Abstract: Owing to the impoundment of the Three Gorges project(TGP),water and sediment conditions,as well as the evolution process,in the downstream of the dam have been changed.The Yaojian reach in the middle Yangtze River is chosen as a typical example of meandering and bifurcated channels.A 2D flow-sediment mathematical model of the Yaojian reach is developed in the study.The bed erosion and deposition in the following 20 years after the impoundment of TGP are calculated and analyzed according to the historical da...