New approach to computing mean velocity and discharge

Estimation of discharge hydrograph may be needed at river gaging stations where discharge is computed by converting water stage using a stage-discharge relation (a rating curve) or multiplying mean velocity with flow cross-sectional area. The mean velocity is computed by converting the measured maximum velocity to mean velocity using a conversion factor. Estimating the velocity conversion factor at stations where measured discharge data are insufficient remains a challenge. This study develops a novel method for determining the conversion factor by combining the entropy velocity profile, a data-driven technique, and a one-dimensional (1-D) flood routing model, and thus develops a method to determine discharge at the weak gauging sites. The method was used with two different assumptions: constant velocity factor and velocity factor depending on the aspect ratio. Results showed that this method optimally estimated the conversion factor.