Abstract:
With the new demands of the 12th Five Year Plan, in terms of navigation, reservoir operation and ecology, new river regulation works for the reach from the Three Gorges dam to the Gezhouba dam are required. So it is very important to recognize the evolution of the river in the recent years. Based on the measured data since the Gezhouba dam was operated, the river channel process between two dams in recent more than 30 years is analyzed. From 1979 to 1983, the river reach silted obviously; from 1983 to 1998, the siltation process slowed down considerably. After 1998, erosion of bed was beginning, in particular, since the operation of the Three Gorges dam in 2003. The deep channel was eroded remarkably in the cross section, along the longitudinal direction, Letianxi and Nanjinguan river reach were eroded mostly, and the middle reach was in a stable condition. Since 2008, the erosion of bed has become slow. In the past 30 years, the river bed was scoured after deposition and became balanced gradually, and the river regime was stable. After the operation of the Three Gorges dam, there was no clear relationship between the reach channel process and sediment condition, but it was influenced distinctly by the flood. The Three Gorges reservoir will continue to test operation, and will gradually enter the normal operation period, the river reach between the two dams will be not easily deposited, slight siltation will be extremely possible, and the river regime and the most part of the channel will be relatively stable.