Study On Multi-objective Optimization Of Water And Sediment Scheduling In Cascade Reservoirs

Sediment problem is one of the important problems in plan and design of reservoir.Especially for the reservoirs that built on the sediment-laden rivers,sedimentation would lead to beneficial losses of flood control,power generation and shipping,and short the service life of reservoirs.There are many successful methods and measures for the scientific management and application of reservoirs at home and abroad.However,there were few researches on water and sediment optimal operation of reservoirs considering both water and sediment benefits,and the research was mainly focused on single reservoir.This paper focused on the multi-objective optimization of water and sediment in cascade reservoirs.Firstly,a one-dimensional sediment transport model for cascade reservoirs was established based on the one-dimensional unsteady,non-uniform and unbalanced sediment transport model of reservoir and reservoir runoff scheduling model.And taking Xiluodu-Xiangjiaba cascade reservoirs as an example,the model was verified by the existing research results.Secondly,a multi-objective optimal scheduling model of water and sediment in cascade reservoirs was devoleped,which can organically combine the objects of flood control,power generation and sediment deposition by using the multi-objective theory and method.The selection of objectives of water and sediment regualtion,model solving and decision-making method were studied.A Multilayer nested Multi Objective Dynamic Programming Successive Approximation iterative algorithm was proposed,which not only successive optimization for each reservoir,but also convert the problem of long-term optimization calculation of sediment deposition into several short-term successive optimization in view of the difficulties and time consuming of long-term optimization calculation of sediment deposition in cascade reservoirs optimal operation.And the non-inferior schemes was evaluated by using the TOPSIS method based on combined weights.Finally,the proposed model and corresponding solution methods are applied to the study on the optimal scheduling of water and sediment in Xiluodu-Xiangjiaba cascade reservoir,and the operation scheme of cascade reservoirs taking into account the requirements of water and sediment is presented.The results of this study can provide reference to the reasonable operation and long-term planning in Xiluodu-Xiangjiaba cascade reservoirs.