual atmospheric temperature, cave location, length, as well as elevation, original references of these data are not included in this paper. The criteria to choose cases of cave air temperature are -THE RELATIONSHIP BETWEEN CAVE TEMPERATURE AND LOCAL ATMOSPHERIC MEAN TEMPERATURE IN MONSOONAL CHINABinggui CaiState Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University & Institute of Geography, Fujian Normal University, Cangshan, Fuzhou 350007, China, bingguicai@qq.comYanhong Chen and Miaofa Li School of Geographical Sciences, Fujian Normal University, Cangshan, Fuzhou 350007, ChinaYongli GaoCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, yongli.gao@utsa.eduAbstractIt is widely claimed that temperature inside a deep karst cal mean atmospheric temperature. To test this hypothesis, we collected temperature data for caves through tween cave temperature and local annual mean tempera China than those from southern China. Many of them temperature may excurse from local mean atmospheric struction using cave deposits such as speleothems.Introduction and paleo-environment reconstruction due to their prereconstruction to determine the amplitude of tempera isotope signals in inclusion water of speleothems (Ue-

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37NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEthe mean annual atmospheric temperature, we use the long term mean temperature calculated with instrumen tal data from the closest meteorological station. The relationship of cave air temperature and outside atmospheric mean temperature is shown in Figure 2. In general, cave air temperature is positively correlated to atmospheric mean temperature, except for three special ther analysis and discussion. For the other cave from Considering the errors arising from measurements of cave air and outside atmosphere. With this criterion, all caves, except for two special caves with hot spring water Figure 1. Schematic map showing locations of caves involved in this study. Figure 2. Scatter plot of cave air Temperature against local atmospheric mean temperature Figure 3. Scatter plot of temperature difference two special caves with hot springs).

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3816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 one cave to the other. Because of the limitation of original and local mean annual atmospheric temperature. Indeed, it is quite interesting that cave air temperature in caves mospheric temperature. This pattern may indicate a unithat the climate in monsoonal northern China has more seasonal variation with cold-dry winter and wet-warm correlate to seasonal climate pattern related to EASM. sis. Further study should increase sample size and improve Conclusions local long term mean atmospheric temperature. Most of perature and local atmospheric mean temperature (FigThe only exception is the cave from Shanxi Province site which is far away from meteorological station. The tween northern and southern China. mate, e.g. cave location (elevation, latitude and longiFigure 5. Schematic map showing locations of caves whose cave temperatures are similar to (blue circle), greater than (red triangle), and lower than (yellow star) local mean annual atmospheric temperatures. Figure 4. Pie chart of three groups of caves. number of caves for cave air temperatures with similar, positive offset and negative offset to local mean atmospheric temperature.

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39NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEof cave air temperature for caves from northern China more distinct seasonal climate than those of monsoonal ing speleothems for paleoclimate reconstruction, especially for paleo-temperature estimation. More data and intensive monitoring, as well as case studies are necessary for further investigations.AcknowledgementsWe are grateful to anonymous reviewers and editors for their constructive suggestions. This research is supportReferences and diurnal variation in CO2 concentration, temperature and relative humidity of the cave air A case study from Water Cave, Benxi, Liaoning, variation of the calcite deposition rate of drip implications for palaeoclimatic reconstructions, O in the meteoric precipitation, drip water and their calcite deposition in Miaodong Cave, Liaoning Province and its implications for palaeoclimate oxygen and hydrogen isotope determination in nanoliter quantities of speleothem inclusion water Figure 6. against elevation above sea level at cave entrance (excluding two special caves with hot springs inside).

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40 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8IntroductionControversy surrounding the location of concentrated animal operations, particularly large dairies, in karst ar eas in the Midwestern United States has increased sigamounts of manure. While manure management for these facilities presents challenges everywhere, the challenges prove even more important in karst areas. Karst This controversy has resulted in lawsuits among state agencies, citizens opposed to the operations and the owners and operators of concentrated animal facilities. Some of the disputes revolve around whether more strinwhether the area in question is a karst area. The disputes raise multiple issues, including the question of how states are regulating location of concentrated animal facilities states treat location of concentrated animal facilities in of concentrated animal facilities and their consequent manure management structures in Illinois, Iowa, Minnesota, and Ohio. The regulations in each state that apply particularly to karst areas are summarized. The author then compares the provisions in the four states, looking Finally, the article concludes with recommendations for regulation of location of concentrated animal facili ties in karst areas.State RegulationsMany states regulate concentrated animal operations, requirements, locational restrictions, and design and construction standards. Although disputes focused on lo-REGULATION OF LARGE DAIRY FARMS IN KARST REGIONS OF THE UNITED STATESJesse J. Richardson, Jr.Morgantown, WV 26506, United States, jesse.richardson@mail.wvu.eduAbstract large dairy farms have located, or proposed to locate, in karst terrain in the Midwestern United States. The large Controversies have erupted in Minnesota, Illinois, and Wisconsin, among other states. In response to the proposed dairies, citizen groups have and states have enacted heightened regulations for dairy centered on state rules and enforcement. However, local led to increased uncertainty for the dairy operation and have struggled to come up with consistent guidelines to deal with dairies in karst. This article reviews the regulation of concentrated animal operations, and particularly manure management within such operations, in selected Midwestern states. The comvary greatly, ranging from no special rules for karst in a in Iowa. Common provisions include vertical separation ities, and more stringent design and construction requirements for facilities located within karst areas. At least two states, Iowa and Ohio, require geological studies prior to locating concentrated animal facilities within karst areas. state regulation of concentrated animal facilities in karst citizens and animal facility operators in the future.

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41NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE signed to ensure structural integrity of the containment structure and to prevent seepage of the stored material to porated into the design standards in accordance AmeriConstruction of non-lagoon livestock waste handling facilities in karst areas must meet the design standards in sult with the soil and water conservation district, the University of Illinois Cooperative Extension Service, or other resources to determine whether the proposed any natural depression in a karst area formed as a result rangle topographic map or Department of Agriculture Iowa Iowa regulates the management of manure from large livestock facilities under the Animal Agriculture ComAnimal Agriculture Compliance Act for Open Feedlot Operations and Animal Truck Waste Facilities Act, Iowa Prior to constructing, expanding, or modifying a conwhether the proposed location is in karst terrain (Iowa centrated animal facilities in karst areas. Attempting to in karst areas as opposed to general regulation of these facilities. The search terms sought to identify regulations tions in many states. In other states, only very limited cilities associated with those facilities and karst features. Four states stood out in the search as including more their manure in karst areas: Illinois, Iowa, Minnesota, examined and summarized. Illinois Illinois regulates manure management under the Illinois Department of Agriculture. Waste handling facilities for livestock waste handling facilities (other than earthern facilities constructed of concrete must meet the strength any future updates. Other general requirements refer to waterstops, waste storage volume and protection from cilities, facilities keeping semi-solid livestock waste and solid livestock waste, and holding ponds used for the tion of livestock management facilities and livestock

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4216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Additional requirements apply to stockpiling dry manure If dry manure is stockpiled on karst terrain for more ded manure stockpiled on karst terrain or an alluvial aquifer area must comply with the same requirements as dry ered or uncovered impoundment used to store manure from an animal feeding operation, which has walls and tures are allowed in karst terrain, increased standards meet the following requirements if storing dry or nondry manure and located on karst terrain: test pits is required. After the soil exploration, the the structure. A 2-foot-thick lawyer of compacted provides that unformed manure storage structures may -

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43NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEtion structure on karst terrain or in an alluvial aquifer area must contain a vertical separation distance of low permeunderlying sand and gravel aquifer (Iowa Code Ann. pits, one at each of the stockpile, is required if accept further standards for the concrete. Iowa regulations also require an increased separaof the state and the operation fails to provide the mini cause a violation of state water quality standards. (Iowa may consider, among other factors, the proximity of the operation to sensitive areas, including karst terrain (Iowa Minnesota with counties with respect to regulating animal feedlots. to the state for permit issuance and other proceedings Construction or expansion of a liquid manure storage the proposed site, if the manure storage area possesses Animal feedlots in these sinkhole areas that are capanot construct a liquid manure storage area where the diswith a secondary liner consisting of a synthetic liner,

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4416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 lined with a secondary liner consisting of a synthetic liner, HDPE liner, or a two foot or greater cohesive soil areas require soils records that identify the soil texture, sinkholes, depression areas in the landscape, known caves, resurgent springs, disappearing streams, karst The owner or operator of an animal feedlot must prepare a manure management plan. The plan must intive measures to minimize the risk of surface water and groundwater contamination when applying maOhio under the purview of the Ohio Department of Agriculting and regulation of concentrated animal feeding facilities, including manure management on such facili ties. Operators of concentrated animal feeding facilities management. Manure storage or treatment facilities shall ed structures, manure storage ponds or manure treatment water monitoring and engineered controls (Ohio Admin. These explorations must also determine whether the tion in karst areas applies to manure storage ponds or manure treatment lagoons located in karst areas (Ohio construction soil levels and located within a karst area a properly designed clay or synthetic liner, when appro-

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45NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Summary of the Four States’ Regulations The state regulations examined ranged from the extremely detailed and complex requirements in Iowa to sions are advanced as to which state regulations are, or cal exploration and special design and construction standards, little detail or guidance is provided. Iowa, on the other hand, includes extremely detailed requirements. Further research needs to determine whether the require Common regulations in the four examined states include vertical separation considerations. Illinois, Iowa, and Minnesota all used these criteria in some respects. All four state regulations also include more stringent design and construction requirements for facilities in karst ar eas. Illinois relies on uniform design and construction while Minnesota and Ohio also require a plan. MinneConclusions and RecommendationsStates vary greatly with respect to whether and how special regulations apply to location of concentrated animal facilities and associated manure facilities in karst areas. these regulations to provide transparency and increased likelihood of acceptance. Many states do not distinguish location of concentrated animal facilities in karst areas from location in other areas. If karst areas are distinguished, often very little additional regulation is provided in karst areas. Illinois, Iowa, Minnesota, and Ohio appear to more roties in karst areas. Even amongst these states, however, minimal regulation in Ohio to detailed and complex regulation in Iowa. However, these four states gener tween animal and manure facilities, and karst features. In addition, more stringent design and construction requirements in karst areas are typical in these four states. fairly typical. The four states included in this study represent the most stringent regulators of concentrated animal facilities and resulting manure in karst terrain. Many states fail to provide any special requirements in karst areas. State legislatures and regulators in states with karst ar eas should study the regulations in these four states and incorporate some of the regulatory techniques. Iowa and ized requirements in Iowa also provide a model. uniform regulations. Iowa and Ohio require studies, while Minnesota requires soil records. The information general requirements. of particular regulatory techniques. In addition, Illinois, In the meantime, states with karst regions that presently fail to provide special protections from groundwater contamination in karst areas from concentrated animal facilities should use the four states examined here as models for regulatory regimes.AcknowledgmentsThe author acknowledges the support of the West Vir

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4616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8References Iowa Animal Agriculture Compliance Act, Iowa Code Table 1. State requirements in karst. Illinois Iowa Minnesota Ohio Vertical separation requirements the facility must ensure structural integrity of the containment structure and to prevent seepage of the stored material to rock if not designed engineer for some standards depending on structure composite lining requirements if less than 20 feet More stringent and construction requirements sional engineer unless vertical separation requirement met Concrete or com posite liner require ments, depending upon vertical separation Ponds or lagoons within karst areas of a manure storage pond or manure pre-construction soil levels and located rigid material like concrete or steel or a properly designed clay or synthetic liner, when appropriate Horizontal separation requirements karst features from certain karst features for certain structures Short-term manure stockpiles may not horizontal distance investigations Soil Exploration Study Soil records re quired Plans nure Management Plan Manure Management Plan on certain facilities Unformed manure storage structures Manure storage area possesses a capacity of more than Increased concrete re quirements X

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47NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEIowa Animal Agriculture Compliance Act for Open Feedlot Operations and Animal Truck Was seq. Iowa Animal Agriculture Compliance Act for Dry Midwest Plan Services Livestock Waste Facilities Champaign, Illinois.

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48 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8CAVE AIR CO2 MONITORING IN SHENQI CAVE, SOUTHWEST CHINAAbstractMonthly in situ monitoring of cave air CO2 and drip water chemistry were carried out in Shenqi Cave, Sichuan, southwest China, during a hydrological year from April con2 concentra IntroductionOver the last few decades, speleothem paleoclimate resingle or multi-proxy geochemical approaches allow for detailed paleoclimate reconstructions (Fairchild and wide range of processes in soil, epikarst and karst zone, as well as fractionation dynamics, can alter proxy data. processes involved, sophisticated monitoring programs 2 plays an imof the dripwater and water supply, as well as the fraction ation and incorporation of isotopic and elemental signarecording cave air pCO2 is critical for those interested in dynamics. However, there are few studies that trace the generation and dispersal of CO2 in deep karst systems, e.g., as a gas and in dissolved form within a linked system comprising soil, caves and the vadose zone. 2 and constitutes a main source for CO2tures, and pore-space of the host rock. Low cave air pCO2 values, relative to the pCO2 of the dripwater, facilitate CO2 degassing, with higher CO2 gradients, lead Another source of cave air CO2 is from the ground air, which exists in gaseous form in the karst vadose zone tures, and pore-space of the rock. More recent studies revealed that ground air is most likely the main source of cave air CO2 rather than soil air (e.g., Mattey et al., 2 ground air is produced -Liangcheng Tan1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sci ences, No. 97 Yanxiang Road, Xi’an, Shaanxi, 710061, China, tanlch@ieecas.cn 2. Institute of Global Environmental Change, Xi’an Jiaotong University, No.99 Yanxiang Road, Xi’an, Shaanxi, 710054, ChinaJingyao ZhaoInstitute of Global Environmental Change, Xi’an Jiaotong University, No.99 Yanxiang Road, Xi’an, Shaanxi, 710054, China, zjyunicorn@stu.xjtu.edu.cnDong LiState Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sci ences, No. 97 Yanxiang Road, Xi’an, Shaanxi, 710061, China, lidong@ieecas.cnYongli GaoDepartment of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, yongli.gao@utsa.edu

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49NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE forest. Spatial correlation analysis indicates that rainfall variations around the area of Shenqi cave are positively cor related with those in southwestern China, especially in the Seven drip-site monitoring stations with glass plates ing on CO2CCO2 productivity in the cave, and hydrothermal CO2 can also act as additional CO2 sources for cave air CO2 (Fairchild causes and dynamics of seasonality in cave air CO2 is fundamental for climate proxies of speleothems (Fair p CO2 on the CO2 productivity of its sources, and cave ventilaHowever, microclimate monitoring in caves is rarely conp CO2C of cave air together. Here, we present results from a one-year and monthly resolved monitoring of cave air p CO2, air temperature and C of cave air in the Shenqi Cave System.Study Area and Methods cave, formed in Triassic dolomitic limestone, has a small the cave, comparing with large variations of temperature and relative humidity outside the cave on diurnal-to seasonmidity inside the cave were continuously measured every Figure 1. Plan view of Shenqi cave. The red circles indicate monitoring sites (Tan et al., 2018). Figure 2. (A) Temperature and (B) relative humidity variations inside (blue) and outside (red) Shenqi cave during September 2014– October 2016. The monitoring interval is two hours. Results reveal a stable temperature and relative humidity inside the cave on diurnalto seasonal-timescales comparing with those outside the cave (Tan et al., 2018).

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5016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8more Ca2+ and HCO, resulting in higher pH values in dripwaters. Consistent with previous studies (Baldini CO2 sources, e.g., one with lower pCO2C tially elevated pCO2C 2, while derived CO2 in soil air pCO2, degassing during calcite concentration outside Shenqi cave sphere CH concen inside the cave. Previous studies suggest high CO2 concentration in unCO2measured in situ sealed until measuring. The CO2C value of atmospheric samples in this paper were mea Results and Discussion ventilation. Karstic vadose zone are generally enriched in CO2 isotopic compositions of CO2 in cave environments are 2-rich Larger pCO2 results in faster degassing and higher calcite deposition rates. Variations in cave air CO2tions are necessary to decipher these relationships and growth and isotopic compositions. Temperatures outside and inside the cave are also strongly seasonal. Monitor ing results show that temperature plays a key role in controlling cave air pCO2 during winter and summer. We have compiled a representative collection of Shenqi cave air pCO2 2 concentrations in Shenqi pCO2 value than the underground river and pool water. After Figure 3. Summary of pCO2 monitoring and carbon isotopic composition of CO2 collected from May 2016 to December 2016 in Shenqi caves. We only show monitoring sites 2# (a), 5# (b), 7# (c) site and 11# (outside the cave, d). The others are similar, but monitoring times are shorter.

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51NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Th dating, Th and U half-life values, and U-Th isotopic coupled plasma mass spectrometry. Earth and process to past environments. Chichester: John Frisia S, Borsato A, Fairchild IJ, McDermott F. environment of formation in speleothems from the Italian Alps and southwestern Ireland. Journal of evidence for decomposition of aged organic matter in the vadose zone as the main source of for C CC of C and C vegetation outside the cave. Higher temperature and monsoon rainfall during summer and autumn enhance the vegetation density and CO2C of air inside Shenqi cave. In contrast, lower temperature and rainfall during winter and spring reduce the vegetation ducing less CO2C values, resulting in C of air inside Shenqi cave. In addition, enhanced ventilation during dry season may also dilute the CO2C values inside ConclusionMonitoring results indicate the air CH concentrations inside the cave. The average CO2 concentrations varied were higher in winter and lower in summer.References Figure 4. Monthly total pH of drip water, pool water and underground river from April 2016 to Dec. 2016. The gray area has shown the summer half year with relatively lower pH values.

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5216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 and oxygen isotope variation in modern calcite monsoon precipitation changes on southeastern

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53 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8TIME SERIES HYDROLOGIC MONITORING WITHIN KARST AQUIFERS OF KEY CAVE AND CATHEDRAL CAVERNS, ALABAMAAbstract Speoplatyrhinus poulsoniPalae monias alabamaeMyotis grisescens from pools within the cave. Cathedral Caverns also has monitored in and near Cathedral Caverns State Park. A rain gauge was installed at each site to evaluate waterand hydraulically connected to Key Cave, was provided at Cathedral Caverns was measured in the cave and at load data and perform routine maintenance, and once a year to collect water samples. Samples were analyzed composition of water collected from Key Cave and CaAnderson Well. The purpose of these studies was to delineate the recharge area and aquifer characteristics of each cave to citizens to develop, manage, and protect the water resources that support these species. Key words: karst, caves, springs, sinkholes, cross sectionsIntroductiondesignated for protection of an assortment of federally protected and state conservation priority species, with Gheorghe M. L. PontaGeological Survey of Alabama, 420 Hackberry Lane, Tuscaloosa, Alabama, 35405, USA, gponta @gsa.state.al.usStuart W. McGregorGeological Survey of Alabama, 420 Hackberry Lane, Tuscaloosa, Alabama, 35405, USA, smcgregor @gsa.state.al.usRandall BlackwoodCathedral Caverns State Park, 637 Cave Road, Woodville, Alabama 35776, randall.blackwood@dcnr.alabama.gov

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54NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEMethodsTime series data were collected using one OTT ecoLog and the immediate vicinity comprise a state park open to springs, caves, and sinking streams. Sinkholes are more frequent in Interior Low Plateaus Province where Key Plateaus Province where Cathedral Cavern is situated Figure 1. Karst and potential karst areas in soluble rock in Alabama with locations of Key Cave Ponta, 2018).

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5516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8sion 2 cave with preponderant autogenic recharge. 2 2, A hydrogeologic cross section was produced to show the Fort Payne Chert aquifer. The initial water level was rewell located 2 km northwest of Key Cave and constructed equipped with OTT Orpheus Mini pressure transducers and data loggers. Various instruments and methods are used in the analyses Equipment used for water sample analyses included a Leeprocedures for the collection, preservation, and retention Key Cave and temperature were measured continuously from DeOf primary importance to the protection of Key Cave and Cave is considered a priority one maternity cave for the -1Distance between the furthest points of a cave on the map.2Branching index is the ratio between the length of the cave and extension.

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56NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 2. Key Cave map.

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5716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 3. and legend after Ponta (2019).

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58NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE extends to the Florence city limits. As such, the spring is located in the headwaters of Sinking Creek, the main spring to recharge the Key Cave aquifer. Due to the loca spring in the future. Cave indicate that the hydrology of the cave is likely and Fort Payne Chert aquifer occurred in an area near the Figure 5. 077Y26001, and Pickwick Reservoir with precipitation from November 1, 2017 to August 1, 2019. Figure 4. Hydrogeological cross section between wells 77 Y 10 001, 77 Y 26 001, Key Cave, and Pickwick Reservoir.

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5916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8is highest from January through April and lowest from storm events, additional water enters the system generat ing a stream in the cave which resurfaces at Key Cave isolated pools in Key Cave. ture decreased with rising water level. After a summer storm event the temperature rose along with water level enters the cave during storm events, and a phreatic zone component recharged several kilometers away from the conductance, temperature, and surface water elevation ter level in Key Cave. Average water level in Key Cave Figure 6. 077Y26001, and Pickwick Reservoir with precipitation from February 20 to March 8, 2019. The water level response in the wells is 11 days later.

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60NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE 2+ values. samples. The elevated chloride concentration in Key concenThe critical nitrate concentration of surface water for exlimit was exceeded in all four water samples collected samples collected in Key Cave had an elevated concen tration of nitrate due, in part, to the presence of the guano in the vicinity of the cave pool. samples collected in the Key Cave area exceeded the Cave were associated with high-water level. However, it Cave are related to the presence of guano in the cave pool. none of Key Cave water samples exceeded the USEPA priwater temperature and conductance was recorded. Figwater in Key Cave. The graph overlapped the water level elevation at all times except during large storm events, cave. Both graphs depict a descending trend of the water level which is in agreement with water-level elevariod monitored. karst aquifer.Water QualityWater samples were collected from three sites in the Key The quality of groundwater in Key Cave is controlled tween the surrounding limestone and groundwater, and quality of groundwater from phreatic aquifers that contemperature values. During summer months (after heavy -

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6116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 A limited group of organic constituents were analyzed in collected water samples. They include total organic Cathedral Caverns lowest pH value recorded during the sampling event. tection limit at all other sampling events. Figure 7. Piper trilinear diagram showing major ion composition of water collected from the Key Cave Wildlife Refuge area.

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62NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEthe spring, our assumption is that these waters discharge Between the Cathedral Caverns entrance and the spring, ductance, temperature, and surface water elevation are derelated with rising water level in the cave. Average water level in Cathedral Caverns is highest from January through derant allogenic recharge. The Cathedral Caverns water shed covers over 20 km22. As shown on the karst hydrogeological map of the area ground stream is Dry Branch, with waters derived from impervious rocks and springs. tion with the cave stream. Cathedral Caverns Well is used In addition, the karst hydrogeological map of the site on monthly discharge measurements in the cave and at Figure 8. Cathedral Caverns map.

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6316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 At Cathedral Caverns, the minimum pH measured was 2+ and SO Water QualityOnly one water sample was collected from Cathedral months, higher water levels typically result in higher Figure 9. Hydrogeological map of the Cathedral Caverns area. 1. Local or discontinuous productive aquifers, or extensive but only moderately productive aquifers: qh1Quaternary. 2. Extensive and highly productive aquifers: Ppv – Pottsville formation. 3. Highly productive karst aquifers: Mb – Bangor limestone MmMonteagle limestone. 4. Local or discontinues productive karst aquifers: Mp – Pennington Formation. Karst hydrogeological symbols and legend after Ponta (2019)

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64NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Conclusionsgated aquatic systems, specific conductance values varied with water level elevation, discharge, and The elevated chloride concentration in Cathedral CavThe critical nitrate concentration of surface water for That nitrate limit was exceeded in the water sample colA limited group of organic constituents were analyzed in the collected water samples. They include total organic Figure 10. Hydrogeologic cross section of Cathedral Caverns. Figure 11. 095A29002r with precipitation and discharge measurements from November 1, 2017 to August 1, 2019.

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6516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 fore, contaminants, such as nitrate, will migrate through the soil to the saturated zone. Additionally, analytical data suggest that shallow groundwater may have a greater input of nutrients to values of constituents from Cathedral Caverns are signifand conductance values to rise.Acknowledgments flow events are diluted during higher water level elThe low levels of ammonia suggest that nitrate in the of ammonia in the unsaturated zone. Furthermore, high nitrate concentrations are associated with elevated chloride concentrations. Consequently, the presence of nifrom soil when the photosynthesis process is dormant. Metals, with the exception of lead, which is pervasive in the investigated waters, do not pose a contamination drinking water standards. Overall, the analytical data indicate that the investigated oped land from surrounding areas. The presence of highly conductive soils in the study area and relatively low Figure 12. 095A29002 with precipitation and discharge measurements from November 5 through 20 2018.

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66NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE ground-water tracers to evaluate the hydraulic plans for the collection and analysis of water Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Hydrogeological assessment for Key Cave, ment is made to the residents and landowners of the study area who graciously allowed access to their property and furnished information on wells and springs and References Listing Methodology. prepared for Waste Contractors, Inc., 20 p. Standard methods for the examination of water and wastewater: Washington, D.C., American

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6716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 for chemical analysis of water and wastes (revised Protection Agency, Environmental Monitoring and for the determination of metals in environmental samples: Washington, D.C., U.S. Environmental Drinking water regulations and health advisories: Information Center.

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68 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8CAPABILITIES, LIMITATIONS AND OPPORTUNITIES FOR STUDYING SINKHOLES USING SYNTHETIC APERTURE RADAR INTERFEROMETRYAbstractWe give an overview of past work using synthetic aper serve and characterize sinkholes, present the advantages Introductionis even larger when cavity collapse in general, includ ing that unrelated to dissolution of rocks, is considered of remote sensing methods to sinkhole location and assessment. Indeed, one can argue that even many groundunderground caverns from the surface. However, here to use for the purpose. all sensors detect ground surface conditions that could and in situ measurements for validation. Sinkhole mapping and change tracking using remote sensing methods with surface elevation, change in elevation, and shape of the depression as the primary sinkhole indicators. These remain the most commonly used sinkhole indicators acwater and vegetation type, particularly that which is different from the surrounding area, are secondary indica snowmelt percolates through the soil, their presence can Although several remote sensing instruments are avail land surface topography mission with ground spacing of promising candidate for measuring the topographic indicators of sinkholes from space. Today there are a numlarger sinkholes, at least, and more are planned for the scheduled for launch in 2022. These instruments and SAR Applied to Sinkhole StudyOverview Cathleen E. JonesJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 USA, cathleen.e.jones@jpl.nasa.gov

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69NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCESingle-pass InSAR (Radar Altimetry or InSAR) to identify terrain with either active or inactive sinkhole activity through elevation contrast and the shape of depressions. graphic mapping. In addition, TanDEM-X data and deimages, WorldDEM, is generated with a horizontal resoit useful only for studying large sinkholes. To date, no for measuring surface elevation and surface deformation ping, i.e., measuring surface elevation. The other form of surface deformation, i.e., change in surface position over antenna and the scattering surface. In the literature, the term the type of sinkhole research and results to date. Repeat-pass InSAR (Differential InSAR or DInSAR) face, so it is useful for identifying actively deforming not map inactive sinkholes or sinkholes that show no or movement indicative of sinkhole initiation and progrescations for catastrophic collapse sinkhole formation (AtFigure 1. Schematic of DInSAR Differential, or repeat pass, SAR interferometry (DInSAR) works by measuring the phase change between the return pulses from a surface imaged at two different times from the same orbit and location. If the surface was displaced during the interval between when the images are acquired, then there is a change in the phase of the backscattered signal. One radar wavelength corresponds path length along the line-of-sight direction. [Derived from (Jones, 2016)]

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7016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8which phase coherence is maintained. Loss of phase coof identical instruments can achieve shorter repeat inter Decorrelation is less severe for longer wavelength raments where temporal decorrelation is not an issue (e.g., However, the measurement of precursory deformation in southern Louisiana. The setting in that case was one with dense vegetation and high soil moisture, so precur sory movement detection is an encouraging outcome for formation like earthquake fault ruptures and volcanic show consistent movement so, e.g., an instrument with racy and does not require tie points to a geodetic frame ated a higher resolution DEM from TanDEM-X imagery Pros and Cons of Spaceborne SAR for Sinkhole Study regular repeated imaging, consistent measurement meth odology independent of location, and seamless imaging erage and regular temporal repeat needed for sustained regional surveying. Depending upon the data access which operate in the microwave portion of the electro illumination of the surface since they emit pulses and instrument depends upon its spatial resolution, measurethe last depends upon the operating frequency of the frequency of the radar, with higher frequency (shorter sinkhole studies, particularly in areas where vegetation the case in sinkhole-prone areas. Typically, measurements of ground deformation using a single pair of images, and ground deformation rates with

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71NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE ever not all land areas are acquired on every pass and, although most land areas are eventually imaged, there is no formal commitment to do so and in practice the NISAR: The NASA-ISRO SAR Missionand applications. The mission will collect data in support of ecosystem, cryosphere and solid earth sciences. The acquisition plan is designed for studying dynamic processes that occur at the week-to-year timescale and for determining the causes and consequences of land surface changes through Earth system modeling. The mission does not have any requirements for sinkhole scipurpose. The mission and its utility for sinkhole studies NISAR Instrument and Mission Description The mission is scheduled to launch from Satish Dwawan erations are likely to extend if the instruments remain in operating condition. lution and a wide imaging swath using a new technology, In areas where sinkhole collapse occurs rapidly, i.e., over weeks to months, frequent updates to the survey are no surface indication to collapse more rapidly than the these artifacts vary on the scale of kilometers or larger so they have less impact on sinkhole detection. To the extent Future improvements in DEM resolution and accuracy monitoring their development from space. for monitoring of the larger active sinkholes.

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7216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8An Assessment of NISAR’s Sinkhole Study Capability and its data are free and open to all, as are the data low vegetation and will maintain higher coherence. excellent long-term ground motion monitoring will provide atmospheric corrections as standard layers in users will not have to implement or purchase specialized processing to remove those artifacts from the neers and decision makers. The activities and white paAcknowledgementstory, California Institute of Technology, under conmainly acquire data over India and targets in its national signed to operate alone or together. The mission will acmission is focused on Earth science, the mission system is designed to provide rapidly processed products, within Figure 2. Schematic of the NISAR Satellite NISAR uses a 12-m diameter antenna technology to obtain a 240-km wide image swath independent of the spatial resolution. The current operational plan is to acquire 6-m x 7-m spatial resolution data over North America and 12-m x 7-m data over much of the rest of the globe’s land areas.

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73NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE formation ground movement associated with the Bayou Corne sinkhole. In: Land L, Doctor D, editors. Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings aperture radar for engineering and environmental References modeling and analysis of sinkholes along the Dead viscoelastic modeling of sinkhole precursory early warning, and sediment properties. Journal using interferometric synthetic aperture radar Conference on Sinkholes and the Engineering and

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7416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Assessing collapse risk in evaporate sinkhole prone areas using microgravimetry and radar interferometry. Journal of Environmental & interferometric radar echoes. IEEE Transactions

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75 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8SPATIAL AND TEMPORAL IMAGING OF A COVER-COLLAPSE SINKHOLE IN WEST-CENTRAL FLORIDA THROUGH HIGH RESOLUTION REMOTE SENSING AND GEOPHYSICAL TECHNIQUESChristine DownsDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, cmdowns@usf.eduTonian RobinsonSchool of Geoscience, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, trobinson@usf.eduGarrett SpeedDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, gspeed@usf.eduJorge Gonzalez GarciaDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, jorgegonzale@usf.eduNoelia GarciaDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, mariagarciaa@usf.eduLori CollinsDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, lcollins@usf.eduTravis DoeringDigital Heritage & Humanities Center, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, tdoering@usf.eduShawn LandryWater Institute, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, landry@usf.eduDavid EilersWater Institute, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, eilers@usf.eduSajad JazayeriSchool of Geoscience, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, sjazayeri@mail.usf.eduSanaz EsmaeiliSchool of Geoscience, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, esmaeili@mail.usf.eduSarah KruseSchool of Geoscience, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620, skruse@usf.eduJochen BraunmillerSchool of Geoscience, University of South Florida, 4202 E Fowler Ave., Tampa, FL 33620 jbraunmiller@usf.edu

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76NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE meters of silty locally as large as 20 m. The groundwater levels are seasonal and highly dependent on rainfall. Following the Abstract the front yard of a home in Pasco County, FL. Starting as a depression, the initial collapse occurred rapcourse of three days. The sinkhole is oval and coneshaped with a northeast-southwest long axis and ridgto characterize the temporospatial surface changes and post-collapse. Surface changes over time are computed Multiscale Model to Model Cloud Comparison algogrowth occurred on the northeast and southwest edges. rizon within sands and silts that appears to correspond long axis, post-collapse activity, and the orientation and gest a northeast-southwest trending linear or elongated Introduction Starting as a depression, the initial collapse occurred rapThe collapse is located in west-central Florida within the the increased cohesion of a relatively higher clay content Figure 1. Data coverage map for each technique. TLS and UAV photogrammetry coverage is shown as coverage extent as opposed to point locations of the scanner, targets, and drone position for presentation purposes. Timeline of events and data collection starting with the initial collapse (red polygon) and including the start of stabilization (arrow). The frequency of repeat acquisition was different for each method. Ground-penetrating radar was collected on different days, but ground coverage does not overlap.

