Discharge formula for flows over open-check dams

Abstract

The present study proposed a discharge prediction model for open-check dams. The open-check dam is composed of a trapezoidal spillway and a rectangular opening located at the bottom of the spillway. The flow conditions, determined using the ratio of water head and dam crest length, for flow over open-check dams were divided into broad-crested and sharp-crested weir flow conditions. For the broad-crested weir flow condition, the discharge equation for rectangular broad-crested weir was proposed to estimate the discharge. For the sharp-crested weir flow condition, a linear combination of discharge equations for rectangular and trapezoidal sharp-crested weirs was proposed to describe the discharge. A series of laboratory experiments were performed in order to calibrate the proposed discharge model. The results showed the discharge coefficient and cross-sectional area ratio (Ar) were highly correlated under two flow conditions. The averaged error between measured and predicted discharge was less than 2%. The previous models displayed averaged errors between 4% and 25% under the present experimental conditions, whereas that of the present model was considerably low. The present model demonstrated favorable accurate and convenient estimation of discharge for flows over open-check dams.