seyed vahid nabavi - Department of Civil Engineering, Khomain Branch, Islamic Azad University, Iran.

Open channel flow measurement structures are so designed that the flow rate can be reliably determined from measurement of the upstream head relative to a reference level in the ‘control section’ of the structure. To measure flow discharge and study the erosion at the brink of free overfalls, the computation of the end depth relationship (EDR) is required in civil engineering practices. A free overfall at the end of an open channel provides a simple means for measuring flow discharge. In fact the discharge can easily be estimated if the critical depth of flow is known and there is a correlation between the brink depth and the critical depth of flow. Due to its practical importance, since Rouse (1936) which was probably one of the first to examine the EDR many investigators studied the free overfall in various channels. This paper presents important laboratory experimental and theoretical investigations on rectangular free overfall.

Brink depth; End Depth Ratio; End Depth Discharge, Flow measurement, Rectangular channel