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7716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of tree canopy. sition of at least six ground control points. Photos were ground, with all areas of the ground having at least nine Additionally, commercial aerial UAV company Halo Imweeks following the collapse. Halo Imaging deployed a ware to produce point clouds, digital surface models, and orthophotos. Halo Imaging provided raw images from their surveys, as well as their processed photogrammetry derivatives. ume as remediation progressed, repeat surveys were compared relative to each other. Since no control (preMoving and temporary features (i.e., people, equipment, the initial morphology of the sinkhole and take repeat measurements at daily, weekly, and monthly intervals n-Crespo standing of rapidly-occurring, multiscale events (Collins In this paper, we present the results of repeat TLS and ture the surface features in and around the sinkhole, and ral component to the high-resolution spatial data necessary to detect small changes in three-dimensional space.MethodsEach dataset has its own horizontal and vertical spatial installed around the sinkhole to detect sinkhole growth, signals from the natural system. One natural event—a wall collapse on the west side of the sinkhole—was recorded 22 days post-collapse and overnight when heavy equipment, cars, and home air conditioning systems are Surface TLS of the collapse and surrounding area was conducta transect that circumvented the collapse. Scans were placed at intervals that ensured line of sight coverage. External spherical targets were placed at various elevations around the sinkhole and used for registration control from one scan position to the next. Scans were Table 1. horizontal vertical TLS 2 mm 2 mm SfM <20 cm <20 cm

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78NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEduce a surface map to compare with the extent and depth Bathymetry Water depth within the sinkhole was mapped on two difing tape performed in an evenly-spaced grid fashion tom of the collapse was mapped using a Lowrance HDS depths, and volume. Water depth data points were converted to point clouds point clouds.ResultsSurface Changes removal of two houses and associated structures that intersected the sinkhole on the east and north side. These structures gradually collapsed over the course of three activity not associated with anthropogenic noise is inter By looking at changes in the perimeter alone we can see Small changes along the walls of the sinkhole, within the area not accounted for. By comparing point clouds with Point clouds were compared to each other using the Multiscale Model to Model Cloud Comparison algorithm face to this normal was compared to the surfaces in a can determine changes occurring underneath tree canopy Subsurface then applied to remove the long wavelength component. A tive peak to the direct wave arrival time. A step-wise aver little to no useful information was returned. Travel time was converted to depth with a constant ground velocity. -

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7916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 collapsed when the sinkhole formed and the one on the east edge continued to collapse inward as the perimeter north edge had also partially collapsed, no change occurred during this time. The water surface within the sinkhole does show a larger positive change, which is es are detected along the side of the partially standing house indicating further damage. Additionally, a negative change is detected on the northwest edge of the sinkhole where more ground material collapsed. sinkhole and much of the edge show a positive change. the perimeter. Seismic records detected sinkhole-related activity on Auwestern edge of the sinkhole. There is also negative surface sults of heavy machinery compacting the top soil. Over the course of the study, the most prominent changes are negative surface changes where the two houses once stood and a positive change along the perimeter changes due to perimeter growth as they are overprinted ern edge where the wall collapse occurred. The negative change within the sinkhole is likely due to a large amount not present in the second comparative dataset. Figure 2. Results of an M3C2 algorithm between SfM photogrammetry datasets on July 18 and July 20, 2017; SfM photogrammetry and terrestrial scanning on July 20 and July 25, 2017; and terrestrial scanning datasets on August 02 and 14, 2017. All results are underlain with July 18, 2017 photogrammetry-derived point cloud for reference. The largest negative change occurs where the perimeter grew (along the east edge July 18-20 and the southwest edge Aug 2-14) and where a partially destroyed home collapsed completely. There is little change detected between July 25 and August 2 (not shown). Small areas of a relatively large change within the sinkhole is due to debris movement. The sinkhole as a whole does experience a positive change in the beginning of August due to large volumes Changes in tree canopy have been removed.

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80NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE data points are not typical of a slope found in natural systems and may represent a small vertical opening or depth Subsurface Structures Subsurface Changes overall shape of the collapse. oval-shaped with a northeast-southwest trending long axis. Within the sinkhole there are ridges on the northwest and west walls. The total volume from the second Figure 3. Relatively large changes as determined by the M3C2 algorithm between SfM photogrammetry datasets on July 18, 2017 and May 05, 2018 underlain with May 05, 2018 photogrammetry-derived point cloud for reference. The most notable negative changes (blue) correspond to houses that collapsed and were removed, perimeter growth on the east side of the sinkhole, and the complete removal of a tree to the west of the sinkhole. The most notable positive change (red) corresponds to the built-up rim around the sinkhole. Additionally, perimeter growth occurred on the southwest edge, but it is overprinted by the rim. The water levels within the sinkhole were slightly lower in May 2018 than immediately following the collapse in July 2017. Changes in tree canopy have be removed.

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8116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 essarily a lithological contact. The interpolated surface for this horizon is compared to the depth of the top of erally dips to the southwest. On the western edge of the down warping of the horizon were noted in consulting anomalies associated with downward migration of sediments. The horizon resides within a sand to silt layer and necessarily a sharp lithological contact (i.e., sand over once a part of the Saxon Lake as seen in historic aerial horizon is deepest where the top of clay is also deepest ered limestone, clays, and sands.DiscussionThe most prominent post-collapse surface changes are houses, rising water levels within the sinkhole, and pefailure, occurs along the northeast and southwest edge, which is also the direction of the long axis. Figure 4. Side by side comparison of sinkhole bathymetry. Water levels remained relatively constant after the initially syn-collapse rise. (A) Before stabilization efforts began the sinkhole was generally oval and cone-shaped with a northeast-southwest trending long axis and ridges on the northwest and west walls. Maximum water depth is 12.2 meters. (B) Post-stabilization measurements show a circle denotes data points not typical of a slope found in a natural system and may represent a small vertical opening or depth anomalies caused by bottom debris. Figure 5. Example of the high-amplitude, semicontinuous horizon observed in GPR and used to interpolate a surface within the uppermost unconsolidated sediment.

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82NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE falls in line with the northeast-southwest long axis of the negative surface changes in the same area.Conclusions lapse sinkhole. The sinkhole is oval and cone-shaped with a northeast-southwest long axis and ridges on the northwest and west slopes. The initial collapse measured eter. This area experienced a large negative change (peas well to when seismometers recorded activity in the failure is occurring in line with the long axis of the collapse. sent a predevelopment surface. Figure 6. (Figure 5). The horizon resides within a sand to silt layer and corresponds to changes in physical properties, but not necessarily a lithological contact. It is shallowest (<0.5 m) to the east and northwest of the sinkhole and generally dips to the southwest. On the western edge of the sinkhole, the horizon appears shallow (1.25.75 m) and quickly becomes deeper (2.5+ m) to the southwest. Interruptions in the horizon (dotted red lines) may be due to local zones of subsidence. The areas in which the horizon is the deepest were once a part of the historic extent of Saxon Lake as seen in early aerial imagery (gray line). The top of limestone (points) is highly variable but is generally deepest around the sinkhole.

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8316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Documenting a Large Collapse Sinkhole in Westfor photogrammetry and remote sensing: A review. County Sinkhole. ground penetrating radar and electrical resistivity A review and application in the mantled with structure-from-motion photogrammetry: precision maps for ground control and directly georeferenced surveys. Earth Surface Processes comparison of complex topography with terrestrial post-collapse activity, and the orientation and depth of The historic lake edges also reveal the collapse—and may have played a role in the location of the collapse.Acknowledgements quality of this paper.Author ContributionsIn order of author list: Christine Downs conceived the presented idea, processed a portion of the terrestrial laanalysis, and integrated data for analysis and presenta work and processed seismic data.References

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84NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE motion photogrammetry. Advances In Landslide Pasco County, Florida. of sinkholes in the karst of west-central Florida. Are improvements in data collection

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85 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8GEOPHYSICS OF A DOLINE SHAFT SYSTEMAbstractMemorial Athletic Field, State College, Pennsylvania was installed within an existing doline shaft system. Although its early history included such uses as waste periglacial sediments as imaged through electrical imof the EI data using a forward modeling program show crogravity data also show the presence of a north-south larger series of voids at depths of greater than 20 meters.Introductioncated in State College, Pennsylvania, has served many pression was used for waste disposal, and referred to velop the area as a recreation space for a new elementary ment design plans for a campus extension that included a sports stadium. There was no real progress with the cluded mining limestone with most of the stone quarried mercial endeavor. of the high school students from State College who gave their lives in World Wars I and II. drainage. A series of storm water pipes were connected years of storm water discharge to the throat is that the GeologyMemorial Field is developed into the karst-forming dolomitic Axeman Formation, a part of the OrdovicianPeter J. HutchinsonTHG Geophysics, Ltd., 4280 Old Wm. Penn Hwy., Murrysville, Pennsylvania, 15668 USA, pjh@thggeophysics.comAlex BalogTHG Geophysics, Ltd., 4280 Old Wm. Penn Hwy., Murrysville, Pennsylvania, 15668 USA, axb@thggeophysics.comDanica R. PilsCalifornia University of Pennsylvania, 250 University Ave., California, PA 15419 USA, pil9785@calu.edu

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86NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Several of karst features, consisting of dolines, voids and show only minor surface depression, on the order of a few meters. Unfortunately, surface expression in the Geophysical MethodsThe geophysical investigation into the extent and nature of the doline shaft system of Memorial Stadium Figure 1. Digital elevation model (1 m grid; North American Vertical Data 1988, 2006 Department of Conservation and Natural Resources PAMAP) of Memorial Athletic Field in State College, Pennsylvania. Upper right inset map shows existing storm drains at Memorial Athletic Field (in red). Figure 2. Works Project Administration workers during the construction of Memorial Field, circa 1937. View of the stadium to the south (from Smith, 2011).

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8716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Electrical Imaging resistance is equal to the ratio of potential to current along a linear distance of a material with a known crosssectional area. Consequently, resistivity is measured in Electrical currents propagate as a function of three mateElectrolytic conductivity is a function of the concentration of total dissolved solids and salts in the groundwater that resistive. Of these three properties, electrolytic conducrocks and soil with increasing: fractional volume of the Materials with minimal primary pore space (i.e., lime lines. Figure 3. Excavation of the subsiding reinforced concrete manhole in April 2013. Note the 0.5 meter diameter pipes feeding the manhole. Figure 4. A portion of the State College, Pennsylvania geologic 1:24,000 quadrangle map. Geologic units include the Ordovician Stonehenge/Larke (Osl); Nittany Formation (On); Axeman Formation (Oa); Bellefonte Formation (Obf); and Benner Formation to Loysburg Formation (Obl) (Berg and Dodge, 1981).

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88NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE physicist, microgravity is used to determine the presence Small changes in rock density produce small changes in tidal response and lunar pull, among other phenomena 2 2 Processing raw gravity data includes corrections for lati tude, elevation, Bouguer gravity, tidal, and terrain. elevation or free-air correction normalizes the gravity the measuring station and sea level which is related to Geophysical InvestigationElectrical Imaging In homogeneous ground, the apparent resistivity is ground, the apparent resistivity represents a weighted average of all formations through which the current apparent resistivity values using the EarthImager proparent resistivity pseudosection. The pseudosection is compared to the actual measurements for consistency. The processed readings were converted to a color that imaging methods. Microgravity Figure 5. Memorial Athletic Stadium showing the funnel-shape to the sinkhole. See text for color scale; map scale as shown with no vertical exaggeration.

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8916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Forward modeling of the gravity data shows that the top the gravity model did not quite meet the exact footprint Structurally, the top of the void has supported the stands for many years. The long-term use of the void as a disrial Stadium was pivotal in determining areas of potential hazards. A plan map of the depth to rock from forwardThe top of rock map generated from forward modeling interpretation did not show the potential for collapse or Microgravity A plan map using gravity data created with a forward modeling program also shows a well-developed claysouthwest-northeast orientation, the deepest portion of Figure 6. Plan map of the sinkhole area beneath the northern bleachers at Memorial Stadium. Depth to top of rock map based of interpreted regional fracture (blue). Plan map based upon North American Datum 83 Pennsylvania North State Plane (m). Figure 7. A 3-D representation of the corrected microgravity data showing the void beneath the northern bleachers. The color contours represent depth to the top of carbonate rock beneath the bleachers. Plan map based upon North American Datum 83 Pennsylvania North State Plane (m).

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90NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE A doline shaft system model most appropriately deConclusion inferred to cut through the center of Memorial Athletic Stadium. A doline exists along the fracture trace that is centrally located within the stadium. The doline, now Further, the deep-rooted fracture that is inferred to Figure 8. Top of rock map based upon the differential gravity and superimposed on Memorial Stadium. Coordinate system North American Datum 83 Pennsylvania North State Plane (m). Area between the blue lines represents the regional fracture system.

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9116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 The throat is currently a discharge point for the City of use of the throat for storm water disposal has weakened sidence in the area around the inlet to the throat. This storm water disposal. view of the extent of doline development within the athclay-plugged doline.References periglacial clay. caverns and enlarged, interconnected fractures. In plan Figure 9. Memorial Stadium. Vertical exaggeration 1.5 times. Figure 10.

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92NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE p. in Culver DC, White WB eds., Encyclopedia of The geology of Pennsylvania: Pennsylvania Pennsylvania, area and their relationship to the general occurrence and movement of groundwater. inversion to generate smooth, two-dimensional Methods in Engineering and Environmental Hutchinson PJ, Balog A, Hoover SE. 2020. Microgravity mapping of an inception doline shaft system. Environmental and Engineering Mine Voids Using Continuous Vertical Electrical Sounding Methods. In: Proceedings of the International Conference on Environmental and method: Part A, gravitational, electric, and Bison Instruments, Inc., Minneapolis, Minnesota.

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93 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8USING ELECTRICAL RESISTIVITY METHODS TO MAP CAVE PASSAGES AND CONDUITS IN THE SAN SOLOMON SPRINGS KARSTIC AQUIFER SYSTEM, WEST TEXAS, USAAbstract Lake Spring Cave, currently the deepest underwater cave in the United States, and one component of the San far West Texas. This work is part of a larger investiga tion of the regional hydrologic framework of the San the impact of new oil and gas operations on water resources and water quality in the region. the mapped portion of the cave. A dye trace study conday through conduits formed in Cretaceous limestone, eventually discharging from San Solomon Spring at Balmorhea State Park, six kilometers east of the cave Solomon Spring.Backgroundpine High, a large oil and gas complex in West Texas in the southwest corner of the Delaware Basin, near the the impact of the development on water resources and water quality in the region. The southwest edge of the of six karst springs that discharge groundwater from Davis Mountains. The springs and related groundwater provide water resources for much of the agricultural activity in the area. The main San Solomon Spring discharges into the pool at Balmorhea State Park, another important component of the local economy. The springs (Cyprinodon elegansGambusia nobilisTryonia cheatumi western edge of the Edwards Plateau, one of the largest greater Edwards-Trinity Aquifer system, conducted University of Texas at Austin (e.g., LaFave and Sharp, regime that has little to do with the Edwards-Trinity Aquifer.Lewis LandNational Cave and Karst Research Institute, 400-1 Cascades Ave., Carlsbad, NM, 88220, USA, lland@nckri.orgMichael JonesNational Cave and Karst Research Institute, 400-1 Cascades Ave., Carlsbad, NM, 88220, USA, mjones@nckri.orgGeorge VeniNational Cave and Karst Research Institute, 400-1 Cascades Ave., Carlsbad, NM, 88220, USA, gveni@nckri.org

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94NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE and surveyed Phantom Lake Spring Cave upstream for cave continues unexplored at its upstream and downstream surveyed ends. Phantom Lake Spring Cave is now the second deepest cave in Texas, and the deepest under rent limit of exploration (ADM Exploration Foundation, into the downgradient section of Phantom Lake Spring Cave and deployed dye detectors in all of the downgradient springs. The dye appeared in the pool at Balmorhea State Park six days later. Dye was not detected at any of the other springs or at any of the four monitored wells, mon Spring. This study unequivocally demonstrated that Solomon Spring in Balmorhea State Park at a minimum Based on geochemical and isotopic data (e.g., Chowdclude that discharge from the San Solomon Springs is volcanic rock in the Davis Mountains a few kilometers gradient springs, including discharge from San Solomon Spring into the pool at Balmorhea State Park, six kilometers east of the cave entrance. This conceptual model analysis of hydraulic and geologic data to support these Figure 1. Physiographic map of south-central Texas. West of the Pecos River (Trans-Pecos region) the Edwards Plateau is sometimes referred to as the Stockton Plateau. The various components of the greater Edwards-Trinity Aquifer System are indicated by color shading (Land and Veni, 2018).

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9516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 cave. These geophysical surveys are part of a larger investigation of the regional hydrologic framework associated with tial to prevent vandalism or drilling into the cave to exploit water resources contained therein. For this reason we are not Methods mapped. Modern resistivity surveys employ an array of the course of a survey, pairs of electrodes are activated of electrodes. Figure 2. = Phantom Lake Cave; 2 = San Solomon and downgradient associated springs. Arrows shading indicates igneous and volcanic rock; blue shading represents carbonate outcrops. Dashed lines show subsurface extent of the Capitan Reef (from Land and Veni, 2018). Figure 3. Generalized geologic map of the Pecos-Van Horn region of West Texas (from Land and Veni, 2018).

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96NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE low electrical resistivity. tivity arrays deployed over Phantom Lake Spring Cave and its extensions were oriented roughly perpendicular to the underlying cave passage, with their center points located over the mapped cave. collected using the initial array of electrodes, the lower overlap. Although this method does not increase the depth longer than the length of the main array. tion data collected during these surveys are used to cor rect the resistivity data for variations in topography at er-2D software. The EarthImager software chooses a resistivity scale designed to highlight natural conditions tempts to do so may yield misleading results. of electrically conductive water or water-saturated soil caves and conduits in the survey area will thus display as Results and DiscussionPhantom Lake Spring Cave ER surveys Most of the mapped portion of Phantom Lake Spring water from inside the cave into a refugium pool, which parameter meter indicate that water in the cave is slightly Figure 4. Gated entrance to Phantom Lake Spring Cave, formed in upper Cretaceous Buda Limestone.

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9716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 much noiser than measurements made over the upgradiof the southernmost mapped station on the cave map. to the explored cave, although one known passage that of the cave passage trends northwest from the entrance for in the passage. The cave geometry at this station displays as a concentrated pod of low resistivity, with a conductive resistivity dipping down from the land surface to the Figure 5. ER line PLC1, located upgradient from, and ~110 m west of the cave entrance. Figure 6. ER line PLC2, located upgradient from, and ~360 m northwest of the cave entrance.

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98NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE the southernmost mapped station in the cave. We chose passage. Buda limestone is no longer exposed at the surface. The cave passage. to drill holes in the rock for installation of the electrodes. The western half of the array was located on alluvium in ity of the data, we nevertheless achieved an exploration which we assume corresponds to a southerly extension of the cave passage. The surface and near-surface geolthe surface outcrop of the Buda limestone dipping down orientation of the conductive zone, also dipping a few degrees to the west, suggests that the passage geometry in the Buda Limestone. Figure 7. ER line PLC4, located downgradient from, and ~280 m south of the cave entrance. Figure 8. ER line PLC6, located downgradient, and ~490 m south of the cave entrance.

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9916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 resistive host rock. array at 2 m electrode spacing with two rollalongs, for a a dirt road extending southeast to northwest, immedi at most of the sites to extend the length of the survey morhea State Park along the west shoulder of the southFigure 9. ER line PLC8, located downgradient and ~850 m SSE of the cave entrance. Figure 10.

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100NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE As with all of the previous surveys near the park, an ir duits into near-surface alluvium. resents unsaturated alluvium. If that is the case, the SS2 dipole array at 2 m electrode spacing with two rolFigure 11. Figure 12. southern arm of the pool at Balmorhea State Park (Figure 10). Figure 13. adjacent to Balmorhea State Park (Figure 10). Several electrodes had to be skipped in this survey because of two road crossings. The low resistivity zone centered beneath electrode 90 is ~23 m north of the spring outlet below the pool diving board.

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10116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 vertical fractures formed in the Buda Limestone. ing that the layer of low resistivity does not extend down Thickness of the alluvial layer overlying the limestone that remains unanswered. The lithologic log from a wa2 m electrode spacing, with one rollalong for a total sur Three days later we reoccupied the site and conducted a near-surface layer of relatively high resistivity exFigure 14A. roll) at 2 m electrode spacing. The low resistivity zone beneath electrode 35 is ~100 m WSW of Figure 14B. single-deployment array (no rollalong) at 3 m electrode spacing. The low resistivity anomaly are 334 m long.

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102NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEDepartment of Transportation, and several private landowners who provided access to their property and lands they administer.References Mullican WF III, Angle ES, editors. Aquifers of Pecos Valley aquifers of Texas. Texas Water history and hydrogeologic setting of the EdwardsTrinity Aquifer system, west-central Texas. US of the Edwards-Trinity Aquifer system, westA conceptual model of the hydrogeologic system of the Edwards-Trinity and related aquifers park reports water in Cretaceous limestone at a depth of known or likely hydrogeologic conditions. The surveys over known portions of Phantom Lake Spring Cave clearly illustrate the cave at its known depth and loca tion. Surveys over unexplored downgradient areas along sistent with the likely extent and position of the continu ation of the cave. ding planes, enlarging them into conduits that discharge San Solomon springs requires further study. The close groundwater from the sources of each spring, while dye tracing data to date suggest no mixing occurs.Conclusions extensive and underinvestigated karstic aquifer system cave passages and karst springs that make up this regional aquifer, in an area where there are few wells or investigation will also provide hydrogeologic context for any impacts on water resources or water quality associated with oil and gas extraction in the region.Acknowledgements Apache Corporation. Field assistance was provided

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10316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 investigation of the San Solomon Spring area: transportation and infrastructure geohazards in Land L, editors. Proceedings of the Fifteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impact of Aquifers of West Texas. Texas Water Development Development Board. Trans-Pecos, Texas. Texas Parks and Wildlife III, Angle ES, editors. Aquifers of West Texas, systems feeding the springs of West Texas. In: the hydrogeologic framework, geochemistry, and and related aquifers in the Pecos County region, of the waters in the San Solomon Spring system, Mullican WF, editors. Aquifers of the Edwards hydrogeology of the Edwards Plateau karst, central Texas. [PhD dissertation]. The University contiguous hydraulically connected units, westdischarging at the springs of Balmorhea. West Mexico: The human impact. In: Land L, Doctor DH, Stephenson JB, editors. Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental of anthropogenic karst phenomena, southeastern reveal karstic paleotopography developed on Land L, Stephenson JB, editors. Proceedings of the Fourteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental

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104NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE inferred from oxygen, hydrogen and strontium of endangered species status for six West Texas DC, editors. Encyclopedia of caves. Chennai: ecological use of karst groundwater resources: A case study from the southwestern USA. In:

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105 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8RELATIONSHIPS BETWEEN SINKHOLE-RELATED FEATURES AND INSAR-DETECTED SUBSIDENCE POINTS IN WEST CENTRAL FLORIDAAbstractSinkholes in west-central Florida are usually formed from the erosion of overlying soil and sediment into one of the leading natural disasters in the area, and therefore, precursory detection is crucial to alleviate risks of property damage. Using the Interferometric Synthetic solve elevation changes over time. Using the Persistent compared against other terrain data. We examine the reIntroduction its high rate of sinkhole activity. Sinkholes in this region are usually formed from the erosion of overlying soil and natural disasters in this area, precursory detection is crucial to alleviate the risks of property damage. Detection technique has a millimeter-scale vertical resolution and therefore can detect small surface changes. It also allows for spatial analysis of potentially sinkhole—related feafully used to assess sinkhole deformation in the Dead Sea Tonian RobinsonUniversity of South Florida, 4202 E Fowler Ave., Tampa, Florida, 33620, U.S., tonianr@mail.usf.eduChristine DownsUniversity of South Florida, 4202 E Fowler Ave., Tampa, Florida, 33620, U.S., cmdowns@usf.eduTalib Oliver-CabreraBoya ZhangSarah KruseUniversity of South Florida, 4202 E Fowler Ave., Tampa, Florida, 33620, U.S., skruse@usf.eduShimon Wdowinski

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106NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEto other surface features. Slope Break Analysis where a single model with the slope and intercept this two-line model was shifted throughout the selected time series to calculate line statistics for locatslope uncertainty values. A p-test was then computed assumption that they may represent sinkhole-related GIS methodsDigitizing Aerial Photos, Near Analysis points and karst-related surface and hydrological features. Previous research approaches focused on creating hazard and risk maps and models for sinkholes using already colin groundwater head, and other surface hydrological InSAR Data Acquisition and Analysis pass interferometry and spotlight acquisition mode were sampling period. For this paper, we focus on one of the 2 in area. The Stanford duce displacement information for three site locations in Methodology points and surrounding surface water and topography, within each time series that indicated a sudden surface movement. These sudden changes in movement (slope points used in this paper. We then use spatial techniques Figure 1. InSAR study area in west-central Florida. This study focuses on site 2 (middle), which is 15 km2.

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10716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Pro. Areas that were apparent surface water features were digitized for analysis. These water features had low pixel values similar to pixel values of the present-day their nearest surface water polygon features were calcu USDA surface water hydrography layer and the digitized time-series slopes and elevation.Results and Discussion imagery, therefore as we would expect the time-series points are closest to surface water features in this layer Figure 2. Example of a time-series dataset location of a slope break a two-line model is moved along the time series. The kink model is then selected by comparing slopes of the lines before and after the kink, the model with the lowest combination of slope uncertainties is selected. The slope break for this dataset is in early 2016. Figure 3. Image of site location in west central Florida overlain by a georeferenced aerial image from 1944. Surface water features can located in Hernando County, Florida. Figure 4. Map of digitized surface water features from the 1944 aerial imagery in Figure 3 and surface water features from the USDA. Time-series subsidence points are also on map.

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108NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEhigher resolution elevation models, we will complete a References sidence points are dispersed across the landscape without regard to elevation. However, we note that sinkholes in Florida depressions that could indicate sinkhole formations. The geoof limestone is very irregular and partially controls topograand lowlands suggesting karst features, which also drive ConclusionThe distance of points to surface water features from correlate with elevation. To further this analysis, using Figure 5. Relationship between elevation from 3-meter DEM (USGS-National Elevation Dataset) of study area and slope of subsidence points. Figure 6. Plots showing the correlation between subsidence rate of each time series point and their distances to the closest water feature from the USDA layer (top) and the 1944 digitized water features (bottom).

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10916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Applications of Critical Zone Hydrogeophysics to Better Understand Hydrogeologic Conditions in Coastal and Inland Wetlands and Waters Survey. Sinkhole precursors along the Dead Sea, Israel,

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110 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8INTEGRATING MONITORING TECHNIQUES FOR A BURIED SINKHOLE IN AN URBAN ENVIRONMENTAbstracttion. The underlying geology comprises marls, limestone and gypsum of the Permian Edlington, Brotherton and rapid rate of dissolution of the gypsum (hydrated calcium scales. Following the collapse that formed a sinkhole in the feature is forming in a recreation area and is one that local residents reported to have grown in dimensions. The density of development precludes the use of satel toring has revealed that this depression lies over a palextends to a depth of a similar order of magnitude. The focused on understanding sinkhole triggering processes. Introduction shire, UK. This required the evacuation of seven houses Gabriella B WilliamsDr. Vanessa J BanksBritish Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham, NG12 5GG, United Kingdom, vbanks@bgs.ac.ukDr. Elisabeth T BowmanDr. Anthony H CooperBritish Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham, NG12 5GG, United Kingdom, ahc@bgs.ac.ukLee D JonesBritish Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham, NG12 5GG, United Kingdom, ldjon@bgs.ac.ukMatthew P KirkhamBritish Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham, NG12 5GG, United Kingdom, mki@bgs.ac.ukDavid J R MorganBritish Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham, NG12 5GG, United Kingdom, djrm@bgs.ac.ukDr. Paul Shepley

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111NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEside the emergency services and monitored the impact ology comprises marls, limestone and gypsum of the It is the rapid rate of dissolution of the gypsum (hydrated human time scales. The sinkhole was remediated with a concrete plug. investigate the remediated feature using geophysical techniques (micro-gravity, electrical resistivity tomogra the density of the ground. These techniques successfully constrained the geometry of the feature. The technique However, the footprint of sinkhole remediation over to interpret the results. of houses, local residents reported that they had noticed diately to the east of the terrace had grown during recent ing triggering processes in gypsum karst.Research QuestionIn the UK, gypsum is not widespread. Triassic gypsum where it is protected from water. However, Permian gypreduce the thickness of the mudstone cover (Cooper, et Figure 2. Geological sequence encountered in the Ripon area, see Figure 4 for legend. Figure 1. UAV survey of the sinkhole feature in November 2016. (Reproduced from British Geological Survey data UKRI (2019) with permission).

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11216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 in the sequence. older Edlington Formation, consisting of mudstone and gypsum, lies directly to the east of the park, where the The purpose of this study is to monitor the rate at which conditions including stratigraphy and mechanical properties. This will feed into a larger study aiming to prosinkhole triggering mechanisms. It will involve further Methods with nested microgravity and passive seismic techniques length spring sensor technology with a typical repeat station approximately every two hours. A line of micro Due to the eastward dip of the Permian rocks and the surrounding areas, artesian springs contain dissolved has passed through and dissolved gypsum from the Edken rock and sediments which extends upwards from the gypsum layer at depth, and therefore connects the conFigure 3. Bedrock geology of the Paddies Park area (red) showing the Brotherton Formation (blue) and Edlington Formation (orange) (Reproduced from British Geological Survey data UKRI (2019) with permission. Contains Ordnance Data Crown Copyright and database rights 2020. Ordnance Survey Licence no. 100021290).

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113NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE termed microtremors. Microtremor measurements from are not of direct geological interest. The gravity anomaly ity values and those determined either from a theoretical prediction for the same location, or relative to the gravity The seismic technique uses seismic noise, which exists everywhere, consisting mainly of low-amplitude sur Figure 4.

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11416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 the surface approximately levelled. The Tromino unit ance contrast, often associated with a soil layer over vs is required for processing and interpretation. For the SH-resonance frequency in a single layer of thickness h Figure 5. Survey point positions. Note that the previously mapped dolines are outdated and their position is not accurate. Contains Ordnance Data Crown Copyright and database rights 2020. Ordnance Survey Licence no. 100021290.

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115NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEthen imported into one of six software packages in order to grid, map or model the data and one of two software packages in order to visualise it.Results the surface depression measures 20 m across and extends scan also shows that the eastern side of the park is slightly lower, and highlights further depressions in the park. The microgravity anomaly plots from a preliminary sur assumed for the cover sequence. The curves are used to calculate the impedance using the software, which produces a vertical cross section of impedance plotted using general purpose surveying. The positional measurement Figure 6. Contour plot of impedance from H/V ratio across Paddies Park depression.

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11616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 to the west of the park that were previously mapped. surveyed, they are situated within a larger area that has The passive seismic result shows an impedance contrast ticipated. This result was achieved using a shear wave DiscussionBoth the gravity surveys and passive seismic surveys show a clear change in the ground composition where the depression lies. The negative gravity anomaly indicates a region of lower density, while the passive seismic results indicate an area of low impedance in the same region. Figure 7. Aerial view of LiDAR scan (NNE to the right). Surveyed sinkhole in top right corner as indicated in white. Elevation in meters above mean sea level. Figure 8. December 2017. Line of section shown in Figure 5. Figure 9. 2019. Line of section shown in Figure 5.

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117NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEIn order to interpret the results further, investigation into the properties of the soil, such as the density, shear wave velocity and water content are required. Once these have References measurements, processing and interpretation, resulting from the dissolution of Permian gypsum the dissolution of Permian gypsum in England: England. In: Land L, Doctor DH, Stephenson Environmental Impacts of Karst: Proceedings of the Thirteenth Multidisciplinary Conference UK: the use of digital data for hazard management. clay, and initial in situ shear wave velocity tests using pedance contrast is associated with a change of soil type at a shallower depth. Further investigation and material testing is required to determine an appropriate value for Vs and the increase exponent. A feature is also present cates another change in strata. of reasons for this change, including seasonal moisture content changes, further compaction of the ground or inaccuracy in the measuring equipment. Further quarterly continuous change with time.ConclusionsPassive seismic surveys and microgravity surveys were taken across the short axis of the depression. The passive seismic surveys show a column of high impedance madensity or higher porosity. The microgravity surveys show neath the depression. From these geophysical surveys it of the depression is the compaction of these deposits. There is some evidence to suggest this compaction will negative anomaly decreased, suggesting an increase in

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118NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE The application of microgravity geophysics in a

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119 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8CROSSHOLE MAPPING OF A SUBSURFACE VOIDAbstract radation due to karst geology. The cement capped woodDue to the dissolution of limestone, water seepage dam included installing engineered secant grout curtains During the intrusive investigation a void was encountered to prevent groundwater from migrating through the void. ings imaged a fracture zone. The fracture zone displayed lower p -wave velocities in contrast to the surrounding material within the survey area. This low velocity zone zones within the fracture in the limestone.Introduction cellular sheet pile structure upstream of the existing dam to prevent groundwater from migrating under the dam. cellular sheet pile structures installed upstream of the existing dam. Peter J. HutchinsonTHG Geophysics, Ltd., 4280 Old Wm. Penn Hwy., Murrysville, Pennsylvania, 15668 USA, pjh@thggeophysics.comMaggie H. TsaiTHG Geophysics, Ltd., 4280 Old Wm. Penn Hwy., Murrysville, Pennsylvania, 15668 USA, mhb@thggeophysics.com Figure 1. A location map of Lock and Dam 8 located south of Lexington, Kentucky.

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120NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE as having transpressive motion (compressional to striketiple episodes of the Appalachian Orogenesis (Morisen, phase faulting under separate yet distinct stress regimes Crosshole TomographyCrosshole tomographic imaging is commonly used when high resolution deep seismic data is needed or a surface p one serving as the source hole and the other as the reis triggered at intervals over the length of the casing that cause the slurry to dissipate into the surrounding fractured rock and voids. This would prevent the secant cur GeologyThe dam site and surrounding area consist of the Middle shale partings throughout its vertical extent (Walcott, Figure 2. Aerial view to the northeast (upstream) of Dam 8 on the Kentucky River as of 2017 showing the completed concreteFigure 3. Left photo shows the collapsed portion of the dam near the left abutment in 1994. Right photo shows dye leakage at the left abutment in 2001 (Welshans et al., 2011).

