Influence of water diversion along the lower Yellow River during flood period "02.9" on river evolution

Based on the systematical analysis of water and sediment routing during small stratified flow sediment transportation, riverbed scour and silting evolution and situation of water and sediment diversion along the river in Xiaolangdi Reservoir on the Yellow River in September of 2002,the unsteady flow quasi-2D numerical model is adopted to calculate and analyze the influence of lower Yellow River water diversion along the channel on river evolution. The calculating result shows that suspended sediment transported by the stratified flow is with small radius, however, according to the small flux, the flow is still in state of over-saturation sediment transport;the proportion of water diversion in lower river accounts for a large part of reservoir sluice capacity, and large quantity of sediment is induced outside of bank, which decreases the silt compared with non-water diversion.