Suggestion on Optimizing Flow and Sediment Regulations as the Operational Methods of the Xiaolangdi Reservoir

This paper analyzed the condition of the lower Yellow River channel after the operations of Xiaolangdi Reservoir and major problems of flow and sediment regulations.It also researched on the and deposition properties of the river bed of the lower reaches during the man-made flood peak.The results show that,after the man-made flood peak and clear water scours for 10 years,the flood discharge capacity of the lower reaches has been effectively restored,which creates favorable condition for transporting sediment by flood.Consecutive flow and sediment regulations for 10 times,have resulted in less efficiency,and new situations occurred like deposition in the lower reaches during sediment discharge,as well as the increase of discharge along the main stem.The flood has the characteristics of scour in rising and deposit in falling,so it is suggested that the Xiaolangdi Reservoir should change its operational method of discharging sediment during falling period.Sediment should be discharged during the rising period of the flood hydrograph and a flood peak that with a gentle hydrograph and longer duration shouldn't be created.This way,the efficiency of sediment transport in the lower reaches can be increased.