How Karst Features Affect Recharge? Implication for Estimating Recharge to the Edwards Aquifer

Recharge in the karst terrain may exhibit distinct characteristics. For the Edwards aquifer in the south central Texas, recharge mainly occurs in the form of stream transmission loss in the outcrop area—a clear manifestation of karst influence on recharge processes. This part of recharge has been quantified fairly accurately using stream gauging stations. However, recharge estimation from the upland areas is much less certain and is generally restricted to the modeling method. In order to understand the strong control of karst features on the recharge potential, and to quantify spatial and temporal variability of recharge in this region, a detailed analysis on the relationship between precipitation and recharge is conducted in this study. The water budget analysis of an upland watershed using synthesized data indicates that recharge in this area may have been underestimated by more than 10% of annual precipitation. We speculate that such high recharge potential and variability are closely related to the karst features and vegetation structure in the region. Process-based hydrologic study has provided us critical conceptual understanding of the recharge processes and regional hydrology. Further investigation to validate the information is warranted.