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The karstic Edwards aquifer provides public supply and springflow for endangered species in drought-prone central Texas. Delineating source areas and flow paths in karst aquifers is important for understanding water availability. Groundwater divides separate the aquifer into different segments (Figure 1). It has been previously proposed that the divide between the Barton Springs and San Antonio segments migrates in response to changes in hydrologic conditions. This study evaluated historical discharge and geochemical data to characterize and quantify the hydrologic connection between recharge from the Blanco River and Barton Springs, the main discharge point for the Barton Springs segment. Hydrologic data, including stream discharge, spring discharge, and estimated stream recharge data (1987 through 2012) for extremely dry hydrologic time periods, when it was inferred that there was likely no recharge occurring within the Barton Springs watershed, were identified and evaluated. A hydrologic connection was inferred between the Blanco River and Barton Springs when estimated recharge from the Blanco River increased and there was a time lagged increase in discharge and gage height at Barton Springs. Sixteen events were identified that met these criteria. The average increase in recharge from the Blanco River for these 16 events was 2.7 ft3/s, while the average increase in discharge at Barton Springs was 1.4 ft3/s. The increase in Barton Springs discharge is likely attributable to Blanco River recharge for 4 of the 16 events, and potentially attributable for another 6 events. The 6 remaining events of increased discharge at Barton Springs are within instrument uncertainty and cannot be attributed with confidence to an increase in recharge from the Blanco River. The geochemical analysis was inconclusive. Results indicate that during dry hydrologic conditions, when the divide is closer to the Blanco River, the Blanco River contributes recharge to Barton Springs and the northern segment. These results are consistent with previous dye-tracing studies (Johnson et al., 2012). Open Access - Permission by Publisher See Extended description for more information.
Barton Springs (Austin, Texas, United States), United States, Geology
1 online resource
Barton Springs/Edwards Aquifer Conservation District, "Evaluating the hydrologic connection of the Blanco River and Barton Springs using discharge and geochemical data" (2013). KIP Data Sets and Technical Reports. 72.