Apparent shear stress-based method on an inclined interface plane for predicting discharge in straight compound channels

Accurately predicting flow discharge in a compound river channel becomes increasingly important for flood risk management and river eco-environment design. This paper proposes a new general approach based on the concept of the apparent shear stress at an inclined interface plane between main channel and floodplains. The new approach with a diagonal plane is applied with a wide range of the author’s experimental data and the data available in the literature, which include 59 datasets. Among them, 27 are homogenous channels of symmetric channels (22 datasets) and asymmetric channels (5 datasets) whereas 32 are heterogeneously roughened channels of symmetric channels (22 datasets) and asymmetric channels (10 datasets). It was found that the new approach improves the accuracy of discharge compared with the DCM for all datasets. The predicted total discharge for straight homogeneous channels has a mean absolute percentage error (MAPE) of 5%, whereas the MAPE error is about 6.7% for heterogeneously roughened channels. • A general approach of discharge prediction is presented based on apparent shear stress on an inclined interface. • Both zonal and total discharge can be calculated using the proposed method. • The predicted results are compared with 59 sets of experimental data along with the DCM.