A New Flow Calculation Algorithm for Weir Box Culverts

In this paper, a new algorithm is presented for flow rating of weir box culverts. Weir box culverts are compound culverts, which consist of a weir box in the front, and a traditional culvert in the back. This configuration makes it quite difficult to obtain accurate flow rating with traditional culvert flow equations. In the new algorithm, flow through weir and culvert is first calculated separately, then iteration method is used to systematically adjust water elevation inside the weir-box and recalculate the flow. This loop keeps on going until the discharge continuity is satisfied with certain convergence criteria. This algorithm has been validated at various weir box culverts. The results show reasonable agreement with field flow measurements.