Study On Reservoir Sedimentation Characteristics In Fluctuating Upstream Water Level Of Three Gorges Reservoir

In the feasibility study of three Gorges Reservoir project, one-dimensional sediment mathematical model play a very important role in the study of reservoir sedimentation. This mathematical model provide fixed bed model test, some or all of the boundary conditions for a variety of solution in the reservoir area of sediment(including changes the stream wise) and downstream riverbed incised to carry on the forecast, inside the water channel for river course construction project provide design basis. At present in the three gorges reservoir, sediment deposition of the discontinuous and one-dimensional sediment mathematical model for predicting sedimentation appeare different, so it is necessary to form the reservoir sediment deposition on the influence of water level have a more clear understanding.According to width and channel model, the near shore backflow zone model and deep pools river, Study flow characteristics of different characteristics of cross section, It turned out that the influence of impact on the upstream and downstream, vertical and lateral velocity distribution of deep pools of upstream and downstream channel model and the near shore backflow zone model has no effect. Width and channel model, impact on the vertical and lateral velocity distribution of upstream and downstream are relatively large. For solutions of velocity distribution, the influence of nears hore channel model for solution of recirculation region in the mainstream area have little influence upon sectional velocity distribution, the sides can present a closed recirculation region, the other two models of solution has a great influence on velocity distribution.According to the definition of kinetic energy correction coefficient, use the vertical velocity distribution and lateral velocity distribution formula under the condition of uniform flow calculation formula, kinetic energy correction coefficient was deduced. Kinetic energy correction coefficient reflects the uniformity of cross sectional velocity distribution and its impact factor has friction velocity, water depth H, the transverse velocity distribution parameter. According to the kinetic energy correction coefficient formula of uniform flow, kinetic energy correction coefficient formula is derived in this paper, its factors are area change rate0A/A, distance area changes and water level H L.According to the Bernoulli equation and calculation method of water surface curve compute some regularities of the variation of the upstream water level three cases deposition. When the width and the downstream river sedimentation occurs, after valley period of water level will be picked up.When the deposition in deep pools, it has no effect on upstream water level basically. When the deposition in the near shore backflow zone, it has no effect on upstream water level basically.