Browsing by Subject "Edwards Aquifer"
Now showing 1 - 20 of 23
- Results Per Page
- Sort Options
Item Beyond the Aquifer : planning for San Antonio's future water supply(2010-05) Laughlin, Nathan Daniel; Butler, Kent S.; Schuster, StefanThis report examines water supply planning issues in San Antonio, Texas. San Antonio is unique among large cities in the United States in that it relies almost exclusively on a single source, the Edwards Aquifer, for its water supply. Because San Antonio’s water demand is projected to outgrow the Aquifer’s capacity, the city must consider other options to extend and augment its current water supply. After describing the hydrogeology and water supply history of San Antonio, this report explains the multitiered water planning structure and current and future water needs for the city. It then studies and evaluates three short-to-mid term water supply options. By continuing to develop its already successful water conservation programs and water reclamation system, San Antonio can delay the need for more costly and environmentally impactful water supply options down the road, and wisely manage the resources it already draws from.Item Edwards Aquifer Storage Assessment, Kinney County to Hays County, Texas(1993) Hovorka, Susan D.; Ruppel, Stephen C.; Dutton, Alan R.; Yeh, Joseph S.The distribution of water in the Edwards aquifer was assessed using a core- and log-based stratigraphic study that included 200 neutron and resistivity logs and 300 porosity and permeability plug analyses. The Kainer, Person, Devils River, West Nueces, McKnight, and Salmon Peak Formations of the Edwards Group were investigated during this study. The aquifer extends over 3,111 mi^2 (8,004 km^2) and thickens toward the south from approximately 500 to 780 ft (150 to 240 m). In the Edwards outcrop, the aquifer thins northward because of erosion and decreased saturated thickness. Porosity data were interpolated between wells to create a three-dimensional cell-based model of porosity. Porosity distribution reflects both the depositional rock fabric and later diagenesis. Small-scale vertical variations in porosity are the result of facies changes caused by high-frequency cyclicity in the depositional environment. Vertical facies stacking influences the amount of dolomitization and diagenetic enhancement of porosity. Subtidal facies deposited during major sea-level highstands are generally undolomitized and exhibit low porosity (4- to 12-percent porosity). Grainstones at cycle tops in the Kainer, Person, and Devils River Formations are typically high-porosity intervals with high depositional porosity that may have additional solution enlargement of pores and pore throats (20- to 42-percent porosity). Dolomitized subtidal facies have very high porosity in intervals with stacked tidal-flat cycles because of preferential dolomite dissolution.Item Edwards Rules Maps Digitization, TNRCC Edwards Project- Contract Number 582-9-12095(1999) Tremblay, Thomas A.On August 20, 1999, a digital version of the Edwards Rules Map Leander NE quadrangle was placed on the Bureau's anonymous ftp site for review by TNRCC. The Leander NE quadrangle was approved by TNRCC, and the remaining 33 quadrangles were digitized. The Edwards Rules map was captured from 34 mylar, paper blueline, and original 7.5' USGS maps. Lines depicting the boundary of the recharge and transition zones of the Edwards Aquifer were tablet digitized from the original maps using the ArcEdit module of ArcInfo. All tics and linear features from an individual map were captured during the initial digitizing session. The digitized coverages were transformed into either polyconic or stateplane (central or south-central zones) projections. Transformation error reports for all quadrangles were recorded as project documentation. The 34 individual coverages were reprojected into UTM zone 14, appended, and processed into a single polygon coverage. Polygons are assigned a numeric code specifying recharge (1) and transition (2) areas.Item Extreme Catfish(North American Native Fish Associaton, 2004) Sneegas, Garold; Hendrickson, Dean A.Below the city of San Antonio Texas lies a vast aquifer known as the Edwards (Balcones Fault Zone) Aquifer. Two rare and unusual catfish reside in the aquifer, Satan eurystomus, the widemouth blindcat and Trogloglanis pattersoni, the toothless blindcat. They are the only known troglobitic catfish in the United States. The only specimens of both species ever collected have come from deep (1,200' to 1,500') artesian wells within the city of San Antonio itself and parts of southern Bexar County.Item Geochemical evolution of ground water in the Barton Springs segment of the Edwards Aquifer(2005) Garner, Bradley D.; Banner, Jay L.The water quality in a karst (limestone) aquifer changes over time, making the application of traditional hydrogeologic principles difficult