Experimental study of end depth-discharge relationship in circular sections carrying spatially varied flows

Since the flow at free overfall is self-calibrated, it has been extensively studied and used for flow measurement by many researchers. Previous investigations were done for different channel geometry, super and subcritical regime, with no lateral inflow along the channel, i.e. there is no variation in the discharge along the channel length. This research was conducted to investigate the discharge-end depth relationship in circular pipes carrying spatially varied flow with increasing discharge. Comparison between manometer reading and direct end depth measurements confirmed the deviation of the pressure distribution from the hydrostatic one. At the brink, nonetheless the data indicated that the end depth ratio in such flow condition is closer to unity than that of constant discharge. Consequently, based on the compiled data a relationship was proposed, which facilitates discharge measurement with reasonable accuracy.