Determination of Discharge Coefficient of a Rectangular Sharp Crested Side Weir Using Dominguez Method

ABSTRACT

A side weir is frequently required to discharge excess flow from a channel to an irrigation canal without causing a significant change in the channel’s water level. In this case, the side weir is ideal. The discharge over the side weir can then be determined by incorporating a suitable discharge coefficient into the head discharge relationship of a rectangular sharp crested side weir using Dominguez method under a subcritical flow condition.

Experiments to determine the Dominguez discharge coefficient CdD were carried out in the civil engineering hydraulics laboratory, university of Ibadan using a multipurpose flume modified to form a branch channel and different dimensions of rectangular sharp crested weir placed at the junction. This study investigated the effects of slope on the Dominguez discharge coefficient varying from 0%, 1%, 2% and 3%.
In this project report, the expressions to compute the Dominguez discharge coefficient of rectangular side weir were presented based on dimensional analysis, linear and multiple regression analysis. It was observed that the upstream Froude number F1, ratio of the upstream head of water over the weir to the width of weir h1/b, ratio of the upstream head of water over the weir to sill height of the weir h1/p and the slope So, all have significant effects on the Dominguez discharge coefficient CdD.
Keywords: Rectangular sharp crested side weir, Dominguez discharge coefficient, Upstream Froude number, Subcritical.