Discharge Estimation in a Tidal River with Partially Reverse Flow

A model for the production of isovel contours in a normalized form, which can be used for estimation of discharge in artificial and natural channels by using a single point of measurement, has been introduced previously by Maghrebi in 2006. Herein, for the first time, application of the model to a tidal river with partially reverse flow, which is caused by opening a sluice gate located asymmetrically close to the right bank of the Ohta floodway in Hiroshima, Japan, is presented. An acoustic Doppler current profiler was used to measure the velocity profiles at different verticals (with several points at each vertical) and then discharge was calculated. In addition, estimated discharge based on each measured point with the aid of the model was obtained. For the measured points away from the low magnitude of isovel values, the predicted discharges are comparable with the measured one. Due to the fluctuations of the measured velocities, instead of a single point of measurement, vertical and horizontal groupings of the measured points were used to estimate the discharge. It is generally proposed to select the measured points from the regions with the corresponding high values of isovels in the range of u/V <-0.5 and u/V>0.5. The overall results have shown that minimum errors are associated with the horizontal groupings.