CRITICAL BETWEEN SCOUR AND SILTATION FOR FLOOD SEASONS IN THE LOWER YELLOW RIVER

The channel bed of the lower Yellow River changes tremendously during flood seasons because of great sediment. Critical conditions between scour and siltation are distinct in different river reaches. The paper summarized previous researches on the critical conditions for the lower Yellow River, analyzed statistically the hydrological data of 422 floods from 1960 to 1999 and set up critical equations for the 4 river reaches. The critical relations between flow discharges and sediment concentration for the 4 river reaches are shown as Fig.4, which indicates that the river channel would be scoured when flow is relatively clear, and 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.