Discharge coefficient of compound triangular-rectangular sharp-crested side weirs in subcritical flow conditions

Side weirs are among the important hydraulic structures for flow diversion in flood schemes or sewer networks. Side weirs are generally rectangular or triangular in shape and have a limitation for precise measurement of low and high flow. Therefore compound side weirs are suggested for accurate flow measurement in a wide range of discharges. In this study, the discharge coefficient of compound sharp-crested side weir consisting of rectangular and triangular part was studied experimentally. The results are in agree with previous study which show the discharge coefficient of a compound side weir is a function of the upstream Froude number ((Fr1), the ratio of weighted crest height of the weir to upstream water depth (w¯/y1) and the ratio of weir length to upstream water depth (L/y1). Based on the experimental data and regression modeling, a dimensionless equation has been developed for estimation of the discharge coefficient and two equations have been proposed for estimation of flow discharge in compound triangular-rectangular sharp-crested side weirs. The results also show that there is a good agreement between estimated and measured data.