Regulation indexes of the medium flood in the Lower Yellow River

The rationality of flow-conveying ability of 4 000m~3/s in the main channel of the Lower Yellow River in the near future was discussed from the runoff condition of forming main channel,mobile-bed resistance,training works and flood control of the floodplain etc.The threshold of the flow discharge which can cause obvious silting in the floodplain and scouring in main channel was then proposed.Besides,the regulating indexes to the flow discharge and sediment concentration released from Xiaolangdi reservoir were proposed according to the sedimentation characteristics corresponding to different discharges in the Lower Yellow River.The indexes are that the over floodplain discharge should be more than 6 000 m~3/s and the concentration be less 300kg/m~3 under the objective main channel,for the light over floodplain flood and non-over floodplain flood the discharge and concentration should be regulated as 4 000m~3/s and 50 kg/m~3.The discharges ranges from 4 000 m~3/s to 6 000m~3/s and from 800 m~3/s to 2 300 m~3/s in the Lower Yellow River should be avoided.