Bottom scour by waves in a water reservoir after a break in its dam

The velocity field of an unsteady water flow in a reservoir after a fast opening of its damper was investigated in laboratory conditions. A long lowering wave traveling upstream was detected. As the flow velocity is increased to U > 23.1 cm/s, almost stationary waves appear in the flow, and their parameters correspond to the parameters of stationary waves on the surface of a stationary water flow with the corresponding Froude number and velocity gradient. In the region of local velocity deceleration, an intense bottom scour was detected under the waves.