Tuesday, October 14, 2008 : 4:00 p.m.

Induced Infiltration from the Rio Grande Replenishes the Hueco Bolson Aquifer – But Will It Last?

Barry Hibbs, Ph.D., California State University, Los Angeles, William R. Hutchison, Ph.D., El Paso Water Utilities, Christopher J. Eastoe, Ph.D., University of Arizona and Alfredo Granados, Ph.D., Universidad Autonoma de Cd. Juarez

Predevelopment groundwater flow (pre-1900's) in the Hueco Bolson aquifer was south from the northern edge of the bolson toward the international border with Mexico. Groundwater moved toward the Rio Grande alluvial valley, where it discharged to the overlying Rio Grande alluvium by cross-formational flow.  In the late 1800's, drillers found that the Hueco Bolson was a very prolific aquifer that provided good quality water.  Since then pumping has increased in both the United States and Mexico and has created two large cones of depression beneath El Paso and Juárez.  Pumping has created an artificial groundwater divide just north of the Rio Grande. 

 Groundwater withdrawals have increased from 40,000 acre-ft/year in the early 1950's to approximately 190,000 acre-ft/year in 2000. Natural recharge along mountain fronts is only an estimated 6,000 acre-ft/year. However, reversal of the hydraulic gradient because of heavy pumping in the Hueco Bolson has created a significant source of recharge from the Rio Grande and Rio Grande aquifer.  The Rio Grande aquifer is recharged along unlined reaches of the Rio Grande.  The Hueco Bolson aquifer, in turn, is recharged by cross-formational leakage from the Rio Grande and Rio Grande alluvium.  Model results presented in this study indicate the quantify of this induced leakage to the Hueco Bolson may exceed 50,000 acre-ft/year.  Tritium and carbon-14 analysis showed the depth of infiltration of river water to more than 500 ft beneath land surface. 

 This critical source of replenishment to the Hueco Bolson aquifer decreases the rate of mining of the aquifer, but drainage ditches and channels are now being lined and removed along this heavily developed corridor.  These changes in the surface flow system will likely curtail rates of groundwater leakage to the Hueco Bolson.  Such changes must be factored into water supply plans for the future.             

 

 

 

 

Barry Hibbs, Ph.D., California State University, Los Angeles Dr. Barry Hibbs is Professor of Hydrogeology at California State University, Los Angeles. His professional and research interests include watershed and wetlands hydrology, arid zone hydrology, hydrogeochemistry of trace elements, and modeling groundwater flow.


The NGWA International Conference on Nonrenewable Ground Water Resources — Sociotechnological Aspects of Nonrenewable Ground Water Resources: Half-Empty, Half-Full, Top-Down, Bottom-Up, and Some Paths Forward