DEFORMATION AND ROUGHNESS CHANGES OF THE MAIN CHANNEL AND FLOODPLAIN IN FLOOD EVENTS (CASE STUDY )

This paper presents an analysis of the data measured at stations along the middle reaches of the Huaihe River in the early 1950s. Its results show that the river bed changed dynamically during a flood process and the variation of the channel cross-section area could be as large as 600-700 m 2, which is 20 to 25 percentage of the cross sectional area of the main channel at bankfull stage. Moreover the channel roughness increased or decreased with erosion or deposition. In case of bed erosion, the effect of roughness change on discharge capacity was evaluated sometimes greater than that of cross-section area change. From a flood control point of view, the roughness near the peak of a flood process characterized by erosion should be given special attention.