DOCSLIB.ORG

REGIONAL DISTRIBUTION of PERMEABILITY in the EDWARDS AQUIFER R­ R E REGIONAL Distrlbution of PERMEABILITY in the EDWARDS AQUIFER R R Final Report R by R Susan D

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
REGIONAL DISTRIBUTION of PERMEABILITY in the EDWARDS AQUIFER R­ R E REGIONAL Distrlbution of PERMEABILITY in the EDWARDS AQUIFER R R Final Report R by R Susan D .::·.t·.·t:: . •..... ·.•... •••. ,··,.,: '. •.~\..... - .· :·.: ... · ,.·\·r~· .... ·.· . .. ..: ... .: .. · ....· . EDWARDS UNDERGROUND WATER DISTRICT REPORT 95-02 REGIONAL DISTRIBUTION OF PERMEABILITY IN THE EDWARDS AQUIFER r­ r E REGIONAL DISTRlBUTION OF PERMEABILITY IN THE EDWARDS AQUIFER r r Final Report r by r Susan D. Hovorka, Robert E. Mace, and Edward W. Collins r assisted by r E. M. Boghld, N. D. johns, jun Uao, and N. L. BaghaJ r r Prepared for Edwards Underground Water Dtstrtct r under Contract No. 93-17-FO r Alan R. Dutton, Prlndpal Investigator Bureau of Economic Geology r Noel Tyler, Director The University of Texas at Austin r Austin, Texas 78713-8924 r january 1995 t r r r' I CONTENTS r. EXECUTI'VE S~Y ••......••.••••.......•....•....••..•.•.........•..................•.••••••..•••••....•••......••••••.•.••••.....••..•.. tx. r ABS'IMcr ..........................................•..........................................................•.•.....•........••••..........••.•...... 1 Nm.ODUcnON .......••....................... ·········································~······················································ ... 3 r Geologic Setting................................ ............. ....... .. .......... .......... ..... .. ......................... ..... ......... ....... 3 r Hydraulic Conductivity-A DeflntUon ...........•••••....•.••............................................................•...... 7 Pr'evlous Work •••••••••..••.••. .. ....••••••••• •• •••••• ••••••••. ••••••..•••••.• •••••••••••••••••. ••.••.••. ••••••• .•••••••... ..••••••••.•. ••• ... 8 Sttucture ......•......................•..........................................•........••.......•..................•...................... s Stratigraphy and Geomorphology .......••••...••••...............•.......•••••••..•••••.••.........•.•..••.................. 9 r Hydraulic Pl'ol)e:rtles ••••... .•......•...... ... ..... .• ... ...•... .. .••••••...... .•••••• •.••••••••••••...•••..... .•••..•. ... ..•.•••••.. .•. 9 Storat::lvlty ............................................................•••.••••......•••............................•••.•.••................ 11 r Hydrologic Simulations •........•.•..•.................................•••••..••••••...•.•••...•••......•••••.•............••••.••. 11 r twfE'niODS •••••.••••••••.••••••.••••••••••••••••.....••••••.•.•••.••••.••......•......••••••••.•••••••••••••••••••••••••••••••••.•••.....•...•••....... 12 Sti'Uctural Data Set ....•....••.•....................•........•..................•............•..••......••••.•.•••••••.......••.....••••.••.. 13 r Isopa.dl MaiJS ••••......•.........••.••••••..••....••••••.•••••.•••••••••••••.•••••.••••••••••.••••.•••••••........•••...•••....••.•••••••••.. _ 14 Spedftc Capadty, Transmissivity, and Hydraulic Conductivity Data Set ..................................... 17 Data Collection ........................................................................................................................ 17 SJ)e'Ciftc Capadty ..•........................•••••...•.••...••••••...............•................••.•............................ 17 . r l'ransmisslvtty and HydrauUc Conductivity ...................................................................... 18 r Calculation of Transmissivity from Specific capadty ............................................................. 19 Well I.oss ..••••••••••••••.......•..•..••••••••••••••.•••.•..•............•.•••••••.•••••••..••••••....•.•••..........•......•.•...... 2:() r Partial Penetradon ...............••......••......•.....................•••••.....•............................................. 21 Analytical Relationship between Transmissivity and Specific capadty ........................... 21 r Empirical Relationship between Transmissivity and Specific Capadty ............................ 22 r Geostatistlcal Analysis .•............••..•••......•.................................................••••••....••..................... 23 Assessment of Vertical Variations in Hydraulic Conductivity ................................................ 25 r Plug and l.og-Based Calculation of PermeabllJty' •.........•.••..••..............••...............•.••..••••.••.•••......... 29 r Ul r l Quantitative Desaiption of Faults, Fractures, and Karst in Outcrop ............................................ 32 l Fracture Mapplrlg ..........................................................................................•.............•.•.......... 33 I Fracture Aperture, Porosity, a11d PenneabUity ................•........•••....•••....••.....••...........•••••...•..•.. 33 l Fracture and Conduit Roughness ..•.....••.•........................................................••.•...•................. 35 I . l Karst Features ................••••.....................................••.....••..•......••••.........•.....••••.......................... 36 ! Dlglta.l Data. Coverages ..............................................••..•.•......•.•..•......................•....••••...........•....... 36 l 1 RESUL1'S •••••••••••••••••••••••• •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 36 Structural FrameworkI of Edwards Aquifer ...................................................................................... 