New Approach for Estimation of Rectangular Side Weirs Discharge in Subcritical Flow

Side weirs are used to divert the flow from a main channel to a desired environmental area. These basic hydraulic elements are commonly preferred in drainage and irrigation systems of surface water. Many studies have been conducted to determine the outflow discharge of side weirs. De Marchi's approach, which assumes constant specific energy along the side weir, can be applied to describe the surface equation and therefore the discharge coefficient. However, the use of this approach is not easy in experimental and theoretical studies. This study presents a new semianalytical approach that determines the discharge capacity of rectangular side weirs. The findings of this new method are consistent with numerical and experimental results. (C) 2016 American Society of Civil Engineers.