Browsing by Subject "aquifer"

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A Parsimonious Model for Simulation of Flow and Transport in a Karst Aquifer
(University of Texas at Austin, 1996-11) Barrett, M.E.; Charbeneau, R.J.
Aquifer Model
(0000-00-00) Univeristy of Texas at Austin; Environmental Science Institute
Delineating controls on hydrologic variability and water geochemistry in central Texas
(2013-08) Wong, Corinne I; Banner, Jay L.
There is a strong concern about how water resources will be affected by future climate change. Investigation of how a hydrologic system might respond to climate change, however, requires a detailed understanding of the controls on and factors that might affect that system. The research presented in this dissertation focuses on improving the understanding of the Barton Springs segment of the Edwards aquifer in central Texas. The first three chapters of this dissertation present research investigating spatial and temporal controls on groundwater geochemistry. The fourth chapter focuses on characterizing and understanding the controls on long-term hydrologic variability by reconstructing past climate from a speleothem (cave mineral deposit) collected from a central Texas cave. On spatial scales, Edwards aquifer groundwater geochemistry is influenced by water-rock interaction (calcite and dolomite recrystallization, gypsum dissolution, and calcite precipitation) and mixing between fresh groundwater and saline groundwater. On temporal scales, variation in groundwater geochemistry is dictated by the extent to which fresh groundwater mixes with recharging stream water. The degree of mixing is sensitive to changes in climate conditions (i.e., more mixing under wetter conditions) and type of flow path (i.e., conduit or diffuse) that dominantly supplies a given site. The geochemistry of stream water, which provides the majority of recharge to the aquifer, is degrading over time and indirectly controlled by anthropogenic sources under both wet and dry conditions. Climate reconstructed from a speleothem suggests that central Texas moisture conditions were relatively constant from the mid to late Holocene (0 to 7 ka), except for an extended dry interval from 0.5 to 1.5 ka. Speleothem δ18O values spike during this dry interval, suggesting that decreases in Pacific-derived moisture or decreased tropical storm activity might have been coincident with the prolonged dry interval. This research has improved understanding of the natural variability of and controls on physical and geochemical components of hydrologic system in central Texas.
Development and Testing of a Model for Determining Optimal Pumping and Recharge of Large-Scale Aquifers
(University of Texas at Austin, 1985-10) Wanakule, N.; Mays, L.M.; Lasdon, L.S.
The Endangered Springflow Act: How the Endangered Species Act Influences Groundwater Law and Protects Springflow in Texas
(The Center for Global Energy, International Arbitration, and Environmental Law, 2015-01) Puig-Williams, Vanessa
Many springs in Texas are in danger of drying up as two contradictory forces – drought and development – collide. As groundwater from an aquifer is pumped for irrigation, municipal, or industrial use, the water level in the aquifer is lowered and the result is decreased flow from springs at the surface. The lack of recharge to the aquifer caused by drought exacerbates the decline in groundwater levels and diminished springflow. Reductions in springflow are problematic because springs sustain numerous creeks and rivers, especially during drought when surface runoff from rainfall is low. As springflow decreases, so does the flow of surface water, degrading aquatic habitats, threatening consumptive uses of water, interfering with recreational activities, and harming water quality. While the Texas State Water Plan indicates that water management strategies will focus on surface water in the future, reliance on groundwater supplies, including brackish sources, to support population growth, agriculture, and a booming oil and gas industry will continue.
Karst and groundwater in northeastern Coahuila: An Edwards Aquifer mirror
(International Union of Speleology, 2009) Sprouse, Peter
The northeastern corner of the Mexican state of Coahuila contains some of the most extensive limestone outcrops in the country, yet the karst and groundwater have seen relatively little investigation. The western (recharge) portion of the area contains ridge tops of Lower Cretaceous rocks over 1500 m in elevation, which slope down to the east and south to plunge underneath less karstic Upper Cretaceous outcrops. This represents a confined aquifer zone where wells can flow under artesian pressure. In this respect it resembles the Edwards Aquifer across the Rio Grande in Texas, with similar carbonate lithologies and karst components. Over 60 caves have been explored in the area, most since the year 2000. Upland portions of the recharge zone contain vertical caves that likely contribute to aquifer recharge, although numerous seep-spring caves in canyon walls disgorge some water prematurely. The canyons themselves are major rechargers, exemplified by El Abra, a horizontal stream cave that is the longest in Coahuila at 1841 m in length. In the lower part of the recharge zone close to the artesian zone, there are a number of caves which are estavelles. These have large funnel-shaped sinkhole entrances that slope down to pits, dropping up to 90 m to flowing streams. These normally take water, but during times of heavy rains in the recharge zone they can become springs.
