GPR with a Bench Model Experiment to Measure Bathymetry and Sediment Accumulation of Faylor Lake, PA

ABSTRACT Waterborne Ground Penetrating Radar (GPR) can be a powerful method for surveying bathymetry, water, and sedimentation volumes within water impoundments like Faylor Lake in Snyder County, Pennsylvania. Current methods for measuring sediment volume in water impoundments often involve invasive techniques, such as collecting cores, which lead to rough estimates due to limited available physical data. This study aims to utilize a custom-made GPR apparatus, which includes a 100 MHz transceiver, a GPR controller, and a GPS device, all mounted on a small 2-person crewed inflatable watercraft. Over 40,000 data points of depth locations spanning the entire lake were collected. The data has been used to generate contour maps and 3D models of the current bathymetry, as well as the original topography of the basin before the dam's construction in 1983. During this study, the lacustrine deposit's dielectric permittivity (ε) was directly measured using a laboratory bench experiment with a 1600 MHz GPR transceiver. The measured ε = 51.69 has enabled the determination of accurate depth values and, subsequently, the sediment volume. The sediment volume represented 20% of the entire lake, with a volume of 139,281 m3. The water volume was also determined with ε = 80, amounting to 663,659 m3. The 3D bathymetry map also shows the outlines of the old Middle Creek channel. The deepest part of the lake was identified on the southeast side, near the drop inlet of the dam, along the old Middle Creek channel, with an average depth of 1.63 m.