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12116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 calculated to produce an apparent velocity model. The model is compared to the actual measurements for conCrosshole Survey V=L/T Where L is distance and T wave front. each geophone and source to calculate the velocity from the Figure 4. Location of 4 crosshole borings (T-1, T-2, T-3, and T-4) and boring B-13 within coffer dam Cell C-2 from design drawing for the rehabilitation of the dam (Welshans et al., 2011). Depth contours (in m amsl) of a fracture zone are shown as green dashed lines.

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122NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE p-wave. To maximize the signal to noise ratio numerous stacks of the data were acquired at each shot location.Analysisp-wave Seismic events were triggered with a Ballard Shear Wave Energy Source. To create a seismic event, water p-wave velocities Seismic methods rely on acoustically quiet areas and are Figure 5. Location of coffer dam, Cell C-2, within the cellular dam system (September 19, 2016). The 18-m diameter coffer dam is in the process of being tremie grouted with a cement-grout mixture subsequent to the crosshole work (September 2015).

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12316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8collected, the p T1–T4 p -wave velocities throughout and is interpreted as heavily fractured and weathered. Bor T3–T4 p Figure 7. Geology in the vicinity of the Kentucky River Lock and Dam 8 (Walcott, 1970). Figure 8. Source to receiver raypaths for the Figure 6. Stratigraphic column from boring B-13.

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124NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE rounding this low velocity zone. T2–T4 which is a long distance for a seismic event to travel sent vuggy conditions. T1–T3 p-wave velocities throughout and is interpreted as heavily fractured and weathConclusion indicate a fracture zone that displays lower p -wave velocities in contrast to the surrounding material within the survey area. velocities throughout, indicative of heavily weathered zones. ooW (FigT3–T2 p red color contours surrounding this low velocity zone. T2–T1 p-wave velocities Figure 9. Borehole orientation with respect to neighboring borehole. Figure 10. Crosshole p-wave velocity tomographs between each cased boring showing top of limestone (blue line); possible void (thin black line on T1–T4) below projected B-13 void (red circle); and fracture (red dashed line).

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12516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 o (from dam. Clearly the secant wall, as installed, will decrease the potential for groundwater to seep through the dam. ooE, consistent with the results presented ment-grout mix prior to the installation of the secant Figure 11. Crosshole p-wave velocity tomographs between each cased boring showing top of limestone (black dashed line); projected B-13 void (red circle); and fracture (red dashed line). Velocity color scale is shown on Figure 10. Figure 12. Cross section A-A’ showing the relationship of the secant wall to the fracture zone (see Figure 4).

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126NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCESeismic methods rely on acoustically quiet areas and are river and water rushing into the cell did not provide a quiet environment for the survey and may have inter pwave. It is recommended to ground truth the seismic zones.Acknowledgements and Mr. Hatton.References Kentucky. U.S. Army Corps of Engineers, Louisville District, Survey, Washington, DC.

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127 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8CHARACTERIZING NEAR-SURFACE KARST SYSTEM UNDER THREE STORMWATER RETENTION BASINS IN SILVER SPRINGS, FLORIDAAbstractWater resources in karst systems are particularly vulner hydrogeological characteristics. Better understanding of near-surface karst systems may inform contaminant transport and protective management of karst aquition of the near-surface karst system. The reported sinkLow conductivity EM zones in the vertical (rather than karst system. The spatial variation of EM response in the vertical coplanar is relatively correlated with the the study area is highly heterogeneous, indicating that transport rates and contaminant transformations in the IntroductionStormwater management in karst regions requires adequate understanding of contaminant transport within springs. Land surface, vadose soil layers, and aquifers -Mohammad ShokriUniversity of Central Florida, Civil, Environmental, and Construction Engineering Dept. 12800 Pegasus Drive, Orlando, FL, 32816, USA, Shokri.m@Knights.ucf.eduYuan GaoUniversity of Central Florida, Civil, Environmental, and Construction Engineering Dept. 12800 Pegasus Drive, Orlando, FL, 32816, USA, yuan.gao@Knights.ucf.eduKelly M. KiblerUniversity of Central Florida, Civil, Environmental, and Construction Engineering Dept. 12800 Pegasus Drive, Orlando, FL, 32816, USA, kelly.kibler@ucf.eduDingbao Wang University of Central Florida, Civil, Environmental, and Construction Engineering Dept. 12800 Pegasus Drive, Orlando, FL, 32816, USA, Dingbao.Wang@ucf.eduNi-Bin ChangUniversity of Central Florida, Civil, Environmental, and Construction Engineering Dept. 12800 Pegasus Drive, Orlando, FL, 32816, USA, nchang@ucf.edu

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128NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEnear-surface conditions in karst areas (Doolittle and Colceiver coils within which electrical current is generated. A primary transmitter coil is set to a discrete frequency lated to mineralogy, porosity, pore water conductivity, and degree of saturation. in the springshed of a high-magnitude freshwater spring karst condition in the area to local municipalities and or ganizations aimed at protecting water quality.Study Area and Geological SettingThe study area is comprised of three water retention 2 to creamy granular limestone and dolomite formation of ropy of hydraulic conditions, resulting from dissolution potential direct connections from contaminated surface point sources of nutrient and contaminants delivering For instance, stormwater management with dry and wet cal activities in their upper layer of soil (Harper and Bakand springs such as Silver Springs in Central Florida has received widespread attention due to excess non-point characterize contaminant transport in karst systems and design protective measures against aquifer contamina tion are necessary in karst regions. Thus, particular atsurface karst systems in the vicinity of water retention detect caverns, sinkholes, conduits and structural dis

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12916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 data was removed for providing more accurate estima Florida, which is associated to velocity of pulses and thus estimation depth, was chosen for the analysis. The the location of main Silver Springs vents, forming a local dry during data collection, however, some parts in the middle Methods Figure 1. Silver Springs springshed in Florida (A, dotted polygon), stormwater retention basins investigated with respect to Silver Springs (B) with including reported sinkholes. Sinkhole data is from Florida Department of Transportation. Note: solid green color lines present border of the basins while light dotted green color lines indicate the geophysical coverage area within the basins.

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130NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEductivity measurements were created using a kriging Results and DiscussionBasin 1 2. A large (approximately further interpretations. The anomalies were categorized in terms of apparent level of severity into severe level depth within the anomaly area in comparison to the sur rounding non-anomaly areas. Considering the dimension The EM data were used for generating spatial variation Figure 2. (A) Collapsed sinkhole near stormwater inlet pipe in Basin 1, (B) small deep soil pipe in Basin 1, (C) partially-collapsed pits in Basin 2 and (D) open sinkhole in Basin 2. Note: surface

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13116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8hole as a conductive zone or an enhanced moisture zone Basin 2 Eleven sinkholes and partially-collapsed pits were re2 anomalies are higher in vertical dipole mode of EM data relation of the EM horizontal dipole contour map is a the comparatively same depths of survey in the horizontal dipole mode of EM data collection (approximately vertical dipole mode of data collection (approximately techniques of detecting potential near-surface karst feaareas are associated with presence of media with low the low conductivity EM zones in the middle-west and of the collapsed sinkhole shown in Figure 2A. That highBasin Feature Features Feature area (m2 Depth Survey area feature to survey Min Max Mean STD Total S 2 S S Table 1. Characteristics of surface and near-surface detected features in the surveyed area of the basins. Note: Under feature column, S indicates surface feature and N-S indicates near-surface features. Surface features include reported data by Florida Department of Transportation. Feature area is the area associated to the features. Survey area is the area within the basin which was surveyed by GPR and EM techniques.

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132NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 3. Variation in EM horizontal and vertical dipoles and GPR anomalies in Basin 1 (A and B), Basin 2 (C and D), and Basin 3 (E and F). The intercoil spacing in EM survey was 10 m. Note: Depth of investigation in EM horizontal dipole is approximately 7.5 m while that is approximately 15 m in vertical dipole mode. The depth of GPR anomalies in each pair map are same.

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13316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Basin 3 potential karst features were detected which were catanomalies are mainly located in the north part of the The analysis of EM conductivity contour lines suggests suggest more development of near-surface potential karst features likely due to deep soil depression imshallower depth of exploration in EM horizontal dipole groundwater through open sinkholes, providing inefprevent additional sinkhole failure, groundwater level in groundwater levels, either seasonal or uncontrolled Figure 4. data (red circle points) within geophysical survey areas (light green color dashed lines) in the Basin 1 (A), Basin 2 (B), and Basin 3 (C).

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134NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Analysis in Measured Conductivity under system exploration: an overview. Hydrogeology and Loading Tool: An integrated approach toward restoration of water-quality impaired karst springs. Fernandes JAL, Medeiros WE, Bezerra FH, Oliveira Jr aerial vehicle imagery. Journal of Applied stormwater design criteria within the state of Florida. Stormwater Academy, University of contaminated water.Summary surface karst conditions in three stormwater manage sins, likely due to intrinsic complex and heterogeneous condition of karst system. For instance, interpretation of transport and water resources management. Stormwater Acknowledgmentsment of Transportation. Authors would like to thank help, advice, and providing equipment for this research.References fractures in thinly mantled karst, east-central

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13516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8to ground-penetrating radar data collection and Conductivity Measurements at Low Induction experimental investigations for cavity research a leachate plume and a fault zone. Journal of Silver Springs Basin, Florida, with an emphasis on leveling. Mantled evaporite karst of Zaragoza city, resistivity technique to the detection of solution enrichment hypothesis in Florida springs: evidence, alternatives, and adaptive management. Ecological Water Management Section, Florida Department of water withdrawals from the Floridan aquifer Forest and vicinity, north-central Florida. U.S. hydrogeological investigations. IHP-VI Series on potential risk of phosphorus to groundwater across constant values of geologic materials: An aid

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136NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE karst terrains: their investigation, monitoring, and mitigation and design of engineering structures on using electrical resistivity method to locate karst

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137 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 investigations were made. Initial Geophysical Methodskarst. The initial investigation of the site included two Terrain Conductivity source coil. The induced current produces a secondary can measure ground conductivity in quadrature-phase AbstractOver a period of several years, multiple investigation methods were used to assess conditions within the area tion was a conventional geotechnical study using autime later sinkholes formed and additional investigations were undertaken. The new investigation added seismic and spontaneous potential geophysics, as well as, rock was excavated to expose the top of rock surface. Comthe exposed conditions show limitations of the methods Introduction cal and geotechnical testing are often performed in adgeophysical methods are often used for investigation of karst with varying degrees of success. These most commonly consist of electromagnetic and seismic methods, though other methods such as gravity survey also have application. sinkhole activity. Investigations were conducted using electromagnetic methods of geophysics together with Michael J. Byle, P.E.Tetra Tech, Inc. One Oxford Valley, Suite 200 Langhorne, PA, USA, michael.byle@tetratech.com COMPARISON OF INVESTIGATION METHODS AT A KARST SITE

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138NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEfairly little variation and no evidence of discreet karst soil sampling, the risk of sinkhole formation was considments. The quadrature phase is typically most useful in karst investigations for measuring variations in the versus soils and voids associated with karst. The method is sensitive to the presence of conductive materials at or tivity of soils, voids, and rock. Capacitively-Coupled Resistivity transmitter and receiver, to induce and measure the cur rent similar to the TC method. Its advantage over conventional resistivity testing is the elimination of the need sured as a voltage at the receiver which is proportional to resistivity is calculated using the appropriate geometric factor for the capacitively-coupled antenna array. The ported in the inverse as conductivity for ease of compari son with the TC data.Initial FindingsThe initial TC investigation indicated generally uniform would indicate karst anomalies. The conductivity was elevated around the site perimeter and along an access to interference from a wire fence on the site perimeter and the presence of slag aggregate in the access roadway. Figure 1. Initial Terrain Conductivity Results. Note the presence of metal detected along roadway and perimeter Figure 2. Capacitively-Coupled Resistivity; 35’ target depth, plotted as conductivity.

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13916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 3. Capacitively-Coupled Resistivity; 50’ target depth, plotted as conductivity. Post Construction Sinkholestwo collapses occurred after a large precipitation event Figure 4 . View of Basin Showing Sinkhole Locations Second InvestigationAs a result of the sinkhole development, additional investigation was conducted with the intent to evaluate the collapse areas and assess likelihood for occurrence of vey, and test excavations.Seismic Refraction pulse is plotted against distance to identify changes in higher velocity. The results of multiple tests are comtogether to assess the iso-velocity topography as contour Spontaneous Potential Spontaneous potential measures the naturally occurring the soil surface. These SP surveys use high-impedance digital microvolt meters to measure naturally-occurring tween almost any two points on the ground surface.

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140NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE cient integrity to stand open.Test Excavations Test excavations were conducted over the area of the geophysical investigation.Results of Second Investigation than was indicated in the initial investigation. The uppermost layer of soil was designated for compression interpreted as an epikarst zone. Sound rock, the deepest graphic assessment of the interpreted top of epikarst and ing locations and elevations are shown on the epikarst voltages known as streaming potentials. Downward instatic attraction surrounding the negative areas. in karst features generating spontaneous electrical potensidence. The reference potential electrode is placed outside the area of measurement. Borings and Televiewer to the top of rock. Standard split-spoon samples were collected to assess soil consistency and type. The hollow The Televiewer is a device that uses optical and acoustic survey methods to record conditions on the walls of the Figure 5. Post Construction Sinkholes

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14116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8The presence of closed conduits within the rock was assessed using rock core and the televiewer. Borehole locations were selected at locations surrounding the sinkhole area along geophysical survey lines for use in ground-truthing the geophysics. In the recovered core, no clear evidence of voids was recorded, however, eviplayed. The openings indicated in the cores were gener of very similar shallow rock depth and considering the were in areas where seismic refraction indicated lows in located to assess deeper rock locations as well. A test trench excavated across the sinkhole area conphysics, however, the rock surface changed much more and inferred top of rock.. The SP testing produced an interesting pattern of values within the site that is expected to correlate to locations trates the results of the SP tests. The zones of downward seepage tend to generally coincide with areas of deeper the rock surface and nature of karst features. Where karst features consist of discrete openings or conduits Figure 6. Seismic Refraction Results: (left) Top of Epikarst (1400 mps/4500 fps); (right) top of inferred rock. Top of rock elevations encountered in borings are shown. Red dotted circle depicts the area of sinkholes and dotted gray lines represent the geophysical survey lines.

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142NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEall trend was similar, the orientation and depth of rock, especially in the deeper areas was not in good agreement. One test trench was excavated along the line of a seismic physics is in fairly good agreement with the highest rock encountered in the test excavation. Similarly, the top of sound rock inferred from the seismic refraction agrees pretty well with the deepest rock encountered in the test excavation. seismic velocities. Since seismic signals travel all mic refraction surveys. Figure 7. Spontaneous Potential Survey Results. Circle depicts area of sinkholes. Line indicates location of test trench and gray dots indicate measurement locations. Figure 8. Rock Core C-5 and Televiewer

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14316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8taneous potential test did identify active seepage areas that agreed well with the locations of features that had as yet, revealed no surface expression. The increased from the SP survey. While, the groundwater dynamdetected. On an interesting note, new sinkholes opened some months after the repair of the initial sinkholes at this site at locations predominantly in the areas indicated potential survey. excavation and televiewer in cored holes. However, test excavation is highly disruptive and would require exten sive soil removal and replacement unless, locations can are limited to a small diameter at a discrete location and use appropriate geophysics to focus the more disruptive intersect features of interest. ConclusionsThe only way to fully identify all covered karst features the top of rock. This is not a practical solution and it is one-to-one agreement in all cases, the spontaneous pothe sinkhole occurrence at the site.Discussion sound rock, which would all have displayed relatively high resistivity. vertical sounding information that would depict the varilikely have resulted in improved results. and the soils, in light of the deep ground water surface. The relatively low density soils have much lower seissolution troughs due to averaging of the wave velocities crossing through pinnacles and soil. While individual Figure 9. exposed during sinkhole remediation subsequent to the test excavation.

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144NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE tion and spontaneous potential, together with ground truthing test excavation, provides the This study indicates the importance of understanding site conditions prior to selecting and relying on a single geophysical method (e.g. the presence of clay, groundwater methods to develop an improved characterization of site tures, spontaneous potential is considered a good low methods are low cost, and often the go-to method for initial surveys, an evaluation of anticipated electrical contrast and consideration of expected groundwater levfor sites like this. References www.astm.org Engineering and Environmental Investigations, Wightman WE, Jalinoos F, Sirles P, and Hanna face in order to assess the risk for development of a site. Surface geophysical methods can provide useful infor mation helpful to the evaluation of karst sites. However, all surface methods have limitations and have reduced resolution with depth. Karst sites are especially challenging and impose many limitations on the interpreta tion of geophysical methods. sidered appropriate for this site due to the clay content of the soils that typically limits the depth of resolution to three feet or less in this area. pict the covered karst conditions at this site, likely due to a lack of electrical contrast at depth due, in Seismic refraction provided an improved piccations within a few feet at a few locations. It is the interpretation of conditions. It is important range of the depths and conditions expected. Coring of the rock provided some evidence of disviewer survey of the cored hole provided high resolution of solution features and voids within the useful to identify and evaluate the nature of karst ruptive and not practical for large scale site assessment. Test excavations are useful for ground truthing where site conditions permit their use. Spontaneous potential provided a very low cost pic

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145 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8frastructure. On average, sinkholes result in more than and this estimate is likely to increase as the U.S. population and related developments continue to grow (Kugions, it is critical to develop the regional management ity mapping is one of the most important steps to mini mize or mitigate the damages associated with sinkholes generally grouped into two: qualitative and quantitative knowledge, and demonstrate the hazard levels in descriptive terms. The quantitative method, on the other hand, is AbstractThe state of Florida sits on the karst terrain where solmon geohazard. These sinkholes have caused damage to property and infrastructure, as well as threatened human life. It is essential to develop a tool for predicting the potential of sinkhole occurrence. This study presents the methodology of the development of the sinkhole hazmethod was employed. A sinkhole inventory map was system thickness, intermediate aquifer system thickness, and proximity to karst features. The results show that the than the Ocala area. This result is consistent with the sinkholes than thin areas.IntroductionSinkholes are a common geohazard in karst areas where related incidents often make headlines in the news, and the sinkholes can cause heavy losses to property and in-Yong Je KimDepartment of Civil, Environmental, and Construction Engineering, University of Central Florida 4000 Central Florida Blvd Orlando, FL 32816, USA, yongkim@knights.ucf.eduBoo Hyun NamDepartment of Civil, Environmental, and Construction Engineering, University of Central Florida 4000 Central Florida Blvd Orlando, FL 32816, USA, boohyun.nam@ucf.eduQipeng Phil ZhengDepartment of Industrial Engineering and Management Systems, University of Central Florida 4000 Central Florida Blvd Orlando, FL 32816, USA, qipeng.zheng@ucf.eduAN ARTIFICIAL NEURAL NETWORK APPROACH TO SINKHOLE HAZARD ASSESSMENT FOR EAST CENTRAL FLORIDA

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146NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEStudy Area 22,000 km2main lithology in the area includes marine limestone, repeated wet and dry seasons. The average annual rainThe mean monthly rainfall dramatically increases from logic sequence underlying ECF is generally divided into aquifer or, if these rocks have no water-supply potenengineers to make well-informed decisions in the management and mitigation of sinkhole hazards. Traditional ed information, not the size information. Since the level of damage varies depending on the size of the sinkhole, it is important to consider the sinkhole size information for accurate sinkhole hazard assessment. In addition, if odology to develop the sinkhole location-size model. In used and could integrate the location and size of the sinkhole occurrence. Figure 1. Location of the study area and sinkhole inventory.

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14716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 from state and federal agencies as well as other digital Sinkhole Contributing Factors In this process, factors that are not correlated with sinkand analyzed for this purpose. Figure 2 shows the cor the sinkhole densities in ECF generally either increase As the value of factors related to soil erosion such as seen that sinkholes are rarely developed in areas with a SAS and IAS thicknesses, generally decreases sinkhole density. In addition, as the proximity to karst features increases, the sinkhole density tends to decrease. lated to each other and that a factor such as proximity positively correlated with SAS and IAS thicknesses and proximity to karst features, and negatively correlated limestone and dolostone. sive karst features, while rarely found in areas further south and along the east coast. The northern area has a hydrogeological characteristics of ECF are closely reData Preparation thickness, SAS thickness, IAS thickness, and proximity to karst features. In this study, the sinkhole inventory and size of the sinkholes. ported sinkhole locations is highly dependent on populasinkholes were found in areas with high population den2

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148NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Figure 2. Correlation between sinkhole density and contributing factors: (a) head difference, (b) recharge rate, (c) soil permeability, (d) overburden thickness, (e) SAS thickness, (f) IAS thickness, and (g) proximity to karst features.

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14916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 sinkhole hazard, and then the sinkhole hazard map was produced. work consists of an input layer, one or more hidden layers, and an output layer. All inputs are fed to the model used to process the inputs received from the input layMethodology tors to sinkhole occurrence was checked to ensure the selected factors are used as input to the model. In the third step, the sinkhole location-size model was developed ushave no size information, the Markov chain Monte Carlo In this process, various statistical analysis methods such Figure 3.

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150NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEThe learning rate is usually the most important hyper n learning rate in the nminmax are the minimum and maximum value of the learning rate, respectively, and d is the delay rate. cluding signal propagation and weight updates. The signals in the data are propagated forward throughout the used to compare the result with the expected output. The error value. Figure 4. Structure of the ANN model. Table 1. Correlation matrix by Spearman’s correlation test. Equation 1

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15116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8ECF in the future. The Category 2 map represents the sinkhole occurrence greater than 0 m corresponds to the velopment, thus the valid time of the model prediction shows four examples of sinkhole hazard maps when the lower in the Ocala area and somewhat higher in the Or lando area. This is consistent with the fact that sinkholes in the Orlando area are on average larger than sinkholes neuron in the input layer represents seven sinkhole conof the weights associated with the connections, which was set to 0.02 for this analysis. The momentum facresearch for minimum errors and was used to accelerate Results and DiscussionThe sinkhole hazard model was constructed using the Box-Cox transformation was applied in order to improve normality in the sinkhole size dataset and also to reduce result, the average and standard deviation of the sinkhole throughout the study area. Ten size categories were consinkhole hazard maps. For example, the sinkhole hazard Figure 5. Sinkhole susceptibility map showing the probability of all sizes.

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152NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEwhere active sinkhole activities are present. Key sinkhole frequency. Missing values of sinkhole sizes were The sinkhole hazard map shows that the northwestern holes in some areas of central Florida region larger than ConclusionsThis paper introduces a methodology to develop the sinkhole location-size prediction model and presents a preliminary result. The study area was limited to ECF Figure 6. Sinkhole hazard maps of (a) category 2 (size: 0 to 3 m), (b) category 3 (size: 3 to 6 m), (c) category 4 (size: 6 to 9 m), and (d) category 5 and up (size: > 9 m).

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15316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 karst terrains of the United States. Hydrogeology Methods, instrumentation, and preliminary assessment of Lake Lucerne, Polk County, Tallahassee, FL. p. and Hydrogeology in West-central Florida -larger sinkholes than the Ocala area. This result is coners produce larger sinkholes than thin areas. As future holes will likely occur in ECF. References sinkhole hazard assessment. A case study from the Conference on Sinkholes and the Engineering Denver, CO: American Society of Civil Engineers. The current status of mapping karst areas and

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154NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Sinkhole Collapse in the United States Compared and the Engineering and Environmental Impacts Machine Learning Models Based on Bayesian Optimization. Journal of Electronic Science and

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155 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 IntroductionSinkholes are known as a naturally occurring hydrogeological process that causes life-threatening events and Many researchers have conduced geological and hy-Abstract state of Florida. This extreme weather event produced gation of the sinkhole sites where openings occurred in the middle of a roadway, was carried-out. Multiple cone lapsed sites. In this paper, a comprehensive case study of a sinkhole collapse is presented. First, a hydrogeological assessment on the sinkhole site was conducted. Second, CPT data were investigated. Particularly, a sinkwere used to estimate soil type and strength parameters as inputs to the FE model. Based on the results of multiRyan ShametUniversity of Central Florida 12800 Pegasus Drive Orlando, Florida, 32816, United States, rshamet@knights.ucf.eduMoataz SolimanUniversity of Central Florida 12800 Pegasus Drive Orlando, Florida, 32816, United States, moatazhs@knights.ucf.eduYongJe KimUniversity of Central Florida 12800 Pegasus Drive Orlando, Florida, 32816, United States, yongje.kim@knights.ucf.eduTimothy CopelandUniversity of Central Florida 12800 Pegasus Drive Orlando, Florida, 32816, United States, trcopeland10@knights.ucf.edu Boo Hyun Nam, Ph.D.University of Central Florida 12800 Pegasus Drive Orlando, Florida, 32816, United States, boohyun.nam@ucf.edu (corresponding)SINKHOLE INVESTIGATION AFTER HURRICANE IRMA

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156NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEwere formed. Just within two weeks after Irma, at least a map of central Florida showing the locations of those It is hypothesized that the extreme rainfall event trigIn addition, a regional-scale sinkhole hazard map of east It is known that extreme water events trigger sinkhole gered the formation of many sinkholes throughout the face water due to rainfall events increases the load on den soils. In this paper, one of the post-Irma sinkhole sites, US analyses. Background on Hurricane IrmaHurricane Irma made landfall in central Florida on Sepof rainfall across the Floridian peninsula. Hurricane Irma at least nine US states. Making landfall in southwest Figure 1. Path of Hurricane Irma (from National Hurricane Center, 2018). Figure 2. Map of central Florida showing postIrma sinkholes.

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15716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 proceeds, the size of the raveled zone increases while within the site. Lastly, a FE analysis was conducted to further investi p-q stress one in Ocala, FL was selected. the well data of upper Floridan aquifer and the resulting sidering a slower respond of Florida aquifer to surface Irma. This occurrence may result in a temporary higher US441 Post-Irma Sinkhole Investigation MethodologyThe research team conducted a post-hurricane investiga First, the hydrogeological assessment at a regional scale technical assessment. This initial assessment investi gated the regional-scale maps of groundwater recharge, ness to understand overall hydrogeological conditions in qualitative and quantitative manner. As seen in the CPT tip resistance (qc soil raveling. Due to the raveling of soils, qc Figure 3. Precipitation and potentiometric elevation trends of Floridan aquifer during time of Hurricane Irma (after USGS 2018). Figure 4. Post-Irma sinkhole investigation tasks

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158NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE elevation. The values of those parameters were varied in the simulations so that critical conditions causing failure p-q ity. Particularly, the p-q stress paths of two critical points raveled zone was modeled as a half-circular cavity and the hydrostatic condition was employed in investigating and initial strength input parameters estimated from cor relations using the CPT resistance values (Kulhawy and Results and DiscussionAssessment of Hydrogeological Factorsvestigated using the maps of those key hydrogeological It is hypothesized that the hurricane raises the surface cavity grows due to the seepage induced soil erosion. Figure 5. Figure 6. Numerical modeling of the US441 site in PLAXIS2D

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15916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8CPT-based Assessment collapse. Selected CPT qc others are relatively distant from the collapse. All CPTs a sinkhole was formed at this site, each CPT location exc values along depth, which is commonly where all hydrogeological conditions are highly favor high potential of internal soil erosion due to groundwater upper Floridan aquifer systems that may expedite the Figure 7. Hydrogeological factor maps showing (A) recharge (B) head difference C) overburden thickness (D) aquitard thickness

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160NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEWhere: qover qravel tover travel the collapse does not always correlate with the sever c Figure 8. CPT tip resistance (qc2 = 95.7kPa)

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16116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8less raveled condition. It was assumed that the soil confore hurricane Irma and contains the typical amount of raveling expected from a normal central Florida soundA half-circular void was assumed to evolve at the soilIn the simulations the radius of the cavity was increased and the analysis was performed at one meter rising increments till reaching the ground surface. Also it is important to note that the anlaysis was conducted under hydrostatic condition. collapse. It is postulated that raveling (or internal erothe surface collapse is not always vertically aligned with the sinkhole source. The sinkhole source, which is the initiation point of cavity growth, is considered as a point of groundwater recharge. Often the raveling progresses as piping channels propagating in a diagonal direction, the sinkhole source. Numerical Analysis Figure 9. Plots of SRR values at the sinkhole site US 441, Marion County

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162NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE generate an increase of hydraulic gradient (i hydraulic gradient leads to large seepage velocity, which FE analysis results support that the impact of raised the failure of collapse. In summary, it is concluded that site is a rapid increase in hydraulic gradient (or seepage collapse type of sinkhole in the site. References the development of sinkholes and karst in Florida, ior was shown as the the size of cavity increases. Point while point B shows the stress path to the right-diagonal direction. In other words, point A shows an unloadingshearing (i.e., the and point B shows a loading-shearing in pore water pressure, resulting in the stress path shifted Summary and ConclusionsThe authors performed an investigation on a sinkhole method includes three approaches: a hydrogeological asholes were formed within two weeks after Irma. Second, Figure 10. Results of numerical analysis: stress path change due to (a) cavity size increase and (b) groundwater table rise.

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16316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 on Estimating Soil Properties for Foundation Alto, California. The current status of mapping karst areas and karst terrains of the United States: Hydrogeology Department of Transportation, Tallahassee, West Virginia. risk evaluation: detection of raveled soils in residual soil in karst. Journal of geotechnical and review on natural and human-induced geohazards Proceedings of the Third International Symposium karst sinkhole hazard mapping using frequency

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164NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE of the impact of local-scale hydrogeologic conditions on sinkhole occurrence in East-Central

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165 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8then released clean into the karst. We have also studied Construction work has provided a series of important through various processes. We have studied the karst along expressways on Classical Karst (southwest Slogion are Triassic and Jurassic limestones and dolomites. This selection of sites includes the most important ar eas of our karst regions. We have acquired a great deal epikarst, and where excavation work has cut deeper in paleokarst. Everywhere the development of the karst left Abstract the country via modern expressways. Almost half of Slovenia is karst and more than half of its supply of water comes from karst aquifers. Slovenia is the home of the Classical Karst region, which gave name to numerous world languages for the type of landscape that develops natural and cultural heritage, the sensitive karst landscape demands from us good knowledge and serious efregular research of karst features revealed during the construction of expressways for spatial planning in karst regions of Slovenia.Introduction closely in the planning and construction of expressways in karst regions. With the consideration of the integrity of the karst landscape in the foreground, we have recommended avoiding important areas of karst phenomand already known caves in the selection of routes for expressways. We have devoted special attention to the Knez Martin1Research Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute Titov trg 2, Postojna, SI-6230, Slovenia, knez@zrc-sazu.si 2University of Nova Gorica, UNESCO Chair on Karst Education Glavni trg 8, Vipava, SI-5271, Slovenia, knez@zrc-sazu.si 3Yunnan University International Joint Research Center for Karstology Xueyun rd. 5, Kunming, Yunnan, CN-650223, China, knez@zrc-sazu.siSlabe Tadej1Research Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute Titov trg 2, Postojna, SI-6230, Slovenia, slabe@zrc-sazu.si 2University of Nova Gorica, UNESCO Chair on Karst Education Glavni trg 8, Vipava, SI-5271, Slovenia, slabe@zrc-sazu.si 3Yunnan University International Joint Research Center for Karstology Xueyun rd. 5, Kunming, Yunnan, CN-650223, China, slabe@zrc-sazu.siPLANNING AND CONSTRUCTION DATA AS A RESOURCE FOR REGIONAL KARST ASSESSMENT; EXAMPLE FROM CONSTRUCTION OF EXPRESSWAYS FROM SLOVENIA

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166NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEto the underground water. The deepest shaft found mea one third are unroofed caves. vidual section of the expressway. As a result, most of the caves were anticipated. In the Kastelec tunnel (Classical tens of construction sections. Most caves were discovered during earthmoving works. Figure 1. Caves opened during the construc tion work on Classical Karst. Legend: 1a-cave, Figure 2. Shaft opened during the construc tion work on Classical Karst. Figure 3. Different caves uncovered during the motorway construction on Classical Karst.

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16716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Figure 4. during the construction work on Classical Karst. Classical Karst, southwest SloveniaIn the karst region of western Slovenia, we have studied surface karst phenomena such as dolines and karren. The numerous newly opened caves have revealed the perforation of individual parts of the aquifer. These include old caves that today are dry since they are located high cal features, patterns of cave networks and their parts, termine important periods in the formation and develop ment of caves and their age. Paleomagnetic determina crises when the groundwater level, connected with the rank them among our oldest caves, and their age exceeds our previous estimates. The opening of unroofed caves, we discovered that these traces of the development of the aquifer helped form the karst surface much more than we previously suspected. Due to atmospheric factors, of all caves discovered all along the layout. Unroofed caves, which are the consequence of the lowering of the karst surface, comprise a new form that we Figure 5. Unroofed cave opened during the construction work on Classical Karst. Figure 6. Unroofed cave opened during the construction work on Classical Karst. have added as a unique form to the international list of

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168NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE history of their former intensive exploitation, primarily for agriculture and water supply. Classical Karst has an extraordinary and rich history. Over a hundred years ago, agriculture and animal farming. After land use was gradAlluvium-covered karst, southeast Slove niaConstruction work on the low and largely alluvium-cov karst surfaces. The water that penetrated through the soil Karst in breccia, southwest Slovenia Vipava Valley provided a unique discovery (Figures Figure 7. Primarily revealed the subsoil shaping of the karst, southeast Slovenia. Figure 8. Large areas of stone forests with their characteristic subsoil rock forms, southeast Slovenia. Figure 9. sediment, southeast Slovenia. types of caves were discovered. Smaller caves character -

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16916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8karst features and presented and preserved them for fur ther study. The research results are also a starting point for spatial planning in karst areas and for protecting the of new railway crossing Classical Karst. istic of karst developed in the most consolidated parts of smaller streams. Fissure caves are the consequence of tacts.ConclusionThe regular research of karst features revealed during riched our knowledge of the natural and cultural heritage and deepened karstological knowledge. In any case, the Figure 10. A cupola-shaped widening of the cave passage, southwest Slovenia. Figure 11. southwest Slovenia. Figure 12. Fissure caves in breccia, southwest Slovenia. Figure 13. During the construction caves of various shape and largeness were revealed dictating further earthworks.

