Author(s): Kejun Yang; Er Huang; Xingnian Liu; Shuyou Cao
Keywords: Compound channel; Conveyance capacity; Comparison and analysis of computational method; Secondary flow
Abstract: Stage-discharge curve plays an important role in hydraulic design, procedure development and basin management. For a compound channel, when water in a main channel flows in an out-of-bank condition and on to the adjoining flood plain, if the conveyance capacity is directly calculated by Manning equation, it results in a deal of error. All kind of methods for predicting conveyance capacity are systemically summarized in this paper. By comparing with different series of experimental data from Engineering Research Council Flood Channel Facility (SERC-FCF), it is found that the discharge error is large by cross-sectional vertical division method (VDM), single channel method (SCM) and equivalent velocity division method (EVDM). Otherwise, the calculation accuracy is high by the other methods. According to the order from high accuracy to low, the methods are，in turn，Liu and Dong method (LDM), channel coherence method (COHM), Shiono and Knight method (SKM), inclined division method type 1 (IDMT1), momentum transfer method (MTM), Xie method (XM), superposing cross section method (SCSM). By comparing the two cases of considering and ignoring the effect of secondary flow by SKM, it is found that the secondary flow has a very small influence on the conveyance capacity. By analyzing the merit and demerit of the above mentioned methods, it is pointed out that COHM is a good method in calculating conveyance capacity.