Potentiometric Maps for Low to High Flow Conditions, Barton Springs Segment of the Edwards Aquifer, Central Texas
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Abstract
Potentiometric maps for the karstic Barton Springs segment of the Edwards Aquifer (Barton Springs aquifer) were constructed using data from high, below average, and low flow conditions. These synoptic potentiometric maps document varying hydrologic conditions and stresses and contain a dense set of data (n= 166 to 231) for this relatively small portion of the Edwards Aquifer (155 sq. mi.), allowing detailed examination of hydrogeologic features and phenomena. Results indicate steep gradients within the extremely dynamic aquifer system, with water-level changes from 20 to 100 feet over large portions of the area. Troughs and ridges in the potentiometric surfaces correspond to preferential flow paths (conduits) with contours significantly changing morphology from one aquifer condition to the next. Influence of discrete and diffuse recharge and discrete discharge (pumping) are evident on the potentiometric surfaces. Potentiometric surfaces for these different conditions provide some insight into the dynamic nature of the southern boundary of the aquifer, and the potential for flow from other sources such as the Trinity Aquifer and saline zone of the Edwards. These maps, and associated data sets, are important for calibrations of numerical models and evaluations of sustainable yield. Potentiometric maps are a significant tool for hydrogeologic characterization of the karst flow system in the aquifer, and when combined with dye tracing and other studies, better characterize the dynamic nature of this system.
