General End-Depth–Discharge Relationship at Free Overfall in Trapezoidal Channel

Abstract

There are relatively few investigations of the free overfall in a trapezoidal channel and its practical use as a flow-measuring device. The flow over a fall in a trapezoidal channel is simulated by that over a sharp-crested weir, taking into account the streamline inclination and curvature at the brink. A general end-depth–discharge relationship, for both subcritical and supercritical flow, is obtained. Discharges predicted using this general relationship are compared with experimental data and with those obtained from other theoretical methods. The surface profiles for the zone between the brink and an upstream section with hydrostatic pressure distribution are also investigated using the energy equation for both subcritical and supercritical flow.