Effect of Fine Material on Transport of Bed Material Load in Hyperconcentrated Flow

In this paper a transport rate equation of bed material load is proposed with the consideration of the effect of fine material's flocculation.The equation indicates that the transport of suspended bed material load in hyperconcentrated flow can be increased significantly due to the reduced settling velocity and Rouse number by the presence of fine grains generally behaving as wash load.Since the fine material mainly comes from upstream watershed,the introduction of fine material's concentration in the calculation of transport rate of bed material load reflects the impact of watershed on sediment transport.Comparison of field data in the Yellow River and the calculation result of present equation shows that the equation can reproduce the phenomenon that the more the fine sediment comes from upstream,the more the coarse sediment is transported in the Lower Yellow River under the same flow conditions.