Study On Optimal Allocation Of Water Resources Of Pump Station Which Can Supply The Ditch Directly And Reservoir System In Middle Region Of Jiangsu Province

Middle region of Jiangsu province has relatively abundant water resources,but the distribution is uneven within a year.Seasonal water shortage is serious and the utilization rate of water resources is low.By optimizing the water resources scheduling of the reservoir and the pump station system,this paper can reduce the abandoned water of the reservoir effectively and improve the water resources utilization efficiency,thus alleviating the seasonal water shortage in the irrigated area.This paper established a mathematical model for optimal operation of irrigation water resources with a single annual regulating reservoir and a single pump station which can supply the ditch directly with external water.The model taked the supply and demand balance of the system in each period as the target,each period's water supply of the reservoir and the capacity of water delivery of the pump station as decision variables,and considered the constraints such as the annual water supply of the reservoir,the annual water capacity of water delivery of the pump station(water right),and the operation criteria of the reservoir.The model is a two dimensional bivariate dynamic programming problem.The dynamic programming successive approximation method is used to solve the problem.During the solving process,the recursive equation of dynamic programming is extended in combination with the constraint of the reservoir operation criterion,and the process of the optimal abandoned water of the reservoir can be calculated,that is,the optimization problem of the third decision variable(abandoned water of the reservoir)can be solved.The modified recursive method can be used as a reference for similar optimization models.This paper takes Wanggang reservoir and Xiao Guowang pump station which can supply the ditch directly in Gengtiao irrigation area,Liuhe district,Nanjing as an example for comparative analysis.This paper did analysis of incoming water and using water as well as carried out water balance calculation when the water frequency is P=50%and 75%.Conventional operation method is adopted to allocate water resources and calculate the water supply of reservoirs and the capacity of water delivery of pump station in different time periods of different representative years.At the same time,using the single reservoir-single station system optimization scheduling model proposed in this paper to optimize the scheduling.Under the condition of P=50%,the water supply in each period of the year area meets the requirements of irrigation area.The water supply of the reservoirs under conventional operation and optimal operation is 9.3 million stere and 9.42 million stere.Compared with the conventional operation,the abandoned water in the optimized operation of the reservoir is reduced by 120 thousand stere,while the supplementary water in the pump station is reduced by 110 thousand stere.Under the condition of P=75%,the water shortage in conventional operation was 3.33 million stere,and in optimized operation was 3.09 million stere.Under the condition of unchanged water withdraw from pump station,the abandoned water in the optimized operation is 240 thousand stere less than that in the conventional operation.The water supply from the optimized operation reservoir is 5.57 million stere,240 thousand stere more than that in the conventional operation.Finally,this paper used Visual Basic to develop the module of optimal allocation of irrigation water resources in pump station which can supply the ditch directly and reservoir system which is suitable for irrigation areas using pump station which can supply the ditch directly and reservoir system to provide reference for management and operation of irrigation areas.