A parsimonious model for simulating flow in a karst aquifer, 1997, Barrett Me, Charbeneau Rj,

This paper describes the hydrologic system associated with the Barton Springs portion of the Edwards aquifer and presents a lumped parameter model capable of reproducing general historical trends for measured water levels and spring discharge. Recharge to the aquifer was calculated based on flow loss studies of the creeks crossing the recharge zone and on estimates of the rate of diffuse infiltration of rainfall. Flow measurements on each creek above and below the recharge zone were used to develop a relationship between how above the recharge zone and the rate of recharge. The five-cell groundwater model, each cell corresponding to one of the watersheds of the five main creeks crossing the recharge zone, was developed to support the management objectives of the City of Austin. The model differs from previous models in that the aquifer properties within cells are allowed to vary vertically. Each cell was treated as a tank with an apparent area and the water level of a single well in each cell was used to characterize the conditions in that cell. The simple representation of the hydrologic system produced results comparable to traditional groundwater models with fewer data requirements and calibration parameters. (C) 1997 Elsevier Science B.V

Can we simulate regional groundwater flow in a karst system using equivalent porous media models? Case study, Barton Springs Edwards aquifer, USA, 2003, Scanlon B. R. , Mace R. E. , Barrett M. E. , Smith B. ,

Various approaches can be used to simulate groundwater flow in karst systems, including equivalent porous media distributed parameter, lumped parameter, and dual porosity approaches, as well as discrete fracture or conduit approaches. The purpose of this study was to evaluate two different equivalent porous media approaches: lumped and distributed parameter, for simulating regional groundwater flow in a karst aquifer and to evaluate the adequacy of these approaches. The models were applied to the Barton Springs Edwards aquifer, Texas. Unique aspects of this study include availability of detailed information on recharge from stream-loss studies and on synoptic water levels, long-term continuous water level monitoring in wells throughout the aquifer, and spring discharge data to compare with simulation results. The MODFLOW code was used for the distributed parameter model. Estimation of hydraulic conductivity distribution was optimized by using a combination of trial and error and automated inverse methods. The lumped parameter model consists of five cells representing each of the watersheds contributing recharge to the aquifer. Transient simulations were conducted using both distributed and lumped parameter models for a 10-yr period (1989-1998). Both distributed and lumped parameter models fairly accurately simulated the temporal variability in spring discharge; therefore, if the objective of the model is to simulate spring discharge, either distributed or lumped parameter approaches can be used. The distributed parameter model generally reproduced the potentiometric surface at different times. The impact of the amount of pumping on a regional scale on spring discharge can be evaluated using a lumped parameter model; however, more detailed evaluation of the effect of pumping on groundwater levels and spring discharge requires a distributed parameter modeling approach. Sensitivity analyses indicated that spring discharge was much more sensitive to variations in recharge than pumpage, indicating that aquifer management should consider enhanced recharge, in addition to conservation measures, to maintain spring flow. This study shows the ability of equivalent porous media models to simulate regional groundwater flow in a highly karstified aquifer, which is important for water resources and groundwater management. (C) 2003 Elsevier Science B.V. All rights reserved

Sinkholes and the Engineering and Environmental Impacts of Karst, 2005, Beck B. F.

Conference Proceedings

Sinkholes and the Engineering and Environmental Impacts of Karst Contains over 70 papers addressing karst topography which impacts water resources, waste disposal, foundation stability, and a multitude of other geotechnical and environmental issues. These papers were presented at the 10th Multidisciplinary Conference held September 24-28, 2005 in San Antonio, Texas and Sponsored by the Geo-Institute of ASCE, P. E. LaMoreaux & Associates, Inc. and Edwards Aquifer Authority. The goal of this conference was to share knowledge and experience among disciplines by emphasizing practical applications and case studies. This proceedings will benefit environmental and geotechnical engineers, and others involved in water resources, water disposal, and foundation stability issues.

Contents:

 Application of Geophysical Logging Techniques for Multi-Channel Well Design and Installation in a Karst Aquifer (by Frank Bogle, ...)

 Case Studies of Massive Flow Conduits in Karst Limestone (by Jim L. Lolcama)
 
 A Case Study of the Samanalawewa Reservoir on the Walawe River in an Area of Karst in Sri Lanka (by K. Laksiri, ...)

