Analysis Of The Changing Regulation Of Sediment Carrying Capacity And Simulation Of Sedimentation In The Three Gorges Reservoir

Reservoir sedimentation has a significant influence on evolution of river-bed and engineering application,it has been a hot research at home and abroad.In the feasibility research of the Three Gorges Project,the one-dimensional model of sediment has played a vital role in the study of sedimentation in the reservoir area.However,since the operation of the Three Gorges Project,the conditions of sediment input of the upper reaches of the Yangtze River have changed significantly,the sedimentation in the reservoir area shows a different response contrast to the demonstration stage,the mathematical model parameters of the sediment need to be redefined.Based on the measured water and sediment data,using the method of sediment discharge?section method?sediment transport equation,The formula of settling velocity is fitted?analysis of the changing regulation of sediment carrying capacity and simulation of sedimentation in the Three Gorges Reservoir,the following conclusions are obtained:(1)Based on the measured data in the reservoir area and the experimental data of settling velocity and flow velocity,the formula of settling velocity and flow velocity is fitted,get the relationship between settling velocity and flow velocity under different conditions.Through the accumulated sedimentation ? sediment concentration ?comparison of estimated longitudinal sedimentation with measured value in the TGR,Verify the relationship between settling velocity and flow velocity conform to the actual situation;(2)Temporal distribution of sediment carrying capacity: The sediment carrying capacity is big before the impoundment of the Three Gorges Dam,the sediment carrying capacity obviously decreased at initial,while the sediment carrying capacities decreased gradually due to the rising of the water level after the impoundment.The sediment carrying capacities at the wide reaches reduced greatly to the values smaller than the sediment concentrations,thus deposition occurred.While the reduction of the sediment carrying capacities at gorges was relatively small,and the sediment capacities were still bigger than sediment concentrations,no cumulative deposition happened consequently;(3)Longitudinal distribution of sediment carrying capacity: The sediment carrying capacity is big in the fluctuating backwater region,while it decreased in the permanent backwater region.But the sediment carrying capacity in the reach of dam 50 ~ 170 km is obviously larger than that of 180 ~ 400 km upstream and the wide reaches of the downstream dam;(4)Analysis of longitudinal sedimentation in the TGR based on the sediment carrying capacity: The sediment-carrying capacity is large at the gorge reaches where the width of the river is narrow,and the sediment-carrying capacity is smaller at the wide reaches where the width of the river is wider.Thus the sediment deposition occurred primarily at the wide reaches,while no deposition occurred at the gorge reaches;(5)According to the prediction of the trend of sediment deposition in the reservoir area,the siltation of the Three Gorges reservoir has been running for 30 years,and the spatial distribution of the sediment deposition in the reservoir area has been the same for 10 years,20 years and 30 years.