Study on critical conditions of scour-and-siltation in flood seasons in the lower Yellow River

The channel bed of the lower Yellow River changes tremendously during flood seasons because of great sediment concentration.Critical conditions between scour and siltation are distinct in different river reaches.The authors summarized previous researches on the critical conditions for the lower Yellow River,analyzed statistically the hydrological data of 422 flood events from 1960 to 1999 and set up critical equations for 4 river reaches(Huayuankou upward,Huayuankou to Gaocun,Gaocun to Aishan and Aishan to Lijin) under different combinations of flow and sediment at 3 stations (Sanmenxia, Heishiguan and Xiaodong).The critical relations between flow discharges and sediment concentration for the 4 reaches were depicted.These relations may be used in the regulation of Xiaolangdi Reservoir in order to mitigate siltation for the lower Yellow River.-