36 l Matrix and Conduit PenneabWty of the Edwards Aquifer ........................................................... .41 Petrographic andI Fades Controls on PerJD.eablllty .................................................................. 43 l I Poroslty'-PenneabWty Relatlonstups ................................................................................. 53 l TranSJDisslvlty' &om: Aquifer Tests ...............................••••••••.••••••.......•••••.•••••••••.............................. 00 I Relationship be~een Transmissivity' and Specific capadty' ................................................... ~ l Analysis of Data •••.••...•...............••........•••••.•••...........•..••••••..•••.............•.....••••........•..•..•••...•••...•• 63 Statistical ~ption of Data ........................................................................................... 63 l Areal Dlst:ribuUon of Transmissivity ...•............•••••••.•....•..•..•..•........••....•........••.................• 66 Spatial RelaUonshlps .......................................................................................................... 70 l i Vertical Varlation of HydrauUc Conductivity' ................................................................... 74 I l Relationship to Mattix Pel'meabWty ................................................................................... 81 Outaop Invest:lga.t:IOns ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.•••••••••••••••• 83 l I Structural Des.alptlon of Fractures •.......................•......•......••.•••..•..............••...............•.....•••••. 83 Fracture Aperture, Porosity, and Penneablllty' ......................................................................... 87 l I Fracture an~ Conduit Roughness ...................................................................................... 91 I ' l l<a.rst •••••••••• ~- •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 91 DISCUSSION...................................................................................................................................... 106 l CONCLUSIONS..................................................................................................................................I 111 Fl1R11-fER WORK................................................................................................................................ 113 l l lv l r r ACKNOWLEDGMENTS ..................................................................................................................... 114 r REFERENCES .. .. .. .. .. ............ ............... ....... .......... .................. .. ..... ............ ... .. ... .......... .. ..... .. .. 114 r Figures 1. Structural, hydrologic, and fades setting of the Edwards aquifer .............................................. 4 r 2. Stratigraphic units within the Edwards Group .•............................•.........••..••.••.......................•.. 6 3. Conceptual models relating the mean hydraulic conductivity to the hydraulic r conductivity and thicknesses of two layers .•............................................................................. 26 4. Variation of transmissivity and spedfic capadty for lnaeasing test interval length ............... 27 r S. Structural aoss section A-A' of the Balcones Fault ZOne at New Braunfels, Texas ................... 40 r 6. GeneraUzed view of a relay ramp ............................................................................................... 4Z 7. Generalized view of sea-level-controlled depositional fades .................................................... 45 r 8. Generalized fades aoss section B-B' of the Edwards Group .............•.......•.............................. .47 9. Schematic diagram of several common pore structures resulting from different r diagenetic histories ..................................................................................................................... 48 10. Relation of measured plug permeability to porosity and calculated permeability ................... 54 r 11. Semllog scatter plot of plug porosity
Load more

Recommended publications
  • USGS Water-Resources Investigations Report 97-4133
    HYDROGEOLOGIC FRAMEWORK AND GEOCHEMISTRY OF THE EDWARDS AQUIFER SALINE-WATER ZONE, SOUTH-CENTRAL TEXAS U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 97–4133 FRESHWATER ZONE SALINE-WATER ZONE Prepared in cooperation with the EDWARDS AQUIFER AUTHORITY and SAN ANTONIO WATER SYSTEM HYDROGEOLOGIC FRAMEWORK AND GEOCHEMISTRY OF THE EDWARDS AQUIFER SALINE-WATER ZONE, SOUTH-CENTRAL TEXAS By George E. Groschen and Paul M. Buszka U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 97–4133 Prepared in cooperation with the EDWARDS AQUIFER AUTHORITY and SAN ANTONIO WATER SYSTEM Austin, Texas 1997 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Acting Director Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services 8011 Cameron Rd. Box 25286 Austin, TX 78754–3898 Denver, CO 80225–0286 ii CONTENTS Abstract ................................................................................................................................................................................ 1 Introduction .......................................................................................................................................................................... 1 Purpose and Scope ...................................................................................................................................................
