Abstract: The flow and sediment regimes downstream of Three Gorges Reservoir have undergone a significant change since the beginning of its impoundment in June 2003.Accordingly, the spatial variations in downstream channel morphology will be adjusted, in particular in the Jingjiang reach of the middle Yangtze River with eroded bank materials.In this study, the lateral migrations of channels in the Jingjiang reach in response to changes in flow and sediment regimes are investigated.The turbulent flow and sediment transport as well as the bank erosion process are simulated by two- and three dimensional numerical models.No significant changes can be found in the overall evolution of channel planform in the Shishou segment in the lower Jingjiang reach.However, localized bank collapses and plane deformations are likely to intensify due to the reduction of sediment transport, especially on the apex of bend.For the Shashi-Xinchang segment in the upper Jingjiang reach, the overall evolution of channel planform is reduced compared to that before reservoir impoundment.Up to 50% reduction can be expected in some local segments.