 Characterization and Water Balance of Internal Drainage Sinkholes (by Nico M. Hauwert, ...) 

 Characterization of Desert Karst Terrain in Kuwait and the Eastern Coastline of the Arabian Penninsula (by Waleed Abdullah, ...)

 Characterization of a Sinkhole Prone Retention Pond Using Multiple Geophysical Surveys and Closely Spaced Borings (by Nick Hudyma, ...)
 
 Combining Surface and Downhole Geophysical Methods to Identify Karst Conditions in North-Central Iowa (by J. E. Wedekind, ...)

 Complexities of Flood Mapping in a Sinkhole Area (by C. Warren Campbell, P.E.)
 
 Conceptualization and Simulation of the Edwards Aquifer, San Antonio Region, Texas (by R. J. Lindgren, ...)

 Database Development and GIS Modeling to Develop a Karst Vulnerability Rating for I-66, Somerset to London, KY (by Michael A. Krokonko, ...)

 Design and Construction of the Foundations for the Watauga Raw Water Intake Facility in Karstic Limestone near the City of Johnson City, TN (by Tony D. Canale, P.E., ...)

 Detection of Three-Dimensional Voids in Karstic Ground (by Derek V. Morris, P.E., ...)

 Development and Evolution of Epikarst in Mid-Continent US Carbonates (by Tony L. Cooley, P.E.)

 Dye Tracing Sewage Lagoon Discharge in a Sandstone Karst, Askov, Minnesota (by Emmit Calvin Alexander, Jr., ...)

 The Effectiveness of GPR in Sinkhole Investigations (by E. D. Zisman, P.E., ...)

 Effects of Anthropogenic Modification of Karst Soil Texture on the Water Balance of ?Alta Murgia? (Apulia, Italy) (by F. Canora, ...)

 Environmental Isotope Study on Recharge and Groundwater Residence Time in a covered Ordovician Carbonate Rock (by Zhiyuan Ma, ...)

 Error and Technique in Fluorescent dye Tracing (by Chris Smart)
 
 Essential Elements of Estimating Engineering Properties of Karst for Foundation Design (by Ramanuja Chari Kannan, P.E., Fellow, ASCE)

 Estimating Grout Quantities for Residential Repairs in Central Florida Karst (by Larry D. Madrid, P.E., ...)

 Evaluation of Groundwater Residence Time in a Karstic Aquifer Using Environmental Tracers: Roswell Artesian Basin, New Mexico (by Lewis Land)

 Experience of Regional Karst Hazard and Risk Assessment in Russia (by A. L. Ragozin, ...)

 Experimental Study of Physical Models for Sinkhole Collapses in Wuhan, China (by Mingtang Lei, ...)

 Fractal Scaling of Secondary Porosity in Karstic Exposures of the Edwards Aquifer (by Robert E. Mace, ...)

 The Geological Characteristics of Buried Karst and Its Impact on Foundations in Hong Kong, China (by Steve H. M. Chan, ...)

 Geophysical Identification of Evaporite Dissolution Structures Beneath a Highway Alignment (by M. L. Rucker, ...)

 Geotechnical Analysis in Karst: The Interaction between Engineers and Hydrogeologists (by R. C. Bachus, P.E.)

 The Gray Fossil Site: A Spectacular Example in Tennessee of Ancient Regolith Occurrences in Carbonate Terranes, Valley and Ridge Subpovince, South Appalachians U.S.A. (by G. Michael Clark, ...)

 Ground-Water Basin Catchment Delineation by Bye Tracing, Water Table Mapping, Cave Mapping, and Geophysical Techniques: Bowling Green Kentucky (by Nicholas C. Crawford)

 Groundwater Flow in the Edwards Aquifer: Comparison of Groundwater Modeling and Dye Trace Results (by Brian A. Smith, ...)

 Grouting Program to Stop Water Flow through Karstic Limestone: A Major Case History (by D. M. Maciolek)

 Highway Widening in Karst (by M. Zia Islam, P.E., ...)

 How Karst Features Affect Recharge? Implication for Estimating Recharge to the Edwards Aquifer (by Yun Huang, ...)

 Hydrogeologic Investigation of Leakage through Sinkholes in the Bed of Lake Seminole to Springs Located Downstream from Jim Woodruff Dam (by Nicholas C. Crawford, ...)

