Geologic and Geochemical Characterization of Cross-Communication Potential within the Northern Edwards Aquifer System, Texas

Ingrid J. Eckhoff, Stephen F. Austin State University


The Edwards Aquifer is a large, complex groundwater system located throughout Central Texas in association with the Balcones Fault Zone. The San Antonio and Barton Spring segments of the Edwards Aquifer have been extensively studied in the past because they provide groundwater resources to the largely urbanized areas of San Antonio and Austin, respectively, and smaller communities along the Interstate 35 corridor. Previous research has been conducted on these southern and central portions of the Edwards Aquifer system, which have characterized the structural, hydrogeological and geochemical variations within the highly karsted region. However, the Northern Segment of the Edwards Aquifer primarily consists of undeveloped rural land, and is therefore lacking sufficient studies to fully understand the structural, hydrogeological, and geochemical systems in this region. LIDAR (Light Detection and Ranging) and remote sensing analyses have enabled identification and delineation of spatial distribution of fractures and karstic features visible at the surface, and provided valuable information regarding the understanding of potential cross-communication between aquifer systems. Water quality data from water wells of the Edwards and Trinity aquifers were extracted from the Groundwater Database of the Texas Water Development Board. ArcGIS was utilized to generate geochemical maps for spatial distribution and correlation purposes. Evidence for probable cross-communication between aquifer systems is discernable when examining the directional trend of constituents and comparing them to highly dense areas of lineaments and sinkhole features. Results from this study provide essential data that can be used in the refinement of groundwater characterization for the northern extent of the Edwards Aquifer System.