Prediction of stage-discharge relationship in two-stage channels

Predicting the stage-discharge relationship in two-stage channels is a significant factor, as it determines the discharge and the degree of flood accurately. There are conventional methods, in which they either do not meet the required accuracy or simplicity. In this paper, a new simple model is developed for symmetric compound channels to predict the stage-discharge relationship accurately. The method is proposed by improving the weighted divided channel method (WDCM), which includes the apparent shear force (ASF), wetted perimeters and B/b ratio. It was concluded that the improved weighted divided channel method (IWDCM) is limited to all rigid symmetric compound channels with B/b ratios greater than or equal to 3. The IWDCM led to an absolute percentage error always less than 10% for total discharges for all smooth and rough cases. The proposed IWDCM method will therefore be very helpful to hydraulic engineers to predict the stage-discharge relationship precisely due to its simplicity.