Improved discharge prediction of straight compound channels based on energy transition

Accurate estimation of flow discharge in a compound river channel is increasingly important in river management and eco-environment design. In this paper, a new model is proposed to improve the prediction of flow based on Energy Concept Method (ECM) and Weighted Divided Channel Method (WDCM) along with the apparent shear stress at the interface between main channel and floodplain. The new model is compared with a wide range of our experimental data and the data available in the literature. The 26 datasets used include homogenously roughened symmetric channels (22 datasets) and asymmetric channels (4 datasets) with various aspect ratios [channel total width (B) at bankfull / main channel bottom (b) =1.5 ~ 15.8] and bed slopes (So = 4.3x10-4 ~1.3x10-2). It was found that the new model has significantly improved the accuracy of flow prediction compared with the ECM and DCM methods against all the datasets, particularly for relatively low flow depths of floodplain where the flow discharge is most difficult to predict correctly. The new model predicts the total discharge well for both symmetric and asymmetric channels, within an averaged relative error of 5%.