or impossible. This research's goal was to advance the understanding of the Barton Springs segment of the Edwards aquifer within and around Austin, Texas. This was accomplished by analyzing time-series water-quality data from long, medium, and short time scales. Analysis provided insights into direction of ground-water flow, sources of spring discharge, and mixing of geochemically distinct waters in the aquifer. The results of this research are of interest because of the aquifers role as a drinking water supply, its role as a habitat for the endangered Barton Springs salamander (Eurycea sosorum), and for its central role in creating the popular Barton Springs Pool. Twenty-six years of water-quality data were compared against contemporaneous streamflow and spring discharge rates to evaluate ground-water connection to surface-water processes. Fifteen of 26 wells in this dataset showed a correlation between these measurements. Ion ratios of Mg/Ca, SO₄/Cl, and Na/Ca showed that active ground-water processes included dilution by recently-recharged surface water, inconguent dissolution, and mixing with water from a saline zone and an underlying aquifer. Four wells were shown to intersect major flowpaths, and five wells were shown to intersect minor flowpaths. Major ion and Sr isotope data collected over two years from four karst springs (Main, Eliza, Old Mill, and Upper Barton Springs) provided insight into water flow in the aquifer. Main and Eliza were fed by ground water from the same flowpath(s) in the aquifer, as their geochemical compositions were indistinguishable. Old Mill received 4-9 percent of its water from a saline zone, as shown by elevated ion concentrations and a quantitative mixing model. Upper Spring obtained some of its water from an isolated subbasin in the aquifer, as indicated by radiogenic ⁸⁷Sr/⁸⁶Sr values measured in this subbasin. Oxygen and hydrogen isotope values indicated that ground water was well-mixed over year or longer timescales. Oxygen isotope samples collected from the springs following a rainfall event showed how stormflow recharge flows to the springs. A hydrograph separation using showed an immediate increase in spring discharge following rainfall but a 12-hour delay before storm water reached the spring. This suggested an advancing front of storm water that expelled pre-storm water from the karst conduits. Discharge of pre-storm ground water was reduced by up to 44 percent after rainfall, suggesting that stormflow pressurized the karst conduit system and reduced gradients between the aquifer matrix and conduits. Specific conductance was also an effective and inexpensive tracer of stormflow, on the basis of its strong correlation (r²=0.96) to oxygen isotope values. Resource managers and scientists may be interested in these findings, as the potential for contamination of this spring system is increased after large rainfall eventsItem Geology and Hydrology of the Northern Segment of the Edwards Aquifer with An Emphasis on the Recharge Zone in the Geogetown, Texas, Area(1987) Kreitler, Charles W.; Senger, Rainer K.; Collins, Edward W.In March 1986, the Bureau of Economic Geology was contracted by the Texas Water Development Board to conduct geologic and hydrologic investigations of the northern segment of the Edwards aquifer along the Balcones Fault System in the Georgetown-Round Rock area, particularly to elucidate the processes and areas of recharge for the Edwards in the Georgetown area. Geological mapping, combined with analysis of fractures in Comanche Peak, Edwards, and Georgetown limestones (Edwards aquifer strata) in the vicinity of Georgetown and Round Rock, Texas, was conducted to provide data useful in identifying potential recharge areas, assessing local groundwater flow, and enhancing our understanding of the geology of the Balcones Fault Zone. Cretaceous Comanche Peak, Edwards, Georgetown, Del Rio, Buda, Eagle Ford, and Austin strata dip gently (1°) eastward and are overlain in some places by terrace deposits and alluvium. Several major normal faults, downthrown to the east, strike northward across the area. Gentle flexures, possibly related to faulting, parallel the faults. Minor normal faults and joints are most abundant in areas adjacent to major faults and flexures. These fractured-strata zones likely parallel the length of the faults or flexure axes and may be as wide as 1.6 km. Most minor faults strike between 340°-040°, have displacements less than 2 m, and dip from 40°-80° both eastward and westward. Most joints strike between 340°-020° and 260°-300°, and fracture densities range from 4 joints per meter to 1 joint per 5 meters in 1 to 2-meter-thick beds.Item Groundwater flow and recharge within the Barton Springs segment of the Edwards Aquifer, southern Travis and northern Hays Counties, Texas(2009-05) Hauwert, Nico Mark; Sharp, John Malcolm, 1944-The Barton Springs