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170NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE largest karst caves discovered in a tunnel during motorway construction in Slovenia‘s Classical Paleomagnetism and magnetostratigraphy of Karst References unroofed caves opened up during the highway and development challenges on karst, 2, Construction, tourism, ecology, protection. Beka-Ocizla cave system: karstological railway planning in Slovenia, (Cave and karst systems of recognising them in karst relief (discoveries during motorway construction at Kozina, South important feature of karst surfaces: examples from J, editor. Encyclopedia of caves and karst science. Waltham T, Bell F, Culshaw M, editors. Sinkholes engineering and construction. Berlin: Springer. p. motorway construction on Classical Karst, (Cave

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171 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 through fractures, conduits, and the rock matrix (White, pacity through these regions give rise to a spectrum of rocks with a well-developed conduit network (Vacher Flow Response to Hydrologic Events in Karst Aquifers AbstractKarst aquifers have unique characteristics that make logic events and conditions in various areas of the karst temporal data analytics methods were applied to precipi tation and groundwater levels from multiple stations and sites along the study area. The analysis showed that there are sites with rapid response in groundwater levels after a rainfall event, whereas others have a slow response to charge modes, antecedent moisture, and storage charac teristics in the epikarst. This study will ultimately help mary and secondary porosity, such as those found in Introduction -Norma I. TorresDepartment of Civil Engineering, University of Puerto Rico, Mayagez, PR, 00681, norma.torres@upr.eduIngrid Y. PadillaDepartment of Civil Engineering, University of Puerto Rico, Mayagez, PR, 00681, ingrid.padilla@upr.eduRaul E. MacchiavelliDepartment of Agroenvironmental Sciences, University of Puerto Rico, Mayagez, PR, 00681 raul.macchiavelli@upr.eduRESPONSE OF GROUNDWATER LEVELS TO HYDROLOGIC CONDITIONS IN THE KARST AQUIFER SYSTEM OF NORTHERN PUERTO RICO

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172NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE response of the groundwater level in wells depends not logical properties of the region (aquifer type, sinkhole of the groundwater levels to hydrologic events and conSite Description extensive and productive aquifers of the island (Padilla unit. Structurally, the rocks form a gently north dipping per aquifer, contained within the Aguada and Aymamon to the surface throughout most of its outcrop area (Pathe coastal zone. It outcrops to the south of the upper aquifer, where it is recharged. There is a direct connec ciated with sinkholes, springs, caves, as well as sinking, losing and gaining streams. Elevation is highest toward the south, where the lower aquifer outcrops, and lowest toward the coastal area, where outcrops of the upper aquifer intermingle with surface alluvial deposits (Torres nected to sinkholes, sinking streams and other surface features provide for direct recharge into the groundwater sponse to rainfall events. lic head potential and gradients dimension of saturated For instance, conduit-controlled regions show rapid water level and pressure response to recharge events, while The response of groundwater to variations in precipita seasonal variations, and estimated groundwater recharge sites. Using correlation and spectral analysis of rainfall and groundwater level time series, they found a rapid groundwater level response to rainfall, with little seasonied the response of groundwater level to precipitation a Mediterranean island with limited resources and very related to multiple factors, including climate, lithol aquifer characteristics of the karst aquifer from western Iran. Through analysis of spring hydrographs, physicochemical parameters, and geological topographical char acteristics they determined that the aquifer was domiThis study assesses the response of groundwater levels -

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17316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8MethodologyPrecipitation and groundwater levels data were integrat ed with hydrogeological characteristics of the aquifer to ent hydrologic events and conditions in the study area, tions have precipitation data in the study area, daily predepth to water level from the ground elevation. Hydrovia sinkholes. Flow in the upper and lower aquifers moves regionally northward toward the Atlantic Ocean occurs at wells, springs, and through seepage at sur and pumping, although several industrial and municipal wells extract from the lower aquifer. These aquifers are the principal groundwater source of water supply in the Figure 1. (a) Hydrogeology of the KA-NPR study area; rainfall stations, wells with groundwater levels information, wells, and springs in the study area; (b) Hydrogeology cross section of the

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174NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Data collected was analyzed using spatial, temporal, study area and to identify the hydrogeological character istics of the aquifer. Wells with water level information were associated with the closest precipitation station to daily groundwater levels in wells and precipitation. The Data was analyzed using multiple statistical methods, including descriptive statistics, correlation analysis, and time series analysis. Time series analysis was performed for wells that have the most amount of continuous data xy tween daily precipitation and groundwater levels time months. The response lag-time was estimated from the 2 monthly precipitation at the nearest precipitation station to a well was compared to the quartiles to classify the seasonal hydrological conditions for the area around the well in a particular month. If the total monthly precipita 2 it was 2 This information was used for the time series analysis, to Results and DiscussionSpring Density on the western side of the study area than on the eastFigure 2. (a) Hydraulic conductivities and (b) sinkhole coverage area; location of wells, springs, and rainfall stations in the study area.

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17516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of springs are generally associated with areas of greater connection to direct recharge into the groundwater system. Precipitation Data Analysis Analysis of precipitation data showed the mean of total monthly precipitation for all stations in the study area tion in the rainfall stations decreased during the next few with the most intense period of drought occurring in Auprecipitation increased compared to the previous year, Groundwater Levels Analysis are presented and discussed here. These two sites repthe study area. in water levels for periods when precipitation increased Figure 3. GIS, rainfall stations, wells with groundwater levels information, wells and springs in the study area.

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176NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE response to precipitation during periods of low precipita lower groundwater levels than the previous years, with water levels near this well show a decreasing tendency through time. is considered a dry month according to the calculated a lag-time higher than the other months in the same year and the previous year. These higher lag-times are gener ally associated with low CCF values and lack of correla ing from storage during drought conditions. Any rainfall Figure 4. Total monthly precipitation from 2011 at NOAA stations in the study area. Figure 5. Time series plot of daily precipitation (upper graphs) and groundwater levels (m amsl) (lower graphs) for Well #1 for: (a) 2011– 2012; (b) 2013; (c) 2015; and (d) 2017. Figure 6. Lag-time and cross correlation for different hydrological conditions in the area surrounding Well #1. The values between rainfall and groundwater levels.

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17716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of the lack of precipitation data in that area for that period of time, water levels show rapid increase. Lag-times in extremely wet conditions ranged from 0 to 2 days, dry and extremely-dry months ranged from 0 to 2 days karst to support recharge into the saturated zone. therefore, likely connected to sinkholes that may cause the rapid response of groundwater levels to precipitation. Slow response of groundwater levels during extremely ductivities. smooth curves in the time series plots. Even with high precipitation changes, groundwater levels peaks are not well ries analysis of groundwater levels and precipitation data hydrologic conditions, with an average lag-time of approxiof the study area, in regions of low hydraulic conductivi ties, low sinkhole coverage, and spring density (Figures low. Low sinkhole coverage near and upstream of this of groundwater levels to precipitation in this well are atand low hydraulic conductivities. Time series analysis for all the wells show that average ticular spatial pattern. From all sites analyzed, most of Figure 7. Time series plot of daily precipitation (upper graphs) and groundwater levels (m amsl) (lower graphs) for Well #2 for: (a) 2011– 2012; (b) 2013; (c) 2015; and (d) 2017. Figure 8. Lag-time and cross correlation for different hydrological conditions in the area surrounding Well #2.

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178NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE lag-times are located at or near areas of higher sinkhole located in an area with many pumping wells that may potential for direct recharge. the hydraulic response of the groundwater system, and aquifer in relation to the response of groundwater levels ence of pumping wells. Uncertainty on the areas that limitations in using the closest rainfall stations for the ize the system thus requires greater temporal and spatial resolution and continuous measurements of rainfall and the recharge of a particular well.ConclusionsTemporal analysis of precipitation and groundwater levels data from multiple wells and rainfall stations in other surface features that promote direct recharge into the groundwater system. Wells showing rapid response sinkhole coverage, whereas those with slow response also show slow response time and lack of correlations periods of low-preceding precipitation. These results are rock matrix and antecedent moisture conditions in which and secondary porosity, such as those found in northern Acknowledgementstional Institute of Environmental Health Sciences of the Ford Foundation. Figure 9. Average lag-time for wells in the study area the different (a) hydrogeological units, (b) hydraulic conductivities, and (c) sinkhole coverage areas.

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17916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8References Bailly-Compte V, Martin JB, Jourde H, Screaton EJ, karst aquifers with sinking streams. Journal of level response to rainfall and estimation of annual geomorphology, 2nd ed. England: John Wiley and modeling of karst aquifers, with particular features: a case study of the central northern karst aquifer characteristics using physicochemical rainfall associated with Hurricane Maria over Karst Aquifer System and Assessment of conduits and matrix in the Floridan aquifer. from: .

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180NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE . . exposure of emerging and legacy contaminants in karst systems: state of knowledge and uncertainty. on phthalate contamination in eogenetic karst groundwater systems. Environmental Pollution hydrogeological and anthropogenic factors on . Vacher HL, Mylroie JE. 2002. Eogenetic karst from the perspective of an equivalent porous medium. developments and opens questions. Engineering

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181 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Introduction Throughout the world, climate change and changes in decline in some areas and rise in others. This paper will With a production well, when the groundwater level levels can raise the cost of energy to pump it to the sur and in a coastal aquifer lowering groundwater levels can cause saline water intrusion from the ocean. The lower water that is deeper in the aquifer. In the long run declin ing groundwater levels in an aquifer can result in less ter supply include Mexico City, Kolkata, Tehran, ShangAbstract 2 reserve during droughts. A monthly groundwater level Limestone aquifer, the non-karst South Coastal Plain on the Internet. The study also looks at rainfall and deare falling. The declining water levels on the south coast terns and not climate change. The island shows spatial correlation. High levels of the index are associated with landslides in areas without aquifers. Low levels of the index are associated with water rationing. The index shows temporal correlation with the index rising or falling for The all-time maximum was a massive rainfall event in ricane Maria was the largest single recharge event in the on demographics, precipitation, and groundwater levels, Plain. Ronald T. RichardsUniversidad Ana G. Mndez, Carolina Campus and Interamerican University Bayamn Campus, Natural Sciences and Technology Department PO Box 2010, Carolina, PR 00984-201010, ronaldtrichards@gmail.comARE THE GROUNDWATER LEVELS FALLING IN PUERTO RICO BETWEEN 1982 AND 2017: COMPARING A KARST AQUIFER WITH NON-KARST AQUIFERS

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182NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE population rose until the census of the US government most lethal landslide in the history of the USA. A mudcomplete collapse of modern society. There was no elec tricity, telecommunications, transportation, newspapers, and supplies of food, water, gasoline, propane, cash, and medicine were very limited. After almost a year of the power was out for three months. It was the second names for the same atmospheric phenomena. Presumhurricane and it is unknown how many will return as the the rainfall of that caused the Mameyes landslide and In the years after Hurricane Maria drought is returning to and in less than a year after the massive rain of Hurricane is increasing and this will cause the atmosphere and the will lead to more evaporation. The atmosphere has virtually no storage capacity and increased evaporation will lead to the average rainfall on Earth increasing. Even as the average rainfall on Earth increases, many wind and Popular conception is that groundwater levels are falling in all parts of the world. Two aquifers famous for falling groundwater levels are the Ogallala in the central United dia and Pakistan. In places the groundwater levels in the increasing the recharge to the non-karst South Coastal industrial production and groundwater production have the closing of factories, sugar mills, and steam-operated railroads has led to decreased groundwater production in some areas. The climate will change. The economy will change. In some areas, groundwater levels will rise, and some ar eas groundwater levels will fall. Long-term groundwater level data are needed from many parts of the world to to other parts of the USA to look for work. The last time

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18316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 stations the rainfall is rising in all parts of the year (Mar it, in some cases, for years. 2 ries of alluvial fans that have coalesced. The size of depositional environment that includes downward movephemeral rivers that lose water to the aquifer. Three of the eight municipios that use the most groundequivalent of counties in the USA. Compared to Puerto Oligocene and Miocene. The sediments slope northward Most of the water for the San Juan metropolitan area low water levels in the reservoirs caused water rationing. At the height of water rationing many homes had water drought was of small scale than one river could have groundwater levels. test part of the island and the south and southwest are in cacti are more common. The rivers are ephemeral, and dry season the median strip of the divided highway ofmap was used to estimate the average annual rainfall Lago Carite is a manmade reservoir on the headwaters of the SCP for irrigation. When sugarcane is watered with and recharges the aquifer. When water is diverted from -

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184NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE rivers that gain water from the aquifer. Three of the eight municipios that pump the most groundwater are in the In this paper the small, disconnected, non-karst aquifers municipios with the most production of ground water. highest production of groundwater. The data includes population, change of population, groundwater consumption, ranking, and the percentage that groundwater is of the total water supply for the municipio. In Puerto the population of other municipios that use groundwater. It has other sources of water and groundwater is only Table 1. The eight municipios in Puerto Rico with the highest groundwater production. The columns are municipio, region, population in thousands, population growth from 2000 to 2010 in percent, the groundwater production in liters per second, the rank of the groundwater production, and the percent of the water supplied by groundwater. Figure 1. Map of Puerto Rico. The map shows the locations of the karst North Coastal Limestone and the non-karst South Coastal Plain aquifers. Rest of Puerto Rico is everything that is not SCP or NCL. The circles are the locations of the non-pumping observation wells used in this study. The municipios shown in bold are the eight with the highest production of groundwater, in liters per second (Molina-Rivera 2014). The municipios not in bold are others that are mentioned in the text. three muncipios in the non-karst SCP, on average gained,

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18516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8ing, or pumping is increasing. In coastal areas where the water levels in the ocean can cause groundwater levels to rise without increasing the total volume of freshwater in the aquifer. Currently, the author is working on a three-part series Methodsdecade or more. This study has data only from the main smaller, sparsely populated islands of Vieques and CulThe lowest water level is given a zero and the highest a more than one water level in a month then an average the index is to calculate the average of all the stations ning average of the monthly averages. If a single month had no groundwater level data, then the average was the average of the surrounding months. made showing the fraction of the wells with data for each year that reached record lows or highs in that year. The main earthquake have left people fearful that their house there are thousands of people camped out in parks or their own lawn. ment the elevation of the saline-freshwater interface at steeper gradient. The saline water in the upper aquifer is of the saline water most of the storage of freshwater will at spatial and temporal patterns of low or high rainfall events and the associated groundwater levels. or decreased pumping. Likewise, groundwater levels can fall if rainfall is decreasing, irrigation leakage is decreas-

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186NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEroller coaster. The index drops for four years until it hits after Hurricane Maria. After Hurricane Maria the index hit its second highest All of this is consistent with declining water levels. SCP and are consistently rising. The results for the index The graph of the fraction of stations each year with reResults points per year. The hypothesis is correct. The Pearson are clearly associated with events on the surface. decline for nine years. The all-time low for the index was in the San Juan metropolitan area. After the drought the Figure 2. Groundwater Index for Puerto Rico, 1982 to 2017. The trend is upward and is rainfall events that did not include a hurricane or major landslide. The upward arrows are periods of water rationing in the San Juan Metropolitan Area. The slope shown on the graph is the change per day. Figure 3. Groundwater sub-index for South Coastal Plain aquifer, 1983 to 2017. The trend shown on the graph is the change per day.

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18716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 peaks would cancel each other out and the index would rationing in the surface water system. The evidence is massive rainfall in all parts of the island. except the non-karst SCP. The western part of the SCP near Ponce has permanent rivers and dams to provide and the area is more dependent on groundwater. graph shows multi-year periods where it is dominated hit record high and only four that hit record low.DiscussionThere is evidence that groundwater patterns in Puerto smaller than the island then each station would rise and Figure 4. Groundwater sub-index for the North Coast Limestone aquifer, 1984 to 2017. The shown on the graph is the change per day. Figure 5. Groundwater sub-index for Rest of Puerto Rico, 1982 to 2017. The trend is upward is the change per day. Table 2. Groundwater trends in Puerto Rico 1982 to 1987. Figure 6. The fraction of the non-pumping observation wells that hit record highs or record lows in each year. The positive, solid line is the fraction of stations that hit record high water levels each year. The negative, dashed line is the fraction of stations that hit record low water levels each year. Between1993 and 1998, 37 wells hit record lows while only two hit record highs. Between 2005 and 2011, 46 wells hit record highs and only four hit record lows.

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188NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE upper aquifer which has high hydraulic conductivity and der of magnitude less than the other examples given. rising for years. This raises the question if the rising groundwater is pushing the saline water out of the aquifalling, rainfall is increasing, the groundwater levels are pushed out of the aquifer. The current pumping condiis more erratic, and the groundwater levels are falling. In and rainfall data are erratic and there is no clear trend. south the overall trend is towards increasing rainfall. Clicausing this divergence. An unintended consequence of recharge of the aquifer. With the switch from furrow to drip irrigation, less water was needed to irrigate crops ing patterns. Before invoking climate change, we need to coaster. Large scale groundwater production in the SCP Figure 7. Groundwater levels at Alomar 1, Santa Isabel, Puerto Rico. The dashed line is sea level. The water levels dropped below sea level in the 1970s rose in the 1980s and have been below sea level almost continuously for more than 24 years.

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18916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Conclusion were used to create a monthly groundwater level index the groundwater level index are associated with destructive events like hurricanes and landslides. Low values of the groundwater level index are associated with water rationing. The largest single recharge event was Hurricane reduced its consumption of groundwater and then closed completely. The current conditions under which groundin the non-karst SCP. All the water levels used in this report were collected References lands are increasing. Coastal wetlands are important for Figure 9. Groundwater levels at Griv well in Arecibo. The dashed line is sea level. The water level has been above sea level continuously since 2004. Prior to 2004 it was often below sea level. Figure 8. Groundwater levels at Yabucoa 7, Yabucoa, Puerto Rico. The dashed line is sea level. The water dropped in the 1970s but has been rising steadily since 1980. The rising water levels in this well have been correlated with the decreasing pumping of groundwater at Richards 1996).

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190NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Kenya. termina-racionamiento-de-agua-para-quienesdissertation. Ascertainment of the Estimated Excess Mortality properties and saline-water intrusion in the Valle from-puerto-rico-grows-as-island-strugglespuertorico-drought-el-nino-tourism-local-waterin irrigation practices and aquifer development Larsen MC, 2000, Analysis of 20th century rainfall

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19116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 framework of the saline-freshwater interface and the calculation of the net recharge in the Dorado

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192 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 and water, which leads to development of fractured car transmissive zones thorough these formations result in The hydraulic and hydrogeological characteristics make amounts of water. In the world, karst regions cover apthe groundwater system through recharge areas, which features associated with sinkholes, sinking streams, caves, conduits, and springs. Water in karst systems moves through fractures, conduits, and the rock matrix. There is still a lack of understanding of the complicated Tracing techniques are powerful tools to understand water movements and contaminant transport in karst sys-AbstractKarst terrains contain very productive aquifers. The hydraulic and hydrogeological characteristics of karst aquito contamination. Their extremely heterogeneous nature prevents accurate prediction of contaminant fate and transport. Even more challenging is to understand the impact of hydrologic condition changes on fate and transport processes. This study aims at characterizing changes in transport processes in the karst groundwater wt and uranine tracers into a spring cave, and monitoring processes of solutes in eogenetic karst with temporal conditions.Introduction Elienisse Rodrguez-MedinaUniversity of Puerto Rico Mayagez, Puerto Rico, 00681, elienisse.rodriguez@upr.eduIngrid Y. PadillaUniversity of Puerto Rico Mayagez, Puerto Rico, 00681, ingrid.padilla@upr.eduFernando PantojaUniversity of Puerto Rico Mayagez, Puerto Rico, 00681, fernando.pantoja@upr.eduKateleen Vargas University of Puerto Rico Mayagez, Puerto Rico, 00681, kateleen.vargas@upr.eduNorma I. Torres University of Puerto Rico Mayagez, Puerto Rico, 00681, norma.torres@upr.eduCHARACTERIZING TRANSPORT PROPERTIES IN KARST CONDUITS UNDER DIFFERENT HYDROLOGIC CONDITIONS

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193NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEtems. Cave tracer test can provide more detailed infor tion can provide more details of internal structure and conduit characteristics in an eogenetic karst system in assess hydraulic parameters of these systems and the events, wet and dry seasons. Study Area (Site)contains the most productive aquifer of the island (Moaquifer is within two hundred meters of the island sur unit overlies the Aguada limestone. Both are formed of compared to the more crystalline in the Aguada formalower aquifer is at greater depths, and it is considered These aquifer system in the northern karst region of thousands of residents and industries. (Veve and Taggart, population and industrial growth in the area. This growth has unfortunately resulted in a long history of contami in the region has led to twelve superfund sites, located The tracer study was performed in El Tallonal natural aquifer of the northern karst region. The Tallonal spring Methodology Figure 1. Principal aquifers and superfunds in

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19416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Different Hydrological Conditions The seasonal hydrological conditions were evaluated i 2 2 , it was clas, it was tems and potentially discharging into the cave conduit Tracers were conducted inside the Tallonal cave using uranine nontoxic and have low detection limits (Axelsson et al., -2 the other experiments. Data Collection Figure 2. Tallonal Spring Cartography (M. Lace). Purple and red circles show tracer injection and sampling point sites, respectively.

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195NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEof measurements. The variance (2 to dispersive and mass transfer processes, was calculated as Discrete sampling consists in taking manual samples in periments lasted one hour, except the one made in July, which lasted half-hour. Samples were collected every 20 In each experiment, the manual samples were collected m Data Analysis sampling location was analyzed qualitatively and quanEquation 1 Where Mn Time of travel (tt moment (M0 Table 1. Statistic results for total monthly rainfall in two NOAA Arecibo Stations. Equation 2 e estimates and measured cross sectional areas at point Equation 3 Total mass recovered was estimated as the product of M0 times were used. Percent mass recovered was estimated mass.ResultsCategorical Rainfall 2, and Results of Tracer Injections All tracer experiments show TCDs with single peaks. Though rhodamine wt and uranine tracers tend to show sites along the cave, uranine concentrations and their respective recoveries are lower. Overall, recovery of

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19616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 dry, tend to arrive at earlier times than those for Octoport in the cave, which lies within an eogenetic karst, is ter systems during previous rainfall events. Estimated velocities within the cave tend to increase with anteced wt. We therefore, focus this work on the rhodamine wt results. As expected, TCDs show earlier arrival times, higher relative concentrations, and lower variance at the as the total antecedent rainfall. For instance, a TCD for shows that maximum concentrations arrive a given disFigure 3. Temporal relative concentration distributions for rhodamine wt and uranine at point B on October 2018. Figure 4. Temporal relative concentration distributions for rhodamine wt at points A, B, and C on October 2018. Table 2. Time of travel and variance of TCDs for rhodamine wt tracer at points A, B, and C on October 2018. Figure 5. Temporal relative concentration distributions for rhodamine wt at points A, B, and C at various dates and hydrologic regimes.

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197NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE estimated from the moment analysis as a result of later The slower velocity from the tracer test compared to the measured ones suggests additional sources of water conditions. times (v the arrival of the peak concentration (vmaxcentrations are logarithmically related to vmax suggesting advection-controlled maximum concentra tions. TCD variances are generally higher for the farthest crease with antecedent rainfall and rainfall-at-month of testing. The highest variances are associated with tracer the highest total antecedent rainfall. The lowest variance lowest rainfall at the month of testing. A non-parametric index representing the sum of ranks for rainfall-at-month of variances and the ranking of variances. These results chanical dispersion and dilution processes. Flow Estimates cross-sectional area and velocities derived from tracer Table 3. Antecedent rainfall, estimated velocities, and variances at points A, B, and C at different test dates. Figure 6. Velocity at peak concentration vs relative peak concentrations. Figure 7. with those estimated form tracer tests (QTT). The circles represent the data, the dash line the linear regression of the data, and the black line is one-to-one relationship.

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19816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of total monthly rainfall during the month of the tracer suggests a large groundwater storage component in these even when experiments are conducted during a dry month. High transport velocities are generally related ciated with long tailing and high variance related to variAcknowledgement Institute of Health. Also, we like to acknowledge the Reference Chichester, England. Flow estimates were used to estimate total mass and esthe end of the TCDs. For comparison purposes, percent recoveries are compared for total mass passing through these points are associated with experiments conducted highest total antecedent rainfall. Discussion and ConclusionTransport experiments using rhodamine wt and uranine tracers in a cave located within an eogenetic karst system ing the month when the experiments were conducted, as Table 4. Flow estimated from rhodamine wt tracer experiments at points A, B, and C. Table 5. Recovery percentage from rhodamine wt tracer experiments from point A through B.

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199NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Islands aquifer system of the commonwealth contamination in eogenetic karst groundwater changes of CVOC concentrations in karst aquifers: analysis of three decades of data speleology. International Journal of Speleology, colloid transport in karst conduits under lowand a changing world: Approaches, of hydrological Spatially resolved information on karst conduit with karst spring hydrographs for rapid catchment Morales, T., Uriarte, J. A., Antigedad, I., and Angulo, Hydrologic Conditions. Journal of Hydrology ,

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200 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8logic years were used to investigate the response of hydrochemical changes to prolonged and severe droughts which highlights the rapid responses of spring to precipitation. All the evidence has shown that as the drought went on, the water from the karstic aquifer kept draining out and the residence time of water got shorter. Meanwhile the water quality of the spring was more sensitive to the rain events. With a small to medium amount of precipitation, the concentrations of Cl of the spring water started to increase a few hours after the AbstractKarst waters from a mountainous recharge area drains sedimentary rocks, which makes the spring acts as an man activities and climate change than the classic conrespectively, even though they share a common outlet performed in Heilongtan Springs. In coincidence, the study area experienced continuously severe droughts in tions of hydrochemical parameters at high-resolution Hong LiuInternational Joint research Center for Karstology, Yunnan University, No. 5 Xueyun Road, Wuhua District, Kunming, Yunnan, 650223, China, hongliu@ynu.edu.cn; School of Resource Environment and Earth Science, Yunnan University, Yunnan University Chenggong Campus, East Outer Ring Road, Chenggong District, Kunming 650500, ChinaRuiyong ChenSchool of Resource Environment and Earth Science, Yunnan University, Yunnan University Chenggong Campus, East Outer Ring Road, Chenggong District, Kunming 650500, ChinaHuacheng HuangSchool of Resource Environment and Earth Science, Yunnan University, Yunnan University Chenggong Campus, East Outer Ring Road, Chenggong District, Kunming 650500Yinghua ZhangSchool of Resource Environment and Earth Science, Yunnan University, Yunnan University Chenggong Campus, East Outer Ring Road, Chenggong District, Kunming 650500, ChinaYongli GaoDepartment of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, yongli.gao@utsa.eduTHE HYDROCHEMICAL RESPONSE OF HEILONGTAN SPRING TO THE 2010 DROUGHTS OF YUNNAN PROVINCE, KUNMING, CHINA

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201NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEfrom the 2 springs normally do not mix. Xiaoshuitan spring is an epikarstic spring with very small discharge higher than shallow karst springs in surrounding areas. trial and municipal water supply source, the spring only serves as an important landscape feature of Heilongtan Park now. The geological setting of the study area is very complex Paleozoic Era, which is highly folded. The lithology conimportant fault in the study area. In the recharge area, Fengcong-depression and Fengcong-valley morphological features are well developed. The karst water is thought Heilongtan fault,and emerges to the surface which is in longed and severe drought. The annual precipitation of Methods tain water temperature, electrical conductivity, pH, and Introduction cal unit. It originated from neotectonic movement and Tertiary sediments or other types of rocks, which makes tive to climate change than the classic spring of a conlocal water supplies. Heilongtan Spring, one of the most supplying water to Kunming City until the late 20th cenHeilongtan Spring karst system is a complex and heterogeneous system in terms of structure and hydrologic However, the dynamics and origins of groundwater and the mechanism of contaminant transport are poorly the study area experienced the prolonged and severe Site DescriptionHeilongtan Spring, one of the main karst springs in Kunming, China, is located in the foothills of Wulao Mounof Kunming Basin. Heilongtan Spring is a typical weakspring and Hunshuitan means muddy water spring. They

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20216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8trical conductivity, and pH parameters of water samples Results and Discussion variations of the spring during the drought. Though the data of water levels in Figure 2 demonstrates seasonal maintain the water level of the spring pool for the sake of tourism and some spring water was used for watering the garden daily. stalled on the roof of the Heilongtan Park headquarters. which were analyzed for concentrations of Ca2+, Mg2+, HCO , Cl +, and PO . The hydrochemical 2+ and Mg2+ values were determined HCO and Cl acid and argentum nitricum liquor titration, respectively, +, and PO were Figure 1. section.

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203NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE cussed responses of the spring hydrochemical parame chemical parameters of the spring had a small range of tivity and pH all reached a peak value, which indicates rainwater and the electrical conductivity decreasing rapand more sensitive to the heavy rainfall event. The reItem Water temp.( pH Ca2+ Mg2+ ClHCOEC(u Min. Max. Mean Min. Max. Mean Min. Max. Mean *N means number of samples. Table 1. Minimum, maximum and annual mean values of water temperature (water temp.), electrical conductivity (EC) and hydrochemical parameters in Heilongtan Spring in 2010, 2011 and 2012 respectively. Figure 2. Daily continuous data of hydrological (water level) and hydrochemical parameters (water temperature, EC and pH) in Heilongtan Spring during March 2010–December 2013, and the rainfall data of 2010 and 2012. The data between the two straight lines (27 July to 11 August of 2011 and 27 April to 25 June of 2012) was not available due to repair of the sensor.

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20416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8lation. In general, instead of the tendency of decreasing The concentration of Ca2+, Mg2+, HCO change syn2+ normally is lower in wet seasons and higher in dry seasons. From 2+ concen2+ con2+ is higher in extreme drought years with a wider range of variations. The value of HCO has the same trend as the concentration of Mg2+ greatly, which implies rapid responses of the spring to precipitation. Meanwhile the water quality of the spring was more sensitive to the rain events. With a small to medium amount of rain, the concentrations of Cl of spring waAll the evidence has showed that with the ongoing drought, the water from the karstic aquifer kept draining out and the residence time of water got shorter. As a consequence, the hydrochemical response of spring water to Conclusions study was conducted during prolonged and severe concentrations of hydrochemical parameters at highvestigate the response of hydrochemical changes to decline, the EC of the spring decreased progressively time, instead of the tendency of decreasing temperagreatly, which implies rapid responses of the spring to precipitation. All the evidence has shown that, with the ongoing drought, the water from the karstic aquifer kept draining out and the residence time of water got shorter. Meanwhile the water quality of the spring medium amount of rainfall, the concentrations of Cl in the spring water start to increase in a few mary, this study demonstrated the high sensitivity and ronmental changes. Figure 3. Ca2+, Mg2+, HCO3 –, Cl–, and NO3 – time variations from 2010 to 2012 in Heilongtan Spring.

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205NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEAcknowledgments References responses of Heilongtan karst spring to to soil CO2 and weather conditions at Chenqi, Puding, SW China. Journal of Hydrology vol.

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206 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 activity ratios, at least two distinct hydrologic environgroundwater signals have lower temperatures and more ecosystem health and magnitudes of impact are expected groundwater discharge.IntroductionKarst aquifers have a vital importance to water supply nomic development of many regions (Parise and Samtion with drinking water, and in many regions, are the AbstractThe peculiar intrinsic geological and hydrogeological of karst aquifers to store and carry contaminants from In coastal settings, the function of karst aquifers is closevices. This research aims to promote understanding of O and hydrogen222 and erentially directs continental groundwater toward the tes ring and the coastline intersect. In this study, 2 under measurements of 222 and lowest radium ages were measured in vicinity of Dorina MurguletTexas A&M University-Corpus Christi 6300 Ocean Drive, Corpus Christi, Texas, 78412, US, dorina.murgulet@tamucc.eduAudrey R. DouglasTexas A&M University-Corpus Christi 6300 Ocean Drive, Corpus Christi, Texas, 78412, US, adouglas1@islander.tamucc.edu Jorge Alfredo Herrera SilveiraCINVESTAV, Km 6 antigua, Carr. Mrida Progreso, Loma Bonita 97310 Mrida, Yuc., Mexico, jorge.herrera@cinvestav.mx Ismael Mario TapiaCINVESTAV, Km 6 antigua, Carr. Mrida Progreso, Loma Bonita 97310 Mrida, Yuc., Mexico, imarino@cinvestav.mx Arnoldo Valle-LevinsonUniversity of Florida SUBMARINE GROUNDWATER DISCHARGE ALONG THE NORTHERN COAST OF THE YUCATN PENINSULA

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207NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE hydrogeological features, such as dissolution processes, in a high capacity of karst aquifers to store and carry contaminants from sources to potential exposures zones economic challenge. Coastal aquifers are a nexus of oceanic and terrestrial hydrologic ecosystems and provide water resources for overexploitation of groundwater resources are likely to mate change (e.g., sea level rise and increased frequency Figure 1. Northern Yucatn karst aquifer, land-sea and the surface and groundwater connec spring at Dzilam the Bravo, (D) Due to the ubiquity of cavities, Yucatn lacks surface rivers, thus oped conduits, towards coastal lagoons and the sea.

