KARST ANALYSES OF THE SALADO CREEK WATERSHED: WILLIAMSON AND BELL COUNTIES, TEXAS

The Edwards Aquifer, a karst aquifer located in Central Texas, is the primary source of drinking water for approximately two million people; indicating proper groundwater management is vital. The Northern Segment of this aquifer is poorly understood compared to other aquifer segments and includes Salado Creek Watershed in north Williamson and southern Bell counties, Texas. In order to maintain water quality, aesthetics and local environment, greater knowledge of primarily porous dolostone and nodular limestone karst in this area is required. Remote sensing of Salado Creek watershed and associated karst offers useful methods for further comprehending the hydrogeology of the Northern Segment of the Edwards Aquifer.

Ground Penetrating Radar (GPR), in particular, allows for greater awareness of the extensive and complex underground water flow contributing to the primary water table of the area. This non-invasive method of subsurface imaging uses radio waves in order to detect changes in boundaries below ground, variations of which are recorded by a receiver and compiled into one analyzable image. Geospatial analyses enable additional non-invasive, remote-sensing characterization of karst systems. Sinkhole delineation from LIDAR analyses enables spatial interpolation of karst development across wider regions. GPR and LIDAR analyses were employed to evaluate karst development in the Salado Creek watershed of the Northern Segment of the Edwards Aquifer.

GPR analyses of known and suspected karst features proved to be of limited application within the study area due to depth of resolution and significant dissolution along intermediate planar surfaces. While known features could be discerned through GPR analyses, confident delineation of potential unknown caves could not be assessed. LIDAR analyses proved useful in delineating major trends in karst development across the study area, indicating that karst development is primarily associated with preferential dissolution along distinct stratigraphic horizons and fractures near-perpendicular to the Balcones Fault System. Distortion of topography, due to heavy anthropogenic activity in the area including ranching and quarrying, complicated remote sensing of karst within the study area.