Flow Measurement with Rectangular Free Overfall

Abstract

Previous experimental works provide different values of the ratio between the end depth and the critical depth. Differences depend on the crosssection shape of the channel, the roughness of the channel, and the characteristics of the nappe (confined or free on the sides). In this paper, the characteristics of a free overfall in a rectangular channel, having different values of the width, are experimentally studied. The measurements show that for practical application, the relationship between the end depth and the critical depth is independent of channel width. For any rectangular channel of given width, a relationship to estimate the discharge by using the depth measured at the end section is proposed.