Brad D. WolaverLiterature Review1-December, 2005 Dr. Yang – Physical ClimatologyGROUNDWATER RECHARGE THE TEXAS-MEXICO BORDER REGION ANDASSOCIATED REGIONAL GROUNDWATER FLOW SYSTEMSABSTRACTPopulation growth in the United States (U.S.) and Mexico is focused in the aridsouthwest. One such region is the Texas-Mexico border region. However, groundwater resourceextraction to meet human water needs often exacts deleterious environmental consequences, suchas spring flow reduction or groundwater capture of surface water bodies. In the arid basins of thisstudy, the evaluation of groundwater recharge to regional flow systems is critical forunderstanding groundwater resource extraction sustainability. As the climate has experienced ageneral drying trend in the southwest U.S. and northeastern Mexico since the Pleistocene Epoch,current recharge to these regional groundwater flow systems may be much less than historicvalues. Thus, prior to the initiation of groundwater development projects in the arid portions ofTexas and Mexico, it is critical to ascertain the extent of regional groundwater systems. This Literature Review will integrate the findings of three papers dealing withgroundwater flow systems of the arid Texas-Mexico border region. In particular, one flow systemfrom will be described from recharge area (Ryan, Lobo, Southeast Eagle, and Wildhorse Flats) todischarge location (San Solomon Springs). While the Texas-Mexico border region is thegeographic focus of this report, aquifers of this region are analogous to the less-studied aquifersin neighboring regions. In fact, my Ph.D. research focuses on understanding regionalgroundwater flow in northeastern Mexico, an area with similar groundwater resourcemanagement challenges and future research will present a novel method of delineating regionsgroundwater systems from recharge source to discharge area.The University of Texas at Austin Jackson School of Geosciences1Brad D. WolaverLiterature Review1-December, 2005 Dr. Yang – Physical Climatology1.0 PROBLEM STATEMENTThe Texas-Mexico border region is a locus for population growth in an arid climate. Infact, average precipitation in El Paso is approximately 22 cm/yr (or approximately 9 in/yr,BBC, 2005). As surface water resources are limited, population centers often exploitgroundwater resources to satisfy unmet need. Unfortunately, unsustainable groundwater resourcedevelopment often exerts undesirable environmental consequences, such as occurred atComanche Springs of Ft. Stockton, Texas, where surrounding groundwater irrigation projectsintercepted groundwater flow from the spring’s recharge area and caused the spring to dry upwithin 20 years of the initiation of pumping, drying a 2,500-hectare irrigation district whichrelied on spring discharge and eliminating the only habitat for the Comanche Springs pupfish(Brune, 2002). Further up the Rio Grande, water resource managers in the Middle Rio Grandebasin of New Mexico fear that unbridled groundwater extraction for municipal uses inAlbuquerque will capture Rio Grande surface flow and jeopardize the State’s mandated waterdeliveries to downstream Texas water users (Tidwell, 2005), a situation that western Texas mayalso face in the future without aggressive groundwater resource management.2.0 SOLUTION: AQUIFER MANAGEMENTThus, in order to balance economic growth with preservation of groundwater-dependentecosystems, it is critical to actively manage groundwater resources. Tantamount to this goal isthe delineation of regional groundwater flow systems in arid regions such as the Texas-Mexicoborder. The goal of this Literature Review is to present an integrated assessment ofhydrogeologic methods used to delineate groundwater flow systems from recharge to dischargein a selected series of aquifers along the Texas-Mexico border region.The University of Texas at Austin Jackson School of Geosciences2Brad D. WolaverLiterature Review1-December, 2005 Dr. Yang – Physical Climatology3.0 GROUNDWATER RESOURCES ON THE TEXAS-MEXICO BORDERThe following section will discuss the results of several studies that have delineatedregional groundwater flow systems along the Texas-Mexico border. Regional aquifers on thenorthern portion of the Texas-Mexico border have been well characterized by EPA andNSF-funded hydrogeologic investigations and include Hibbs and Darling’s (2005)characterization of basin-fill (alluvial) aquifers and of west Texas and Northern Chihuahua basedon hydrogeologic techniques developed in analogous aquifers of the Great Basin of Nevada.Further to the east, Uliana and Sharp (2001) traced regional groundwater flow paths usinggeochemistry and isotopic analyses from dozens of wells. One of the first works that assessed thehydrogeology of the westernmost portion of Texas is Gates and others, 1980.3.1 Groundwater of Westernmost TexasThe following section discusses Gates and others’ (1980) evaluation of the fresh andslightly saline groundwater resources of westernmost Texas (Figure 1). This work delineates thegroundwater resources of westernmost Texas to determine sustainable production levels in orderto satisfy growing demands in spite of groundwater head declines of as much as 95 feet in theEl Paso vicinity from 1903-1976 and approximately 150 feet in Lobo Flat for irrigation (south ofthe City of Van Horn).3.1.1 BackgroundIn order to assess available groundwater resources in westernmost Texas, the study isaccomplished in three phases. Phase 1 pertains to the collection of hydrogeologic data, includingan inventory of wells, springs, groundwater levels, and groundwater quality. Phase 2 conducts aThe University of Texas at Austin Jackson School of Geosciences3Brad D. WolaverLiterature Review1-December, 2005 Dr. Yang – Physical Climatologyseries of geophysical surveys, the primary being earth resistivity to determine the thickness ofalluvial basin fill and groundwater quality. Airborne electromagnetic, seismic refraction, andaeromagnetic surveys were also conducted to supplement the surface resistivity survey. Phase 3conducts exploratory borehole drilling (total borehole depths between 1,100 and 2,000
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