A new approach for predicting discharge in straight, symmetric homogeneous compound channels

Accurate estimation of flow discharge in a compound river channel becomes increasingly important in river flood risk management and eco-environment design. In this paper, a new approach is proposed to improve the prediction of flow based on the concept of the apparent shear stress at the diagonal interface between main channel and floodplain. The new approach is compared with a wide range of our experimental data and the data available in the literature. The 22 datasets used include homogenously symmetric channels, which have various aspect ratios[channel total width (B) at bankfull/main channel bottom (b) =1.5～15.8]and bed slopes (S =3.0x10 ～2.024x10). It was found that the new approach has significantly improved the accuracy of flow prediction compared with the conventional DCM (divided channel method) against all the datasets, particularly for relatively low flow depths of floodplain where the flow discharge is most difficult to predict correctly. The new approach predicts the total discharge well for homogeneously symmetric channels, within a relative error of 5% on average. Furthermore, the new approach can have a better prediction of zonal discharge percentage compared with the DCM.