Bed profile downstream compound sharp crested V-notch weir

Abstract

Triangular weirs are commonly used to measure discharge in open channel flow. They represent an inexpensive, reliable methodology to monitor water allocation. A compound sharp-crested weir consisting of two triangular parts with different notch angles was used. The lower triangular part of the weir handles the normal range of discharges while the upper part measures the higher peak flows. This paper evaluates experimentally the local scour downstream compound sharp crested V-notch weir. Forty-eight (48) experimental runs were conducted. Three models of weirs with different geometries (combination of notch angles), four upstream water levels, three water levels at the tailgate, and two bed materials were used. Multiple regression equations based on energy principal and dimensional analysis theory were deduced to estimate the local scour downstream of the weir models. The developed equations were compared with the experimental data. The comparison between the local scour downstream classical V-notch weir and a compound sharp-crested weir consisting of two triangular parts with different notch angles was found to be unnoticed. The study recommended using the compound V-notch weir to pass high discharges instead of the classical V-notch weir.