End Discharge Relationship for Free Overfall Affected by Upstream Bed Roughness and Slope

The experimental program of this paper was restricted to free vertical drop structure at the end of the rectangular channel. The roughness and slope of the bed of approach channel are the aim of this study to show their effects on End Depth Ratio (EDR). Three different roughness from smooth (n = 0.009) to rough (n = 0.019) with four-bed slopes from horizontal (S_o = 0) to S_o = 0.01 were adopted with total 72 runs. The analysis of experimental data was focused on the variation of EDR as a roughness and/or bed slope changed. Also, the design formulas have been derived statistically for numerous practical situations and recommended to be used as predictive equations for both EDR and discharge.