 The Hydrologic Function of the soil and Bedrock System at Upland Sinkholes in the Edwards Aquifer Recharge Zone of South-Central Texas (by A. L. Lindley)

 An Integrated Geophysical Approach for a Karst Characterization of the Marshall Space Flight Center (by Lynn Yuhr, ...)

 Integrated Geophysical Surveys Applied to Karstic Studies Over Transmission Lines in San Antonio, Texas (by Mustafa Saribudak, ...)

 Judge Dillon and Karst: Limitations on Local Regulation of Karst Hazards (by Jesse J. Richardson, Jr.)

 Karst Groundwater Resource and Advantages of its Utilization in the Shaanbei Energy Base in Shaanxi Province, China (by Yaoguo Wu, ...)

 Karst Hydrogeology and the Nature of Reality Revisited: Philosophical Musings of a Less Frustrated Curmudgeon (by Emmit Calvin Alexander, Jr.)

 Karst in Appalachia ? A Tangled Zone: Projects with Cave-Sized Voids and Sinkholes (by Clay Griffin, ...)

 Karstic Features of Gachsaran Evaporites in the Region of Ramhormoz, Khuzestan Province, in Southwest Iran (by Arash Barjasteh)

 Large Perennial Springs of Kentucky: Their Identification, Base Flow, Catchment, and Classification (by Joseph A. Ray, ...)

 Large Plot Tracing of Subsurface Flow in the Edwards Aquifer Epikarst (by P. I. Taucer, ...)
 Lithology as a Predictive Tool of Conduit Morphology and Hydrology in Environmental Impact Assessments (by George Veni)

 Metadata Development for a Multi-State Karst Feature Database (by Yongli Gao, ...)

 Micropiling in Karstic Rock: New CMFF Foundation Solution Applied at the Sanita Factory (by Marc Ballouz)

 Modeling Barton Springs Segment of the Edwards Aquifer Using MODFLOW-DCM (by Alexander Y. Sun, ...)

 Multi-Level Monitoring Well Completion Technologies and Their Applicability in Karst Dolomite (by Todd Kafka, ...)

 National-Scale Risk Assessment of sinkhole Hazard in China (by Xiaozhen Jiang, ...)

 New Applications of Differential Electrical Resistivity Tomography and Time Domain Reflectometry to Modeling Infiltration and Soil Moisture in Agricultural Sinkholes (by B. F. Schwartz, ...)

 Non-Regulatory Approaches to Development on Karst (by Jesse J. Richardson, Jr., ...)

 PA State Route 33 Over Bushkill Creek: Structure Failure and Replacement in an Active Sinkhole Environment (by Kerry W. Petrasic, P.E.)

 Quantifying Recharge via Fractures in an Ashe Juniper Dominated Karst Landscape (by Lucas Gregory, ...)

 Quantitative Groundwater Tracing and Effective Numerical Modeling in Karst: An Example from the Woodville Karst Plain of North Florida (by Todd R. Kincaid, ...)

 Radial Groundwater Flow at Landfills in Karst (by J. E. Smith)
 
 Residual Potential Mapping of Contaminant Transport Pathways in Karst Formations of Southern Texas (by D. Glaser, ...)

 Resolving Sinkhole Issues: A State Government Perspective (by Sharon A. Hill)

 Shallow Groundwater and DNAPL Movement within Slightly Dipping Limestone, Southwestern Kentucky (by Ralph O. Ewers, ...)

 Sinkhole Case Study ? Is it or Isn?t it a Sinkhole? (by E. D. Zisman, P.E.)

 Sinkhole Occurrence and Changes in Stream Morphology: An Example from the Lehigh Valley Pennsylvania (by William E. Kochanov)

 Site Characterization and Geotechnical Roadway Design over Karst: Interstate 70, Frederick County, Maryland (by Walter G. Kutschke, P.E., ...)

 Soil Stabilization of the Valley Creek Trunk Sewer Relief Tunnel (by Jeffrey J. Bean, P.E., ...)

 Some New Approaches to Assessment of Collapse Risks in Covered Karsts (by Vladimir Tolmachev, ...)

 Spectral Deconvolution and Quantification of Natural Organic Material and Fluorescent Tracer Dyes (by Scott C. Alexander)

 Springshed Mapping in Support of Watershed Management (by Jeffrey A. Green, ...) 