Segment, part of the karstic Edwards aquifer in Central Texas, is a Sole Source aquifer, is habitat to rare karst species, and provides water to a well-loved municipal swimming pool, yet its hydrogeologic properties remain insufficiently understood. For this study, the hydrogeologic characteristics of the Barton Springs Segment were investigated using several approaches, including mapping of hydrostratigraphic units and faults, measurement of upland infiltration, groundwater traces, and aquifer tests. The depositional environment, diagenesis, fracturing, down-dropped and dipping faulted blocks, and subsequent dissolution were determined to play important roles in controlling groundwater flow-path development within the Barton Springs Segment. In particular, downdropped fault blocks create groundwater gradients to the southeast that influence flow in the Edwards outcrop area. Upland internal drainage basins were found to be extremely efficient at conveying recharge to the underlying aquifer. The maturity of natural internal drainage sinkholes can be measured by its bowl volume, which grows in proportion to the catchment area it captures. A 19-hectare internal drainage basin, HQ Flat sinkhole, was monitored for rainfall, evapotranspiration, soil moisture, and discrete runoff to the cave drain. During a 505-day period, 5.5% of measured rainfall entered the cave drain as discrete recharge, 26% of measured rainfall infiltrated through soils on the slopes, and the remaining 68% was lost through evapotranspiration. This amount of upland infiltration is consistent with infiltration measurements in other karst areas and is much larger than the 1% upland recharge of rainfall that was previously estimated. A chloride mass balance indicates that at the adjacent Tabor research site, about 50% of rainfall infiltrates to a 6-meter depth. Dye-tracing and pump tests demonstrated that primary and secondary groundwater flow paths are the major influence on transmissivity within the Barton Springs Segment. Groundwater tracing breakthroughs reveal very high advection and relatively low dispersion. Drawdown response to pump tests indicates a very high degree of anisotropy, controlled by location of groundwater flow paths. Overall the Barton Springs Segment is a mature karst aquifer with highly developed rapid, discrete network for both recharge and groundwater-flow.Item Hydrochemical facies in the badwater zone of the Edwards Aquifer, central Texas(1989) Clement, Tonia Judith, 1944-; Sharp, John Malcolm, Jr., 1944-The Cretaceous Edwards and Georgetown Formations and their stratigraphic equivalents form two extensive carbonate aquifers in central Texas. These faulted, cavernous, and highly transmissive formations are the sole source of water for many communities, including the City of San Antonio. At the badwater line, which delineates a hydrogeologic boundary from 1 to 21mi (2-34km) south and east of the outcrop, the total dissolved solids concentration of the groundwater changes abruptly from less than 500 mg/l to over 1000 mg/l. Although the boundary is relatively stable, some water from the badwater zone migrates updip toward major springs and well fields. Unlike the water in the freshwater zone which is predominantly Ca-HCO₃, the chemistry of the badwater zone changes along the strike of the aquifer. From west to east, the first hydrochemical facies is Ca-SO₄ with a low chloride concentration. Faulting is minimal, and chlorides previously trapped in the pores or adsorbed by the carbonates have been flushed. This facies is produced by the dissolution of anhydrite in the badwater zone. As the potentiometric surface declines and the intensity of faulting increases to the east, sodium and chloride concentrations also rise. The hydrochemical facies changes first to Ca-Mg-SO₄ with high sodium and chloride concentrations and then, in the area of maximum faulting, to Na-Cl with calcium, magnesium, and sulfate subordinate. Using PHREEQE computer modeling, the second facies can be simulated by mixing fresh water with a Na-Ca-Cl oilfield brine and saturating it to specific states with calcite, dolomite, and gypsum. The origin of the Na-Cl facies with Na/Cl molar ratios close to one is still problematical. The fourth hydrochemical facies borders the northern segment of the aquifer and is predominately a Na-Cl-SO₄-HCO₃ water, the anions being approximately coequal in milliequivalents per liter. This last facies is almost identical to groundwaters in the underlying Trinity Group which probably have provided some recharge to the aquifer. Leakage from the Trinity Group or updip migration of bad water also may affect the quality of fresh water in this areaItem The hydrologic function of small sinkholes in the Edwards Aquifer recharge zone(2005) Lindley, Adrien Lewis; Sharp, John Malcolm, Jr., 1944-Thin soils on Cretaceous karst bedrock typify the Edwards