The Edwards aquifer lies in the structurally complex Balcones fault zone and supplies water to the growing city of San Antonio. To ensure that future demands for water are met, the hydrological and geophysical properties of the aquifer must be well-understood. Fractures often occur in a power-law distribution. Fracture distribution plays an important role in determining electrical and hydraulic current flowpaths. The thesis research presents an evaluation of the controlled-source electromagnetic (CSEM) response for layered models with a fractured layer at depth described by the roughness parameter, BV, such that 0</=BV, associated with the power-law length-scale dependence of electrical conductivity. A value of BV=0 represents homogeneous, continuous media, while a value of 0<BV shows that roughness exists. 1-D synthetic modeling shows that the existence of a fractured layer at depth is apparent in the CSEM time-domain response for models representing aquifers. The research also provides an analysis of the Seco Creek frequency-domain helicopter electromagnetic survey data set by introducing the similarly defined roughness parameter BH to detect lateral roughness along survey lines. Fourier transforming the apparent resistivity as a function of position along flight line into wavenumber domain using a 256-point sliding window gives the power spectral density (PSD) plot for each line. The value of ?H is the slope of the least squares regression for the PSD in each 256-point window. Changes in BH with distance along the flight line are plotted. Large values of BH are found near well-known large fractures and maps of BH produced by interpolating values of BH along survey lines suggest unmapped structure at depth.

This 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. / text

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 327-339). Available also in a digital version from Dissertation Abstracts.

Thesis (M.A.G.)--Texas State University-San Marcos, 2007. / Vita. Includes bibliographical references (leaves 53-55).

Thesis (M.A.G.)--Texas State University-San Marcos, 2007. / Vita. Includes bibliographical references (leaves 53-55).

Water auditing is an emerging method of increasing accountability for water utility systems. A water loss audit according to the methodology of the International Water Association (IWA) is applied to a major North American water utility, San Antonio Water System (SAWS), which is already a leader in conservation policies. However, some modifications to the auditing process are needed for this model’s application to a North American utility. These improvements to the IWA methodology include: calculating system input volume from multiple methods of measurements as well as numerous input points, incorporating deferred storage consumption (in this case aquifer storage and recovery) principles into the auditing process, calculating a volume of unavoidable annual real losses (allowable leakage) for a system with varied pressure zones, and defining procedures for assessing customer meter accuracy for a system. Application of the improved IWA audit method to SAWS discovered that its system input volume is being significantly undermeasured by current practices, current water loss control programs are very effective, customer accounting procedures result in large volumes of apparent loss, and current customer meter accuracy is adequate but could be marginally improved. Application of the audit process to the utility is beneficial because it facilitates increased communication between utility departments, assesses shortcomings in current policies, pin-points areas needing increased resources, and validates programs that are performing well.

Changes with land cover and land use are closely integrated with water and other ecological processes at the land surface. Nowhere is that more apparent than in the Edwards Aquifer region of southcentral Texas. The Edwards Aquifer contributing and recharge zones cover approximately 18,000 square kilometers in parts of 15 counties in Texas and includes San Antonio and Austin, the nation's eighth and nineteenth largest cities, respectively. Population growth within the counties that intersect the Edwards Aquifer contributing and recharge zones has taken place over the last two decades, with the logical translation being an expanded infrastructure. This implies that a greater amount of impervious surface coverage and other land cover changes have occurred. This work quantified the changes in land cover within the Edwards Aquifer contributing and recharge zones between the years 1986 and 2000. Increasing trends in impervious surface area and woodland growth were identified. Additionally, a new ArcView software tool was developed to process SSURGO soil data for use within the ArcView SWAT model. Hydrologic modeling for the Upper Sabinal River watershed, located within the Edwards Aquifer region, revealed that the high resolution SSURGO data produces different results when used in place of the existing STATSGO soils data. Finally, an index of urbanization was developed and evaluated to assist investigators in identifying potential areas of urbanization.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 123-132). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 401-431). Available also in a digital version from Dissertation Abstracts.

For thousands of years freshwater springs provided the foundations of human settlement in Texas, from Native Americans to Spanish missionaries to German immigrants. However, over the last generation in Texas – and across much of the United States and the rest of the world – water has become just another convenience of modern life, available at the turn of a handle or push of a button. But times are changing. In Texas a perfect storm is brewing as the population booms and water resources deplete, and many people believe water will soon overtake oil as the next big play in the state. Already there is a sustained effort by companies and investors to secure major water assets and rights. At the same time, almost paradoxically, Texans continue to overuse water for lush lawns, poorly suited agriculture, and overtaxed infrastructure without considering the long-term impacts of these habits. As recently as a generation ago, during the previous drought of record in Texas in the 1950s, most Texans either relied on rain for survival – for livestock or agriculture – or knew a family member that did. That connection to water has been all but lost over the last 50 years as reservoirs have brought reliable water supply to an increasingly urbanized population. Now flushing the toilet is as familiar as most people get with the water cycle. Sharlene Leurig, a young woman who is extremely passionate about water in both her professional and personal life, is both a throwback to a different Texas and a promising indicator of how Texans might come to grips with the new water future coming down the pipe. I follow Leurig on her quest to document springs across Texas while also meeting with veteran water experts who’ve spent their lives submerged in the issue. / text