Evaluation of 1-D and 2-D models for discharge prediction in straight compound channels with smooth and rough floodplain

Accurate estimation of discharge capacity of flooding rivers is extremely important in flood control projects. Floodplains are often covered with vegetation which generally increases the flow resistance, and affects the conveyance capacity. Several numerical methods have been proposed by researchers for predicting the stage-discharge relationship in compound channels. The hydraulic behavior of compound channel flow with vegetated floodplains is very complex. Hence, the accuracy of numerical discharge prediction methods must be investigated in compound channels with vegetated floodplain. In this paper, experimental results are presented for flow capacity of an asymmetric compound channel with vegetated and non-vegetated floodplain. An attempt has been made to compute the discharge with different 1-D and 2-D methods, including Single Channel Method (SCM), Divided Channel Methods (DCMs), Coherence Method (COHM) and Shiono and Knight Method (SKM). The results are then compared with experimental data. The results show that the SKM model is more accurate in discharge prediction than other models studied in the present study. Also, the DCM-ID model is found to be less accurate in discharge prediction in compound channels with smooth or rough floodplain.