Hydrodynamic Modelling of the Nanjing Reach in the Yangtze River. : Managing the impact of Three Gorges dam

Abstract: Due to the impoundment of the Three Gorges Dam a decrease in sediment flow has been a major factor for erosion on the riverbed further downstream in the Yangtze River. This rapport studies the water flow conditions in the Nanjing reach. It also examines the effect of building a diversion dike at the head of the reach as a measure to redistribute some of the water flow to the northern branch. This branch suffers from a declining water flow, largely as a consequence from the erosion in the southern branch. By constructing a numerical model model with the software SMS, the current conditions of the reach were simulated. The simulated diversion dike having best effect on diverting water was able to improve the split ratio with 4.3 percentage points.