Using an ADCP, Depth Sounder, and GPS for Bathymetric Surveys

The river outlet works at Fontenelle Dam, part of the Seedskadee Project in southwest Wyoming, has a long history of concrete abrasion damage. Consequently, the project manager has requested assistance to identify the cause of the damage. Reclamation's Water Resources Research Laboratory will conduct a physical model study to determine the cause of the damage and to design necessary modifications to prevent the damage from reoccurring. As part of the preparation for the model study, bathymetry data for the river outlet works channel was needed to construct the topography in the physical model. The project manager also requested bathymetry data for the river outlet works structure to verify areas of abrasion damage and material accumulation identified during a recent underwater inspection. The bathymetric data were collected using an acoustic Doppler current profiler (ADCP), depth sounder and a hand-held GPS receiver. This paper presents details on the bathymetric survey techniques, considerations regarding depth and positional uncertainty, and a comparison of the bathymetric data with design data.