Comparison of different methods for predicting zonal discharge of straight heterogeneously roughened compound channels

flood mitigation, eco-environment design, restoration, sediment transport. This paper compares four most recently developed 1-D methods, namely Interacting Divided Channel Method (IDCM), Energy Concept Method (ECM) and Modified Divided Channel Method (MDCM) and Apparent Shear Stress Method (ASSM), against a wide range of our experimental data and the data available in the literature. The 32 datasets used include heterogeneously roughened symmetric channels (22 datasets) and asymmetric channels (10 datasets) with various aspect ratios [channel total width (B) at bankfull / main channel bottom (b) =2.6 ~ 15.8], bed slopes (So = 4.3x10-4 ~1.3x10-2), and ratios of Manning's roughness between floodplain and main channel (1.1 ~ 3.9). It was found that none of the methods performed well against all the datasets. Compared with the traditional Divided Channel Method (DCM), all above methods, in general, predicted both the total discharge and main channel discharge reasonably well within 12%, but they had relatively large errors for the prediction of the zonal discharge, particularly for floodplain with large roughness. The ASSM has shown the best overall performance on both the total and zonal discharge prediction.