Marine Services :: Flood Control and Reservoir Capacity Studies
DEA provides single-beam hydrographic surveys, water level observations, and Acoustic Doppler Current Profiler (ADCP) flow measurements for flood stage analysis.
For example, DEA runs annual cross-section surveys on the Cowlitz River to monitor sediment transport from Mt. St. Helens runoff. Our cross-section surveys also have supported flood analysis of the Willamette Valley, the Snake River, and the Columbia Basin extending from the Pacific Ocean into Idaho and Montana. We conduct detailed surveys of bridges to document restrictions for model input. Data is organized and compiled for direct entry into USACE’s HEC-RAS. Each cross-section is photo-documented and a geodatabase of photos is provided to aid modelers with roughness coefficient determinations.
Reservoir capacity surveys include the use of high-resolution multibeam sonar for underwater mapping and upland vessel-based laser scanning or aerial mapping for detailed modeling of reservoirs and accurate capacity curve calculations. DEA has also worked on projects that have included comparison to pre-impoundment or earlier mapping efforts for assessment of sediment migration.