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20816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8functioning of karst aquifers is closely linked to the sea coastal areas. These physical mechanisms shape the dehealth of human and estuarine ecosystems (Bear et al., water resources and their impact on coastal communi ties is especially relevant in developing countries, where poverty and education level make these challenges more gardless of its source (e.g., meteoric fresh groundwater concerns of pollutant inputs to the coastal seas via karst spring discharges and contaminant exposure for humans tinued residential and agricultural development of inland aquifer recharge areas, particularly in developing countries, is polluting groundwater and the sea in the form climate conditions and human activities could alter the to the surface estuaries. In addition, sources and magni heterogeneities. in areas with high density and intensity of point dishave large implications on the health of ecosystems, especially where point discharges are dominant. For instance, studies show that along the northern coast of the peninsula, there are four hydrological zones that have status of the near-shore marine waters (Herrera-Silveira upwelling, on spatial scales is poorly understood. Fur thermore, unknown are the types and degree of groundThis study aimed to determine the magnitude and sources of groundwater discharge to the northern coast of are employed to evaluate the spatial heterogeneity of groundwater discharges. These types of measurements Study Area ue, food and energy demands will continue to increase, ecosystems, this study focused on the approximately sensitive karst dominated environment in the northern cally, the dry season extends from March to June and the

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209NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE karst aquifer is largely scale-dependent with preferenwater forms a distinct lens on top of the intruding marine The hydrogeologic characteristics of the coastal area as inputs to the coast are virtually groundwater, which is features such as faults or lineaments. These unique char acteristics explain the existence of three important north coast freshwater discharge zones: Estuario Celestn (Cea mature karstic system in the peninsula. Soil cover is Thus, rainwater percolates rapidly through the porous The aquifer consists of a thin freshwater lens that is unFigure 2. Map of the study area showing the locations of sampling stations, cenotes and subma rine springs sampled in this study, towns and cities, and cenotes located throughout the Yucatn covered each day in also shown .

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21016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8This equation assumes radium activities and activity raand desorption from sediments. Consequently, radium mass is moving away from the discharge point due to curring continuously over a wide area. The short-lived isotope is normalized to the long-lived isotope with activities that are expected to only decrease due to dilution. Continuous radon-222 (222Rn) measurements Continuous radon-222 (222Mexico, to San Felipe, Mexico, (corresponding to stasects from San Felipe to Celestn, Mexico, over four 222 separated from the water into the headspace of the cham 222 due to the presence of a coastal aquitard along the north 2 d rainy seasons.MethodsSample collection and analysisRadioactive isotope measurements lived Activities of 222 sory. Radium water ages since the radium left its source, was calculated using the ratio of the short-lived (i.e., to the long-lived (i.e., CO is the is Equation 1. the activity ratio of the discharging groundwater source SL

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211NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE I cavity ringdown spectrometer with uncertainties of and hydrogen isotopes were measured relative to the accepted international standard Vienna Standard Mean Oceanic Water and are report in the conventional delta Results and DiscussionSpatial-distributed radon-222 SGD rates and radium-water agesTotal 222 sured during the nearshore continuous survey range . The highest rates were measured starting a few kilometers east of Dzilam de Bravo and continue closer to Progresso. The highest rate was don surveys were conducted at a relatively fast speed estimated due to limited response time of the detectors tion, radon measurements are integrated over an average Radon-222 -derived submarine groundwater discharge rates cause of the unreactive nature and short half-life (T 222 ous 222 total 222total is the decay corrected activity of 222is the activity of 222o is the i sedatm is the losses due to atmospheric evasion, and Fmix is the losses due to mixous radon measurements to quantify groundwater disof 222 altered the apparent 222 as change in tidal height occurred over large distances 222strained, thus the Fo and Fi terms were neglected. It is collected at each sampling station following the methods radon activities, which in this case were selected from the sampled coastal springs, 222 Equation 2. Equation 3.

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21216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Figure 3. (A) 222Rn-derived SGD rates, (B) 224Ra:223Ra, (C) 224Ra:226Ra activity ratios for surface 18O for surface water stations and cenotes and springs.

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213NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEdium ages seem to correlate for the nearshore transect spanning from El Cuyo to Chelem to the west. On the increasing with a peak at Celestn. Here, the radium waspring. Interestingly, the oceanic currents take a northerly turn a few km east of Celestn, thus limiting the carryover of depleted radiogenic signature waters tomagnitude higher than in all our measurements along the range as the coastal springs samples as part of this study. Oxygen and hydrogen stable isotopes, salinity and temperature activity ratios and the increasing surface water ages from urally, it is expected that radon will degas and dilute with distance from the source. Also, the long-lived tivities will decrease due to dilution with more depleted seawater while creasing activities of radium isotopes to the west from Figure 4. Radium activities and salinity for surface water and cenotes and springs.

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21416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 during summer months groundwater has lower tempera cant, is expected to decrease surface water temperatures warms up when it moves away from the coast. Temclimatic (i.e. latitude, elevation, distance from the coast, acteristics of the area and exchange with groundwater respectively, with the most depleted signatures measured tures, in this instance associated with lowers salinities two of the coastal springs and the fast drip sample (from Groundwater discharge source indicators Figure 5. 224Ra:226Ra activity ratio plotted against (A) salinity, (B) temperature, and (C) 18 are given as r and p-values, respectively.

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215NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE with depth. Thus, coastal discharges originating from in our study. However, if originating from deep strucnotes at further distances inland to shallow more coastal openings where it is exposed to sunlight and heat, thus experiencing further isotope enrichment and an increase tant, groundwater inputs are of lower temperatures while more recent groundwater discharges are warmer (Figure groundwater inputs, or in other words weaker groundwater signals, the sea surface temperatures are lower and isotope signatures are higher. linities of, or nearly, zero. Thus, although not well congroundwater inputs. On the other hand, nearshore such as those in the eastern most portion of the study low groundwater input. Lower water-rock interaction signatures with depth in a few cenotes located inland in Figure 6.18O. 18O plotted against (B) salinity and (C) of correlations given as r and p-values, respectively.

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21616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 expected to weaken the groundwater signal when mea essentially relative indicators of groundwater discharge magnitudes rather than quantitative assessments. 222ter tracer, was found in the area around Dzilam de Bravo, with the radium water ages along the sampled coastline, est while radium activities and corresponding ages are charge. This discrepancy is related to the more distant oceanic waters, it carries high amounts of radium. throughout the coastline indicates the presence of at least signals are associated with lower seawater temperatures, Strong groundwater signal areas are of higher seawater and lower radium ages or more enriched in the longlived radium isotopes. water discharge are expected to have implications on the is occurring along the study area, inland anthropogenic ger groundwater signals with the previously reported degree of ecologic health. Acknowledgments leads to lower radioisotope activities while the oxygen and hydrogen isotope signature of the recharging rainwater is slightly altered. This stretch of the transect, consists of strongly developed karst features (Perry and ed through conduits to further inland recharge areas or occur during rain events, rapidly discharging to the sea low unconsolidated formation that overlies the highly locally, thus conversion of radon inventories to advective groundwater discharge rates using a potentially more engroundwater inputs. Although more detailed characterization of coastal ically impacted area is east of Dzilam de Bravo with the to the west, inside the ring of cenotes, following the poConclusion

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217NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEImplications for red tide events. Continental Shelf S, Alcocer J. 2002. Development of a protection strategy of karst limestone aquifers: the Merida aquifers to groundwater use and climate change. Evaluation of the health status of a coastal ecosystem in southeast Mexico: Assessment of aquatic vegetation. Marine Pollution Bulletin Kantn-Manzano C, Herrera-Silveira, J. and Karstic Environment. Bulletin of environmental to characterize water ages and coastal mixing rates: a sensitivity analysis. Limnology and groundwater discharge estimates at a Florida degradation, and recovery potential of estuaries Lutz W, Prieto L and Sanderson WC. 2000. Population, and the Center for Water Supply Studies at Texas A&M University-Corpus Christi. References zone of saline intrusion in a coastal karst aquifer Bear J, Cheng AH-D, Sorek S, Ouazr D, Herrera I. concepts, Methods and Practices. Kluwer dynamics of groundwater input into the coastal zone via continuous radon-222 measurements. J discharge of groundwater into the coastal zone. J groundwater discharge of nutrients and copper to Dulaiova H, Burnett WC, Chanton JP, Moore WS, Bokuniewicz HJ, Charette MA and Sholkovitz E.

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21816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 in coastal aquifers: is our technology ready for the capacity for resilience among coastal counties groundwater discharge as a source of nutrients discharge: controls and potential impact. Journal settlement in coastal zones. Journal of coastal 222 Assessment of Potential Exposure Pathways in source of dissolved nutrients to an arid coastal Composition of a Coastal Environment: Flanders hazards in karst areas: recognition, analysis and water resources in karst. Environmental Earth Mexico: its hydrogeologic characteristics and Peninsula. The Lowland Maya Area: Three Millennia at the Human-Wildland Interface. Food discharge rates and water residence time of 222

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219NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Valle-Levinson A, Marino-Tapia I, Enriquez C, climate change and population growth. science Characterizing sources of groundwater to a tropical coastal lagoon in a karstic area using radium isotopes and water chemistry. Marine CVOC concentrations in karst aquifers: Analysis

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220 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Introduction on drinking water from karst aquifers (Ford and Wilage and hydrological processes in these systems. This poses a challenge especially in karstic areas since karstider to characterize karst systems. One of the most poputo study the transit time and dispersion of water entering the ods like pumping test are conducted in order to analyze terization of the entire aquifer. The investigation on the role of the vadose zone in water recharge and its processes has The vadose zone is composed of the soil, the top weathAbstract of drinking water in many regions in the world. Understanding its recharge processes is important for a tal approaches to study karst aquifers mostly focus on the characterization of the entire aquifer using the disintegration of its output signal measured at the spring. Despite the important role of the soil and epikarst for age, evapotranspiration, and groundwater recharge at moisture measurements creating recharge is the one with a tropical climate as expected, as the one with the Mediterranean show similar results. Other parameters in the future.Romane BerthelinChair of Hydrological Modeling and Water Resources, Freiburg University, Friedrichstrasse 39, Freiburg, 79098, Germany, romane.berthelin@hydmod.uni-freiburg.deMirjam SchellerChair of Hydrological Modeling and Water Resources, Freiburg University, Friedrichstrasse 39, Freiburg, 79098, Germany, mirjam.scheller@gmx.deJustine BergChair of Hydrological Modeling and Water Resources, Freiburg University, Friedrichstrasse 39, Freiburg, 79098, Germany, bergjus94@gmail.comAndreas HartmannChair of Hydrological Modeling and Water Resources, Freiburg University, Friedrichstrasse 39, Freiburg, 79098, Germany, andreas.hartmann@hydmod.uni-freiburg.deUSING SOIL MOISTURE OBSERVATIONS TO CHARACTERIZE KARST GROUNDWATER RECHARGE PROCESSES AT FIVE CONTRASTING CLIMATE REGIONS

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221NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEDescription of Sites regions that have local or regional relevance for water dedicated to the description of the sites. However, more description of each plot. Puerto Rico (PR) zone of a private natural reserve. With an annual aver tropical moist forest zone with exotic plants as Castilla elastica (S. Guarea Guidonia (L. The main geological units found in the studied area are limestones from the late Oligocene and early Miocene Aguada show characteristic features of karst like deep mogotes water resources of the island lies in the upper layer of mogotes area is mainly due to The soil of the Tollonal karstic area is, according to the minimal and simple development of horizons (Beinroth high water retention capacity. Besides, the soil shows moderate fertility and high acidity whereof growth can Spain (ES) north of the city of Malaga in Spain, with a catchment area the porosity of the rock decreases with depth. These char weathered and non-weathered rock can lead to the formaon recharge processes and therefore on the water storage. since a shallow epikarst has a higher proportion of large monitoring network to characterize karst recharge and ferent climate regions. Measurements of soil moisture are conducted at a high spatial and temporal resolution. They soil and epikarst heterogeneity on spatiotemporal dynamThe Monitoring ConceptThe experimental concept is designed to investigate the the karst system recharge and evapotranspiration. To adclimate, Mediterranean, humid oceanic, humid moun-

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22216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8United Kingdom (GB) The United Kingdom site is located on the property of the Sheepdrove Organic Farm, in south England at the West Berkshire Downs. The climate of this site is classiarea, where the main aquifer of the region is situated. The the area is Chalk of Upper Cretaceus age (Wheater et al., Thick roots are present in the entire soil depth at most of Germany (DE) in higher altitudes. The vegetation is Mediterranean scrusic clays and evaporate, Flysch clays and sandstones and Cretaceous-Paleogene marls, and presents a high fracturaIn the study area, two main soil types are found: patchy leptosols, which is a shallow soil with a thickthe depth. More roots and deeper are found in the soil at the forest than in the grassland area. Figure 1. derived from the World Karst Aquifer Map (Chen et al., 2017).

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223NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Jurassic and Cretaceous rock series present. Karst features are located at the interface of limestone and dolomite rock has a texture varying from silty to clayey. A rocky layer Australia (AU) The Wellington Caves site is located in a reserve on the town of Wellington. The temperature at the site ranges The deep-water marine sediments of the Ordovician Oakdale formation and the limestone of the middle reserve. Both the forest and grassland sites are situated on the massive limestone. There are no permanent of the caves and has a high potential connectivity with conditions. The soil at the study site is extremely dry. At the grasssoil. Deeper horizons show a sandy clay texture, folSelection of Plots and Set Up lected. One is located in a grassland area, the other one in used in order to choose two plots with a similar slope and exposure within the site. For the soil moisture mea ResultsFigure 2 shows the dynamics of soil moisture at each plitude of soil moisture values quite high compared to the other sites. Also, the amplitude of reaction of soil moisreaction seem larger at the Australian site, and smoother grassland. At the Spanish site, no soil moisture reaction compared to the rest of the time series, the soil moisture

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22416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 2. Soil moisture measurement time series recorded at different depths at each site for two different land covers and precipitation. events that occurred during this period, which indicates snowfall and storage of rainfall within the snow cover. At the Australian site, no soil moisture events at all seem among the sites, we consider two seasons (one from Ocseparately. In order to identify periods of recharge, we moisture conditions close to saturation. Accounting for

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225NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE of porosities found at loamy soils that developed over the forest than in the grassland. The forest values are as in the grassland are higher than at all the other sites. the two seasons at the forest plot. At the grassland plot, value compared to the other sites. At the Spanish site, the and grassland sites. At the English site, the median is the site presenting the higher median value at the forest seasons at the forest plot and higher during the season at the grassland plot. This site presents the lower range Considering the soil moisture values expected to create to occur more often than at the other sites, at every seaand Spanish sites, not a lot of soil moisture values reach the threshold, with a slightly higher occurrence during Discussiontween forest and grassland: the soil moisture in the forest and the soil not so much present. The forest soil moisture is, in fact, the lower value compare to all the other Spanish site, the summer season is very dry: no precipi tation event and so no soil moisture events were recorded. That is why it presents a higher soil moisture value values are similar. The English site also presents a higher soil moisture values are similar to the Spanish ones. This the wintertime despite precipitation events. This is due to the snowfall period and no melting during this time. As moisture median values. The Australian site presents the The grassland and forest plots present similar values. present the highest soil moisture values at the grassland plot and this is coherent with the climate conditions. As the Australian site presents the lowest values. Indeed, the site that presents more soil moisture measurements reaching the threshold to initiate recharge is the grassmoisture measurements reaching the threshold is the fact that the forest plot is mostly composed of a dense soil moisture measured. this site presents the highest values of soil moisture at its reaching the potential soil moisture value to initiate recharge. The fact that high values of soil moisture are

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22616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 the climate has a high annual precipitation is recorded there. The Australian site, with its semi-arid climate shows only a few measurements reaching the threshold to create potential recharge. This is coherent with results presented in a preliminary analysis comparing soil moisture dynamics and drip dynamics in a cave at the Australian site. The recharge at this site is measured countthe measured period, only one rainfall event, creating the highest soil moisture value, initiated recharge into the system. The rest of the time, the rainfall was either We have to consider that many other parameters can cedent conditions, soil texture, and vegetation (e.g., Fu and so climates remains qualitative. In the presented study, the description of the time series results remains visual. Analyses of soil moisture reacvidually. This would allow the extraction of parameters and thus the characterization of each soil moisture reacsites. Other investigation as the comparison of measured each site. Moreover, the choice of threshold to initiate each site depending on their soil description. Figure 3. Boxplot of the soil moisture measurements at each site depending on the land cover and the season. A range of soil moisture value from 35% to 65% at which recharge is expected is represented within the yellow frame.

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227NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEConclusions and Outlookpotentially to recharge. However, its forest plot presents network in the soil of the forest. This is the only site with the conducted analyses. Other patterns as the fact soil moisture measurements creating potential recharge is concordant with the climate conditions. In addition, Spain and England present similar values. Here their different climates cannot explain their similar soil moisture measurements. processes through the soil and epikarst. In order to explore other parameters, individual analyses of soil moisBased on previous work exploring soil moisture at ic method to extract events and associated parameters could allow, for example, the inclusion of antecedent soil moisture conditions and rainfall characteristics in the analyses. The analyses of soil moisture events could tween forest and grassland. Moreover, the comparison of soil moisture reactions to the spring signal of the studied system will allow linking soil moisture measurement to ReferencesBehrensmeyer AK, Darmuth JD, DiMichele WA, Ecosystems through Time. Chicago, IL: The University of Chicago Press. Vale A, Hartmann A. A soil moisture monitoring network to characterize karstic recharge and Syst. Discuss. , . Hydrogeological Model of Flow and Transport . Controls of Preferential Flow at the Landscape Scale. Hydrology and Earth System Sciences .

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22816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Characterization of the Dynamics of Spring and Stream Water Systems in the Berchtesgaden . Flow in Karst Conduits Under Unsteady Flow . Speleology. International Journal of Speleology . zone hydrology and its relevance for paleoclimate . Capacity Controls Energy Partitioning and Water Use in Karst Ecosystems on the Edwards Plateau, . Spatially Dense Drip Hydrological Monitoring Caves, South East Australia. International . Keshavarzi M, Baker A, Kelly BFJ, Andersen MS. . Spain. In Conference Proceedings of EuroKarst . Karst on the Hydrology of the Berchtesgadener Ache Basin: A Comprehensive Summary of Karst United States Department of Agriculture Forest Identifying the Flow Systems in a KarsticFissured-Porous Aquifer, the Schneealpe, O and Mapping and Protection Zoning of Karst Springs. . Composition and Implications for Speleothem . from SW Mediterranean (Betic Cordillera, S .

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229NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Tracers to Determine the Hydrogeological Functioning of a Karst Aquifer: The Villanueva . in a Karst Aquifer: A Conceptual Model Based on . of Paris. Surface Modelling. Hydrology and Earth System . Dynamics in a Mediterranean, Semi-Arid Karst . the impact of climate and land cover change in . . Framework of the Saline-Freshwater Interface and Castilla elastica en el carso del norte de Puerto . . . . Time Lag of Epikarst-Spring Hydrograph .

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230 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8cal precipitation. The deuterium excess values of these cate little evaporation during precipitation and groundwater movement. tween water quality of springs and local geoenvironmen tal conditions, evaluate the impact of long-term climate variations and wet and dry conditions on water qualter understanding on how the karst aquifer responds to recharge events and potential contamination.Introductionthe importance of understanding limited water recourses AbstractIn any natural system, environmental and geomorphic responses are more extreme and frequent when caused or other aquifer types in that they are composed of complex sources for societies and ecosystems, karst aquifers are for proper protection. drochemistry data from sampling sites within the Honeycut Hollow Creek Watershed, Blanco County, Texas. Flow measurements revealed that the discharge of Honeycut Creek Spring does not respond to local precipita in southcentral Texas resulted in minimum discharge, which is one order of magnitude lower than the discharge the salinity of spring water is higher with elevated levels of nitrate and higher concentrations of other ions, especially sulfate. onstrate relatively long residence time of groundwater discharge of Honeycut Spring does not respond to lo-Robert SalinasCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, Robert.Salinas@my.utsa.eduYongli GaoCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, yongli.gao@utsa.eduLijun TianCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, Lijun.Tian@utsa.eduYunxia LiCollege of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan, China 410081, liyx@hunnu.edu.cnScott GardnerC.L. Browning Ranch, 159 Browning Drive, Johnson City, Texas, 78636, USA, clbrowningranch@gmail.comINVESTIGATION OF WATER QUALITY AND GROUNDWATER FLOW IN A KARST WATERSHED IN BLANCO COUNTY, TEXAS

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231NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEother springs in the ranch, residing in the Cow Creek cut Spring Location, running south to north, which traand Cow Creek Limestone formations. Four ephemeral ranch, with a six-to-nine-foot layer of Hensell Sand For Hensell Sand Formation to expose the Cow Creek Lime Sand Formation, and Cow Creek Limestone all fall The local formations yield very small to moderate quantities of fresh to slightly saline wells in most of the countion channels carrying large quantities of water (Follett, river and small streams play critical roles in the ecology ferent plant communities two are found nowhere else ranch, as well as scattered orchards, it was converted in land stewardship and environmental preservation practices. All livestock grazing and agricultural growth have with hydrochemistry data (pH, water isotopes, anions, term climate variations and extreme weather conditions among the four sampling sites. The ultimate goal of this standing of how the aquifer responds to recharge events and potential contamination.Hydrologic Setting and spring that reside within the ranch. These creeks in to run dry, even during periods of drought. Additionally, Honeycut Spring discharges from a lower formation than Figure 1. Map of the Pedernales River Basin within the Texas Hill Country. The Browning Ranch, southwest of Johnson City, rests within the Honeycut Hollow Creek watershed just south of the Pedernales River.

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23216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of water chemistry to display dissolved constituents in these water samples are shown in the Piper diagram (Fig2+ and Mg2+. While for anions, the dominant ion is HCO . However, there is a trend towards SO during heavy precipitation Discussion Honeycut Creek in the upstream of the spring, and the phosphate, sulfate, lithium, sodium, ammonium, poWith no recent livestock or agriculture use, contamiuents linked most likely to vegetation recovery and compared at individual levels in comparison to water quality standards. Sand is comprised of weakly cemented clay, quartz, and Geochemistry and Isotope Data path, dissolution, precipitation, and ion-exchange processes occur. Ionic concentrations depend on the composition of the precipitation, geological structure and mineralogy of aquifer formations and contact time with aquifer host no response to precipitation. This is most likely due to long underground residence times while mixing within which may indicate little evaporation during precipita tion and groundwater movement. Figure 4. Piper diagram for the four sampling sites; April 2017 to February 2019. Figure 3. Isotope values for four sampling sites spanning March 2017 to October 2019. Figure 2. C.L. Browning Ranch and the prominent formations within its boundaries including four sampling sites. In addition to the sites at the Honeycut Creek (green) and Honeycut Spring (blue), there are two tributary sampling sites: Tributary 1 (yellow) within Turkey Creek and Tributary 2 (red) within Rock Creek.

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233NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEUtilizing water quality regulations all tested ions were compared against maximum contaminant level goal sampling sites, levels did not meet or surpass water qualPeak level of sulfate within the Honeycut Spring were SMCL. These high TDS levels occurred during a month Calcium and Magnesium are dominant cations in most Precipitation and Discharge LevelsTDS responds to precipitation events, with some lag time. The discharge of Honeycut Spring reached its Discharge does not have a fast response to precipitation, eycut Creek. Peaks of discharge are present during low levels of predischarge and precipitation are not consistent (FigConclusions HCO types, while the Honeycut Hollow Spring is Ca-Mg-HCO type and shifts to Ca-Mg-SO type in constant with no response to precipitation due to long lished reservoirs. The discharges of Honeycut Hollow Creek and Honeycut Hollow Spring do not respond to local precipiperiods of the year. Spring sulfate levels increased after intense precipitation events which are likely ous limestone. Table 1. Average, maximum, and minimum nitrate, and sulfate of the four sampling sites against national primary drinking water regulations (U.S. EPA, 2009). Concentrations Table 2. Average, maximum, and minimum observed levels of barium, calcium, magnesium, and TDS against national primary drinking water regulations (U.S. EPA, 2009). Concentrations below the detection limit are

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23416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 7. Precipitation levels (blue) against discharge of Honeycut Spring (green) and Honeycut Creek (purple) over the period of October 2018 to September 2019. Figure 6. Precipitation levels (blue) against TDS for Honeycut Spring (red line) over the period of March 2018 to October 2019. Figure 5. Concentrations of nitrate and sulfate of sampling sites in comparison to TDS from April 2018 to September 2019.

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235NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE References Using geochemical data and modelling to enhance regional deep aquifer, Aquitaine Basin, south west Texas at Austin. Blanco County, Texas. Texas Water Development for a Trinity Cretaceous sequence, central Texas, Austin, TX. Flowering plants of Trans-Pecos Texas and Migratory Birds of Texas: Who They Are and Minor Aquifers of Texas. Map. . primary-drinking-water-regulations . Hays, and Travis Counties. The Meadows Center for

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236 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8ing of the plumes correlated to voids encountered and ter tracing. Following this incident, WPD and BSEACD events in the future. of humans or the resident endangered salamanders, the regulatory agencies.Introduction the lifeguards at Barton Springs sent a photo of the rapidgist. Several representatives from the department made their way to the pool to investigate the cloudy white that are collected continuously at Main Barton Spring AbstractThe City of Austin Watershed Protection Department to protect Barton Springs, one of the largest springs in the state that also functions as a municipal swimming pool, sediment plumes of unknown origin emerged from Main Barton Spring and Eliza Spring, presenting an atypical respond to a known location, pollutant, and spill volOf the four springs that make up the Barton Springs Barton and Eliza Springs, which narrowed the source regional groundwater traces. The concentrated spikes in dispersion and thus a source relatively near the springs. days prior to the event, and the plumes were not typical of storm responses. Following these lines of evidence, tial geothermal heat pump well system located approxi-Lindsey Sydow, P.G.City of Austin Watershed Protection, 505 Barton Springs Rd., Austin, TX, 78704, United States, lindsey.sydow@austintexas.govDavid A. Johns, P.G.City of Austin Watershed Protection, 505 Barton Springs Rd., Austin, TX, 78704, United States, david.johns@austintexas.govSarah J. Zappitello, P.G.City of Austin Watershed Protection, 505 Barton Springs Rd., Austin, TX, 78704, United States, sjzappitello@gmail.comThain Maurer, C.H.M.M.City of Austin Watershed Protection, 505 Barton Springs Rd., Austin, TX, 78704, United States, thain.maurer@austintexas.govENVIRONMENTAL FORENSIC INVESTIGATION OF MYSTERY SEDIMENT PLUMES AT BARTON SPRINGS, TEXAS

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237NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEmiddle of which comprises much of south Austin and is referred to as the Barton Springs segment of the Edwards are more stagnant and residence times are longer. ton, Williamson, Slaughter, Bear, Little Bear, and Onion revealed that all parameters were within typical ranges result of natural events. The lifeguards informed WPD personnel on site that plume that was quickly circulating throughout the pool at approximately the same time of day as Plume 2 had City of Austin and regulatory partners in determining the source of these discharges and explores how communi dated as a result of this event.Hydrogeologic Setting & Backgroundtends across central and southwest Texas along the Balcones Fault Zone. The aggressively weathered, lateCretaceous Edwards Formation outcrops along the fault zone, generally dipping to the southeast where it is conFigure 1. Drone footage of the white sediment plume (Plume 2) in Barton Springs Pool on December 19, 2018 (Bradshaw, 2018). Figure 2. Barton Springs Pool is clear under typical conditions. Figure 3. Barton Springs Edwards Aquifer in and near Austin, Texas.

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23816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8manders: the Barton Springs Salamander (Eurycea sosorumEurycea water looensis popular and economically important recreation center, important services it provides and its inherent sensitivity well-studied for several decades. Decades of Data groundwater velocity data. This information has allowed Upper Spring and, to a lesser extent, from Old Mill from Main Barton, Eliza, and Old Mill Springs, with times usually range from hours to days depending on the City of Austin has collected physicochemical parameters these creeks either saturates the matrix material in the at the Barton Springs Complex or Cold Spring. springs discharging from the Edwards Aquifer: Main Barton Spring, Eliza Spring, Old Mill Spring, and Upes into Barton Creek upstream of the pool. The springs Figure 4. as determined by over 20 years of ongoing aquifer tracing studies (from Zappitello and Johns, 2018b).

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239NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE rapid recharge following rain events, and even lowering the water level in the pool for cleaning. response, WPD maintains a catastrophic spill response plan for incidents in the Barton Springs Zone. Barton Springs Spill Response Plan investigation and mitigation of pollution discharges to wacompliance and mitigation for any illegal activities. to the four springs within the Barton Springs Complex. vice, develop a catastrophic spill response plan for Barton lation of salamanders within Barton Springs Pool. Since initial implementation, the plan has gone through multiple revisions and updates to incorporate aquifer information ommended courses of action vary depending on pollutant type, spill volume, and discharge at Barton Springs, which is an indicator of groundwater velocity and thus contaminant transport time.Forensic Investigation water quality sonde, and a chlorine analyzer. Due to the unknown nature and source of the plume, the pool was rescue if they were in danger. Chlorine was not detected, Initial Response and Gathering Evidence sediment. As already stated, Eliza Spring was discharging white sediment like Main Spring, in visually similar and Sunset Valley Basins as potential source areas for Spring indicated the source of the sediment was closer to construction sites within the area of interest, since the on-site was not a leading theory. DSD agreed to send checked the creeks in the recharge zone for evidence of tion activity. checked for sediment, water discharging from Main

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24016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 suspended in the pool continued to circulate for several hours. WPD hydrogeologists used this time to examine source of the plume. This information was used to create the following day. Turbidity Concentrations in Barton Springs were on site responding to Plume 2 the following day. er than the white sediment from Plume 2 that was still phenomena. fall in the days preceding the sediment plumes, and the sediment plume responses did not mimic the physicosult of fresher water diluting the mineralized water that any of the three plume discharges. A heavy rainfall event the aquifer through recharge features. The recovery for During storms like the one that occurred a few days after entering the aquifer through karst features carries increased concentrations of nonpoint source pollutants. In order to enhance the quality of water entering the aquifer, BSEACD maintains an automated intake structure for the largest capacity recharge cave in the area, Antioch to the aquifer of the six creeks crossing the recharge zone Figure 5. Responses in Barton Springs. Turbidity responses to the three sediment plumes in conductance response to a large storm event (rainfall totals of 5.5 cm or 2.75 inches) several days later.

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241NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE entering the pool with enough force to circulate against is housed. If this period is excluded, none of the spring these storm events occurs over days rather than over hours Limited Dispersion from Source to Spring der high aquifer conditions, groundwater velocities up to kilometers away could still arrive at the springs within a day. However, a nearer source seemed likely to WPD dissipation of the plumes. Minimal dispersion indicated that the source was most in the relatively gradual arrival and departure of the tur Even when material is introduced rapidly, such as dye tions. Plume Arrival Times Assuming that these sediment discharges were gener of the release was likely at least 2 hours away assuming that the source of the discharge was likely no more than of the sediment within the aquifer that the releases had occurred on the same day they arrived at the springs. Spatially, this made it most likely that the source was Figure 6. Storm Turbidity Responses in Onion Creek and Main Barton Spring. Turbidity Onion Creek at Antioch Cave, approximately 25 km (15.5 miles) south of Barton Springs. Note 100x difference in scale. Figure 7. Dye Trace Breakthrough Curve and Recovery. Dye injected into Fenceline Sink on Little Bear Creek (23.7 km/14.75 mi from Main Barton Spring) takes days to return to baseline levels (Zappitello and Johns, 2018a).

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24216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 for investigators that it was related to activity early in the emphasizing for investigators that these were discrete completion when white. when many WPD responders were still present at the pool, a WPD water quality compliance specialist was small drill rig operating at a residential construction site. Conversations with the driller revealed that, during the previous few days while drilling heat pump wells for a residential geothermal heating and cooling system, the crew had encountered a void on the evening of Decem and had to use more grout than typical for a well of that had also encountered a smaller void while drilling a difThe timing of these events was consistent with travel Straight-line travel times from the residence to Main the plumes arrived at Eliza Spring following arrival at Figure 8. Geologic Map of Flow Path from Well Site to Main Barton Spring. The well site is in the upgradient from Main Barton Spring. Table 1. Summary of available evidence.

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243NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE added as it escaped into the conduit. air rotary method runs air at a high pressure through a previously clogged conduit.Enforcement Actions system site agreed that the drilling activity there was the likely source of the sediment discharges to Barton Springs. The DSD Enforcement Coordinator issued a Stop Work Order to cease all construction activities and a misdemeanor citation for Discharge of Pollution to a wells, the total depth of the wells and the void horizon ily put them within the zone to intercept conduits within lowed to resume with BSEACD supervision under the condition that wells were drilled only to a total depth at the shallower depth to achieve the same level of heat exchange for the geothermal system.Conclusions & ImplicationsThe Edwards Aquifer tracing program is critical to understanding the sensitive Barton Springs system and has Furthermore, although this was not a planned tracing event, the sediment plumes acted as groundwater tracers the spring with access to hourly internet data uploads peak, and duration of the sediment discharge to within As a result of this event, the BSEACD worked with BSEA. The revised guidelines apply to all wells per Figure 9. Geologic Cross Section from 1912 Paramount Drive to Main Barton Spring. Cross section depicting drilled well depths at the site intercepting the water table.

