On the Mutual-Dependence Relation between the Upstream Depth and Discharge of the Flow Passing through Sluice Gates

Abstract

As for the flow passing through gates, it is becoming more and more necessary to evaluate not only the discharge but also the upstream depth in order to plan for flood management of the area upstream of the gates because of the extraordinary heavy rain fall in these years. The present study aims to formulate the mutual-dependence relation between the upstream depth and discharge of the flow under sluice gates in free flow condition employing momentum theorem. As the results, unique relationship was obtained between the upstream depth normalized by gate opening, h₀/a, and the normalized critical depth of open channel flow, h_c/a. The relationship proved to be expressed by a quadratic equation between these two dimensionless parameters from which expressions of the upstream depth and discharge of the flow in question were obtained. The obtained expressions showed both good agreement with the previous experiments and consistency with the previous discharge formulas.