River channel evolution characteristics of Jingjiang reach of the Yangtze river in the late period

From long series of data,the water coming from upstream of the Jingjiang reach of the Yangtze river has no increasing trend and the sediment has decreased obviously since 1990s. The flow and sediment diverted into the Dongting lake through 3 diversion outlets presented decreasing trend, especially for Ouchi diversion outlet. 1998 big flood had obvious influence on river bed evolution. Both the river channel and beach of upper Jingjiang reach were scoured and the beach scouring was more serious. For the lower Jingjiang reach, the river channel was scoured and the beach was silted up, and in general, the lower Jingjiang reach presented silting state. This paper analyses emphatically the evolution of the main river reaches since 1998 big flood, such as Shashi and Shishou reaches. The change characteristics of the river channel are sediment shoal movement, main streamline swing, the head-on scouring site moving downstream generally and bank collapse occurring frequently.