aquifer recharge zone in central and south Texas U.S.A. Most of the recharge occurs in major streambeds in this region, but abundant evidence of active karstic dissolution suggests that some of the recharge is occurring in the uplands. The City of San Antonio uses the karstic Edwards aquifer as its main municipal water source, and is undergoing rapid development in the uplands of the aquifer recharge zone. What is the risk to water quality of development over typical small-scale yet abundant upland karst features? This project is designed to determine more precisely what constitutes a significant recharge feature in the context of state law by directly measuring infiltration rates of typical upland karst features. The hydrologic function of the soil and bedrock system in small sinkholes, identified by their morphological characteristics, and background areas is determined by large-scale constant head infiltration tests, microtopographic and soil thickness surveys, dye tracing and subsequent excavation of features, and imaging the subsurface with GPR. Measurements made with a large-scale single ring infiltrometer compare typical upland karst features to paired control plots. The average infiltration per unit head for sinkholes is slightly higher than background in areas with similar soils (0.30 1/hr for sinkholes and 0.27 1/hr for background), though both are within the range for local soils. Results from infiltrometer experiments indicate the thin clay soils typical in the uplands dominates the infiltration process, yet recharge via these features under natural conditions is greater than background when ponding occurs due to their maintained microtopography. As the thin soils typical in the uplands of the Edwards aquifer recharge zone dominate the infiltration process in these small sinkholes, as shown by ring infiltrometer experiments, the risk of recharging poor quality water via these small features from developed areas sufficient to pose a threat to aquifer water quality is little greater than backgroundItem Impacto ambiental en la franja fronteriza ante la apertura del confinamiento de desechos tóxicos peligrosos en Spofford, Texas(El Colegio de la Frontera Norte, Piedras Negras, Coahuila, Mexico, 1996-12) Rodríquez Martínez, Juan ManuelEn este trabajo se reune y se presenta información geológica, climatológica y geohidrológica de la cuenca de Maverick de cuyo análisis se concluye lo siguiente: Tomando en cuenta que la dirección de los vientos denominantes en invierno es del norte, existe el riesgo de polución de partículas radiactivas hacia las ciudades de Eagle Pass, Piedras Negras y la región de los cinco manantiales. La presencia de fallas y fracturas en el subsuelo vinculadas al sistema Luling son posibles medios de conducción y contaminación de los acuíferos presentes en la cuenca de Maverick (conglomerado Sabinas Reynosa y Edwards) así como la cuenca geohidrológica del Río Bravo. Por los lixiviados de los depósitos tóxicos y radiactivos que empresas americanas pretenden construir en el poblado de Spofford, Texas, en el Condado de Kinney, existe la posibilidad que suelos y aguas subterráneas en territorio mexicano puedan ser contaminadas por los lixiviados de estos confinamientos, pues ambos países comparten una misma cuenca geohidrológica.Item New methods for quantifying and modeling estimates of anthropogenic and natural recharge : a case study for the Barton Springs segment of the Edwards Aquifer, Austin, Texas(2011-05) Passarello, Michael Charles; Pierce, Suzanne Alise, 1969-; Sharp, John Malcolm, 1944-; Cardenas, Bayani R.Increased population and recent droughts in 1996 and 2009 for the Barton Springs segment of the Edwards Aquifer have focused attention on groundwater resources and sustainability of spring flow. These springs serve as a local iconic cultural center as well as the natural habitat for the endangered Barton Springs salamander. In response to the potential compromise of these vulnerable groundwater resources, a two-dimensional, numerical groundwater-flow model was developed for the Barton Springs / Edwards Aquifer Conservation District and other governmental entities to aid in aquifer management. The objective of this study is to develop new methods of quantifying and distributing recharge for this model. The motivation for conducting this study includes the following: recent availability of more extensive data sets, new conceptual models of the aquifer system, and the desire to incorporate estimates of urban recharge. Estimates of recharge quantities and distributions for natural and artificial sources were implemented within this model to simulate discharge at Barton Springs and water-level elevations from January, 1999 to December, 2009. Results indicate that the new methods employed generated good agreement amongst simulated and observed discharge and water-level elevations (Root mean