Study on Sediment Delivery Ratio,Rate of Silting and Characteristic of Sediment Transport of the Lower Yellow River Channel

The paper puts forward the relational expression of sediment delivery ratio of the whole section and section by section of the lower reaches based on silt-discharge data of each flood occurred in the lower Yellow River and on the operational conditions of late period of debris retaining of the Xiaolangdi Reservoir.The outcomes show that the range of channel scour and fill of the upper section is greater than that of the lower section,therefore,the evolution of river bed of the lower Yellow River is fast and unstable;the cross section of the lower section where is bottle-neck section for transporting sediment into the sea,is narrow and deep,the range of scour and fill of the lower section is small and river bed stable after regulating discharge regime at the upper section.The effect of reservoir regulation to the sediment reduction of the lower channel is small.On the contrary,it reduces the amount of sediment flowing into the sea,speeding up the sedimentation in the reservoir and increasing the water consumption for sediment transport.How to properly control sediment by the reservoir is an issue and needs further study.