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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 52 (2002), Pages 122-122

ABSTRACT: Groundwater Flow Modeling to Estimate Fresh and Brackish Previous HitWaterNext Hit Previous HitAvailabilityNext Hit in the Lower Rio Grande Valley, South Texas

Chowdhury, Ali H. Mace, Robert E.

ABSTRACT

The Texas Previous HitWaterNext Hit Development Board is constructing a 3-D finite-difference groundwater flow model for the Gulf Coast aquifer in South Texas using MODFLOW and MT3D codes to assess the Previous HitavailabilityNext Hit of fresh and brackish Previous HitwaterNext Hit. The Chicot, Evangeline, and Jasper aquifers and the Burkeville Confining System comprise the four layers of the model. All four layers in the model thicken considerably (total thickness of up to 12,000 feet) downdip towards the Gulf of Mexico. Model layers were developed using pre-published information and additional data acquired from geophysical logs. There has been little historical change in Previous HitwaterNext Hit levels over most of the model area. Groundwater flows west to east from the outcrop areas towards the Gulf of Mexico. Recharge is mainly from rainfall in the outcrop areas, canal losses and return flow in the irrigated areas, and the Rio Grande in the south. Rainfall decreases from east (26 in/yr) to west (19 in/yr). Groundwater pumping was about 17,000 ac-ft/yr in 1980 and nearly doubles by 1999. Part of the model area has mesquite with deep root systems capable of extracting significant quantities of Previous HitwaterNext Hit by evapo-transpiration (ET). ET rates for mesquite can potentially be as much as 95 percent of the rainfall depending on the depth of the Previous HitwaterNext Hit table, density and age of the stands. Initial model runs indicate that recharge is about 2 to 3 percent of rainfall. Brackish Previous HitwaterNext Hit for desalination constitutes a significant portion of the groundwater available for future use.

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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES

Texas Previous HitWaterTop Development Board, Austin, Texas

Copyright © 2003 by The Gulf Coast Association of Geological Societies