Research On Optimal Allocation Of Water Resources In Counties In Over-exploited Groundwater Areas

Hebei Province is extremely short of water resources.Hengshui City,located in the east of Hebei Province,has a per capita water resource less than 1/2 of the province's per capita level.The main source of water is groundwater,accounting for 89%.Over-exploitation of groundwater has formed the country's most serious "Jizaoheng" groundwater over-exploitation funnel.Jing County is located in the center of the funnel.At present,the deep groundwater level in all areas of Jing County is below 0 m,and the intensification of the contradiction between water supply and demand has become a key factor affecting the sustainable development of the local economy and society and the stability of the ecological environment.As Jing County has limited water resources,in order to ensure its sustainable economic and social development,it is inevitable to implement optimal allocation of water resources.Taking Jing County as an example,this paper constructs an optimal allocation model of regional water resources,and uses an improved non-dominated ranking genetic algorithm to rationally allocate water resources.This article mainly conducts research in the following aspects:(1)Summarize the basic situation of Jing County,analyze the water supply and demand data of Jing County in its current year.It is pointed out that the main problems in the development and utilization of water resources are the prominent contradiction between supply and demand,insufficient capital investment,insufficient development and utilization of unconventional water,and unreasonable water supply structure.(2)Combining Jing County's national economic development plan,the "Three Red Lines" and local basic data,this paper selected 2017 as the current level year,2025 and 2035 as medium and long-term planning level years,and the quota method and index forecast method are adopted to conduct the water demand forecast for each planning level year of Jing County,which is divided into basic scheme and enhanced water saving scheme;according to the water supply plan of Jing County,the supply and demand balance analysis for different planning level years is carried out,and the analysis found that there is a phenomenon that water supply exceeds demand in different planning levels.(3)Taking regional economic,social and environmental benefits as the optimization goals,and the water demand and water availability of each water sector as constraints,considering the constraints of the "Three Red Lines" indicators,the Jing County water resources optimization allocation model is established.(4)In view of the multi-objective and multi-constrained characteristics of the water resources allocation optimization model,the commonly used optimization methods are compared and analyzed,Finally,a fast non-dominated hierarchical sorting algorithm(NSGA-II algorithm)with an elite retention strategy is selected to optimize the allocation of water resources for the enhanced water-saving plan in Jing County,then this paper uses the penalty function to improve the NSGA-II algorithm to solve the optimal allocation model of water resources in Jing County.Solved the problem of NSGA-II's insufficient ability to deal with the problem with constraints.(5)The improved NSGA-II algorithm is used to obtain the optimal allocation of water resources in Jing County under different levels of the enhanced water-saving program with different guarantee rates.This paper takes the different needs of decision makers into account and selects three typical solutions for analysis of water distribution proportion,water shortage and benefit target value.The results show that the optimization model and method proposed in this paper are applicable and reasonable,and can provide effective data support for decision makers.