Water Quality and Coupling Between Surface and Ground Water: West Texas, Southern New Mexico, and Northern Chihuahua

1. Purpose and Objectives: The basic societal problem of living in desert regions is an adequate supply of fresh water. The El Paso / Juárez metropolitan region and surrounding agricultural lands obtain their water from the Rio Grande and from intermontane-basin aquifers (Hueco and Mesilla Bolsons). In the deep aquifers groundwater usage greatly exceeds recharge levels and the water use constitutes mining; however the shallow groundwaters are in close communication with the Rio Grande, irrigation canals, and irrigation drains. The major problem with the surface and shallow groundwaters is water quality in the form of salinity. Repeated water reuse for irrigation and municipalities along the Rio Grande leads to a buildup of salinity to the point where river waters and irrigation return flows frequently exceed federal drinking water standards for total dissolved solids. They propose to apply a sophisticated computer model considering saturated flow, unsaturated flow, dissolved species transport, and heat transfer to several cross sections along the Rio Grande near and across the US/Mexico border. The city will use that data when considering policy concerning water. Once the computer provides data, the water will then be desalinized for use.

2. Funding: $70,000 for entire project (approximately).

3. Partners: Southwest Center for Environmental Research and Policy (SCERP), University of Texas at El Paso (UTEP).

4. Description: The brackish surface and shallow groundwater serves as a source of recharge for deeper aquifers leading to declines in deeper groundwater quality over time. In order to better manage this limited resource we must understand a) how water use decisions (e.g., lining of irrigation canals) relate to changes in water level and salinity in shallow groundwaters and b) the chemical and physical coupling between the shallow and deeper, partially confined groundwater layers. This study will allow for a better understanding of these questions.

5. Methodology: Reverse Osmosis. A membrane will be applied to the brackish water. As the water passes through the membrane, the salt will be extracted and removed from the groundwater. Therefore, the membrane will serve as a filtering mechanism, hence cleaning the brackish, groundwater.

6. Results: The results of this study have not been reported and thus are unavailable.

7. U.S. Contacts: John Walton, UTEP Civil Eng. Dept., (915) 747-5057 E-mail: jwalton@cs.utep.edu