 Sustainable Utilization of Karst Groundwater in Feicheng Basin, Shandong Province, China (by Yunfeng Li, ...)
 
 Transport of Colloidal and Solute Tracers in Three Different Types of Alpine Karst Aquifers ? Examples from Southern Germany and Slovenia (by N. Göppert, ...)

 Use of the Cone Penetration Test for Geotechnical Site Characterization in Clay-Mantled Karst (by T. C. Siegel, ...)

 The Utility of Synthetic Aperture Radar (SAR) Interferometry in Monitoring Sinkhole Subsidence: Subsidence of the Devil?s Throat Sinkhole Area (Nevada, USA) (by Rana A. Al-Fares)

 Void Evolution in Soluble Rocks Beneath Dams Under Limited Flow Condition (by Emmanuel S. Pepprah, ...)

Conceptualization and Simulation of the Edwards Aquifer, San Antonio Region, Texas, 2005, Lindgren R. J. , Dutton A. R. , Hovorka Susan D. , Worthingtons . R. H. , And Painter Scott L.

Numerical ground-water flow models for the Edwards aquifer in the San Antonio region of Texas generally have been based on a diffuse-flow conceptualization. That is, although conduits likely are present, the assumption is that flow in the aquifer predominantly is through a network of small fractures and openings sufficiently numerous that the aquifer can be considered a porous-media continuum at the regional scale. Whether flow through large fractures and conduits or diffuse flow predominates in the Edwards aquifer at the regional scale is an open question. A new numerical ground-water-flow model (Edwards aquifer model) that incorporates important components of the latest information and an alternate conceptualization of the Edwards aquifer was developed. The conceptualization upon which the Edwards aquifer model is based emphasizes conduit development and conduit flow, and the model can be considered a test of one of two reasonable conceptualizations. The model incorporates conduits simulated as generally continuously connected, one-cell-wide (1,320 feet) zones with very large hydraulic-conductivity values (as much as 300,000 feet per day). The locations of the conduits are based on a number of factors, including major potentiometric-surface troughs in the aquifer, the presence of sinking streams, geochemical information, and geologic structures (for example, faults and grabens). The model includes both the San Antonio and Barton Springs segments of the Edwards aquifer in the San Antonio region, Texas, and was calibrated for steady-state (1939.46) and transient (1947.2000) conditions. Transient simulations were conducted using monthly recharge and pumpage (withdrawals) data. The predominantly conduit-flow conceptualization incorporated in the Edwards aquifer model yielded a reasonably good match between measured and simulated hydraulic heads in the confined part of the aquifer and between measured and simulated springflows. The simulated directions of flow in the Edwards aquifer model are most strongly influenced by the presence of simulated conduits and barrier faults. The simulated flow in the Edwards aquifer is appreciably influenced by the locations of the simulated conduits, which tend to facilitate flow. The simulated subregional flow directions generally are toward the nearest conduit and subsequently along the conduits from the recharge zone into the confined zone and toward the major springs. Structures simulated in the Edwards aquifer model that tend to restrict ground-water flow are barrier faults. The influence of simulated barrier faults on flow directions is most evident in northern Medina County.

Potential for Vertical Flow Between the Edwards and Trinity Aquifer, Barton Springs Segment of the Edwards Aquifer, 2011, Smith Brian A. , Hunt Brian B.

Interconnection of the Trinity (Glen Rose) and Edwards Aquifers along the Balcones Fault Zone and Related Topics, 2011,

The proceedings volume contains nine contributions presented during the Karst Conservation Initiative Meeting held in February 17, 2011 at The University of Texas at Austin.

The Edwards and Trinity Aquifers are critical water resources, supplying high-quality potable water to over two million people in the greater Austin-San Antonio region of central Texas, USA. These Cretaceous carbonate aquifers are hydrogeologically juxtaposed by extensive Miocene tectonic deformation associated with the Balcones Fault Zone, where the younger Edwards Group limestone has been downthrown relative to the older Trinity Group. The karstic aquifers are managed separately by regional water regulatory entities, and they have been historically treated as independent systems, both scientifically and from a water policy standpoint. Recent awareness of a significant interconnection between the Edwards and Trinity Aquifers has resulted in a number of hydrogeologic investigations documenting how they may actually operate as a single system. Studies related to upland recharge variability (spatial and temporal), stream loss, phreatic dye tracing, multi-port well monitoring, geochemistry, biologic habitat analysis, geophysics, and groundwater modeling indicate that the two are much less separated than previously observed. Summaries of these investigations conclude that changes in management strategies may be required to properly protect the quantity and quality of water in the Edwards and Trinity Aquifers.

