DELINEATING CONTRIBUTING AREAS TO KARST SPRINGS USING NEXRAD PRECIPITATION ESTIMATES AND CROSS-CORRELATION ANALYSIS

Coupling spring discharge and Next Generation Radar (NEXRAD) using cross-correlation analysis provides a tool for understanding the relationship between groundwater recharge and discharge in karst aquifers. By running a cross-correlation analysis on rainfall and nearby spring discharge a map of maximum correlation and lag time can be created for the contributing area of the spring. Contributing area maps were produced for both Barton Springs and Jacob’s Well, two karst springs near Austin, Texas, USA. Barton Springs is an area with a precise estimate of the recharge area. The current map of the recharge area and the NEXRAD derived map show good agreement in the spatial location of the recharge areas. Conversely, Jacob’s Well has not been sufficiently studied to delineate a precise contributing area map. This study provides an estimate of the location of the contributing area. At this point, results from this analysis on a karst aquifer in Texas are qualitative. However, the general relationships and spatial distributions are helpful in constraining inputs to regional groundwater models. The methodology provides insights to water regulators and stakeholders in managing and developing future study plans for the aquifer.