Water and sediment graded management to alleviate the “secondary suspended river” in the lower reaches of the Yellow River

The “secondary suspended river” poses a huge threat to the safety of embankment in the lower reaches of the Yellow River. The formation of the “secondary suspended river” is mainly attributed to the “less water and more sediment, inconsistent water-sediment relationship” of the Yellow River. Through the analysis of the relationship between the evolution of the lower reaches of the Yellow River and the loss caused by disasters and flood and magnitude of sediment concentration, this paper thinks that the Yellow River must pay attention to the graded regulation of water and sediment. For small and medium-sized flood with small sediment concentration, according to the flood magnitude and the reservoir water volume in the upper and middle reaches, Impoundment and filling water to build the peak time at the right time is necessary and the flood processes which are less than 2600 m3/s should be avoided in the scheduling process. Based on the shape of river channel of high flow flood in floodplain and average flow flood in floodplain, and the difference between the sediment transport efficiency of flood and the difference between the loss to the lower floodplain area, the average flow flood in floodplain which is between 6000 m3/s should be avoided in the scheduling process as far as possible. In order to relieve the development trend of the “secondary suspended river”, the regulation of “brushing groove of silt beach” should be insisted on for large flood. But the high sediment concentration flood should be avoided because of its serious destructive effect on the lower reach. At the same time, it also calls for strengthening the research and popularization of reservoir sediment treatment and sediment resource utilization technology