Estimation of river discharge using mean velocity equation

For the improvement of the conventional stage-discharge curve equation based on just stage, this study proposed a method to estimate river discharge using hydraulic characteristics, such as hydraulic radius, bed slope, depth, etc. Hydraulic gradients in Manning’s Equation and Chezy’s Equation, both of which are among mean velocity equations, were computed using those characteristics. For that computation, hydrological data actually measured in a laboratory channel and a natural open channel from the Albert University Report were used. And then, river discharge was calculated using the hydraulic gradients. For comparison with the conventional method of inversely calculating roughness coefficients, their power function was formulated. And river discharge estimated using the proposed method was compared with the corresponding one estimated using stage-discharge relations. As a result, the proposed method showed results more approximate to measured discharge. An analysis of discrepancy ratio distribution revealed that non-dimensional errors lied within the ranges of −0.2 to 0.23. This indicates that river discharge estimated using the proposed method showed some improvements in accuracy, compared with river discharge estimated using the conventional stage-discharge curve equation or inverse roughness coefficients.