Predictive model for stage-discharge curve in compound channels with vegetated floodplains

The governing equation of the discharge per unit width, derived from the flow continuity equation and the momentum equation in the vegetated compound channel, is established. The analytical solution to the discharge per unit width is presented,including the effects of bed friction, lateral momentum transfer, drag force, and secondary flows. A simple but available numerical integral method, i.e., the compound trapezoidal formula, is used to calculate the approximate solutions of the sub-area discharge and the total discharge. A comparison with the published experimental data from the U. K.Flood Channel Facility(UK-FCF) demonstrates that this model is capable of predicting not only the stage-discharge curve but also the sub-area discharge in the vegetated compound channel. The effects of the two crucial parameters, i.e., the divided number of the integral interval and the secondary flow coefficient, on the total discharge are discussed and analyzed.