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24416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 guidelines include limiting non-production wells such as the heat pump wells involved in this incident to total of drilling techniques that could introduce contaminants servative grouting and well-completion techniques when grout loss is encountered. event. The permitting process within city limits is parsed mit from the City of Austin (municipalities do not regulate Although this event was not planned, it provided new information similar to a groundwater tracing study and a unique opportunity for testing and improvement of the were harmed during these plume discharges, and regular monitoring of the springs and the salamander population have shown no lasting impacts to the aquifer or its AcknowledgementsSpecial thanks to Brian Hunt and Justin Camp with the and Development Services Departments who was involved in the response to this event and the ensuing enforcement actions. References say . Segment of the Edwards Aquifer, Southern Travis District and City of Austin Watershed Protection appendices. Within the Barton Springs Segment of the Hays Counties, Texas. PhD Dissertation, Southwest and MoPac South into the Barton Springs Segment of the Edwards Aquifer, Travis County, Texas. City of Austin, Watershed Springs Segment of the Edwards Aquifer, Hays in the Cretaceous Edwards Limestone, Central Sinkhole Conference on Sinkholes and Engineering and Environmental Impacts of Karst,

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245NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFlowpaths in the Vicinity of San Marcos Springs, water quality of the Edwards Aquifer associated with Barton Springs in the Austin area, Texas. Segment of the Edwards Aquifer, Hays and Travis Hydrologic Divide Between the San Antonio and Barton Springs Segments of the Edwards Controls for a Karst Aquifer in Central Texas In: White WB et al., editors. Advances in Karst Tracing in the Barton Springs Edwards Aquifer: Onion Creek and Little Bear Creek. City of Austin of Barton Springs Edwards Aquifer Tracing. Oral United States. Texas. Paper in progress for Proceedings of the Conference on Sinkholes and the Engineering and

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246 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Introduction proximity, geologic structure, presence of unique species, water chemistry, geochemical storm responses, and and documented in the literature. Comparing and contrasting physical and chemical water quality parameters Main Barton Spring and Eliza Spring are two of four ment of the Edwards Aquifer along with Cold Spring and underlying Person and Kainer Formations of the EdEliza Spring are located along the same geologic fault, ential dissolution along faults often creates pathways for endangered salamanders, the Barton Springs Salaman der and the Austin Blind Salamander, though Eliza and Abstract and assumed due to proximity, geologic structure, presence of unique species, water chemistry, and groundwater tracing studies. Fifteen-minute water quality monitor releases of sediment to the aquifer and resulting changes lar at each spring. Sediment is not a traditional groundopportunity to compare responses at the two springs. ton Springs Segment of the Edwards Aquifer provides vidual springs. Main Barton Spring feeds a popular and dangered salamanders, the Barton Springs Salamander and the Austin Blind Salamander. These salamanders are two springs is important for management of the endanSarah J. Zappitello, PGCity of Austin Watershed Protection 505 Barton Springs Rd. Austin, TX, 78704, United States, saj.zappitello@austintexas.govDavid A. Johns, PGCity of Austin Watershed Protection 505 Barton Springs Rd. Austin, TX, 78704, United States, david.johns@austintexas.govLindsey Sydow, PGCity of Austin Watershed Protection 505 Barton Springs Rd. Austin, TX, 78704, United States, lindsey.sydow@austintexas.govHYDROGEOLOGIC CONNECTIVITY OF TWO MAJOR SPRING ORIFICES: MAIN BARTON AND ELIZA SPRINGS TEXAS

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247NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE of the Barton Springs complex and Cold Springs (Haumented to discharge water from the same groundwater Spring at a maximum resolution of once a day and at Main Barton Spring at a maximum resolution of once an A long history of physical and chemical water quality Main Barton is often used as a proxy for the conditions at Eliza. Water quality parameters are typically measured populations respectively. ton Springs Segment of the Edwards Aquifer for more Figure 1. The four major springs that comprise the Barton Springs complex and mapped locations of geologic faults. Figure 2. Location of Barton Springs and the Barton Springs Segment of the Edwards Aqui fer in Austin, Texas.

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24816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8The current analysis takes advantage of an accidental release of sediment through the aquifer which reached ment plumes arrived at Main Barton Spring and Eliza Barton Springs pool was caused when a void was encountered during drilling for a geothermal heat pump the springs and turned the pool a milky white color. The spring in sediment release response times are compared Methods the two springs: Main Barton and Eliza. The water quality sonde at Main Barton Spring is maintained and oper cies. The sondes at Main Barton Spring and Eliza Spring use the units of measurement. The sensors are similar in that lengths of light to make the measurement (Anderson an infrared or monochrome light with a wavelength of The sensor used at Eliza Spring is an OTT Hydromet once a month following standard procedures outlined conductance (a measurement related to the dissolved geochemically link storm response from recharging watersheds to karst springs, since the recharging storm wathe stored aquifer water that contains higher levels of dissolved minerals due to longer contact with the host rock. The storm response manifests as a trough in the Figure 3. within the Barton Springs Segment of the Edwards Aquifer, from Zappitello et al (2019). Adapted from (Hauwert et al 2004, Hunt et al 2005, Smith et al 2006, Hauwert 2009, Smith et al 2012, Hauwert 2012, Hunt et al 2013, Zap pitello and Johns 2018).

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249NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEsensor clock is set two to three minutes ahead of either iPhone standard time from a cellular network tower or not precisely equivalent in magnitude for environmental the measurements are valid parameters for comparison conductance is measured using an OTT Hydromet Hymately once a month following standard procedures outResults serve as indicators of the arrival of the pulse of sediment surement at Main Barton Spring for each pulse of sediTable 1. Magnitude and time of turbidity peak at Main Barton Spring and Eliza Spring. Figure 4. Graph of turbidity measured every 15 minutes at Main Barton Spring and Eliza Spring showing all three pulses of sediment. Date Eliza Spring Main Barton Spring Initial Time Peak Time Peak Initial Time Peak Time Peak er at Eliza than at Main Barton for the second and third sites and documented impacts at the springs (Sydow et al

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25016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 The response of each spring to storm events is another the watersheds of Williamson Creek, Onion Creek, and are likely due to the two storm peaks and recharging waJuly storms were more focused over the watershed of Barton Creek, Slaughter Creek, Bear Creek, Little Bear DiscussionComparing the timing and duration of the sediment plume at the two springs provides insight into the rela in the water may get to Eliza Spring at the same time or slightly later than Main Barton Spring and the pool. fault, it seems logical for the water to arrive at Main amount of time. Figure 5. Pulse one on the evening of 12/18/2018: graph of turbidity measured every 15 minutes at Main Barton Spring and Eliza Spring. Figure 6. Pulse two on the afternoon of 12/19/2018: graph of turbidity measured every 15 minutes at Main Barton Spring and Eliza Spring. Figure 7. Pulse three on the afternoon of 12/20/2018: graph of turbidity measured every 15 minutes at Main Barton Spring and Eliza Spring.

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251NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE for comparing Main Barton Spring with Eliza Spring in the context of past groundwater tracing studies. Past similar water sources (as outlined in the Manchaca Figure 9. 9 September 2018 rainfall totals for watersheds over the contributing and re charge zones of the Barton Springs Segment of the Edwards Aquifer. ONI = Onion Creek, WMS = Williamson Creek. Figure 8. September 2018 geochemical storm response at Eliza Spring and Main Barton Spring as past studies was at most once a day at Eliza Spring and once an hour at Main Barton Spring. Examining arrival times and transport dynamics of the sediment that ar however, this event provided an opportunity to compare responses to an acting tracer at the two springs at the ment measured during previous groundwater tracing exof groundwater movement within the Barton Springs Segment of the Edwards Aquifer varies due to aquifer levels and the overall amount of water in the aquifer. The frequently used as a relative scale for the aquifer level. -

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25216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8geotechnical drilling and arrival of sediment at Barton of storm responses at the two springs provides insight into the aquifer dynamics during time periods when large pulses of water are added to the system. The response at Eliza Spring consistently mirrors the response at Main Barton Spring with a slight delay. The delay in the storm through the karstic Barton Springs segment of the Edwards Aquifer occurs in caves and conduits, so variation Figure 10. July 2018 geochemical storm response at Eliza Spring and Main Barton Spring as char Figure 11. 4-9 July 2018 rainfall totals for watersheds over the contributing and recharge zones of the Barton Springs Segment of the Edwards Aquifer. WMS = Williamson Creek.

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253NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEReferences Segment of the Edwards Aquifer, Southern Travis District and City of Austin Watershed Protection appendices. Within the Barton Springs Segment of the Hays Counties, Texas. PhD Dissertation, Southwest and MoPac South into the Barton Springs Segment of the Edwards Aquifer, Travis County, Texas. City of Austin, Watershed Austin, Watershed Protection Department, Short of Long Term Monitoring Data at Karst Springs, Springs Segment of the Edwards Aquifer, Hays in the Cretaceous Edwards Limestone, Central Sinkhole Conference on Sinkholes and Engineering and Environmental Impacts of Karst, single conduit intercepted during the well drilling. Since the water quality measurements at Main Barton Springs pool and at Eliza Spring. Knowing that Eliza at the pool is important for the management of this spring system. The Barton Springs complex is actively manders, the Barton Springs Salamander and the Austin Blind Salamander, with Eliza Spring and Main Barton Spring as the most populated springs within the complex. The proximity of these two springs along with the aquifer-dwelling nature of the salamanders has promptwater quality measurements from Main Barton Spring aquifer may arrive slightly sooner at Main Barton than at Eliza, and the lead time may vary depending on aquifer conditions, distance from the water source to the springs, Recommendationster to arrive at Eliza Spring than Main Barton Spring, additional sampling at smaller time intervals such as Evaluating response times at shorter time intervals would require precise synchronization of equipment clocks at example applying statistical methods to characterize water chemistry responses to storms, are planned to evalu Main Barton Spring.Acknowledgements Watershed Protection Department for their assistance

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25416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Texas. Paper in progress for Proceedings of the Conference on Sinkholes and the Engineering and Environmental Impacts of Karst 2020. Turner M. 2000. Update of Barton Springs Water Austin, Watershed Protection Department, Short continuous water-quality monitors—Station operation, record computation, and data reporting: in the Barton Springs Edwards Aquifer: Onion Creek and Little Bear Creek. City of Austin, Austin, Watershed Protection Department, Data Flowpaths in the Vicinity of San Marcos Springs, Springs Segment of the Edwards Aquifer and Its Concentrations at Barton Springs. City of Austin, Barton Springs and surrounding springs in Austin, for Future Analysis. City of Austin, Watershed Segment of the Edwards Aquifer, Hays and Travis Hydrologic Divide Between the San Antonio and Barton Springs Segments of the Edwards of Mystery Sediment Plumes at Barton Springs,

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255 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Cypress Creek, generally upgradient of the spring. This information was used to delineate a groundwater management zone, which was then recommended to the local groundwater conservation district and a local stakehold er group. Using the springshed delineation, rules have limit increases in permitted pumping, to further restrict the amount of groundwater pumped during drought, and Introduction Antonio, Texas, is experiencing some of the highest population growth rates in the country. With very little AbstractHays County is experiencing some of the highest growth rates in the country, and groundwater is the primary option for water in the county. One spring in the study area, logical and water resources of the region. A springshed delineation study was conducted at the request of the local groundwater conservation district to identify the geoeas for water-supply wells, springs, and aquifers in karst from a large phreatic cave passage with over a mile of surveyed passages in the Cow Creek Limestone of the Middle Trinity Aquifer. The aquifer has varying degrees structure maps, potentiometric maps, hydrographs, and Brian A. Smith Barton Springs/Edwards Aquifer Conservation District 1124 Regal Row Austin, Texas, 78748, USA, brians@bseacd.orgBrian B. HuntBarton Springs/Edwards Aquifer Conservation District 1124 Regal Row Austin, Texas, 78748, USA, brianh@bseacd.orgMarcus O. GaryEdwards Aquifer Authority 900 E. Quincy San Antonio Texas, 78215, USA, mgary@edwardsaquifer.orgDoug A. WiermanThe Meadows Center for Water and the Environment, Texas State University 601 University Drive San Marcos, Texas, 78666, USA, dawierman@aol.comJeff A. WatsonZara Environmental 1707 West FM 1626 SPRINGSHED DELINEATION IN A KARST AQUIFER IN HAYS COUNTY, CENTRAL TEXAS

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256NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEconcern to the groundwater districts, Hays County government, and to the users of the aquifers. Impacts from charge to the downstream Edwards Aquifer. Endangered species at Barton and San Marcos Springs within the Edogy and recharge to the Edwards Aquifer.Hydrogeologic SettingThe study area includes central and western Hays Counof the study area. face consist of gently dipping Lower Cretaceous lime tion showing the stratigraphy of the study area. Except on the Edwards and Trinity Aquifers. In the western por tions of the county, where there is no Edwards groundwater, the dominant sources of water are the Trinity The State of Texas preserves and protects groundwater through groundwater conservation districts. The Hays covers the western portion of Hays County and the study Most wells in the study area are small-capacity domestic and ranch wells and are exempt from regulation. Largermunicipal and irrigation use. Larger-capacity wells are demand for groundwater and the resulting impacts are of Figure 1. Jacob’s Well in the foreground and view of Cypress Creek looking downstream.

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25716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 2. Geologic map of the region around Jacob’s Well (JW), Pleasant Valley Spring (PVS) and the Jacob’s Well watershed. fractures and dissolution features. The Cow Creek For Shale separates the Cow Creek from the underlying Sligo and Hosston formations of the Lower Trinity. The Upper Trinity Aquifer is composed of the Upper headwaters of drainages. The underlying Middle Trinity Aquifer is the primary aquifer in the study area and is the water supply for most of the groundwater production in the study area and is the source of water for Jathe Cow Creek. The Cow Creek is a highly transmissive and karstic unit and the primary aquifer unit within the Middle Trinity Aquifer. charging from the Middle Trinity Aquifer into Cypress

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258NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEtrending west-dipping fault within Blanco County, and a series of en-echelon east-dipping faults, known as the exposing all three geologic units of the Middle Trinity The geologic units of the Middle Trinity Aquifer dip gently from west to east through the study area until reach ing the Tom Creek and Balcones fault zones. East of Jaand create relay-ramp structures that can provide lateral permitted and exempt pumping have resulted in periodic Geologic Structures provide the foundation of our geologic and structural Cow Creek were created using outcrops and geophysical Figure 3. Geologic structure map of the region around Jacob’s Well (JW). Contours intervals are in feet. 1,000 ft = 305 m.

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25916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 associated with faults can locally increase the lateral and Within the Dry Cypress Creek Watershed (the section cludes an anticline trending west to east across the waperpendicular to the orientation of normal faulting. This Trinity Aquifer.Groundwater FlowUsed with caution, potentiometric surface maps can proFigure 4. Stratigraphic section of the study area. Figure 5. Cross section of study area showing general stratigraphy and location of cave passage associated with Jacob’s Well. The scale on the left shows elevation above mean sea level (amsl) in 100-ft intervals, equivalent to 30-m intervals.

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260NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE and groundwater discharges through the Hensel and the to the down-dip Edwards Aquifer in Hays County (Hunt Unique features in the potentiometric map are related to central Hays County occurs coincident within the horst Middle Trinity Aquifer is generally west to east from generally follow the structure contour gradients, which Trinity Aquifer is generally from the northwest to south-Figure 6. Potentiometric surface map of the region around Jacob’s Well. Con tours intervals are in feet. 1,000 ft = 305 m.

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26116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Three areas were delineated in the study to have certain hydrologic characteristics and varying degrees of hydrotraverse. These types of potentiometric troughs are comTom Creek Fault Zone suggest that these faults in the along certain portions of the faults in this zone. However, Figure 7. Location map of the three hydrogeologic areas outlined by this study. JWJacob’s Well; PVSPleasant Valley Spring

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262NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEcharge values, as a percentage of precipitation, results in corresponds to a springshed size equivalent to the area 22 22 22 the volume of rainfall for this same period was calcu the rainfall is recharge, then an area equal to two grids, 22 the rainfall is assumed to recharge, then an area equal 22 suggest Dry Cypress Creek Watershed could account for fective recharge as a percentage of annual rainfall ranged recharge, as a percentage of rainfall, was annualized into 2 mi2 unique hydrologic and hydrogeologic features that were considered as part of the evaluation to delineate areas ment zones.Jacob’s Well Springshed Area ing the area within Dry Cypress Creek Watershed and the Dry Cypress Creek Watershed. potentiometric data indicate a convergence of groundThis hypothesis that the Dry Cypress Creek Watershed is Jacob’s Well Water-Balance Methods through soils and discrete recharge via karstic features.

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26316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 springs. sponsive to the rainfall and the change in river stage in noted similar evidence for hydrologic separation for the ported from modeling of the Trinity Aquifer, which is karstic Edwards Aquifer. Thus, the range of annual efmately equal to the area of the watershed upgradient of 22 constrained within the Dry Cypress Creek Watershed. 22 22 ations presented here generally support the hypothesis recharge occurring in the Dry Cypress Creek Watershed 22 Regional Recharge Area of the Middle Trinity Aquifer occurs over a much larger area of western Hays, Blanco, Comal, and Kendall counties where all the Middle Trinity units are exposed and to a portion of the springshed for the perennial Pleasant important Middle Trinity karst spring discharging into During drought, Pleasant Valley Spring is the sole conPleasant Valley Spring is hydrogeologically similar to Figure 8. Hydrographs of Jacob’s Well, Pleasant Valley Spring, and the Blanco River. rainfall equals 25.4 mm.

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264NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEWater-Level DataWater-level data from wells in the vicinity of the Tom cated south and east of the Tom Creek Fault Area (down ter-level response to recharge events than up-dip wells due to the karstic nature of the Middle Trinity Aquifer Tom Creek Fault AreaThe Tom Creek Fault Area is an area down gradi Well Springshed Area and portions of the Tom Creek Fault Area indicate these areas are hydrauli applies to the Tom Creek Fault Area within the Cypress Creek watershed.Figure 9. Blanco River in cubic feet per second (cfs). Note 1.0 cfs = 28.3 liters per second. The scale on the upper left shows elevation above mean sea level (amsl) in 100-ft intervals, equivalent to 30-m intervals.

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26516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8within the Cypress Creek Watershed as mapped in FigCreek Fault Zone appear to have a less of a hydrologic area within the Tom Creek Fault Zone and Cypress Creek SummaryDue to the rapidly growing population and demand for spring. This has negative ecological and recharge impacts to the downstream resources. Limiting groundwamechanism to ensure adequate groundwater levels and Evaluations of hydrogeology, water levels, and water of the Dry Cypress Creek Watershed are a good approxiWells within a portion of the Tom Creek Fault Zone are Well. Considering all these data and hydrologic zones, and could help maintain water quality. drafted rules for this area that would restrict permits for cant reductions in pumping during periods of declared drought.Future StudiesSome uncertainties remain such as the amount of precipitation events. These potentiometric elevations are very similar to and only slightly higher than the eleva associated karst conduits are the dominant hydrologic features controlling the hydrologic heads upgradient of sipate quickly. to recharge events. Two Middle Trinity wells located wet and drought cycles than with individual precipita tion events. logic section resulting in longer, slower, vertical or lat eral recharge pathways. supply wells show a potential hydrologic connection to

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266NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE B.M. and Scranton, D.F., cartography, scale resources of the Paleozoic and Cretaceous aquifers in the Hill Country of central Texas: Texas Water an example from Dinaric karst, Environmental BSEACDBarton Springs Edwards Aquifer Estimates. Ph.D. Dissertation, Jackson School of Hollow quadrangle, Texas: University of Texas at quadrangle, Texas: University of Texas at Austin, Management Zone Hays County, Texas. Technical Conservation District, Hays County, Texas. Meadows Center for Water and the Environment, of the potentiometric contours that were used to help deof the Middle Trinity Aquifer. It is not known how exunderlying Cow Creek Limestone other than the conmapped over a mile of cave passage that extends northwithin the springshed and the upgradient areas northwest of the springshed are needed. Key tasks that are planned for the near future are installation of two or more monizones, discrete measurements of potentiometric pressure quality analyses. Additional studies are necessary to determine how long-term drawdown of the aquifer due to when these additional studies are completed.Acknowledgments nical team consisting of the authors of this manuscript. tetti, and Alex S. Broun. We would also like to thank the anonymous reviewers for their comments that consider References Management on the Hydrologic Budget and Water Map of Texas: University of Texas at Austin,

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26716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Cypress Creek watershed and their implications Conservation District. Smith, B., Hunt, B., Andrews, A., Watson, J., the Trinity and Edwards Aquifers, Central Texas, USA, in Hydrogeological and Environmental Andreo, F. Carrasco, J. Duran, P. Jimenez, and J. LaMoreaux, Environmental Earth Sciences, Karst Aquifers of Central Texas. In I.D. Sasowsky, Sinkholes and the Engineering and Environmental Interactions in the Trinity Aquifers, Central Texas. Hydrogeochemical and Hydrogeological Evidence Investigation of the Middle Trinity Aquifer in Utilizing Eddy Covariance Evapotranspiration. potentiometric map of the Middle Trinity Hunt, B.B., B.A. Smith, A. Andrews, D.A. Wierman, and Travis Counties, Central Texas, Sinkhole Minnesota Implications for the Trinity and Edwards Aquifers Middle Trinity Aquifer, Central Texas. BSEACD portion of the Trinity Aquifer of Texas: Texas application for estimating aquifer recharge. plan. The Meadows Center for Water and the Environment, Texas State University, San Marcos,

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268NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEWierman, D.A., A.S. Broun, L. Llano, and A.H. Hydrogeologic Atlas of the Hill Country Trinity Aquifer, Blanco, Hays, and Travis Counties, Hays County, TX. Meadows Center for Water and the Environment, Texas State University at San Marcos, TX.

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269 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8could address the origin of groundwater, and intercon concentrations O and H and origin of recharge, residence time of groundwater, and formations. Hydraulic head data further support limited wards and Trinity Aquifers is limited in the study area. These implications support independent groundwater management of these two essential aquifer systems in Central Texas.IntroductionThe Edwards and Trinity Aquifers provide water supplies for more than two million people in central Texas for municipal, industrial, and agricultural uses. However, water shortages occur in the Edwards Aquifer due to excessive pumping of groundwater and recurrence of historic droughts in central Texas. Water quality is also Abstract of Central Texas that provide water supply for over two million people and contain springs that are hydrologically and ecologically important to the region. The Edunderstanding the hydrologic connection is necessary surveys, dye-tracing experiments indicated the existence Trinity aquifers in some areas. However, lateral interarea Barton Springs segment of the Edwards Aquifer. in this study area. This study focuses on hydrochemical data collected from multiport wells to assess the degree Trinity Aquifers. Multiport wells allow the collection tiple isolated hydrostratigraphic units within the same Lijun TianCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, Lijun.Tian@utsa.eduBrian A. SmithBarton Springs/Edwards Aquifer Conservation District, 1124 Regal Row, Austin, Texas, 78748, USA, brians@bseacd.orgBrian B. HuntBarton Springs/Edwards Aquifer Conservation District, 1124 Regal Row, Austin, Texas, 78748, USA, brianh@bseacd.orgJames D. DosterCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, djangodoster@yahoo.comYongli GaoCenter for Water Research, Department of Geological Sciences, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249, USA, yongli.gao@utsa.eduGEOCHEMICAL EVALUATION OF HYDROGEOLOGIC INTERACTION BETWEEN THE EDWARDS AND TRINITY AQUIFERS BASED ON MULTIPORT WELL ASSESSMENT IN CENTRAL TEXAS

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270NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEH and time of groundwater, and mineral-solution reactions Trinity Aquifers is limited in the study area. This impli cation supports independent groundwater management of these two essential aquifer systems. Hydrogeologic Setting The smallest segment, the Barton Springs segment of the source water of Barton Springs is the Edwards Aquifer. The Middle Trinity Aquifer is the primary source of groundwater west of the BFZ. In the Barton Springs segment of the Edwards Aquifer tant source of water, as the Edwards Aquifer reaches its capacity due to drought restrictions. However, there crucial implications for the management of the Trinity Aquifer. The Trinity and Edwards Aquifers are hydrogeologi aquifers in the multilayered aquifer system (Bense et al., Edwards and Trinity Aquifers. However, hydraulic head data within the hydrostratigraphic units illustrate limited tions. Hydrochemical and isotopic data of groundwater have water cycle, such as the origin of groundwater, and inter However, few studies have systematically investigated the evolution of hydrochemical and isotopic signatures across the Edwards and Trinity Aquifers at the same location. The Barton Springs Edwards Aquifer Conservawere used in the wells to isolate sampling zones to alwe could evaluate geochemical data to determine unique natural markers for groundwater compositions of each TDS, SO wards and Trinity Aquifers are considered statistically Figure 1. Schematic view of the multiport well components for the top monitoring zone (Hunt et al., 2016).

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27116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 predominately a massive shell fragment limestone with rudist and reefs present for its lower section (Stricklin Trinity Aquifer within the study zone is generally unData Analysis and Visualization Anions Cations Anions Cations CBE 2+, Mg2++, K+, Sr2+ , SO , Cl terization. groundwater samples are shown in the Schoeller diagram three multiport wells in Hays County, referred to here as recharge zone, and the Driftwood well is located in the The multiport well approach allows the sampling of multiple known and isolated hydrostratigraphic units within zones within the Edwards Aquifer, Upper and Middle spring and well samples from the Lower Trinity Aquifer in the research area were sampled, measured, and utilized for statistical analysis in this study. Figure 2. Geologic map of the Barton Springs segment of the Edwards Aquifer (central Texas) with well locations. Figure 3. Cross section from contributing zone, diagram of fault structure that could facilitate lateral communication between aquifers. Map and cross section are adapted from Wong et al. (2014).

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272NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCECa2+ and Mg2+ for anions, there are similar concentrations of HCO and Cl, however, there is a trend towards SO dominance in the Trinity Aquifer. Aquifer are Ca2+-HCO type with a trend toward Ca2+SO type in the Upper and Middle Trinity Aquifers. The there is an increasing trend for TDS in the Upper and Middle Trinity Aquifers. Multiple Comparisons parison procedures are applied for the TDS and concen hydrochemical data among all aquifer types. much more symmetrical than the original TDS data. The ed than original TDS data for all aquifers. There are similar residual variances are consistent for three Trinity Aquiwards Aquifer group. The residual plot for log TDS data approximately symmetric against the estimated group The visualization of multiple comparisons for TDS data Trinity Aquifers. The Tukey multiple comparisons (FigAquifer is lower than all the three Trinity Aquifer units. Thus, TDS in the Edwards and Trinity Aquifers are disFigure 4. Schoeller diagram for the multiport well hydrochemical dataset. Blue=Edwards Aquifer, Yellow=Upper Trinity, Red=Middle Trinity, Square=Ruby Ranch well, Circle=Antioch well, Triangle=Driftwood well. Figure 5. Durov diagram for the multiport well hydrochemical dataset. Blue=Edwards Aquifer, Yellow=Upper Trinity, Red=Middle Trinity, Square=Ruby Ranch well, Circle=Antioch well, Triangle=Driftwood well.

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27316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 6. Histogram plots for the TDS (A) and log TDS (B) for all samples; normal Q-Q plots for TDS (C) and log TDS (D) of different Aquifer types. Figure 7. The S-L plot for log TDS: square root of the absolute values of residuals against the estimated group averages (A); the scatter plot of the residuals against the estimated group averages (B); the normal Q-Q plot of the ANOVA model residuals (C).

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274NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Edwards Aquifer indicates its younger groundwater age conconcentrations for the three concentration in the Edwards Aquifer. There is no mineralogical source of nitrate in these aquifers. Excess nitrogen in water could come from natural sources (organic matters from leaves and animal higher nitrate concentrations in the Edwards Aquifer might indicate potential sources of contamination. The groundwater takes place. Therefore, the Edwards AquiTrinity Aquifer. The visualization of multiple comparisons for SO conconcentrations, there are similar means of SO concentrations, SO concentra tions in the Edwards Aquifer are much lower. Sulfate concentrations are identical among Upper, Middle, and Lower Trinity Aquifers. This indicates that gypsum layers exist in the three Trinity Aquifer units or Aquifer units. Much lower sulfate concentrations in the Edwards Aquifer than all three Trinity Aquifer units sugand Trinity Aquifers is likely limited. tween the Edwards and Trinity Aquifers are considered claim that at least one means of the log SO , and Cl Isotopic Signatures Owaters. However, the isotopic signatures of all aquifer O values as long-term average prelittle evaporation occurs during recharge to these aquifers. Figure 8. Boxplots for log TDS by aquifer types (A) and Tukey multiple comparisons for the means of the log TDS by aquifer types (B).

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27516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8H and C The H signature of groundwater might indicate the large portion of surface-water recharge, and the low H signaTherefore, the Lower Trinity Aquifer might receive lim ited surface water recharge. Sr Figure 9. Boxplots for log NO3by aquifer types (A) and Tukey multiple comparisons for the means of the log NO3by aquifer types (B). Figure 10. Boxplots for log SO4 2by aquifer types (A) and Tukey multiple comparisons for the means of the log SO4 2by aquifer types (B).

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276NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE minerals. (mean Sr might indicate groundwater from the Edwards Aquifer, which indicates the progressively long residence time and increasing wards Aquifer. During the drought period, the interaction preferential dissolution of dolomite and precipitation of calcite might occur in the downdip parts of the Edwards Ca ratios of groundwater.ConclusionsMost water samples of the Edwards Aquifer are Ca2+HCO type. The Upper and Middle Trinity Aquifers are generally Ca2+-SO dissolution of gypsum layers in the three Trinity Aquifer units. concentrations concentra tion of the Edwards Aquifer are lower than all three Trinconcentration is higher in the Edwards Aquifer. Table 1. The ANOVA table for comparison of means of the log TDS for four aquifer types. Note Figure 11.18 samples by different aquifers. Figure 12. 14C vs. 3H regional mixing trend for all groundwater samples by different aquifers. Figure 13. Sr/Ca ratios vs. 87Sr/86Sr for all groundwater samples by different aquifers.

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27716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8H and provided information on the origin of recharge, residence time of groundwater, and mineral-solution reactions in The geochemical data from the multiport wells indicates in the study area. This implication supports independent groundwater management of these two important aquifer systems.References apparent groundwater ages, and the evolution of Edwards and Trinity Aquifers of Central Texas. groundwater interconnection of the Edwards and Trinity aquifers, Camp Bullis, Bexar and Comal Counties, Texas. Interconnection of the Proceedings from Karst Conservation Initiative Edwards Aquifer storage assessment, Kinney County to Hays County, Texas: San Antonio, Texas, Compilation of pumping tests in Travis and Hays Counties, central Texas. Barton Springs Edwards Conductivity Testing in the Edwards and Trinity Aquifers Using Multiport Monitor Well Systems, Hays County, Central Texas. Barton Springs the Trinity aquifer of Texas. Texas Water Aquifer, central Texas. In Kuniansky EL, precipitation and cave drip waters, central Texas, data for resource management planning. Edwards Aquifers along the Balcones Fault Zone and characterization of the Edwards and Trinity Lower Cretaceous Trinity Deposits of central Texas: Austin, University of Texas, Bureau of Economic Wong CI, Kromann JS, Hunt BB, Smith BA, Banner Edwards and Trinity Aquifers in central Texas.

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278 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Introduction the island, occurring on the north and south coasts and in small patches throughout the central part of the Comdramatic inland and coastal landforms, extensive lime stone aquifers, coastal wetlands and estuaries, and through the many caves and cave systems that drain the are sinkholes. They are an inherent part of the karstiprocesses including dissolution of underlying strata, coland non-karst processes such as landslides, and wind From a touristic perspective, sinkholes have served as through a series of collapsed sinkholes. At the same time, sinkholes pose a challenge to the installation and mainte of new sinkholes. In the present paper an examination is made of the state -Abstract of the island, occurring on the north and south coasts and in small patches throughout the central part of the Commonwealth. The karst is expressed through dramatic inland and coastal landforms, extensive limestone aquifers, coastal wetlands and estuaries, and through the many caves and cave systems that drain the landscape. which form from a variety of processes including disvoids, and landslides. From a touristic perspective, sinkscope located within a large sinkhole, and the route of Analysis of sinkhole occurrence and density have shown However, despite touristic and academic interest, sink2 the ever-growing impact of human development on the lapses. Patricia KambesisCenter for Human GeoEnvironmental Studies, Western Kentucky University 1906 College Heights Blvd, Bowling Green, KY 42127 USA, pat.kambesis@wku.eduIra D. SasowskyDepartment of Geosciences, University of Akron Akron, OH 44325-4101 USA, ids@uakron.eduBrittiny P. MooreDepartment of Geography, Texas State University San Marcos, TX 78666 USA, brittiny.moore00@gmail.comSINKHOLES AND KARST IN PUERTO RICO: PICTURESQUE AND PROBLEMATIC

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279NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEies shared as well as frequency analyses of areas with BackgroundGeology provinces. The oldest rocks comprise a central volcanicplutonic province which trends east-west and represents central core rocks are from Late Jurassic to Early Creta entire karst terrain. Hydrology Some of the allogenic recharge sinks at or near the igderlying drainage systems which ultimately resurge into levels on the north and south coasts respectively. Figure 1. Karst areas of Puerto Rico. Derived from: Alemn Gonzlez, 2010.

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28016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8The karst aquifers consist of relatively young and porous units. This creates a stacked series of aquifers (Figure springs, from the central highlands, as is typical in an island setting.Geomorphology who conducted much of the original karst research on sinkholes. The southern limestones are more structur throughout the interior of the island and represent reldocumented in some of the Cretaceous segments (Miller ize the various limestone units including cockpits, cone Sinkholes Overviewcesses. Dissolution sinkholes form where aggressive with the atmosphere. Bedrock collapse sinkholes, which are rare, occur when the ceiling of a cave collapses, exposing the cave passage to the surface. Bedrock collapse sinkholes develop and are dependent on the geology of the area, including geologic structures, and the maturity of the process in relation to geologic time. eas where surface sediments are thicker or contain more tected for extended time periods. are the most common type associated with develop ment. These sinkholes tend to impact infrastructure like ral water-drainage patterns due to construction or new Figure 2. Map showing distribution of rainfall on Puerto Rico. Source: NOAA 2010.

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281NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE material triggers an underground collapse of supporting sinkhole areas that commonly have sinkholes that are 2 2. Map overlays show the Sinkholes Case StudiesSuperfund siteaquifers throughout the region, as well as numerous hisInformation in this section is drawn from the three Figure 3. 10x vertical exaggeration. From: Giusti, 1978.