    [Show full text]
  • LOCAL SPOTLIGHT Edwards Aquifer, San Antonio, Texas, United States—Protecting Groundwater
    LOCAL SPOTLIGHT Edwards Aquifer, San Antonio, Texas, United States—Protecting groundwater Photo: © Blake Gordon Photo: © Blake Gordon North America Left. Officials release a benign "tracer dye" into Edwards Aquifer drainage systems to chart flows and track the underground water pathways. Right. Hydrogeologist descends into a sinkhole to check on the Edwards Aquifer. The challenge As one of the largest, most prolific artesian aquifers in the world, the Edwards Aquifer serves as the primary source of drinking water for nearly 2 million central Texans, including every resident of San Antonio—the second largest city in Texas—and much of the surrounding Hill Country. Its waters feed springs, rivers and lakes and sustain diverse plant and animal life, including rare and endangered species. The aquifer supports agricultural, industrial and recreational activities that not only sustain the Texas economy, but also contribute immeasurably to the culture and heritage of the Lone Star State. AUSTIN The aquifer stretches beneath 12 Texas counties, and the land above it includes several important hydrological areas. Two areas in particular— the drainage area and the recharge zone—replenish the aquifer by “catching” rainwater, which then seeps through fissures, cracks and sinkholes into the porous limestone that dominates the region. While this natural filtration system helps refill the aquifer with high-quality water, the growing city of San Antonio is expanding into territories of the very sensitive recharge zone, increasing the risk of contamination. In Edwards Aquifer SAN ANTONIO addition to a rising population, the state’s water supplies have been impacted by multi-year droughts. By 2060, Texas is projected to be home to approximately 50 million people while the annual available water resources are estimated to decrease by nearly 10 percent.
    [Show full text]
  • Late Cretaceous and Tertiary Burial History, Central Texas 143
    A Publication of the Gulf Coast Association of Geological Societies www.gcags.org L C T B H, C T Peter R. Rose 718 Yaupon Valley Rd., Austin, Texas 78746, U.S.A. ABSTRACT In Central Texas, the Balcones Fault Zone separates the Gulf Coastal Plain from the elevated Central Texas Platform, comprising the Hill Country, Llano Uplift, and Edwards Plateau provinces to the west and north. The youngest geologic for- mations common to both regions are of Albian and Cenomanian age, the thick, widespread Edwards Limestone, and the thin overlying Georgetown, Del Rio, Buda, and Eagle Ford–Boquillas formations. Younger Cretaceous and Tertiary formations that overlie the Edwards and associated formations on and beneath the Gulf Coastal Plain have no known counterparts to the west and north of the Balcones Fault Zone, owing mostly to subaerial erosion following Oligocene and Miocene uplift during Balcones faulting, and secondarily to updip stratigraphic thinning and pinchouts during the Late Cretaceous and Tertiary. This study attempts to reconstruct the burial history of the Central Texas Platform (once entirely covered by carbonates of the thick Edwards Group and thin Buda Limestone), based mostly on indirect geological evidence: (1) Regional geologic maps showing structure, isopachs and lithofacies; (2) Regional stratigraphic analysis of the Edwards Limestone and associated formations demonstrating that the Central Texas Platform was a topographic high surrounded by gentle clinoform slopes into peripheral depositional areas; (3) Analysis and projection
    [Show full text]
  • Map Showing Geology and Hydrostratigraphy of the Edwards Aquifer Catchment Area, Northern Bexar County, South-Central Texas
    Map Showing Geology and Hydrostratigraphy of the Edwards Aquifer Catchment Area, Northern Bexar County, South-Central Texas By Amy R. Clark1, Charles D. Blome2, and Jason R. Faith3 Pamphlet to accompany Open-File Report 2009-1008 1Palo Alto College, San Antonio, TX 78224 2U.S. Geological Survey, Denver, CO 80225 3U.S. Geological Survey, Stillwater, OK 74078 U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY U.S. Department of the Interior DIRK KEMPTHORNE, Secretary U.S. Geological Survey Mark D. Myers, Director U.S. Geological Survey, Denver, Colorado: 2009 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Suggested citation: Clark, A.R., Blome, C.D., and Faith, J.R, 2009, Map showing the geology and hydrostratigraphy of the Edwards aquifer catchment area, northern Bexar County, south- central Texas: U.S. Geological Survey Open-File Report 2009-1008, 24 p., 1 pl. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. 2 Contents Page Introduction……………………………………………………………………….........……..…..4 Physical Setting…………………………………………………………..………….….….….....7 Stratigraphy……………..…………………………………………………………..….…7 Structural Framework………………...……….……………………….….….…….……9 Description of Map Units……………………………………………………….…………...….10 Summary……………………………………………………………………….…….……….....21 References Cited………………………………………….…………………………...............22 Figures 1.
