Effect of Cross Section Regulation in Flood Period on the Capacity of Conveyance Flood of the Lower Yellow River

The change of water level is the reflection of the interaction between stream flow and river boundaries. The interactions are different for different rivers. For ordinary rivers, deformations of riverbed are not intensive and changes of water level depend mainly upon changes of discharge. For rivers with sediment-laden, such as the Yellow River, changing quickly of river boundaries, channel erosion and floodplain deposition, erosion in flooding up and deposition in flooding down are the main characteristics of river variation in flood period. Cross section regulation affects the change of water level greatly. In this paper the effect of main channel erosion on the capacity of average or low sediment concentration conveyance flood are analyzed from quality to quantity in details. The research result is very significant to guide flood protection of the Lower Yellow River.