square error of 0.5 m3 sec-1 and 10.5 m, respectively). Additionally, these recharge calculations are decoupled from Barton Springs discharge which eliminates the circular logic inherent with the previous methodology. Anthropogenic, or artificial, recharge accounts for 4% of the total recharge between January, 1999 and December, 2009. Using observed data to quantify contributions from leaky utility lines and irrigation return flows, recharge estimates were completed with spatial and temporal resolution. Analyses revealed that on a month by month basis, anthropogenic contributions can vary from <1 to 59% of the total recharge. During peak anthropogenic recharge intervals, irrigation return flow is the most significant contributor. However, leakage from utility lines provides more total recharge during the study period. Recharge contributions from artificial sources are comparable to the mid-size watershed contributions over the ten-year analysis period. Urban recharge can be a critical source for buffering seasonal fluctuations, particularly during low flow periods. Outcomes are relevant for habitat conservation, drought response planning, and urban groundwater management.Item A new phase in water resource allocation : the case for groundwater markets in Texas(2013-05) Avioli, Lauren Faye; Oden, MichaelThis report explores the application of a market framework to allocating water resources, with a specific focus on groundwater resources in Texas. Water markets have been touted by economists as an efficient and effective means of reallocating a scarce natural resource and have been implemented in various forms across the western United States. This report discusses the characteristics of water markets that allow them to efficiently allocate water resources as well as the need for institutional oversight to address negative externalities, including environmental and third party impacts. A description of Texas law and regulation of groundwater resources is also given and analyzed in the context of establishing widespread groundwater markets in the state. Several case studies, both in Texas and in other western states, are also analyzed to determine best practices for the creation of a statewide system of groundwater marketing. The report concludes with several recommendations based on these case study analyses and in light of the current legal and regulatory obstacles to widespread water markets in Texas.Item Predictions of Groundwater Levels and Spring Flow in Response to Future Pumpage and Potential Future Droughts in the Barton Springs Segment of the Edwards Aquifer(2000) Scanlon, Bridget R.; Mace, Robert E. (Robert Earl), 1967-; Dutton, Alan R.A two-dimensional numerical groundwater-flow model was developed for the Barton Springs segment of the Edwards aquifer to evaluate groundwater availability and predict water levels and spring flow in response to increased pumpage and droughts from 2000 through 2050. A steady-state model was developed on the basis of average recharge for a 20-yr period (1979 through 1998) and pumpage values for 1989. Hydraulic conductivity zones (10) were adjusted to obtain good agreement between measured and simulated hydraulic heads. Zones of hydraulic conductivity ranged from 1 to 1,000 ft/d. We conducted transient simulations using recharge and pumping data for a 10-yr period from 1989 through 1998 that includes periods of low and high water levels. Good agreement was found between measured and simulated flow at Barton Springs (root mean square error [RMSE, average of squared differences in measured and simulated discharges] 17 cfs) and between measured and simulated water levels in many of the monitoring wells (mean RMSE 40 ft). The simulation results overestimate spring discharge by about 10 cfs during low flow periods. To assess the impact of future pumping and potential future droughts on groundwater availability, we conducted transient simulations using extrapolated pumpage for a 10-yr period (2041 through 2050) and using average recharge for a 3-yr period and recharge from the 1950s drought for the remaining 7 yr. Results for this scenario predict that flow in Barton Springs will become very low ( 4 cfs) toward the end of the drought. Because of the bias in the simulation results, the combination of drought and future pumpage could result in no discharge at Barton Springs. Additional scenarios were simulated that included current pumpage and no pumpage. These simulations indicate that with current pumpage, spring discharge will decrease to levels similar to those calculated for the end of the 1950s drought (11 cfs). No pumpage resulted in discharges as low as 17 cfs. Actual flows, which may be about 7 cfs because of the bias in the simulation results, indicate that drought conditions similar to those of the 1950s will require no pumpage if spring discharges similar to those of the 1950s are to be maintained.Item Presentation: The Edwards Aquifer: Will There Be Water For Texas?