    [Show full text]
  • Stewardship of the Edwards Aquifer
    STEWARDSHIP OF THE EDWARDS AQUIFER What is the Edwards Aquifer? “The Edwards Aquifer is one of the most valuable resources in the central How does this affect me? Aquifer: an underground area that holds enough water Texas area. In most places, it takes time for stormwater to travel to provide a usable supply. over land and filter through soil to reach the rivers and This aquifer provides water for lakes that supply drinking water to residents. In the municipal, industrial, and agricultural Edwards Aquifer region, recharge features provide a direct link between groundwater and our underground uses as well as sustaining a number of water supply. This means that stormwater pollution rare and endangered species. directly affects the quality of our drinking water. To preserve these beneficial uses, As a result, TCEQ has implemented extra water quality San Antonio ReportSan Texans must protect water quality in requirements to protect the aquifer. Examples include Source: this aquifer from degradation water quality treatments like rain gardens and water resulting from human activities.” quality ponds, as well as erosion and sedimentation While other aquifers in Texas are made up of sand and controls at construction sites. gravel, the Edwards Aquifer is a karst aquifer, composed - Texas Commission on Environmental of porous limestone formations that serve as conduits Quality (TCEQ), RG-348 for water as it travels underground. (Edwards Aquifer Authority) As shown in the graphic to the right, the Edwards Aquifer region encompasses much of South Central Texas. Portions of the City Antonio ReportSan of West Lake Hills lie within the Edwards Aquifer Contributing and Recharge Zones.
    [Show full text]
  • Geological Society of America Bulletin
    Downloaded from gsabulletin.gsapubs.org on January 11, 2012 Geological Society of America Bulletin Structural framework of the Edwards Aquifer recharge zone in south-central Texas David A. Ferrill, Darrell W. Sims, Deborah J. Waiting, Alan P. Morris, Nathan M. Franklin and Alvin L. Schultz Geological Society of America Bulletin 2004;116, no. 3-4;407-418 doi: 10.1130/B25174.1 Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geological Society of America Bulletin Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society.
    [Show full text]
  • Albian Rudist Biostratigraphy (Bivalvia), Comanche Shelf to Shelf Margin, Texas
    Carnets Geol. 16 (21) Albian rudist biostratigraphy (Bivalvia), Comanche shelf to shelf margin, Texas Robert W. SCOTT 1, 2 2 Yulin WANG 2 Rachel HOJNACKI Yulin WANG 3 Xin LAI 4 Highlights • Barremian-Albian caprinids biostratigraphic zones are revised and integrated with ammonites and benthic foraminifers. • New caprinid rudist species are the key to revising long-held correlations of Albian strata on the Co- manche shelf, Texas. • On the San Marcos Arch, central Texas, the shallow shelf Person Formation is the upper unit of the Fredericksburg Group. • The Person underlies the basal Washita Group sequence boundary Al Sb Wa1 and the Georgetown Formation. Abstract: Rudists were widespread and locally abundant carbonate producers on the Early Cretaceous Comanche Shelf from Florida to Texas, and on Mexican atolls. As members of the Caribbean Biogeogra- phic Province, their early ancestors emigrated from the Mediterranean Province and subsequently evol- ved independently. Comanchean rudists formed biostromes and bioherms on the shelf interior and at the shelf margin. Carbonate stratigraphic units of the Comanche Shelf record rudist evolution during the Barremian through the Albian ages and an established zonal scheme is expanded. This study documents new Albian rudist occurrences from the Middle-Upper Albian Fredericksburg and Washita groups in Central and West Texas. Rudists in cores at and directly behind the shelf margin southeast of Austin and San Antonio, Texas, complement the rudist zonation that is integrated with ammonites and foraminifers. These new rudist data test long-held correlations of the Edwards Group with both the Fredericksburg and Washita groups based solely on lithologies. Rudist and foraminifer biostratigraphy indicate that the Edwards Group is coeval with the Fredericksburg not the Washita Group.
