Bathymetry and Sediment Accumulation of Walker Lake, PA Using Two GPR Antennas

Elaine Langone Center, Terrace Room

Silting within all man-made reservoirs can be a major problem. Exploring a lake’s bathymetry with Ground-Penetrating Radar (GPR) techniques is one way to identify the magnitude of sediment accumulation in these reservoirs. In this study, the bathymetry and sediment accumulation of Walker Lake, PA were explored with two frequency GPR Antennas. The apparatus developed in this study included two antennas placed on an inflatable boat towed by a 14 feet Jon Boat powered by a 55 lbs. thrust electric trolling motor. Depending on the depth of the lake, either a 400 or 100 MHz antenna was applied to identify the bathymetry, the amount of sediments deposited, and its distribution. A total of eighteen transects were taken along the entire length of the lake. Using multiple processing software including RADAN 7, GPR Viewer, SAS 9.1.3 and MATLAB three-dimensional and contour surfaces of the pre-1971 topography and bathymetry of Walker Lake were developed. The bathymetry, the volume of sediment and its accumulation rate were successfully estimated. The lake was found to vary between few cm to 9 m in depth. Deposition of sediment takes place mainly near the inlet of the lake and gradually decreases toward the dam while the depth of the water increases. The depth of sediment deposit ranges between few centimeters and 1.85 ± 0.15meter.