Groundwater Pollution Risk And Water Function Assessment In Qaidam Basin

This paper is based on the "Groundwater Pollution Investigation and Evaluation in theMidwest Region" project of the China Geological Survey and the "Investigation and Evaluation of Groundwater Resources and Environmental Problems in the Qaidam Basin" project.The groundwater function evaluation and pollution risk assessment are the main research contents.The pollution risk assessment is based on the groundwater antifouling performance evaluation,and the groundwater pollution risk assessment is performed under the influence of the pollution source hazard;The main evaluation factors of the groundwater function assessment are based on the groundwater quality,the evaluation of groundwater potential and ecological sensitivity.Considering the groundwater pollution risk of this condition,the geological environment functions,resource functions and ecological functions are evaluated,respectively,and then the groundwater function is evaluated according to the groundwater function evaluation system and evaluation method.The main results are as follows:1.The single-factor assessment results of groundwater quality were basically consistent with the overall evaluation results,which all indicated that the water quality of Dulan County,Golmud City,Dachaidan Town and Delingha City in the southeast of the Qaidam Basin are of good quality while the Leng Hu Town,Mang Ya Town and Wulan countyin the northwestof the Qaidam Basin is relatively poor.In order to ensure the safety of residents' domestic water and livestock drinking water,single-factor evaluation results are selected as groundwater quality evaluation results.2.The antifouling performance evaluation results show that the antifouling performance of poor areas are mainly concentratedin the salty brine area of the central basin with shallow groundwater and poor natural protection power,while the better antifouling performance areas are mainly concentrated in mountainous areas or flushing floods and accumulation of plains with deeper groundwater and good natural protection power..3.The areas with higher pollution risks are mainly located in Huatugou Town,Lenghu Town,Dachaidan Town,andaround some lakes in the middle of the basin,such as Wulan Lake,Tuosu Lake;the areas with low pollution risk are mainly located in high altitude plains and mountainous regions.The antifouling performance is relatively good.Although there are some metal deposits in the area,these pollutants are not easy to enter the aquifer and thepollution risk is relatively low.4.The main achievements of groundwater function evaluation are as follows:(1)The development area covers 11.27% of the total area,including centralized development zones and decentralized utilization areas,which are mainly distributed in Golmud City,Delingha City,Xiangride Town,Mahai Basin and Huatugou Basin.(2)The protected area covers 31.85%of the total area,including groundwater conservation area and ecologically fragile area,distributed in the vicinity of the groundwater overflow belt in the south of the basin,and in the center and the west of Huahaizi Basin and Delingha Basin,and the west of Huatugou Basin,Wulan County and Chahanwusu Town.(3)The area of the reserved area accounts for56.88% of the total area,including unexploitable areas,emergency water sources and reserve areas,which are mainly distributed in most plain areas in the middle of the basin and some areas around Dachaidan Lake.