Relation between scour/siltation and flow/sediment combination for floods in the lower Yellow River

The channel bed of the lower Yellow River changes tremendously during flood seasons because of great sediment.Flow and sediment conditions for scour and siltation are distinct in different river reaches.The previous researches on the relation between channel formation and flow/sediment conditions are summarized for the lower Yellow River,the hydrological data of 422 floods from 1960 to 1999 are statistically analyzed and the sediment transport equations are set up for the 4 river reaches.Then the critical conditions between scour and siltation for the 4 river reaches are derived as a function of flow discharge and sediment concentration as shown in Fig.5,which indicates that the river channel would be scoured when flow is relatively clear,and would be filled when flow is relatively muddy.These relations may be used in the regulation of Xiaolangdi reservoir in order to mitigate sedimentation for the lower Yellow River.