(2002-10-18) Environmental Science Institute; Sharp, JohnItem Report of Investigations No. 141 Hydrogeology of the Edwards Aquifer, Austin Area, Central Texas(University of Texas at Austin. Bureau of Economic Geology, 1984) Senger, Rainer K.; Kreiter, Charles W.The Edwards Formation, on the downthrown side of Mt. Bonnell fault in the Austin, Texas, area (Hays and Travis Counties), is part of the northeastern extension of the Edwards Underground Reservoir, the primary source of water in numerous counties along the Balcones Fault Zone. Recharge to the aquifer is supplied mainly by creeks that cross the Balcones Fault Zone southwest of Austin. Barton Springs is the major point of discharge. Changes in water levels of wells in the area correlate positively with changes in discharge at Barton Springs, suggesting good interconnection. The potentiometric surface of the aquifer changes significantly from high flow to low flow at Barton Springs. During low-flow conditions, ground-water flow lines converge in the eastern part of the Balcones Fault Zone. Water Ievels are also much lower (less than 30 m) and indicate flow from the "bad-water zone (water with 1,000 mg/L TDS or more from downdip in the Edwards Formation).Water chemistry at Barton Springs also varies between high and low discharge. Concentrations of sodium, chlorine, sulfate, and strontium increase with decreasing discharge, indicating influx from the "bad-water" zone. This influx of highly saturated "bad-water into the fresh-water aquifer theoretically results in a decrease in saturation state with respect to calcite and dolomite. The decrease in saturation state would enhance carbonate dissolution at the interface between fresh water and "bad-water" zones, thereby increasing permeabilities in this section of the aquifer. The Edwards aquifer generally contains a consistent calcium bicarbonate water. In some areas of the fresh-water section, however, leakage from the Glen Rose Formation increases the sulfate and strontium concentrations. Leakage occurs across fronts created by large displacements of faults that bring the Edwards Formation into contact with the Glen Rose Formation updip.Item Storage dynamics of the upper Nueces River alluvial aquifer: Implications for recharge to the Edwards Aquifer, Texas(2019-09-26) Hackett, Caroline Croft; Rempe, Daniella M.; Gary, Marcus OThe karstic Edwards Aquifer is a crucial water resource in south-central Texas, serving as the primary water source for over two million people in the greater San Antonio area. The Nueces River basin is the largest contributor of recharge to the Edwards Aquifer, and recharge has traditionally been measured as the difference between river discharge at the upstream and downstream ends of the Edwards Group outcrop (Edwards Aquifer Recharge Zone, EARZ). This study investigated the extent to which groundwater in alluvial terraces and younger, near-channel alluvium deposits impact the timing and magnitude of recharge from the Nueces basin. Estimates of alluvial storage derived from geologic maps and sparse groundwater data suggest that over 21,000 acre-feet (25.9 x 106 m3) of groundwater are stored in the upper Nueces River alluvial aquifer, with an estimated maximum capacity of over 75,000 acre-ft (92.5 x 106 m3). However, the dynamics of alluvial bank storage and drainage from the alluvial aquifer and their impacts on downstream recharge are unknown. In this study, river water storage and transport in alluvium were investigated using differential gaging, dye tracer testing, baseflow recession analyses, and floodplain groundwater mass balances. Field investigations were made at a gaged, alluvium-lined reach of the Nueces River where the river partially supplies a major tributary that maintained baseflow during the 2011 drought (whereas river flow ceased). Significant streamflow losses in the study area are largely the result of storage in high conductivity gravels adjacent to the channel, with some recharge to the alluvial aquifer and discrete recharge into bedrock. The baseflow contribution from the upper Nueces River alluvial aquifer contributes up to 100% of river flow during low flow conditions in the basin. The magnitude and shape of baseflow recession is dynamic between the growing and dormant seasons. These findings have implications for groundwater pumping from the upper Nueces River basin alluvial aquifer and the management of recharge to the Edwards Aquifer.Item Supplementary animation & Data for: Satan’s skeleton revealed: a tomographic and comparative osteology of Satan eurystomus, the subterranean Widemouth Blindcat (Siluriformes, Ictaluridae). Proceedings of the Academy of Natural Sciences of Philadelphia 165: 117-173(Proceedings of the Academy of Natural Sciences of Philadelphia, 2017) Lundberg, John