Contents (click to open individual articles)

Introduction and Acknowledgements 

I nterconnection of the Edwards and Trinity Aquifers, Central Texas, U.S.A. 
Marcus O. Gary 

Spatial and Temporal Recharge Variability Related to Groundwater Interconnection of the Edwards and Trinity Aquifers, Camp Bullis, Bexar and Comal Counties, Texas 
Marcus O.Gary, George Veni, Beverly Shade, and Robin Gary

Potential for Vertical Flow Between the Edwards and Trinity Aquifer, Barton Springs Segment of the Edwards Aquifer 
Brian A. Smith and Brian B. Hunt

Could Much of Edwards Aquifer “Matrix Storage” Actually be Trinity Aquifer Contributions from the Blanco River? 
Nico M. Hauwert

Geophysical Correlation of Haby Crossing Fault (Medina County) and Mt. Bonnell Fault (Travis County) and Their Implications on T-E Interconnection 
Mustafa Saribudak

Edwards Aquifer – Upper Glen Rose Aquifer Hydraulic Interaction 
R.T. Green, F.P. Bertetti, and M.O. Candelario

Interaction Between the Hill Country Portion of the Trinity and Edwards Aquifers: Model Results 
Ian C. Jones

Using Tracer Testing Data for Resource Management Planning 
Geary Schindel and Steve Johnson

Demonstrating Interconnection Between a Wastewater Application Facility and a First Magnitude Spring in a Karstic Watershed: Tracer Study of the Tallahassee, Florida Treated Effluent Spray Field 2006-2007  
Todd R. Kincaid, Gareth J. Davies, Christopher L. Werner, and Rodney S. DeHan

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COVER-COLLAPSE SINKHOLE DEVELOPMENT IN THE CRETACEOUS EDWARDS LIMESTONE, CENTRAL TEXAS, 2013, Hunt B. B. , Smith B. A. , Adams M. T. , Hiers S. E. , Brown N.

Sudden cover-collapse sinkhole (doline) development is uncommon in the karstic Cretaceous-age Edwards limestone of central Texas. This paper presents a case-study of a sinkhole that formed within a stormwater retention pond (SWRP) in southwest Austin. Results presented include hydrogeologic characterizations, fate of stormwater, and mitigation of the sinkhole. On January 24, 2012, a 11 cm (4.5 in) rainfall filled the SWRP with about 3 m (10 ft) of stormwater. Subsequently, a sinkhole formed within the floor of a SWRP measuring about 9 m (30 ft) in diameter and 4 m (12 ft) deep. About 26.5 million liters (7 million gallons) of stormwater drained into the aquifer through this opening. To determine the path, velocity, and destination of stormwater entering the sinkhole a dye trace was conducted. Phloxine B was injected into the sinkhole on February 3, 2012. The dye was detected at one well and arrived at Barton Springs in less than 4 days for a minimum velocity of 2 km/day (1.3 mi/day).Review of pre-development 2-foot topographic contour and geologic maps reveals that the SWRP was built within a broad (5,200 m2; 6 acre), shallow depression bounded by two inferred NE-trending fault zones. Photographs taken during SWRP construction showed steep west-dipping bedrock in the northern SWRP wall. Following collapse of the sinkhole, additional hydrogeologic characterization included excavation to a depth of 6.4 m (21 ft), surface geophysics (resistivity), and rock coring. Geologic materials consisted mostly 89of friable, highly altered, clayey limestone consistent with epikarst in-filled with terra rosa providing a cover of the feature. Dipping beds, and fractured bedrock support proximity to the mapped fault zone. Geophysics and surface observations suggested a lateral pathway for stormwater flow at the junction between the wet pond’s impermeable geomembrane and compacted clay liner for the retention pond. The collapse appears to have been caused by stormwater down-washing poorly consolidated sediments from beneath the SWRP and into a pre-existing karst conduit system.

Mitigation of the sinkhole included backfill ranging from boulders to gravel, a geomembrane cover, and reinforced concrete cap. Additional improvements to the SWRP included a new compacted clay liner overlain by a geomembrane liner on the side slopes of the retention pond.