Page - 700 - in Book of Full Papers - Symposium Hydro Engineering

3. RESULTS The result was an inspection that provided high-resolution georeferenced bathymetry expressed as point cloud data, crack detection, and spall crack size. Fig 1. Bathymetric Contour Map of Dam Reservoir and Spillway 4. CONCLUSION Underwater survey sites can present unique challenges, especially near dams where water level conditions can change dramatically. In the case of unforseen low water, access to key shallow areas can become impossible using manned vessels or even ROVs, both of which require sufficient draft to manouver. In the case of personnel on the water, safety is of course the primary concern. Shallow water is still dangerous. Work vessels can strike rocks or become grounded. It only takes about 20 cm of swift moving water to knock someone off their feet. Cold water only adds to the dangers. Additionally, sensors need to be deployed as close as is practicable to the water surface, and ROVs and the underwater portion of the hull of manned boats would partially block the sensor field. This would require additional manouvering to ensure coverage of shadow areas. The USV solved these problems firstly by removing most of the danger to human life. Shoreside safety precautions were no less important, but overall the field aspects of this program was far safer and more efficient. Additionally, data collection was done more efficiently and to a higher consistent standard. 700