Evaluation Of Groundwater Resources And Demonstration Of Reserve Water Source In Wenchang Space City,Hainan Province

Water is an extremely valuable natural resource that is indispensable for the survival of humans and other living things.Since Hainan Province obtained the status of the largest special economic zone and free trade port in China,its economy has been developing rapidly,and the living standards of urban residents have been greatly improved.However,with the rapid development of social economy,the demand for groundwater resources in this province has also increased year by year,and environmental geological problems such as high-speed iron water,groundwater acidification,groundwater pollution and seawater erosion have appeared.This paper evaluates the quantity and quality of groundwater resources in Wenchang Space City,demonstrates its back-up water source,and puts forward suggestions for rational development and utilization.Specifically,this paper mainly carries out the following two aspects of research:（1）Evaluate the groundwater resources in Wenchang Space CityAccording to the meteorological,hydrologic and hydrogeological conditions of the study area,the parameters are partitioned.Then,different methods were used to evaluate water resources.Firstly,the groundwater resources in the study area were calculated as 4.84×10⁸m³/a by rainfall infiltration method.Secondly,the groundwater exploitable resources are0.21×10⁸m³/a,the groundwater potential coefficient is 2.88,and the exploitation surplus is0.137×10⁸m³/a,and the single index method is used to evaluate the groundwater quality.The evaluation results show that:（1）the groundwater resources and geothermal resources in this region are abundant,and the exploitation potential is still great;（2）The chemical types of groundwater in this area are Ca-HCO₃type,HCO₃·Cl type,Cl·HCO₃type,etc.The water quality of diving and confined water in the study area is more than 98%above class III,that is,the overall water quality is good.Only a few sections（Yantang town,Changpo Town,Tayang Town and part of Futian Town）due to industry,agriculture,artificial breeding led to serious pollution of diving.（2）Demonstrate the reserve water resourcesTwo reserve groundwater sources（Moon Bay and Eastern suburbs）were selected.The evaluation of the Moon Bay reserve water source area is as follows:On the basis of collecting the previous work data and investigating the meteorological,hydrological,geological and hydrogeological data of the area,the initial values of each hydrogeological parameter are preliminatively determined according to the pumping test,rock and soil layer distribution,lithology and groundwater level dynamics in the study area,and the groundwater numerical model is established by using GMS software.Based on the water level dynamics of4 longguan Wells in Yueleang Bay hydrogeological unit,the model is identified and verified,and the model is finally obtained.Then,numerical method,water balance method,rainfall infiltration coefficient method,calculation of emergency recoverable resources and checking calculation of water level recovery period were used to calculate each water resource quantity of Yueleang Bay water source.The results showed that the reserve water resource quantity was sufficient.In case of a major emergency,if the emergency water supply was provided for90 days,The water resources of the backup water source can meet the water supply demand during the emergency period.The comprehensive index method is used to evaluate the groundwater quality of Yueleang Bay back-up water source.The results show that the water quality of this back-up water source is good,and the water points exceeding the standard are scattered.It is suggested that highly polluting industries should be prohibited from entering the Yueguang Bay emergency water source area,and a groundwater red line should be set 500m away from the coastline to avoid seawater intrusion.The evaluation of the reserve water source in the eastern suburbs is as follows:Water balance method,rainfall infiltration coefficient method,calculation of emergency recoverable resources and checking calculation of water level recovery period were used to calculate the water resources of the eastern suburbs reserve water source respectively.The results showed that the reserve water resources were sufficient,and the water resources stored in the reserve water source could also meet the water supply demand during the emergency period in case of major emergencies.Based on the comprehensive index method,the groundwater quality of this back-up water source is mainlyⅢandⅣwater,and the groundwater is basically suitable for drinking water of residents.It is suggested that the distribution of spot pollution sources and their influence on groundwater quality should be found out in the next step of water source exploration.In addition,supervision should be strengthened to prohibit the free discharge of aquaculture sewage.