Measured Flow Disturbance Around Different ADCPs and Mounts

NVE has measured flow disturbance around various ADCPs and mounts/floats/trimarans to try to confirm or dispute previous studies by OSW, USGS. The background/reason for doing this is that after starting to use the OSW, USGS extrap/qrev software and alarming number of measurements show tat the vertical velocity distribution shall be constant/no-slip, and not power/power. The method has been to drive long reaches on a still lake and to compare the water velocities close to the instruments by the velocities at some depth. If no flow disturbance, they will be the same. If disturbed flow, there will be a difference. Presented by; Kristoffer Florvaag-Dybvik NVE (Norwegian Water Resources and Energy Directorate)