Research On Multi-Objective Regulation Model Of Water And Sediment In Three Gorges Reservoir

After the reservoir is built on the sandy river,a large amount of incoming sediment from upstream is intercepted in the reservoir area,which not only occupies the effective storage capacity of the reservoir,affects the performance of the reservoir,but also severely shortens the operational life of the reservoir.At the same time,the sediment deposited in reservoir area will also lead to a significant reduction in the sediment content of the outflow,which will cause serious erosion of the downstream river.In this paper,the problems of multi-objective regulation of water and sediment in the Three Gorges Reservoir during flood season are mainly studied from those aspects:establishment and solution of both of one-dimensional river network unsteady flow and sediment mathematical model and multi-objective regulation model of water and sediment,and the practical application of them.First of all,Considering the variability of water flow and the inflow of tributaries in a river,a one-dimensional river network unsteady flow and sediment mathematical model is established,and can be solved by three-level algorithm and catch-up method.Then,combining the water and sediment model with the reservoir dispatching model,using multi-objective theories and methods to analyze each target in reservoir dispatching,selecting the maximum power generation amount,the minimum sedimentation amount in the reservoir area,and the minimum downstream erosion amount as the goals,a muti-objective regulation model of water and sediment is established which can be solved by combining discrete differential dynamic programming algorithm and successive optimization algorithm to solve the model.And in order to meet the "no aftereffect" principle of dynamic programming,the "virtual database" submodule is embedded in the water In the muti-objective regulation model of water and sediment,the technique for order preference by similarity to ideal solution based on combination weights is used to evaluate the non-inferior schemes obtained.Finally,the above model is applied to the calculation of sediment erosion and sedimentation in the Three Gorges Reservoir and its downstream rivers.The results show that the one-dimensional river network unsteady flow and sediment mathematical model can accurately reflect the situation of water and sediment in the river section;the established multi-target regulation model of water and sediment can draw a non-inferior relationship between power generation,siltation in the reservoir area,and downstream river erosion.The larger the amount of power generation,the larger the amount of sedimentation,the more serious the erosion of the downstream channel,and then the technique for order preference by similarity to ideal solution mothed is used to evaluate the non-inferior schemes to obtain an operation scheme that can make the reservoir perform in balance,thereby providing a decision-making reference for the long-term reasonable operation of the reservoir.