Lubbock County Pilot Study for Development of a Hydrogeologic Geographic Information System (HGIS) to Support TNRCC Implemation of Risk Reduction Rules
(1997) Hovorka, Susan D.; Mace, Robert E. (Robert Earl), 1967-; Porterfield, Susanne
Regional hydrologic, geologic, soils, and cultural background information and data from 217 leaking petroleum storage tank (LPST) sites in Lubbock County, Texas, are used to construct an Arc/INFO Geographic Information System (GIS). The study evaluates the use of this technology to provide context information for new site evaluation and risk assessment as well as to evaluate the effectiveness of past site characterization, risk assessment, and remediation strategies. Methods and costs of producing the database in this pilot study are described. Several analyses of these data are presented as a demonstration of the uses of this tool. The heterogeneity within the unsaturated zone is characterized spatially and statistically. Hydrologic variables including water level and hydraulic conductivity from well tests are mapped. The effect of this observed variability on Risk-Based Corrective Action (RBCA) calculations is assessed. The evolution of contaminant plumes can be viewed, and relationships between plumes and water-supply wells quantified. This pilot study demonstrates an application of GIS technology to a moderate-size dataset of contaminated-site information. The demonstration is intended not only to provide information about the Lubbock County study area but also to serve as a prototype and feasibility study for the application of this technology to other large contaminated-site datasets, including LPST-site data in other major urban areas, other types of contaminated sites, and industry applications.
Management of The Edwards Aquifer: A Critical Assessment
(University of Texas at Austin, 1993-08) McKinney, D.C.; Watkins, D.W. Jr
Potential Impacts of Subsurface Hydrogen Storage on Groundwater
(2022-12-02) Callan, Madison
Predicting Response of An Aquifer System to Uranium Extraction Oakville Aquifer, Texas Coastal Plain
(1982) Galloway, William E.; Henry, Christopher D.; Smith, Gary E.
The initiation or expansion of uranium mining in the Texas Gulf Coastal Plain, utilizing both open-pit and in situ leach methods, raises concerns about the potential impact on groundwater within mineralized aquifers. Understanding the hydrodynamics, hydrochemical evolution, and matrix geochemistry of these aquifers is essential for implementing effective protection and restoration measures. To address these issues, the Oakville Sandstone, a significant Coastal Plain aquifer, was chosen as a natural laboratory. The Oakville Sandstone comprises deposits from several major fluvial systems. The geometry and composition of these facies, along with superimposed structures and topography, play crucial roles in determining groundwater flux, aquifer transmissivity, and regional hydrochemical evolution. Groundwater flux patterns, especially in the shallow portions suitable for mining, can be highly complex and influenced by various factors. Studying the interrelationships among hydrodynamics, hydrochemical evolution, and matrix geochemistry in the Oakville Sandstone will provide insights into the effectiveness of mining technology in coastal plain aquifer systems. This research will aid in developing strategies to mitigate potential impacts on groundwater quality and ensure sustainable uranium mining practices in the region.
Reclaimed Water System at Build Out
(City of Austin, 2011) City of Austin Water Utility
Upland Recharge in the Coahuilan Edwards Aquifer
(Geological Society of America, 2010) Sprouse, Peter
The northeastern corner of the Mexican state of Coahuila contains some of the most extensive limestone outcrops in the country, yet the karst and groundwater have seen relatively little investigation compared to other areas. The western (recharge) portion of the area contains ridge tops of Lower Cretaceous rocks over 1500 m in elevation, which slope down to the east and south to plunge underneath less karstic Upper Cretaceous outcrops. This represents a confined aquifer zone where wells can flow under artesian pressure. In this respect it resembles the Edwards Aquifer across the Rio Grande in Texas, with similar carbonate lithologies. Proportions of recharge between upland and drainage channel sources have been the subject of debate in the Texas portion of the Edwards. Recent karst investigations to the northwest of Muzquiz have shown that upland caves and sinkholes play a significant role in aquifer recharge. Three north-south trending anticlinal ridges have horizontally-bedded mesas extending off of their east sides. Much of the rainfall on these mesas enters recharge features and never makes it to surface drainages. Over 125 of these mesa recharge features have been identified thus far, resulting in 30 mapped caves. Five of these are among the ten deepest in the state, dropping rapidly in vertical shaft series up to 240 m deep. Loose silt plugs at the bottom of these shafts likely represent a nearby base level where flow deceleration causes sediment loads to drop. Eventual exploration past these plugs may reveal horizontal conduits leading onward to springs and the artesian zone of the Coahuilan Edwards Aquifer. In the lower part of the recharge zone close to the artesian zone, there are a number of caves which are estavelles. These have large funnel-shaped sinkhole entrances that slope down to pits, dropping up to 90 m to intersect flowing streams. These sinkholes normally take water, but during times of heavy rains in the recharge zone they can become springs. A number of large artesian springs occur to the east of the Sierra del Burro and the Sierra de Santa Rosa. These comprise a regionally important water source that is under increasing demand. The Coahuilan Edwards is home to the endangered Mexican Blindcat Prietella phreatophila, yet knowledge and regulation of aquifer conservation is lacking.
Water-Resource Development & Management in the Edwards Aquifer Region
(LBJ School of Public Affairs, 1972) Butcher, William S.; Hazleton, Jared E.; Moore, Walter L.; Redford, Emmette S.