    [Show full text]
  • Groundwater Availability of the Barton Springs Segment of the Edwards Aquifer, Texas: Numerical Simulations Through 2050
    GROUNDWATER AVAILABILITY OF THE BARTON SPRINGS SEGMENT OF THE EDWARDS AQUIFER, TEXAS: NUMERICAL SIMULATIONS THROUGH 2050 by Bridget R. Scanlon, Robert E. Mace*, Brian Smith**, Susan Hovorka, Alan R. Dutton, and Robert Reedy prepared for Lower Colorado River Authority under contract number UTA99-0 Bureau of Economic Geology Scott W. Tinker, Director The University of Texas at Austin *Texas Water Development Board, Austin **Barton Springs Edwards Aquifer Conservation District, Austin October 2001 GROUNDWATER AVAILABILITY OF THE BARTON SPRINGS SEGMENT OF THE EDWARDS AQUIFER, TEXAS: NUMERICAL SIMULATIONS THROUGH 2050 by Bridget R. Scanlon, Robert E. Mace*1, Brian Smith**, Susan Hovorka, Alan R. Dutton, and Robert Reedy prepared for Lower Colorado River Authority under contract number UTA99-0 Bureau of Economic Geology Scott W. Tinker, Director The University of Texas at Austin *Texas Water Development Board, Austin **Barton Springs Edwards Aquifer Conservation District, Austin October 2001 1 This study was initiated while Dr. Mace was an employee at the Bureau of Economic Geology and his involvement primarily included initial model development and calibration. CONTENTS ABSTRACT .......................................................................................................................................1 INTRODUCTION..............................................................................................................................1 STUDY AREA...................................................................................................................................3
    [Show full text]
  • Edwards Aquifer Region 1615 N
    EDWARDS AQUIFER REGION 1615 N. St Mary’s Street • San Antonio, Texas 78215 • 210.222.2204 • 1.800.292.1047 • www.edwardsaquifer.org Drainage basins in the drainage area collect surface water runoff and funnel it into streams that cross the recharge zone. In the artesian zone, the water fl ows generally from west to east. Water movement through the Edwards Limestone Drainage County Lines is generally slower south and east of the fresh Area EAA Jurisdictional Boundary water zone. This water remains in contact with Recharge San Antonio City Limits the limestone and gypsum longer, allowing NORTH Zone dissolved mineral concentrations to increase Major Rivers to over 1,000 milligrams/liter. Artesian Minor Rivers WEST EAST Zone Intermittent Streams SOUTH How Does The Aquifer Work? Th is generalized diagram of a north-south cross section of the Edwards Aquifer streams that fl ow downhill to the recharge zone. In the recharge zone, where region highlights the key components of the aquifer and how they inter-relate the Edwards Limestone is exposed at the land surface, the water actually enters About 85% of precipitation falling and function to form a natural underground system for storing water. the aquifer through cracks, crevices, caves, and sinkholes, and then percolates on the area is lost back to the further underground into the artesian zone. Here, a complex network of atmosphere by evaporation or Th e Edwards Aquifer is a karst aquifer, which means it consists of porous, interconnected spaces, varying in size from microscopic pores to open caverns, by transpiration of water vapor honeycombed formations of Edwards Limestone and other associated limestones from vegetation.
