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Simulated effects of projected pumping on the availability of freshwater in the Evangeline Aquifer in an area southwest of Corpus Christi, Texas

Water-Resources Investigations Report 85-4182

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Abstract

This study is an investigation of the continued availability of freshwater in the Evangeline aquifer along the Texas Gulf Coast and the potential for degradation of the water quality by saline water intrusion. Recharge to the aquifer occurs by the infiltration of precipitation in the outcrop area and by cross-formational flow from deeper aquifers. The pre-development recharge rate is about 6 to 8 cu ft/sec. Discharge, under natural conditions, is upward into the Chicot aquifer and to the Nueces River or Gulf of Mexico. Intensive pumping by irrigators, industries, and municipalities over the last 80 yr has created a cone of depression as deep as 219 ft below sea level under the city of Kingsville in Kleberg County. The total rate of pumpage in 1982 was 29.6 cu ft/sec. A mathematical model of the flow and water quality in the Evangeline aquifer was developed using available data to simulate the historical effect of pumping on the potentiometric surface and water quality, and to simulate the effect of projected pumping on the potentiometric surface and water quality to the year 2020. The water quality in the aquifer is only marginally suitable for drinking water. The chloride concentration before development in the 1930 's and 1940's, ranged from 9 to 1,971 mg/L. The mean chloride concentration was 353 (standard deviation 262) mg/L. The potential sources of water quality degradation on a regional scale are: saline water intrusion from under the Gulf of Mexico; movement of poor quality water within outlying sections of the aquifer; and downward leakage from the overlying Chicot aquifer. Leakage from the Chicot is the most likely to cause serious regional water quality degradation. The simulations and the sensitivity tests of the aquifer properties, conditions, and assumptions indicate that vertical conductivity of the Chicot aquifer is the most sensitive and least well known part of the system. Two simulations of the projected pumping--a low estimate , as much as 46.2 cu ft/sec during 2011-20; and a high estimate, as much as 60.0 cu ft/sec during the same period--indicate that no further regional water quality deterioration is likely to occur. (Author 's abstract)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Simulated effects of projected pumping on the availability of freshwater in the Evangeline Aquifer in an area southwest of Corpus Christi, Texas
Series title:
Water-Resources Investigations Report
Series number:
85-4182
Edition:
-
Year Published:
1985
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
vi, 103 p. :ill., maps ;28 cm.