The sediment erosion and deposition in the backwater region are influenced by both Danjiangkou Reservoir and the channel. The range and amount of the sediment changes depends largely on the maximum and the minimum operation water levels which have big effects on the backwater region. According to the analysis on the existing 36 - year measured data of Danjiangkou Reservoir, the sediment change in backwater region is characterized by the periodically so - called feature of “two erosions and one deposition”, and it develops toward equilibrium transport status along the channel. Under the control of the two operational water levels, there are two periods of bed formation and two corresponding cross sections in the flood and the dry seasons, respectively. In these cross sections, four bed formation developments, featured with so - called “channel first and bars second”, can be identified. Both the deposition and the dynamic equilibrium reservoir - reach develop progressively from upstream to downstream. In the dynamic equilibrium reach, there are only two types of channels, i.e., straight and meandering. Consequently, the bed change within the backwater region develops toward the uniform form.