    [Show full text]
  • The Edwards Aquifer (Part A)
    E-PARCC COLLABORATIVE GOVERNANCE INITIATIVE Program for the Advancement of SYRACUSE UNIVERSITY Maxwell School Research on Conflict and Collaboration THE EDWARDS AQUIFER (PART A) Amidst of one of the worst Texas droughts in recent memory, attorney Robert Gulley wondered why he had left his position at an established law practice to take on the position of program director for the Edwards Aquifer Recovery Implementation Program (EARIP). As the program director, Robert now worked for 26 different organizations and his job was to assist them, using a consensus-based stakeholder process, through one of the most contentious and intractable national disputes involving scarce groundwater resources at the Edwards Aquifer, one of the most valuable water resources in the Central Texas area. This dispute had already spanned decades and, to make this task even more daunting, the competing interests on both sides had made numerous unsuccessful attempts over the years to resolve this conflict. Hot weather, droughts, and the resulting conflicts between stakeholders are frequent occurrences in Texas. Robert, who had returned to his home state specifically for this position, knew that this drought would only intensify the tensions amongst the stakeholders involved. The Edwards Aquifer (“Aquifer”) provides approximately 90 percent of the water for over two million people living and working in the South-Central Texas area. The Aquifer supplies the water that services the city of San Antonio and other municipalities; a multi-million agricultural and ranching industry in the western part of the region that views water as a coveted property right; as well as the recreational activities that provide the backbone of the economies of rapidly-growing, nearby cities of San Marcos and New Braunfels (Figure 1).
    [Show full text]
  • Barton Springs Segment of the Edwards (Balcones Fault Zone) Aquifer, Central Texas
    OLD G The Geological Society of America Memoir 215 OPEN ACCESS Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer, central Texas Brian B. Hunt Brian A. Smith Barton Springs/Edwards Aquifer Conservation District, Austin, Texas 78748, USA Nico M. Hauwert Balcones Canyonland Preserve, City of Austin, Austin Water, Wildland Conservation Division, Austin, Texas 78738, USA ABSTRACT The Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer is a prolifi c karst aquifer system containing the fourth largest spring in Texas, Barton Springs. The Barton Springs segment of the Edwards Aquifer supplies drinking water for ~60,000 people, provides habitat for federally listed endangered salamanders, and sustains the iconic recreational Barton Springs pool. The aquifer is composed of Lower Cretaceous carbonate strata with porosity and permeability controlled by dep- ositional facies, diagenesis, structure, and karstifi cation creating a triple permeability system (matrix, fractures, and conduits). Groundwater fl ow is rapid within an inte- grated network of conduits discharging at the springs. Upgradient watersheds pro- vide runoff to the recharge zone, and the majority of recharge occurs in the streams crossing the recharge zone. The remainder is direct recharge from precipitation and other minor sources (infl ows from Trinity Group aquifers, the San Antonio segment, the bad-water zone, and anthropogenic sources). The long-term estimated mean water budget is 68 ft3/s (1.93 m3/s). The Barton Springs/Edwards Aquifer Conserva- tion District developed rules to preserve groundwater supplies and maximize spring fl ow rates by preserving at least 6.5 ft3/s (0.18 m3/s) of spring fl ow during extreme drought.
    [Show full text]
  • Geologic Summary
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE G 4032 provided by UT Digital Repository T3 cs 2005 C6 GEOL MAPS Miscellaneous Map No. 43 eologic Map of the West Half of the Taylor, Texas, 30 x 60 Minute Quadrangle: Central Texas Urban Corridor, Encompassing Round Rock, Georgetown, Salado, Briggs, Liberty Hill, and Leander Edward W. Collins ;;;;;;;;;;;;;;; -!!!!!!!!!!!!!!! Ill - Q. < - :::E ;;;;;;;;;;;;;;; CJ .J - 0 rn w ;;;;;;;;;;;;;;; er c(J -;;;;;;;;;;;;;;; " c(J U) c(J 0 = c() Ill ;;;;;;;;;;;;;;; ::r 0 ~ ...-'! 0 - ru N Ill 0 ;;;;;;;;;;;;;;; M - I- N = M 0 - 'It' -!!!!!!!!!!!!!!! - " Bureau of Economic Geology Scott W. Tinker, Director John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin Austin, Texas 78713-8924 2005 Miscellaneous Map No. 43 Geologic Map of the West Half of the Taylor, Texas, 30 x 60 Minute Quadrangle: Central Texas Urban Corridor, Encompassing Round Rock, Georgetown, Salado, Briggs, Liberty Hill, and Leander Edward W. Collins Bureau of Economic Geology Scott W. Tinker, Director John A. and Katherine G. Jackson School of Geosciences The University of Texas at Austin Austin, Texas 78713-8924 2005 ( CONTENTS ABSTRACT ....................................................................................................................... l INTRODUCTION ............................................................................................................ 1 Methods .....................................................................................................................
    [Show full text]