AN EFFICIENT METHOD FOR MEASURING DISCHARGE OF A RIVER WITH SHORT-TERM REVERSED FLOWS
An efficient method for estimating discharge of rivers with short-term reversed flow is developed using entropy-based velocity distribution equations. The proposed method, called adaptive horizontal entropy method (AHEM), allows an adaptive range of velocity sampling using a stationary horizontal acoustic Doppler current profiler (HADCP). In AHEM, the mean velocity is related to the averaged HADCP velocities in a linear relationship after establishing velocity distribution parameters. To test the performance of AHEM in measuring short-term reversed flows, AHEM is deployed at Yahara River in Wisconsin, and the estimated discharges are then compared with measurements by a moving boat vertical ADCP. The results show that it performed well for short-term reversed flows. Root mean square error of AHEM estimation is 0.37 m3/s, the mean relative error is 13.1% and the coefficient of determination is 0.984. In comparison with the well-established index velocity method, AHEM yielded slightly lower errors, indicating reasonable accuracy. AHEM can reliably estimate discharge using a flexible HADCP data coverage area without recalibration and also adapt to changes in the velocity distribution by using fit velocity distribution parameters.