Optimal Water Allocation Method Based On The Improved Genetic Algorithm For A System Of A Reservoir And Two Pumping Stations

The subtropical monsoon climate zone is featured with the abundant water resources but uneven temporal and spatial distribution,so seasonal water shortages are frequent.Therefore,it is particularly important to optimize the allocation of water resources,rationally allocate and use water resources,in order to improve the utilization rate of water resources and effectively alleviate regional water shortage problems,when the total amount of water resources and the scale of current water source projects are limited.Based on the present research,an optimization model for the joint operation of a system of a reservoir and two pumping stations is developed in this paper.Based on the judgmental constraints of the operation rule,an improved genetic algorithm is proposed.By taking Zhaoqiao Irrigation District as the study case,the following aspects were developed:（1）A nonlinear optimization model for the joint operation of a system of a reservoir and two pumping stations is developed in this paper.In this model,the water supply of reservoir and pumping volume of pumping stations in each period are two types of decision variables,which are subjected to the annual available water in the reservoir,water rights of the two pumping stations and the operation rule of reservoir.However,the modern intelligent algorithms may fail in dealing with constraints of if statements like the operation rule of reservoir in this model.（2）In light of the shortcoming of the classical genetic algorithm,a modified genetic algorithm is proposed by comparing the different methods for dealing with constraints.The modified algorithm showed a better adaptability to the operation rule.The modified genetic algorithm may provide a reference for similar modern intelligent algorithms to solve optimal water resources allocation for multiple reservoirs and multiple pumping stations system.（3）This paper takes Zhaoqiao irrigated area in Liuhe District,Nanjing City as an example to conduct a case study.At the 50%and 75%probability of exceedance,calculate the incoming water volume,water consumption and analysis to balance supply and demand,as well as use conventional scheduling methods to allocate water resources respectively.At the same time,the optimal allocation model of water resources for the Zhaoqiao irrigated area system is constructed,and the minimum water shortage,the optimal water supply of the reservoir,the process of spill water,the pumping volume of irrigation pumping station and the pumping volume of replenishment pumping station are found by using genetic algorithm.And then,analyzing and comparing the results between optimization method and conventional scheduling.The results show as follows:At the 50%probability of exceedance,the water shortage has been reduced by 30,000 m3,and the water spill has been reduced by 350,000 m3.At the 75%probability of exceedance,the water shortage has been reduced by 110,000 m3 and the water spill has been reduced by 100,000 m3.Analyzing and comparing the results between optimization method and the traditional method.The results show as follows:At the 50%probability of exceedance,the water shortage has been reduced by 310,000 m3 and the water spill has been reduced by 200,000 m3.At the75%probability of exceedance,the water shortage has been reduced by 190,000 m3 and the water spill has been reduced by 150,000 m3.（4）The optimized allocation module of water resources for the joint operation of a system of a reservoir and two pumping stations was developed in this paper.This module can supply the ditch directly and reservoir system with a reservoir and two pumping stations.