Estimation of discharge coefficient of the overshot gates, based on the brink depth, under free and submerged conditions

Overshot gates are used as a flow measuring device to fix the upstream water level. Flow through the overshot gates under submerged conditions often has many problems, mainly due to the need to measure the tail-water depth. In this research, the application of the brink depth, instead of tail-water depth, has been selected to overcome this problem. Many experiments were conducted with nine different angles of the overshot lip under free and submerged conditions. The discharge coefficient of the gate was estimated based on the brink depth. Besides, the flow discharge through the gate was evaluated through an equation based on the energy equation and the stage-discharge relation. The results showed good consistency and high accuracy under free and submerged conditions which refers to the suitability of the proposed equations for flow discharge and water depth because of their theoretical basis. © 2021 Indian Society for Hydraulics.