Estimation of Groundwater Recharge in Texas Related to Aquifer Vulnerability to Contamination

This study aimed to estimate groundwater recharge rates for major porous media aquifers in Texas, essential for assessing aquifer vulnerability to contamination. Recharge rates were estimated through one-dimensional unsaturated flow modeling and limited field studies in the Southern High Plains and Seymour aquifers. Field studies involved measuring soil physics and environmental tracers in soil samples from boreholes in various land use settings.

Numerical modeling of unsaturated flow utilized long-term climatic data, soils data, and vegetation data. Simulated recharge rates varied from 54 mm/yr in west Texas to 720 mm/yr in east Texas, positively correlated with precipitation. High recharge rates in east Texas suggest climate is not the limiting factor, with soil texture and vegetation playing crucial roles in reducing recharge. Layered soil profiles led to locally variable recharge estimates, but areally weighted averages were less variable and positively correlated with precipitation. Vegetation significantly reduced recharge rates in all cases, with simulations including vegetation and layered soil profiles resulting in recharge rates ranging from 0.2 to 114 mm/yr.

The 30-year average recharge rates across simulated stations in the state were positively correlated with precipitation, suggesting long-term precipitation as a predictor of recharge. This comprehensive approach provides valuable insights into groundwater recharge dynamics, crucial for assessing aquifer vulnerability to contamination.