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28216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 4. Map showing relation of Puerto Rico karst and dense sinkhole areas to high population density and major roads. Derived from Gould et al. 2008 and Alemn Gonzlez, 2010. Figure 5. Frequency distribution of areas hav ing many sinkholes > 30m deep. Based on data from Alemn Gonzlez, 2010. masks. In this process, sheets of metal were etched with a strong acid, and the excess ferric chloride solution was low pH metal-rich solution into the groundwater. This ing water quality in the region. Additionally, wastewater study which included review of the physical characteris involved included analysis of topographic maps, soils investigation, an on-site hydrogeologic investigation which included monitoring well installation and repair of an artesian well, a karst hydrogeologic investigation which included aquifer and tracer tests, geochemical northward direction, towards the Atlantic Ocean. How

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283NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 6. Plan map of the RCA del Caribe Barceloneta facility showing buildings, on-site sinkhole, and adjacent mogote topography. Source: Nittany Geoscience, 1994.

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28416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 allowing copious upward leakage of water from the ar though no evidence of open conduits was found. The site ever, the end result of the study revealed a surprisingly ferric chloride containments, the acidic solution came into contact with the limestone and was immediately neutralized. This rise in pH resulted in the precipitation tion within the strata. Consequently, the only ongoing no further remedial action was necessary.Coastal Cave Collapses stones that are scattered through the central parts of the caves occur at various elevations from sea level to was discovered on the north coast of the island at aperosion is likely to result in more surface collapse into house structures and resorts are having negative impact on the coastal karst resources of the island.Storm Induced Cover Collapse the north coast karst where naturally occurring sinkholes it is the human-induced sinkholes that negatively impact development infrastructure in these areas. of a water main. The water scoured away the sediment The sinkhole was of the cover collapse variety, occurring mon and catastrophic causes of ground failure in karst holes will likely continue to wreak havoc on the roads

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285NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE in temperate and tropic karst regions. In: Multidisciplinary Conference on Sinkholes and Parguera quadrangles, southwest Puerto SummarySinkhole development has a complex history in Puerto new sinkhole development from littoral and erosional processes. The growth of population and supporting infrastructure also induces increased sinkhole develop sary remediation of sinkhole collapses adds to the growing economic challenges of the island.References map of the Penuelas and Punta Cuchara

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28616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 United States: A digital map compilation

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287 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8and DEM analysis indicate that sinkhole occurrence and character have changed over time. Introduction there is an inner escarpment (more commonly used as entire area that would theoretically drain toward the limited rainfall means that a large area of the watershed Abstract and Salado Formations. Surface features of sinkholes, relatively shallow, and groundwater is removing halite photo interpretation, DEM analysis, remote sensing and Andrea K. Goodbar Geospatial Collaborative 3027 E. Derrick Road, Carlsbad, NM 88220, USA, agoodbar.newmexico@gmail.comDennis W. PowersConsulting Geologist 170 Hemley Road, Anthony, TX, 79821, USA, dwpowers@evaporites.comJames R. GoodbarGoodbar Consulting 3027 E. Derrick Road, Carlsbad, NM, 88220, USA, goodbarjr@gmail.comRobert M. HoltDepartment of Geology and Geological Engineering University of Mississippi, University, MS, 38677, USA, rmholt@olemiss.eduKARST AND SINKHOLES AT NASH DRAW, SOUTHEASTERN NEW MEXICO (USA)

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288NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Draw. to meteoric water at the surface. Dissolution and erosion Draw in support of the growing potash industry in the that solution of upper Salado halite created the draw and quadrangle geological map. Figure 2. Principal stratigraphic units at Nash Draw. M-x/H-x portions of the Rustler indicate mudstone (M-x) to halite (H-x) facies changes from left (west) to right (east) in southeastern al.(2003). Figure 1. depression (white/black dashed outline) within larger potential watershed area (blue outline). Watershed designation: Salt Lake. HU: 1306001117. For reference, the approximate center of the WIPP site is longitude -103.7914 degrees, latitude 32.3697 degrees.

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28916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 As an example, evidence for dissolution is more precise In this article, we summarize the current status of our Basins Within BasinsUsing topographic maps, aerial photography, and ground dividing along a general topographic high. Most of the of active and inactive drainages, areas with individual constraints for WIPP hydrology at the time, these param not located precisely. and assigning other parameters was to provide data for cation and characterization. waters recharge in karst features developed in upper face karst features. Figure 3. Thirty topographic basins were delineated by Powers (2014). Basin 16 does not exist; it was combined with basin 14 after re-evaluating the divide between them. Nash Draw underlay from USGS NED.

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290NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEare at and near the surface in these areas, and various karst features are more common. Topographic separashallow closed depression and more or less centripetal drainage. The south side is an escarpment with a divide moved. The generally accepted explanation is that these topographically higher areas. Several square kilometers near the lowest point display interconnected drainage on relatively hard ground. The lowest point is a karst valley with numerous sinks, dolines, and caves, and it is does not allow straightforward passage of water. A pestorage in an area that receives an average annual rainfall standing points and areas for recharge to the underlying sediments and rocks. It helps organize features into poGeographic Information System (GIS) Approach and Data pretation of old and new aerial photos, and remote sensFigure 4. A. Flooded low area of basin 6 on sin 5 on 9/20/2014.

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29116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8ing. Many details of the software, hardware, and tools Digital Elevation Models (DEM) Analysis Analyst Hydrology Toolset was used to create raster data tify sinks within the DEM as well as locate and address error within the DEM. were generated using the same parameters. Figure 5. drainage, similar to the watershed area. Drainage is connected to the Pecos River; B. Surface monly terminating at or near alluvial dolines, swallets, or caves. When no threshold value is assigned, which proximately what one would expect from this area with

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292NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEsystems are considered. closely. Figure 6. A. have been observed and located (see Field Mapping with Global Navigation Satellite System); B. observed and located (see Field Mapping with Global Navigation Satellite System). Figure 7. Detail of surface drainage analysis with 3-m threshold for basin 18. Karst features are included where they have been observed and located (see Field Mapping with Global Navigation Satellite System).

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29316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Field Mapping with Global Navigation Satellite System ute quadrangle maps and noted several larger examples. lakes. These, however, were again only reported as prestailed location data. let, cave, karst feature (includes remnant karst, pits, of mouth, reported features in the topographic analysis, aerial photo analysis, DEM sink analysis, and old-fashAerial Photo Interpretation Earth iterations are of excellent quality. Aerial photos of a small area near a potash mine tailings photograph does not appear to show the sinks easily are similar. More recent photos show that the additional the sump. There are modest depressions south of this reFigure 8. Well-developed small sinks in the vicinity of a potash tailings pile on the western side of Nash Draw are not apparent in 1945 aerial photography (photoreferenced for location). Best resolution available.

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294NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEHydrologyWhile investigating water sources to support the early stratigraphically mainly in the solution residue of the Lang concentrated much of their study at or near Latler units and the contact zone with the Salado. Mercer southwest, and the current recharge point at the eastern and the east recharge point dominated. The east recharge point is still dominant. Field study shows that the sinks in the eastern end developed in the Magenta Dolomite red sediment that has at least partially plugged some inRemote Sensing Landsat imagery has not proven useful in extracting speFigure 9. The sump at the southern end of basin 18 illustrates changes with time in Nash Draw. Prin

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29516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 rameters for tracer tests to help evaluate the hydrology Dissolution through geophysical logs, mapping of shafts at WIPP, narrow margin over which the upper Salado is removed is lower in elevation under the structural trough. Holt Figure 11. Scallops at the cave entrance of the primary swallet for basin 18 are 6+ cm Figure 10. The primary swallet and associated cave in basin 18 in January 2014 captured most of the water entering the basin. At the base of the sinkhole, a bedrock crevasse dropped ~5 m to a horizontal passage trending south for ~8 m before constrictions halted exploration.

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296NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEAcknowledgements the analysis does not represent the views of any organization or government agency. We also appreciate two helpful, detailed reviews of the draft manuscript.References dissolution at and near the Waste Isolation related to proposed expansion of potash mining impacts of potash industry discharge and escarpment. The data are somewhat limited to map top Most of the sinks, swallets, and caves are developed in or caves in this area. There are larger depressions, likely due to deeper dissolution of upper Salado halite (Powers Summary south-southwest, eventually discharging into the Pecos mines. ideas of surface and near-surface hydrology. Tracer tests and executed, and such tests would require a long-term perspective and commitment to maintain. Draw karst features, develop and report a more detailed partners to continue the work.

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29716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Conservation Service, Conservation Engineering ML, Slay ME, Bitting CJ, editors. Proceedings of Proceedings.pdf in the WIPP vicinity. In: Land L, Lueth VW, and postdepositional alteration within the dissolution at a radioactive waste disposal site,

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298NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE induced ground deformation and associated

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299 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8tions in shallow groundwater level have helped reacti agents in eroding the overlying materials.Introduction west of the town of Attawapiskat in northern Ontario, Cape Henrietta Maria Arch that separates the erosional lites, various geotechnical, hydrogeological and environvelopment. Pliocene glaciations and post-glacial Tyrrell Sea deposition and continuous isostatic uplift have created a unique environment for karst development on the area east of the Victor mine site was recommended as Abstract within the James Bay lowland of Canada consist of preglacial sinkholes and post-glacial sinkholes. Most of Silurian Attawapiskat limestone at the Process Plant site after the thin peat and unconsolidated sediment cover exposed. One unique pre-glacial sinkhole was reported of the Paleozoic formations to a depth of approximately glacial depositional environments. The post-glacial sinkholes have developed after the area emerged from the with open drains and intermittent sinking streams are the primary form in the exposed reefal limestone of the Atpost-glacial sinkholes have developed around perimeters sinkholes are likely linked to the pre-glacial ones, which provided the pre-existing conditions for the post-glacial sinkhole formation. The increases in hydraulic gradient -Wanfang ZhouHana Engineers & Consultants, LLC Knoxville, Tennessee, United States, zhou_wanfang@yahoo.comMingtang LeiInstitute of Karst Geology Guilin, Guangxi Province, China, lmt@karst.ac.cnJames W. LaMoreaux PELA GeoEnvironmental Inc. Tuscaloosa, Alabama, United States, JLamoreaux@pela.comDaniel S. GreenPELA GeoEnvironmental Inc. Tuscaloosa, Alabama, United States, dgreen@pela.comPRE-GLACIAL AND POST-GLACIAL SINKHOLES IN SILURIAN CARBONATE ROCKS IN THE JAMES BAY LOWLAND, CANADA

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300NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE study presented in this paper was to determine if karst sinkhole occurrence during mine dewatering. Figure 2 ration Camp, Bedrock Trench, and Bioherm Complex Zone that are related to this karst study. The Victor mine Geologic and Hydrogeologic Settings poor drainage. Muskeg developed rapidly in these areas of poor drainage and covered the deposits further reducing their erosion. Only on the high ground along the larger rivers and on the remnant cores of ancient reefs Underlying the muskeg is a series of glacial, marine and namic nature of the region over the relatively recent geomarine waters of the Tyrell Sea. During this time a generally uniform layer of clay and silt was deposited on the Figure 1 Location of study area

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30116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 forms a regional aquitard. The upper Attawapiskat unit derlie the Attawapiskat limestone extending to a depth of er formations are primarily composed of limestone and limestones, and evaporites. The hydrogeological conditions in the study area are characterized with distinct aquifers and aquitards. The to east under natural conditions. Local components of extensive aquitards. Total dissolved solids measured in fers. Fresh water is present in the peat and upper Attawapiskat limestone aquifers. The groundwater in the mixture of fresh water, relic Tyrell Sea water, and water in contact with evaporites. Saline groundwater is in the Sinkhole Study Figure 2 Distribution of karst features along and between Attawapiskat River and Nayshkootayaow River

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302NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEamsl. Additional sinkholes were reported at the Central Bedrock Trench, Exploration Camp, and Bioherm Complex Zone, the sinkholes developed in the Paleozoic car consist of pre-glacial sinkholes and post-glacial sinkthe post-glacial sinkholes were recognized at Explora tion Camp and the Bioherm Complex Zone. Pre-glacial sinkholesPre-glacial sinkholes formed in the geological past priLithology Description Holocene Peat Muskeg of the surface at the site. The peat is typically several meters thick, with an upper, spongy, transmissive zone and a deeper, mucky, relatively non-trans missive zone. Pliocene Post-glacial Marine and Fluvial Deposits of the larger rivers, to greater Silurian Upper Limestone are highly porous and contain high concentrations of trilo separated from one another eroded or intervening areas are Silurian Blueforms a regional aquitard. Silurian Lower Limestone or Dolomite of the lower Attawapiskat dolomites, and evaporites. Table 1 Summary of main lithologic units Figure 3 Pre-glacial sinkholes exposed at Process Plant site

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30316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8cavities were present on the nearly vertical walls of these sinkholes. depression that ran northwest to southeast across the width of the north central portion of the Process Plant a paleo-stream channel along with several deep deprespear to drain water when they were exposed. The feature approximately a meter wide the true depth of the feature is unknown. Two pre-glacial sinkholes were exposed on the walls of the sinkhole at the north end of the quarry. This sinkhole was referred to as the Bedrock Trench northeast of the the shape of the Bedrock Trench is irregular and elongat ed in the northeast-southwest direction. The exact size of ganic detritus, lacustrine silts and clays, and sands and drained, seasonal karst lake. Such large-scale features as the Bedrock Trench do not this trench along a structurally weakened zone with later such as a collapse or solution-enlarged fracture, which existed prior to glacial scouring. Because the Bedrock speculated that formation of the Bedrock Trench was asthe Bedrock Trench was an evaporite solution collapse Figure 4 Buried sinkhole exposed in Central Quarry (dashed red lines indicating sinkhole walls) Figure 5 Schematic diagram of the Bedrock Trench

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304NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEPost-glacial sinkholesThe post-glacial sinkholes have developed after the area BP. They occur in two regions, the reefal limestone of the upper Attawapiskat unit along the Attawapiskat outcrops in the peatland. The representative sinkholes glacial sinkholes correspond to the two distinct karst hyglacial sinkholes. cut through tens of meters into mid-Silurian limestone in response to the continuous isostatic uplift. The upper and thus the depth of the karst dissolutions. The river entrenchment has dissected the limestones to create numer ing streams and are connected to small caves. Because is not aggressive in dissolving the limestones. These alluvial sinkholes are likely linked to the pre-glacial ones. The pre-glacial sinkholes provide the initial conditions for the post-glacial sinkhole formation, and the greater through the claystone unless the pre-existing pre-glacial sinkholes were already deeper than the claystone. ed as an aquiclude to prevent shallow peat water from eral drainage is also poor with hydraulic gradients of less than 0.002. Sinkholes occur where the mild acidic water These ranged in size from relatively small openings to Crescent-shaped sinkholes are another common feature recharge is anticipated within the crescent-shaped sinkFigure 6. Conceptual model of post-glacial sinkholes Figure 7. Sinkhole at perimeter of a bioherm

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30516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 of dissolution, particularly those north of the Attawapisfactor in forming the post-glacial sinkholes. Because the spring and fall or following large rainfall events, raising tuations in groundwater level in the peat cause scouring of the sediments that were deposited in pre-existing karst features.ConclusionsThe study area of the James Bay lowland is underlain development. Two types of sinkholes were recognized in the study area: pre-glacial and post-glacial. The The post-glacial sinkholes are surface features and occur in the reefal limestone of the upper Attawapiskat unit land. The post-glacial and pre-glacial sinkholes exposed tively shallow and occurred in the upper Attawapiskat limestone, whereas the Bedrock Trench cut through most have developed after the area emerged from the Tyrrell culation is the driving force for their development. The post-glacial sinkholes are part of the current hydrogeological karst system, whereas the pre-glacial sinkholes tion of these two types of sinkholes is informative to understanding of the hydrogeological conceptual site model for the groundwater simulation and evaluation of the environmental impact of dewatering in the Victor mine. likely linked to the pre-glacial ones, which provided the initial conditions for their formation. Understanding of post-glacial sinkhole development requires knowledge of the pre-glacial sinkholes. The increases in hydraulic gradient in response to the isostatic uplift and seasonal primary force causing erosion of the materials overlying them. While the formation of the Bedrock Trench is delution. References The challenges of dewatering at the Victor Diamond Mine in northern Ontario, Canada. Mine of the Attawapiskat karst and peatland candidate Figure 8. Crescent-shaped sinkholes at bioherms

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306NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE on peatlands of the James Bay lowland: the role of Victor Diamond Mine, northern Ontario, Canada: 0_2. of Parks, Ontario. Environmental Assessment Agency. dewatering. Proceedings of Mine Water Solutions Prahana. Victor Diamond Mine predicted engineering and Hudson Bay and James Bay lowlands region interpreted from aeromagnetic data, east sheet. Sader JA, Hattori KH, Kong JM, Hamilton SM, James Bay lowlands, Canada, and their application northern Ontario, Canada: cross-cutting and

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307 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 to the formation of these features. IntroductionEvents such as the ongoing Sinkhole Conference series strate an enduring interest, and evolving understanding, zones, the need for understanding these features and the processes that form them increases. Concurrent with this, and indeed with a generally ex panding recognition of the importance of karst terranes, ally, features such as caves and the like in such settings cases. descriptions of several type-cases. For this purpose, for example traditional karst developed on calcarenites cemented quartz sandstones such as the calc-eolianite Loyalhanna Limestone of Pennsylvania (Schmidt, Abstract holes. A review of the literature shows rather limited attention given to these features. In the glaciated region have examined numerous sinkholes in sandstones, with a variety of morphologies. The most commonly found along fractures, while the surrounding rock remains intact. Mechanical as well as chemical processes are in ate dissolution, and found in the desert environment of are developed in a quartzite. Swallet cave entrances are found in other locations, such as the Aonda Cave system greatest shafts are found at the margins of the plateau, a occurrence of sinkholes in quartz rocks is not limited to tropical environments, though. All of these cases emAs a consequence, rapid groundwater movement and its Ira D. SasowskyDepartment of Geosciences University of Akron, Akron, OH 44325-4101 USA, ids@uakron.eduE. Calvin Alexander Jr.Department of Geosciences, Department of Earth & Environmental Sciences University of Minnesota, 116 Church St. SE, 150 Tate Hall, Minneapolis, MN 55455 USA, alexa001@umn.eduSINKHOLES DEVELOPED IN SANDSTONE

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308NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE tance of such features are explored. Development of “karst” features in sandstones rather resistant geologic material with regard to weathwas thought that tropical conditions (high temperatures, shown that these can form in areas having neither of these extremes, and that quite extensive cave systems equivalent molar quantity of calcite. The temperature efat very high values. Therefore, dissolution of quartz does not require, nor necessarily indicate, present or for mer tropical temperatures. What is critical is that wawhen integrated across the time frame of its existence. Sinkholes developed in sandstone occur through a vaExamples of sandstone sinkholesThe following sections provide a sampling of features the literature.In Carboniferous sandstone/ conglomerate, Ohio, USAIn the glaciated region of northeast Ohio numerous small sinkholes occur in sandstones and conglomerates, with a variety of morphologies. The area is at an elevation of The sinkholes are primarily associated with the margins found, as in the Kniss Preserve area of Summit County. unconsolidated material lies over a void, and the mate area. In the case of quartzose sandstone the underlying some settings of Ohio. holes are also present in northeast Ohio. The most dramatic of these is an entrance to Little Mountain Caverns morphological mapping, as well as lithological and geometric analyses to understand the genesis of the voids. Mechanical as well as chemical processes are in play here. It was concluded that initial mechanical fractures drove the continuing enlargement. In Precambrian sandstone, Minnesota, USA -

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30916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Less well known is the presence of extensive sandstone stone, a Mesoproterozoic age quartz arenite (Tryhorn A detailed study of the formation in Pine County identi taining wetlands in many places. Streams have incised nected to the sinkholes has resulted in environmental Massive collapse, “Devils Kitchen”, Ari zona, USA Figure 1. Views of the largest sandstone sinkhole in Ohio, an entrance to Little Mountain Caverns, Ohio. a) From the top, looking South, b) Interior, looking North. Photos by IS. Figure 2. Pine County, MN, from Shade et al., 2015 .

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310NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEand has average low and high temperatures of 0and The area is not known for caves or karst development, Figure 3. Views of Devil’s Kitchen, Arizona. a) Panoramic photograph from East side looking Southwest to Northwest, b) Photograph from mountainside above, looking South, c) Interpretive diagram (Lindberg, 2010). Photos by IS. north central Arizona. The area draws visitors from afar tween the Colorado Plateau to the north, and the Basin -

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31116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 evidence of the role of water, or dissolution. The walls are primarily overhanging and angular, and angular rock In orthoquartzite, Venezuela known in sandstone are found on the tepuis (isolated tarare ecosystems, as well as fantastic features such as Anm. The tepuis were initially examined for their karst poin the way of karst features. In recent years many teams caves. Local relief is extreme, for example at Sarisariholes are on the edges of the plateaus. They invoked as the cause for this geography. Some of the features Figure 4. Aerial view of Sima Menore on Sarisariama Tepui (foreground), about 150 m diameter. Image copyright Robbie Shone, used with permission.

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312NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEcluded that all of the large sinkholes were gravitational collapses related to dissolution of underlying siliciclastic Figure 5. Maps and cross sections of 7 major sinkholes on Sarisariama Tepui; with permission of the authors and publisher (Sauro et al., 2019).

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31316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Discussion and conclusionsSinkhole development in siliciclastic sandstones occurs in a wide variety of environments, and over a wide range of scales. The features are commonly proximal to areas the potential for high hydraulic gradients, enlarged apparticle transport and dissolution. In some cases, iniappears that this limitation on dissolution processes can providing copious amounts of water. In the examples holes found in siliciclastic sandstones occur in many rainfall situations to deserts. Taken together, this empha sizes the need to consider full geologic history and the rock settings. This includes factors such as groundwater Acknowledgments viewers provided very helpful comments, for which we are quite grateful.References Alexander EC, Jr., Alexander SC, Piegat JJ, Barr KD, discharge in a sandstone karst, Askov, Minnesota. In Beck BF, editor. Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Tenth Multidisciplinary Conference: A new view on their genesis, hydrogeology and Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Fourteenth contamination of natural springs and seeps, Cuyahoga Falls, Ohio, USA: Environmental systems in the Berea Sandstone and Sharon

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314NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE and Hydrology Proceedings: Charleston, West Shade BL. 2002. The genesis and hydrogeology of a sandstone karst in Pine County, Minnesota p. sandstone karst of Pine County, Minnesota. In: Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Fourteenth the Hinckley Sandstone of east-central Minnesota. Minnesota: A centennial volume. Minnesota engineering and construction, Berlin, Springer, karst in southeastern Venezuela: International quartz sandstone: Evidence from the Jurassic of solutional weathering processes and forms in quartz sandstones and quartzites. Earth-Science assessment in Minnesota using a decision tree the northern midcontinent gravity high: Journal of development in the Bahamas and Bermuda. In: shallow marine geology of the Bahamas and mechanisms for the largest sandstone sinkhole in rate and origin of karst landforms and caves Conference on Sinkholes and the Engineering and Environmental Impacts of Karst and the of giant sinkholes and caves in the quartz

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315 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 sally across the nation and illustrated regional sinkhole hotspots in known areas of well-developed karst. Limi tations of the automated method includes false positive depressions resulting from artifacts generated during the computer processing of the elevation models, and inclu sion of depressions resulting from non-karst geomorphic processes. More thorough examination of the screening criteria for depressions is required.Introduction gions across the United States, as well as regional or -AbstractMost methods for the assessment of sinkhole hazard existing closed depressions in karst areas. In the United tent methodologies applied at the state or county level conterminous U.S. using a common methodology. Automated algorithms for extraction of closed depressions selected according to location within geologic units having the potential for karst, and screened for occurrence in areas of developed land, open water and wetlands, and areas of glacial and alluvial sediment cover. The results were used as the input to create a nationwide depression density map. Our results were compared with karst depression density maps for diverse karst regions within states that have existing closed depression inventories. Daniel H. DoctorU.S. Geological Survey, Florence Bascom Geoscience Center, 12201 Sunrise Valley Drive, MS926A, Reston, Virginia, 20192 USA, dhdoctor@usgs.govJeanne Jones USA, jmjones@usgs.govNathan WoodU.S. Geological Survey, Western Geographic Science Center, 2130 SW 5th Avenue, Portland, Oregon 97201 USA nwood @usgs.govJeff FalgoutU.S. Geological Survey, Advanced Research Computing (ARC) Group, Denver Federal Center, Mail Stop 302, Denver, Colorado 80225, USA, jfalgout@usgs.govNatalya I. RapstineU.S. Geological Survey, Advanced Research Computing (ARC) Group, Denver Federal Center, Mail Stop 302, Denver, Colorado 80225, USA, nrapstine@usgs.govPROGRESS TOWARD A PRELIMINARY KARST DEPRESSION DENSITY MAP FOR THE CONTERMINOUS UNITED STATES

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316NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE tional Map dataset (processing for extraction of closed depressions. The extraction of the depressions from the DEMs was conducted closed depressions in the DEM according to a hydrologic out across all edges of the elevation surface. As a result the DEM of lower elevation than all surrounding cells, the elevation of that cell is raised to the elevation of the tive degree of karst development in any given region. To do so would have required accumulated geospatial data and analysis of surface karst depressions (sinkholes and taset on the occurrence of closed depressions in karst ar eas at the national scale. The methodology for doing so is consistent resolution that would permit extraction of closed tions in density of surface depressions across the landscape. Such a map is useful for depicting the relative degree of karst development within areas geologically prone to karst development and may inform land managers as to potential MethodsTo automate the delineation of closed surface depressions, Figure 1. Flow chart illustrating the processing steps taken to condition the DEMs after progressive

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31716TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8orites, and volcanic pseudokarst from the national karst potential karst unit polygons. All depressions intersected others excluded. Removal of Depressions According to Geometry The settings applied to the level-set algorithm of Wu depth threshold of 2 m, and a slicing interval of 2 m. A 2 m depth threshold was chosen since the root mean greater lidar coverage of the nation (Archuleta et al., extraction of depressions with a minimum size threshold 2 The depression polygons were also screened according to the following geometric shape criteria: 2 and less than 2 m maximum depth were excluded to avoid spurious depressions that may have occurred near the minimum size threshold. 2. Polygons of purely rectangular shape and we applied several other means of screening out depressions according to multiple land cover and geologic atRemoval of Depressions According to Land Pre-conditioning of DEMs to Reduce Creation scriptive purposes only and does not imply endorsement In order to facilitate operation on DEMs for the entire timized to operate on large datasets. The code was redesigned and expanded to iterate over a set of input data ditioning to iteratively recondition the original digital elpressions. Conditioning and extracting depressions from tions would provide access to multiple servers with large Retention of Depressions in Karst Areas The resulting geospatial layers of closed depressions were screened to retain only those features occurring within areas of potential karst or pseudokarst and then -

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318NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEsion locations. Depressions density per square kilometer was calculated using the Point Density tool within applied tool settings used a circular moving window 2 area. As a result of smoothing along the moving window, the density value assigned to any 2. Therefore, the density values are not integers (i.e., a count of points within ues. the grid against the resolution of the data, as well as to consider any comparative datasets in the future. Several 2 adequately capture the density of depressions, since the 2 and depression areas did not overlap. according to these classes. Comparison of Depression Density with Independent Datasets tained from State geological surveys and private citizen polygons, and closed depressions were removed wherever for developed land, three categories of developed land were selected as an indicator of mapped impervious sur faces: low intensity, medium intensity, and high intensity development, where intensity refers to the degree of light Depressions were not removed from the class of Develand open water avoided the inclusion of permanently In addition, depressions were removed that intersected a of roads and streams was to avoid inclusion of manmade closed depressions as a result stormwater management avoid anomalies in the elevation models due to inaccura cies in locations of incised stream channels. Removal of Depressions in Glacial and Alluvial Geologic Units considered as karst depressions, the depressions were cial sediment and any type of glacial sediment greater Creation of Karst Density Maps The pre-screened polygons were then converted to centroids and used to create density maps of closed depres-

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31916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8as yellow and orange colors represent poorer agreement, and red indicates no agreement. For example, if a grid cell and would fall in the lower left corner of the comparison mated depression density map, the resulting comparison the upper right corner of the comparison matrix. that were unique to each dataset, therefore not compa comparison matrix results. An explanation for the comDiscussionDiscussion of the results of the automated depression exlar to several of the other states that have data that were compared to the automated results. Unlike the other tween the automated results and the state validation data. a high to moderate depression density and the automated methods indicate a very low depression density (matrix some lack of agreement where the state data indicated a low or very low depression density, and the automated method indicated a moderate to high depression density The map of the comparison matrix results shown in FigFor the purpose of this preliminary work, only those states having complete or nearly complete statewide coverage of depression data were included for compari son with the automated results. These states were AL, karst areas in the eastern and mid-western U.S. (Weary performance of the automated routine. Although the validation datasets from each state were mated density values into new classes provides internal consistency and normalization among the various data have placed all density results within an individual state is simple for ease of visualization and to facilitate comparison with the automated results.Results the validation datasets and the automated depressions are shown in Figure 2 for four examples of the six semethod captured more numerous depressions within a cation values were generally in good agreement. Comparison of Independent State Data with Automated Data two input rasters and generates a new comparison raster assigned to the input density rasters. The comparison raster was then mapped and evaluated for similarity ac

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320NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 2. independently mapped depression datasets for validation and comparison with the automated

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32116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8where more depressions were mapped via the automated map of the comparison matrix results also shows where unique cells occur that were generated only in the state Figure 3. Comparison matrices illustrating the relative degree of agreement between the Results are shown for states where full or nearly full coverage of the state was available as an independent dataset. See text for details. validation, or only in the automated results. The gray than 0 only occurred in the automated data, while the sity greater than 0 only occurred in the validation data.

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322NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEsota and northeastern Iowa, and near to the Mississippi literature are the prominent pseudokarstic terrains in volcanic rocks in the western U.S., or the evaporite karst areas in central Oklahoma. Other areas that stand out on this map are where glacial some areas in northeastern Illinois, northern Wisconsin and parts of east-central Ohio. Although depressions in areas currences of glacial cover are included in the map. Many closed depressions can occur in glacial sediments as a result of periglacial processes such as melting of permafrost and cause karst areas were not initially recognized within the to eliminate depressions outside of potential karst areas Preliminary National Depression Density Map Although preliminary, this map illustrates hotspots of closed depression density in several well-known karst areas around the U.S., such as the state of Florida, central and eastern Tennessee, the Pennyroyal Plateau in western er Valley karst of West Virginia, central and southeastern Pennsylvania, north-central Ohio, southeastern MinneFigure 4. Depression density maps for depressions mapped independently by the Geological Survey of Alabama (left), and those obtained from the automated method (right). Note the greater density of the automated depressions in general, except for the southwestern of Weary and Doctor (2014).

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32316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 shows a greater density of depressions than was expected, despite the removal of wetland and alluvial sediments. One factor not yet accounted for are depressions that form in as those found within the Carolina Sand Hills, and areas in eastern Kansas. Aeolian depressions within Carolina Bays and those formed from purely aeolian processes in parts of ConclusionThe results presented here indicate that the automated methods employed for extraction of closed depressions in various karst regions across the U.S. Although many the automated methods than were contained in the state Figure 5. Map of the comparison matrix of 4, in which cells containing only depressions mapped by the state survey are shown in black. The other values correspond to the comparison matrix key as shown in Figure 3. pressions formed through non-karst related geomorphic rocks that have glacial or other sediment cover (Figwork and revision of the overall dataset.ReferencesArchuleta CM, Constance EW, Arundel ST, Lowe AJ, . Land L, Doctor DH, Stephenson JB, editors, Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Thirteenth . The current status of mapping karst areas and karst terrains of the United States. Hydrogeology and karst areas of the United States of America.

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324NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFigure 6. potential for karst within the conterminous United States. Note the high density of depressions along the southern Atlantic Coastal Plain, in glaciated regions of the mid-west and northeastern U.S., and in volcanic pseudokarst regions of the western U.S. Additional work needs to be done to determine where in these regions the depressions result from karst processes or from other geomorphic processes.

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32516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 . Depression Hierarchy in Digital Elevation Models .AppendixOnline resources for state-wide sinkhole datasets. Minnesota karst feature inventory points: tory-pts Missouri sinkhole data: Iowa karst and sinkholes: iowa Kentucky sinkhole data: Ohio sinkholes and karst geology: . Accessed United States. United States Department of sediments in the glaciated United States east of . Accessed Survey. . Digital Elevation Model. In: Doctor DH, Land L, and Stephenson JB, editors. Proceedings of the and the Engineering and Environmental Impacts

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326NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Pennsylvania karst feature data: Tennessee sinkhole data: Virginia karst features data:

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327 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 associated with sinkholes, springs, and caves, as well as sinking, losing, and gaining streams (Ford and Wilface features provide for direct recharge into karst aquiporosity and highly transmissive zones. Karst systems charge zones that later transmit water to the phreatic zone, and from the phreatic zone, groundwater travels horizontally to discharge points, including emerging in hydraulically connected springs, lakes, rivers and wells dustrial, agricultural, and ecological integrity. The karst source of drinking water and supporting important ecoAbstractSevere drought conditions, along with excessive water extraction, has imposed huge stress on groundwater resources in many regions across the world. Knowledge of potential recharge zones can provide authorities valuland development, or environmental protection. This along with high-resolution World-View satellite imagery to determine potential recharge areas in the karst region eters, such as geology, precipitation, lineament density, drainage density, topographic wetness index, slope, land layers and analyzed for groundwater recharge potential, map generated categorizes groundwater potential zones into four categories: high, moderate, low, and very low. area. Even though this methodology was implemented regions and can provide critical information regarding Introduction such as limestone and dolomite, experiences consider Luisa I. Feliciano-CruzUniversity of Puerto Rico, Mayagez, Puerto Rico, 00681, luisa.feliciano@upr.eduIngrid Y. PadillaUniversity of Puerto Rico, Mayagez, Puerto Rico, 00681, ingrid.padilla@upr.eduJonathan Muoz-BarretoUniversity of Puerto Rico, Mayagez, Puerto Rico, 00681, jonathan.munoz@upr.eduSarah J. BeckerUS Army Corps of Engineers Engineer Research & Development Center, Geospatial Research Laboratory, Alexan dria, VA 22315-3864, sarah.j.becker@erdc.dren.milEMPLOYING GIS TECHNIQUES AND UNSUPERVISED LEARNING TO DELINEATE GROUNDWATER RECHARGE POTENTIAL: A CASE STUDY IN THE KARST REGION OF NORTHERN PUERTO RICO

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328NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Study Sitestudying groundwater recharge. Methodologies such as recharge zones and for determining the relative weight Figure 1. Location of the Tallonal Natural Reserve study site with respect to the north coast aquifer, Puerto Rico. Major rivers near the area include Ro Grande de Arecibo and Ro Tanam.