G.; Hendrickson, Dean A.; Luckenbill, Kyle R.; Arce H., MariangelesThe Widemouth Blindcat, Satan eurystomus Hubbs and Bailey 1947, was the second of four stygobitic species of Ictaluridae discovered in the subterranean waters of southern Texas and northeastern Mexico. The skeletal anatomy of Satan has been scarcely known from a few, dated radiographs. Using additional radiographs and high resolution CT-datasets for two well-ossified specimens, we applied high-resolution X-ray computed tomography (HRXCT) to visualize, illustrate and describe the bony skeleton of Satan. We also provide an online archive of still and animated tomographic images of the skeletal anatomy of this little-known species. The skeleton and soft anatomy of Satan are distinctive. Twelve skeletal autapomorphies are described that singularly distinguish Satan within Ictaluridae and, probably in combination, from all other catfishes. Some of these are reductive losses or simplifications of skull bones (e.g. loss of one infraorbital bone; reduced ornamentation of the pterotic bone) and joint complexity (e.g. simple overlapping frontal-lateral ethmoid articulation; loosely ligamentous interopercle-posterior ceratohyal joint). Some of the autapomorphies are anatomically and perhaps developmentally complex (e.g. a novel series of three midline joints closing a middle span of the posterior cranial fontanel; a deeply excavated temporal fossa and an unusually enlarged interhyal bone). The tiny dorsal-fin spinelet (first lepidotrich) of Satan has a novel peaked and twisted shape. Ten apparent and exclusive synapomorphies within Ictaluridae gathered from this and previous studies suggest that Satan and Pylodictis are closest relatives. Most of these are functionally related to prey detection and suction feeding: fusion of the symphyseal mandibular sensory pores and increase in the number of preoperculo-mandibular canal pores; depressed, flattened heads and wide transverse mouths; prominent posterior process of the lateral ethmoid alongside and below the frontal bone margin; vertical and blade-like supraoccipital posterior process; unique arrangement of the parasagittal and occipital muscle-attachment crests on the skull roof; large triangular panel of integument within the operculum framed by the opercle, preopercle and interopercle bones; elongated posterior ceratohyal; and, form of the fourth supraneural and loss of its anterior nuchal plate. In contrast, fifteen synapomorphies recovered by Arce-H. et al. 2016, are confirmed suggesting that Satan is one of the four stygobitic ictalurids comprising a “Troglobites” subclade within the family: (Trogloglanis, Satan, Prietella phreatophila, P. lundbergi). These features include three stygomorphic and reduction apomorphies that are exclusive within Ictaluridae: loss of fully developed eyes and pigmentation, and simplification of the fifth vertebra and its joint with the Weberian apparatus. Twelve other synapomorphies shown by the Troglobites are also apparent homoplasies of character states shared with various other ictalurids. These include reductive characters such as shortened lateral line canal, reduced infraorbitals and underdeveloped or incomplete ossifications of the pterotic, supraoccipital, hyoid arch bones and transcapular ligament. Also, the Troglobites and various other ictalurids have: an adnate adipose-caudal fin, foreshortened anterior cranial fontanelle, reduced ventral wings of the frontal bone, replacement of bone by cartilage in hypohyal joints; incompletely ossified transcapular ligament, and consolidation of some hypural bones. Completing a full morphological character dataset across the Troglobites has been impeded by incomplete specimen preparations and study of P. lundbergi and to a lesser extent, P. phreatophila and Trogloglanis.Item Surface water recharge in karst : Edwards-Trinity Aquifers-Nueces River system(2015-05) Kromann, Jenna; Sharp, John Malcolm, Jr., 1944; Gary, Marcus O.; Johnson, Joel PThe karstic Edwards Aquifer is a primary source of water in south-central Texas for domestic, agriculture, and industrial uses. Significant recharge into the aquifer occurs as surface water streams, including the Nueces River, cross the Recharge Zone (RZ). Recharge models use data from two stream gauges, located above and below the RZ. These gauges are used to compute recharge into the aquifer; this may underestimate recharge volume because the actual water balance is complex. Synoptic gain/loss studies show that: flow rates change significantly as the river passes through extensive unconsolidated alluvium, gain/loss in reaches varies temporally, and recharge may be occurring in the Contributing Zone (CZ). From these synoptic studies, a 10-km reach of the Nueces River near Montell, TX, was identified that loses 100% of flow over the CZ during low stream flows. In this study reach, Candelaria Creek runs