Abstract

The sediment erosion and deposition in tail water region is influenced by both reservoir and channel. The range and amount of the sediment changes depends largely on the maximum and the minimum operation water level which have big effects on the tail water region. According to the analysis on the existing 36-year measured data of DanJiangKou Reservoir, the sediment change in tail water region is characterized by the periodic so-called feature of “two erosions and one deposition”, and it develops toward equilibrium transport status along the channel. Controlled by 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 reach develop from upstream to downstream. In the dynamic equilibrium reach, there are only two types of channels: straight and meandering. Consequently, the bed change within the tail water region develops toward the uniform flow conditions.

Keywords: Reservoir, Varying Backwater Region, Sediment Erosion and Deposition, Bed Formation, Channel Type, Dynamic Equilibrium, Uniform Flow