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32916TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 and rainy summers and dry winters. Temperature aver MethodologyThe groundwater recharge potential in the study area eight thematic information layers for the area: geology, precipitation, lineament density, drainage density, analysis of remote sensing data was carried out using and was used to develop the lineament density thematic used to develop the drainage density, topographic wetness index, and slope thematic layers. Thematic layers portal ( Multi-Criteria Decision Analysis (MCDA) An MCDA was conducted to assign a weight to each parameter within a thematic layer. The values selected were discussed in further detail. Table 1. Parameters and weights considered for the study. Parameter Weight Land Use Agriculture Bare 2 Forest Water Geology Sand Deposits 0 Alluvium 2 Swamp Deposits 0 Limestone Volcanic Precipitation (mm) 2 TWI 2 Drainage density 2 (m/m2) Lineament density 2 (m/m2) Slope (degrees) 2 Sinkhole density 0 (%) 2

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330NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE potential groundwater recharge area. To account for this, zero was assigned to the sand and swamp deposit drainage areas, and a value of one was assigned to represent to recharge. Hence, the study area will not contain this region to the north. The resulting geology thematic layer Precipitation The annual average rainfall in the northern karst region Lineament Density to faults, linear sink holes or fracture zones (Dasgupta geological or topographic maps or satellite images, since Geology The geology of the area surrounding the study site is form three aquifer systems: the north coast limestone Five main geologic units were considered for this layer: sand and swamp deposits, limestone, alluvium, and volcanic rock. Particularly the sand and swamp deposits that surrounds the mogotes. In these sand and swamp deposits along the north coast lies the most important Table 2. thematic layers. Parameter TWI Lineament density Drainage density Precipitation Geology Land use Slope Sinkhole density 20 Figure 2. Karstic hills in the study area.

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33116TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8automated lineament detection methods, such as principal vised learning method that employs matrix operations to mensions. In other words, PCA transforms the original satellite imagery, which is usually highly correlated, into the polylines in a vector layer to extract lineaments. The default parameters were used. Drainage Density and discharge components. The extraction and analysis they usually appear as lines or linear formations whose mapping is done visually using enhanced images. HowFigure 5. Lineament density thematic layer for the study area. Figure 4. Precipitation thematic layer for the study area. Figure 3. Geology thematic layer for the study area.

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332NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEhigher degree in low lying valleys and, in the case of karst systems, through sinkholes. The slope thematic ern region of the study area. Land Use/Land Cover populated areas, which are mostly impervious. The land Sinkhole Density Sinkholes are commonly encountered in karst regions to develop a quantitative map of karst development per centage per unit area. A digitized version of the sinkhole Topographic Wetness Index cesses. It is commonly used to quantitatively simulate Applications of TWI include the study of processes, such geochemical or pollutant transport modeling, and the TWIln tan Slope The steepest slopes are commonly associated with lower Figure 6. Drainage density thematic layer for the study area. Figure 7. TWI thematic layer for the study area.

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33316TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8shed. Analysis also shows, as expected, that areas with more likely to occur in agricultural and forested areas. the groundwater recharge potential study is shown in ResultsA depiction of the groundwater recharge potential map recharge is more likely to occur in the limestone areas gion moves regionally northward toward the Atlantic that the drainage density follows this pattern, showing cial water discharge occurs. In terms of soil moisture, the TWI calculated for the region showed higher values toward the coast due to low-lying areas in the karst water Figure 10. Sinkhole density thematic layer for the study area. Figure 9. Land cover/land use thematic layer for the study area. Figure 8. Slope thematic layer for the study area. Table 3. Percent of recharge potential. Recharge potential Area % Very low Low Moderate High

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334NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE References . hierarchy process as a multicriteria decision Delineation of groundwater recharge zones and . . Sons. information system, and multi-criteria decision improved Topographic Wetness Index ConclusionsDelineation of groundwater recharge potential zones regions and can provide critical information regarding Acknowledgments Figure 11. Groundwater potential recharge map.

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33516TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 on phthalate contamination in eogenetic karst groundwater systems, Environmental Pollution . Environmental awareness series: Alexandria, . assessment of the groundwater recharge potential CVOC concentrations in karst aquifers: Analysis . . data capture and topographic wetness indices. . of potential exposure pathways in karst groundwater systems in Vega Alta, Puerto Conference for Engineering and Technology Sons. Hydrogeology and simulation of ground-water hydrogeological and anthropogenic factors on .

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336 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Ordovician Hawthornden Schist and metamorphosed Silurian Kuala Lumpur Limestone, capped to the west remained exposed. Consequently, the Silurian limestone the Kenny Hill Formation, placer deposits and alluvium associated with the Klang Valley. Abstract local level climate extremes and physical hazards for tion atmospheric and physical hazards in the context of or validate the mapping. Vanessa J BanksBritish Geological Survey, Nicker Hill, Nottingham NG12 5GZ, UK, vbanks@bgs.ac.ukElanni AffandiDepartment of Geology Tham Fatt NgDepartment of Geology Universiti Malaya, 50603, Kuala Lumpur, Malaysia, thamfatt@gmail.comChristian ArnhardtBritish Geological Survey, Nicker Hill, Nottingham NG12 5GZ, UK, chrarn@bgs.ac.uk Zamri Ramli Ibu Pejabat Jabatan Mineral dan Geosains Malaysia, Aras 8 dan 9, Menara PjH, No. 2, Jalan Tun Abdul Razak, Presint 2, 62100 Putrajaya, Malaysia., zamri@jmg.gov.myFerdaus AhmadIbu Pejabat Jabatan Mineral dan Geosains Malaysia, Aras 8 dan 9, Menara PjH, No. 2, Jalan Tun Abdul Razak, Presint 2, 62100 Putrajaya, Malaysia.Joy PereiraThe National University of Malaysia Institute for Environment and Development (LESTARI) 43600, Bangi, Malaysia, joy@ukm.edu.myHelen ReevesBritish Geological Survey, Nicker Hill, Nottingham NG12 5GZ, UK, hjre@bgs.ac.uk SINKHOLE SUSCEPTIBILITY MAPPING IN THE KUALA LUMPUR AND THE NEED FOR A BURIED KARST DATABASE

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337NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE comprehensive literature review of karst landforms and processes in the Kuala Lumpur region. Potential proIntroductionThe Kuala Lumpur Multi-Hazard Platform that was genForecasting Local Level Climate Extremes and Physical Hazards for Kuala Lumpur, comprises a decision support tool for the city council DBKL (Dewan Bandaraya Kuala scaled meteorological forecasting and geohazard infor comprising Malaysian and UK Partners from academia Met Malaysia, Department of the Environment Malaysia to use it. The structural setting is complex within Kuala Lumpur: with the Kuala Lumpur Fault Zone, during the Creta component of the tin reserves of the Kuala Lumpur area nacles where they remained exposed. Consequently, the ment types, including the Kenny Hill Formation, placer deposits and alluvium associated with the Klang Valley. es with depth. The exception is in the areas known as the slump zone, associated with dissolution of underlyhidden hazard, as encountered at Petronas Towers (Per the Kenny Hill Formation overlies the Kuala Lumpur Karst compartments or cores during thrusting. Domal forms

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33816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 also includes dolines, cavities, overhangs, mass rock indicative of Pleistocene interglacial high sea levels at as a 200m hill that is the only natural exposure of the limestone in the Kuala Lumpur area. The phreatic nature of the caves suggest that they formed under difdrainage is a remnant of the former. In their assessment Table 1. Summary of the geological history of Kuala Lumpur.

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339NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE karst developed at rock head and the more pervasive detionally, there is some evidence of hypogene karst, likely associated with late stage iron mineralization (Banks et GeohazardsThere is a legacy of ground related collapses in the Kuala ure due to excess pore pressures resulting from rapid in residual soils and schists, as well as the Kenny Hill SinkholesDolines associated with the Batu Caves are generally ered sediments. It is understood that most are triggered particularly common in areas where the cover thickness Figure 2. Limestone hills rise to 200 m above Figure 1. Sub vertical bedding in marbleised limestone of the Kuala Lumpur Formation.

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34016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 potential for sinkhole formation at the planning stage of Figure 3. Structural alignment of shaft in Batu Cave, Kuala Lumpur. Sinkhole susceptibility tors: lithology, soil type, land use, water level decline and proximity to groundwater and applies a normalized weighting of each of the criteria. The resulting suscepthe sinkholes are within the moderate and low susceptito use the literature and stakeholder engagement to consider the processes potentially associated with karst and sinkhole triggering in the Kuala Lumpur region to gener from the literature and engagement with stakeholders, the limestone in the Kuala Lumpur region. and the potential slump zone. It is anticipated that this Figure 4. (a) Sinkhole susceptibility map for Kuala Lumpur with (b) conceptual model to show the slump zone corresponding to thrusting of the Kenny Hill Formation and the Kuala Lumpur Limestone Formation.

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341NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCETable 2. thrusts with the potential for striped karst resulting from the dissolution associated with the generation of sulphOur current understanding of sinkhole triggering pro

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34216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 and capture geometrical information (width, depth, and gering and inception processes, as well as location and impact. The recording of impact data provides informa Acknowledgements References systems in some tropical karst outcrops, West Press. University Press. Malaysia. University of Malaya and the Peninsular Malaysia. University of Malaya and the peninsular Malaysia Workshop on stratigraphic Malaysia. University of Malaya and the Cenozoic Stratigraphy. In Hutchison, CS. and Malaysia. University of Malaya and the and Ampang Jaya. The International Archives of Peninsular Malaysia. University of Malaya and the

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343NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEtectonic development. Journal of Southeast Asian for the prediction of karst in the Kuala Lumpur Limestone. International Association of karst in the Kuala Lumpur Limestone Formation: Two for Kuala Lumpur. Paper presented at Petaling Jaya, Malaysia. of Wilayah Persekutuan and surrounding areas: Malaysia. study of Kuala Lumpur, Malaysia. Engineering properties of residual soils of the Kenny Hill Formation in the Shah Alam area, Selangor. engineering and their construction. Springer Peninsular Malaysia and their relationships to the

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344 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 used to develop karst landscape maps for other counties throughout southeastern Minnesota. The maps were developed to help citizens and government entities identify karst areas so they can deal with the unique myriad of issues that come with karst. The connections to enlarged underground pathways allow for spills or surface applications of chemicals. Introductionnections to underlying fractures and enlarged pathways allows for rapid transport of water, creating unpredict sues like spills or surface applications of chemicals. of karst are not always present at the surface (springs, Abstract of the karst landscape helps identify the groundwater such as springs, sinkholes, and sinking streams, are not always present, therefore karst landscapes were identi setting. includes the surface and its connections to underlying aquifers. Identifying and mapping these units allows for ning. Karst landscape unit maps were created as part of the products for Houston County for the Minnesota Depart-Jeffrey A GreenMinnesota Department of Natural Resources Division of Ecological & Water Resources 3555 9th St. NW Suite 350 Rochester, MN, U.S.A., 55901 John D. BarryMinnesota Department of Natural Resources Division of Ecological & Water Resources 500 Lafayette Road St. Paul, MN 55155-4040 john.barry@state.mn.usDEVELOPMENT OF KARST LANDSCAPE UNIT MAPS FOR HOUSTON COUNTY MINNESOTA, U.S.A.

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345NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE toring, and spring temperature monitoring (Luhman et Fluorescent dye tracing from pseudokarst stream sinks to springs found they occupy a consistent position in the stratigraphy and have unique hydrologic characteristics. Spring monitoring for discharge, temperature and chemistry were used to categorize springs and demonstrated Hydrostratigraphy epochs and is informally known as the Driftless Area. and siliciclastics units are aquifers. The aquifers transmit and type, elevation, and geologic setting to characterize Maps were developed for Houston County, Minnesota, which is located in southeastern Minnesota in an area ates and siliciclastics. Karst is predominately present grained siliciclastics.Mapping Methods The development of the Karst Landscape Units was an replicated in other karst areas. Karst feature location and type were retrieved from the searchers, local residents, government agencies, aerial Spring locations came from the Minnesota Springs Inin the county. ysis, leading to a preliminary conceptual model of Karst chemistry. Figure 1. Location map for Houston County, Minnesota

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34616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 voids, conduits, and fractures. Human activities impact pathogens, and other contaminates move into the shalSurface karst in Houston County is primarily found in Oneota Dolomite. The St. Peter Sandstone, a siliciclas southeastern Minnesota.Karst FeaturesThe formation of surface karst features (sinkholes, holes where the soil underneath is carried away into consinkholes occurs in areas where the Shakopee Formation Springs are points where groundwater emerges from Figure 2. Bedrock Geology, Hydrostratigraphy, common karst feature position, and Karst Landscape Unit position for Houston County.

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347NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Karst upland St. Peter Sandstone: aquifer with moderate infractures Shakopee Formation: aquifer with high fracture ity Oneota Dolomite: aquifer with generally low Karst and pseudokarst escarpment Jordon Sandstone: aquifer with relatively high ity fractures St. Lawrence Formation: aquitard with gener Karst and pseudokarst escarpment, lowland plain Wonewoc Sandstone: aquifer with moderate inLowland plain Eau Claire Formation: aquitard with primarily Mt. Simon: aquifer with relatively high inter Karst Mesa The Karst Mesa Unit has the youngest (upper Ordoviridges in the southwestern part of the county where the the Cummingsville and Platteville, typically with diam the mapped sinkholes. Springs and seepage occur at the vide cool isothermal water that supplies the numerous trout streams of the county. Stream sinks are points where surface water disappears tions. Stream sinks occur in two forms: discrete loca tions or locations where water disappears gradually in Sandstone or Shakopee Formation, the discrete form is commonly found in valleys where the St. Lawrence or sinks is similar to karst, however these conduits do not catchment areas using watershed tools and digital eleva leys, many large surface water catchments are directly ing stream reaches.Karst Landscape UnitsThe positions of the Karst Landscape Units are sche matically shown next to the stratigraphy in Figure 2 and aquifer or aquitard. Most of the hydrostratigraphic Karst mesa Cummingsville Formation: aquifer with very Decorah Shale: aquitard with very low perme-

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34816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 3. Karst landscape units of Houston County, Minnesota. Surface water springsheds show the contributing areas of the landscape that drain to sinking stream locations. -

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349NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEThe primary characteristic that separates this unit from Karst and Pseudokarst Escarpment the lowland plain. The ridgetops and hill shoulders are Sinkholes and solution openings are found in the mapped sinkholes. Streams commonly sink into voids in the lowermost Jordan and the upper St. Lawrence on are ephemeral, as they often move up and down the valley depending on stream stage. Flood events can close One example is Indian Springs Creek, which is now peclastic lowermost Jordan, upper St. Lawrence and upter time of travel from stream sinks in this setting to the spring resurgence points approaches that of classic phology, spring occurrence and sinkhole density. Karst Rolling Upland unit and forms a plateau that covers the central, western dissected plain of rolling topography that is moderate to steeply sloping. Unconsolidated materials are generally transmissivity layer located at the contact of the Shakopincluding catastrophic wastewater treatment facility fail Upland is wells completed in the Shakopee, Oneota and karst Escarpment. Some areas of the unit are delineated and divide stream valleys. These ridges are prominent local topographic features that commonly have unique meters of unconsolidated material overlying the Shapercent of the mapped sinkholes which primarily occur ameter.

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35016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Figure 4. Karst landscape units of Houston County, Minnesota and the distribution of Prairie du Chien and Jordan aquifer wells and springs. ranges from dozens to hundreds of meters per day. The Springs are numerous, primarily discharging from the there are several large Jordan springs in the county. Field

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351NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEFlowing wells commonly occur in wells completed in the Eau Claire and Mt. Simon formations, as they are under artesian conditions in the river valleys and along the from unconsolidated sands. clipped to add to the Lowland Plain those areas with less SummaryKarst feature inventory and mapping is a standard practice for the analysis and management of karst areas. In Houston County, Minnesota, karst landscape units were developed using additional factors. This process char acterized the karst and pseudokarst areas of the county and assisted in the development of interpretation criteria. with successful results. water resource and land management issues.AcknowledgmentsHolly Johnson assisted greatly with cartography, graphics development, and editing. References time origins of sinkhole collapse failures in sewage lagoons in southeast Minnesota In: Land Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Thirteenth springs in southeast Minnesota has shown that they events. However, unlike karst conduit springs, they do not have corresponding changes in temperature, chem Water sampling of select wells and springs in the counters and is one of the identifying characteristics of this landscape unit. distances were set from the St. Lawrence Formation and the Jordan Formation. The resulting polygons needed to our conceptual model of the groundwater mixing zone at the edges of the dissected valleys. We accomplished this vations and data on spring chemistry, spring discharge, spring stratigraphy, stream sink locations and groundwater hydrology. Lowland Plain The Lowland Plain is the only non-karst landscape in of the dissected valleys across the county. The largest Pseudokarst Escarpment are exceptions. and Mt. Simon Sandstone.

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35216TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 Assessment Methods for Paleozoic Bedrock Legislative-Citizen Commission on Minnesota of Paleozoic Bedrock Springsheds in Southeast Minnesota. In: Doctor D, Land L, Stephenson, JB editors. Sinkholes and the Engineering and Environmental Aspects of Karst. Proceedings Luhmann AJ, Covington MD, Peters AJ, Alexander SC, Southeast Minnesota, U.S.A. In: Doctor DH, Land L, Stephenson JB, editors. Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Fourteenth Multidisciplinary Characterize a Siliciclastic Pseudokarst Aquifer, Southeast Minnesota, U.S.A. In: Sasowsky, ID, Byle, MJ, Land L, editors. Sinkholes and the Engineering and Environmental Impacts of Karst: Proceedings of the Fifteenth Multidisciplinary of Minnesota, with the assistance of the Minnesota Engineering and Environmental Impact, A.A. EC, Jr, Beck B, editors. Sinkholes and the Engineering and Environmental Impacts of Karst, American Society of Civil Engineers, Proceedings

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353NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE Department of Agriculture, data for Houston County, Minnesota. its impact on nitrate concentrations in streams. prediction of aquitard integrity. Hydrogeology Part A. Fish Department. the engineering and environmental Aspects of

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354 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Introduction surface include vegetation removal, soil changes, and the processes and functions of the karst system such as: loss of soil, deterioration of water quality, degradation of The goal of this paper is to outline some of the concepts used in developing a procedure for evaluating distur designated for forestry activities and includes a comreport on the status of karst resources and to aid in the improvement of forest practices. The procedure is conresource assessor (who is not necessarily a karst special -Abstractverse ecological impacts if the nature and characteristics of karst systems and processes are not considered. This is particularly the case for the well-developed and for forestry activities in the region typically comprise of current forestry practices are adequately protecting and the environmental status of surface karst feature samples features within the sample area. A series of questions are then asked with respect to forest practices and management, with the aim of continual improvement. Adof data collection, storage and transfer. This procedure for other land use development or resource activities that occur on karst.Tim StokesTerra Firma Geoscience 1480 Sherwood Drive, Nanaimo, British Columbia, Canada, V9T 1G7. tstokes@island.net Earth Science Department Vancouver Island University, 900 Fifth St, Nanaimo, British Columbia, V9R 5S5, Canada. tim.stokes@viu.caA PROCEDURE FOR EVALUATING LAND DISTURBANCES AT THE SITE LEVEL IN FORESTED KARST AREAS OF BRITISH COLUMBIA, CANADA

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355NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE primarily considered as the physical actions imposed on in impacts and changes to the natural physical, chemical dure.Background several karst regions of the world including west Florida, ample, vegetation removal and associated soil loss on karst in China has led to its transformation into a ‘rocky provided a detailed summary of these issues and gave estimates for the recovery times for soils on karst, plus outlined ways in which restoration could occur. Another amples of similar rocky karst landscape change following vegetation removal around the world include such Tasmania, Europe and southeast Alaska (Ford and WilFigure 1. Forestry activities in a karst area of northwest Vancouver Island with a clearcut and forest road in centre of image. Yarding debris pile in foreground on edge of landing.

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35616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 face, as well as slow tree regeneration. A more recent intensive study was completed in the forested karst of and chemical properties of drip waters was carried out ferent geomorphic settings from alpine, interior plateau the temperate forested karst occurs along the west coast forested karst in these areas is limited. However, reern Vancouver Island compared clearcut (and mostly tree regeneration at the karst sites. The Forest Practices Board of BC has produced two reports on karst. The second was a special investigation report on the management of karst resources on northern Vancouver report did not provide the data or a clear rationale supfeature data from northern Vancouver Island (Stokes, and that carefully designed retention areas were likely rates.Methodology provide advice and improvements to current forest prackarst are the micro-, mesoto macro-scale surface karst designed around the mesoscale surface karst features as These mesoscale surface karst features are important Figure 2. Distribution of carbonate bedrock and potential karst in BC along with the location of Vancouver Island, Haida Gwai and Mid/North Coast (adapted from Stokes Figure 3. Forest covered karst of British Columbia and the three-dimensional karst

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357NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE of the karst system. premise that careful management of mesoscale surface streams, karst springs, cave entrances and other features will help to protect and maintain the associated karst round surface karst features. step is to identify the site for sampling, which harvesting and road construction have occurred. In most cases clear-cutting is the main harvest equipment. Forest road construction is used for machine access and tree transport equipment and Figure 4. Flow chart of the FREP Karst Evaluation Procedure with the Basic Level and ‘Advanced Options’.

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35816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 pits and landing areas. Treed retention areas or reserves are typically left in the centre or along wildlife trees, individual surface karst features identify karst potential polygons delineated at selection of evaluation sample sites is carried resources can also come from forest licensees, 2. Delimiting Karst Sampling Areas either sample all surface karst features in the site treed retention areas that occur internal or external selected can vary depending on the terrain and site Selection and Sampling Surface Karst Features potential karst in the sample area, and to develop The locations of the known surface karst features are plotted onto a working map and a tentative may not permit sampling of all features, so a careful selection process is required to ensure that the variety of features ultimately sampled is representative of the site, and that some level of randomness is applied. Features may occur as large grike or can occur as a complex of nested or enclosing depression that also functions as a sink point for a sinking stream. In the latter case all karst depression that encloses the cave entrance Clusters of surface karst features such as sinkholes may only require sampling of one or two sinkholes rather than every sinkhole. A series of simple sampling. Evaluation of Surface Karst Features the condition of the feature is evaluated using the Figure 5. A recently harvested cutblock on karst with treed retention areas surrounding surface karst features. Exposed epikarst in foreground and middle of image, plus evidence of burning. Figure 6. A complex surface karst feature in a second growth forest. The large sinkhole functions as a window with water emerging to right of image and sinking to left.

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359NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE example, with a sinkhole the plan view, shape, diameter and depth are recorded. A key part of this the mouth or threshold of the cave entrance is zone is added to the outside edge of features to account for some of the roots of large trees and discrepancies in determining the limits of the feature. Once measurements and characteristics of seven core indicator questions related to current forestry activities are applied indicator questions asked at each of the surface is gathered on the extent and amount of these indicator questions means that the surface karst 2. Typically, ten or more on surface karst features is lacking for a selected less. Cave Evaluations information. This evaluation determines whether: 1 . These biophysical indicator questions and in part come from other FREP evaluation procedures. 2 . Note, these disturbances are not necessarily independent of each other and it is anticipated that some duplication may occur. Advanced Options In certain situations, the retention areas surrounding surface karst features Figure 7. Area of disturbed sinkholes with windthrown/overturned trees and windsnapped trees. Figure 8. Soil and bedrock disturbance along edges of a large grike with burning and the introduction of logging debris.

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36016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 are consistently displaying evidence of post-harvest these sites in more detail to measure the size of As another example, if a karst sample area has very area and any associated treed retention area could Following the evaluation and provide some preliminary analysis of the information gathered. The proportion of the areas. The procedure also provides information imply less impact as this requires more in-depth requires more research and study of the ecological processes and responses of these features to karst feature then no adverse impact has occurred. At the end of the procedure the assessor is required to answer a series questions practices and improvements to karst management at the site. using Filemaker software and the data are gathered and taken, and along with maps, stored digitally using the software. Typically, a hard copy checklist is kept on ther testing and pilot training for assessors is anticipated ConclusionsThe focus of the procedure is to assess the state or condition of surface karst features using seven core distur a digital checklist using Filemaker software and an Apforest practices in karst areas. Acknowledgements this document.References associated resources: a resource assessment. U.S. Department of Agriculture and Forest Service,

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361NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE through an application in an island karst setting. Seasonal changes of organic matter quality and quantity at the outlet of a forested karst system Mediterranean karst areas: the example of Sardinia Coastal BC. Forest Practice Board of BC, Special Vancouver Island. Forest Practice Board of BC, deforestation upon limestone slopes in deforestation of the stone forest karst aquifers of Southwest China: Impacts causes and restoration. terrain. In: Maoutinho P, editor. Deforestation west-central Florida and southeast Italy. Journal

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362 16TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 ous studies have recognized that these automated meth Most authors concentrate on small-scale study areas 2 and DEMs to monitor and detect sinkholes (Miao et al., typically have little to no variation in terms of lithology, a single formation. Studies on sinkhole genesis and decommonly look at geological, geomorphological, and factors with sinkhole occurrence and clustering (Ciotoli Since this is the case, studies on sinkhole genesis have studies on sinkholes are limited and most data are only Abstract the genesis and development of these sinkholes were related to various geomorphologic, geologic, and hyvaries with respect to the relative age of the underlying karstic formation, slope, and elevation. Most sinkholes such as those presented in this study are useful for sinkIntroductionIn recent years, sinkhole studies have transitioned from -Regina Martha G. LumongsodNational Institute of Geological Sciences, College of Science, University of the Philippines Diliman P. Velasquez cor. C.P. Garcia Avenue, Diliman, Quezon City, National Capital Region, 1101, Philippines, rglumongsod@up.edu.phNoelynna T. RamosNational Institute of Geological Sciences, College of Science, University of the Philippines Diliman P. Velasquez Street cor. C.P. Garcia Avenue, Diliman, Quezon City, National Capital Region, 1101, Philippines, noelynna.ramos@up.edu.phRoseanne V. RamosDepartment of Geodetic Engineering, College of Engineering, University of the Philippines Diliman Melchor Hall, Roces Street cor. Osmea Avenue, Diliman, Quezon City, National Capital Region, 1101, Philippines, rvramos@up.edu.phGIS-BASED SPATIAL ANALYSIS OF SINKHOLES IN CEBU CITY, PHILIPPINES: INSIGHTS ON SINKHOLE GENESIS AND DEVELOPMENT

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363NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEfound on news articles and mandated agency reports. usually incoherent due to lack of local study sources. which they occur. Morphological measurements were correlated with various geological and geomorphologi cal factors (e.g., lithology, slope, proximity to faults, standing sinkhole formation and development in tropical countries like the Philippines.Study Area clastic rocks and limestone with occasional coal stringMethodology Figure 1. General lithology of Cebu Island showing the location of Cebu Island). Cebu Is land is predominantly underlain by sedimentary formations. The map also shows the location of Cebu City (Fig. 2), which is mostly underlain by Pleistocene to Recent sediments.

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36416TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8logical factors: formational unit, lineaments, streams, eldelineate the streams in the area using hydrology tools. Terrain analysis was used to analyze the topography of vide information on the lithology of the area as well as Sinkhole PolygonsSinkhole polygons were measured for the following geometric properties following the methods of Doctor and pactness, eccentricity, index of circularity, and orienta ers: formational units, slope, and elevation. The total area of sinkholes, percent sinkholes, and sinkhole denSinkhole Centroids used for point data analyses such as frequency and proximity. Each sinkhole was treated as a centroid under the assumption that sinkhole development progresses from a point source due to focused dissolution (Ford and Wilfrom the original sinkhole polygons, as well as the elstreams and lineaments were also investigated using against the following factors: formational unit, orienta distances from the nearest stream and lineament (Faivre Figure 2. Hillshade map of Cebu City. Sinkholes were treated both as polygons and points (centroids) in this study. Table 1. Sinkhole features calculated for the morphometric analyses in this study (White, 1988; Doctor & Young, 2013; Miao et al., 2013). Feature Area Compactness Eccentricity is the semi minor axis Circularity index Sinkhole density Percent sinkhole

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365NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEResultsSinkhole geometry22. The largest total area sinkkm2 2 of minimum and maximum values, there is a seemingly increasing trend in area from the youngest to the oldest formational units. Three measures of circularity were used in this study: eccentricity, compactness, and circularity index. These indices all refer to how close the shape of the sinkholes is to that of a perfect circle. However, each index uses increase in eccentricity within the older formations, with means more circularity. The plot of compactness (Figure wards increasing relative age, with the lowest compact oldest among the four. Streams and lineaments the sinkholes occur within less than 200 m from a stream ting frequency versus distance from the nearest linea eament distance does not seem to have any correlation, with the histogram showing four peaks in the following m away from the nearest lineament. Since there seems to eaments, the orientation was then looked at. Most sinkholes trend west and northeast, following the trend of most streams and lineaments, respectively. Slope and elevation Sinkhole frequency was also geographically compared lished when elevation is compared with frequency (Figor less. These pertain to the multiple sinkhole centroids that are found near the coast. Figure 3. Plots of area (A), eccentricity (B), compactness (C), and circularity index (D) versus the different formational units arranged based on increasing relative age. All four parameters show an increasing area and decreasing circularity with increasing relative age of bedrock.

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36616TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8Formational units and relative age general decreasing trend with increasing relative age can luvium. If these anomalously high values are separated, density with increasing relative age of formational unit.Discussionelevation, and presence of streams and lineaments. The increasing manner from that of a perfect circle with increasing relative age of the underlying karst formation hole density tends to increase given the same trend (FigFigure 4. (A) Simple geomorphological map of Cebu City showing streams, lineaments, and seen by their similar trends: west for streams and northeast for lineaments (D).

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367NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCE ing increase in sinkhole area relative to the total area of more circular sinkholes in the more recent deposits can Figure 5. Slope (A) and elevation (B) maps of Cebu City showing sinkhole centroids. A decreasing trend in frequency with increasing slope steepness can clearly be observed (C). No general trend is established when it comes to elevation, but it can be noted that most sinkholes are found below 50 masl.

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36816TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8lows their values to approach near circular dimensions. The shape, orientation, and frequency of sinkholes were near areas with water, such as streams (Ford and Wildepends on the orientation of the nearest stream or linea ment. This explains the two dominant trends in the strike the orientation of streams, and northeast, which is the in slope and elevation across the study area. Most sinklowing longer and more concentrated dissolution of the ConclusionThis study related the morphometry and frequency of sinkholes with the geological and geomorphological facFigure 6. 1983). A general decreasing trend in frequency with increasing relative age of limestone-bearing bedrock can clearly be observed (B). Since most of the sinkholes occur on Quaternary Alluvium, the percent sinkhole and sinkhole density that is yielded is anomalously high (D). Separating the values from this deposit leaves a trend of increasing percent sinkhole and sinkhole density with increasing relative age of formation.

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369NCKRI SYMPOSIUM 8 16TH SINKHOLE CONFERENCEReferences in sink as an environmental estimator. Ecological Philippines. 2nd ed. Manila: Mines and of sinkholes using a semi-automatic approach genesis and evolution in Apulia, and their interrelations with the anthropogenic environment. Doctor KZ, Doctor DH, Kronenfeld B, Wong DWS, using geographically weighted regression. In: ric and terrain analyses. The results of the morphometric analyses and correlation show that there are at least four ter, which positively feeds the dissolution of the under sooner. Moreover, the direction of elongation of sinkof sinkholes which is consistent with the general trend of streams and lineaments in the area, respectively. served that with increasing relative age, there is also an increase in sinkhole area, percent sinkhole, and sinkhole due to sinkhole coalescence, a phenomenon that occurs with sinkhole development, which decreases the total to the treatment of sinkholes as centroids. It is recom mended in future studies for the distal points along the To improve and further this study, it is also recommend Overall, this study serves as a guide in preliminarily dewell as similar areas.

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37016TH SINKHOLE CONFERENCE NCKRI SYMPOSIUM 8 sinkholes. paleoenvironmental studies in the Tertiary of paleoenvironmental studies in the Tertiary of Sedimentary Formations of the Visayan Basin, Sinkholes and the Engineering and Environmental Impacts of Karst. Proceedings of the Eleventh L, Doctor DH, Stephenson JB. Proceedings of the and the Engineering and Environments Impacts in the UK: the use of digital data for hazard physical causes of sinkhole formation in the UK. In: Doctor DH, Land L, Stephenson JB. Conference on Sinkholes and the Engineering monitoring and early warning: An experimental

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NCKRI SYMPOSIUM 8 Proceedings of the 16th Multidisciplary Conference on Sinkholes and the Engineering and Environmenal Impacts of Karst 2020

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NCKRI SYMPOSIUM 8 Proceedings of the 16th Multidisciplary Conference on Sinkholes and the Engineering and Environmenal Impacts of Karst National Cave and Karst Research Institute400-1 Cascades Avenue Carlsbad, New Mexico 88220 USA


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