parallel to the dry segment of the Nueces River for 2.5 km; the creek contributes 52-64% of flow measured at the USGS recharge index gauge. The main sources of flow to the creek are two springs, hypothesized as possibly being sourced from: underflow from the Nueces River, a combination of Trinity Aquifer groundwater and river underflow, or solely groundwater from the Trinity Aquifer. To investigate recharge in the CZ and the source water for springs that contribute flow to Candelaria Creek, a variety of methods were used including: hydrograph and gain/loss analyses, potential evapotranspiration calculations, and interpretation of specific conductance, temperature, chemical, isotopic, and near surface geophysical data. The data suggest that the springs are likely sourced from both Nueces River underflow and Trinity Aquifer groundwater. Defining the source of the springs that contribute to Candelaria Creek is important to understand the complex water balance in the Nueces River and the role of underflow/storage in this system. It was found that underflow was a significant source of spring flow, but could not account for the total amount of spring flow; this suggests the Trinity Aquifer also contributes flow to the springs. A water balance estimates that recharge in the CZ at 6,213,048-9,814,814 m3 per year, which is between 0.9 to 2% of total recharge to the Edwards Aquifer and 4 to 11% of Nueces Basin recharge may be unaccounted for over the CZ during low hydrologic flow conditions. This water balance suggests that there is significant recharge occurring over the CZ and some recharge may be unaccounted for based on the current method used to calculate recharge.Item The Future Of Water In San Antonio: An Evaluation Of Ways To Meet Demand By 2070(2019-05-01) Hudock, Mathias; Lieberknecht, KatherineAs climate change progresses, the city of San Antonio, Texas is likely to face increasing stress on its water supplies. While the city’s water utility, the San Antonio Water System, has planned several projects to bolster the city’s supplies, these are unlikely to be enough in the face of San Antonio’s growing population and the future reduction of the Edwards Aquifer’s recharge. As such, this article evaluates three additional options for meeting San Antonio’s projected 2070 water demand according to their cost-efficiency, additional benefits and drawbacks, and likeliness of gaining public acceptance. Making San Antonio’s drought-period water restrictions permanent would only satisfy a fraction of the future water deficit, while either city-wide rainwater harvesting or a new reservoir project would more than compensate for the deficit. A reservoir project would be a far more cost- efficient option, while city-wide rainwater harvesting would provide flood mitigation, avoid disrupting riparian habitat, and would be more likely to be accepted by the residents of San Antonio, particularly in light of the earlier failed Applewhite Dam and Reservoir Project. As such, city-wide rainwater harvesting was evaluated as the most viable option, with a reservoir still being possible if San Antonio’s leaders could successfully convince the public of its utility.Item Theory-guided data science : combining machine learning with domain expertise to predict springflow(2020-05-06) Pease, Emily Camille; Pierce, Suzanne Alise, 1969-Traditionally, science follows a theory-based approach through which physical equations are used to model natural phenomena. In this recent era of artificial intelligence and "big data", there is a shift into a new paradigm of scientific discovery. The paradigm of theory-guided data science (TGDS) enables scientists to perform data science modeling while retaining their domain expertise to produce informed results consistent with the physical system. Predicting springflow discharge from Comal Springs using machine learning was determined to be an appropriate case study. The Edwards Aquifer in central Texas serves as the primary water supply for over 1.5 million Texans, providing water for recreational activities, businesses, and down-stream users. Additionally, these waters serve as a home to many aquatic species, eight of which are endangered or threatened. Quantifying springflow is essential in regulating groundwater resources in the Edwards Aquifer, especially during drought conditions. Here, a theory-guided predictive machine learning model for springflow estimation at Comal Springs is developed. First, feature engineering is performed to discover relations between data available in the Edwards Aquifer region, selected through theory-guided parameter initialization. Next, multiple machine learning models were explored and tested in their ability to model a complex springs system. Finally, theory-guided refinement of data science outputs was performed to make the model results consistent with what is possible in nature.