Water Budget Assessment of the
Southwestern Segment of the Carrizo-Wilcox Aquifer
Ronald T. Green1, F. Paul Bertetti1, Ronald L. McGinnis1,
Richard V. Klar2, and Bradford Wilcox3
1Geosciences and Engineering Division, Southwest Research Institute,
6220 Culebra Rd., San Antonio, Texas 78228
2Raba Kistner Consultants, 12821 West Golden Ln., San Antonio, Texas 78249
3Texas A&M University,
College Station, Texas 77843
ABSTRACT
The southwestern Texas segment of the Carrizo-Wilcox Aquifer has been significantly impacted by pumping that started in the late 1800s. Pumpage rates increased into the 1960s and remained high (i.e., >100,000 acre-ft/yr) through the mid-1980s, after which pumpage decreased to approximately 65,000 acre-ft/yr. Lowering of the potentiometric surface of the Carrizo-Wilcox Aquifer has slowed in recent years, but there is no evidence that this lowering has stopped. While the connection between pumpage and lowering of the potentiometric surface elevation in this area are relatively well understood, there is large uncertainty associated with sources and rates of recharge. Field studies and related analyses were undertaken to determine the sources and rates of recharge of the Carrizo-Wilcox Aquifer to allow for effective management of the water resource. These studies determined that direct recharge by precipitation over the recharge zone is limited and that the largest sources of recharge are focused in the Nueces River and in the gravels of the Leona Formation in the Leona River floodplain. The average total annual recharge of the southwestern segment of the Carrizo-Wilcox Aquifer may be less than 30,000 acre-ft, significantly less than current pumping rates.
Green, R. T., F. P. Bertetti, R. L. McGinnis, R. V. Klar, and B. Wilcox, 2009, Water budget assessment of the southwestern segment
of the Carrizo-Wilcox Aquifer: Gulf Coast Association of Geological Societies Transactions, v. 59, p. 305-320.
AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana