Tianjin Groundwater Pollution Risk Assessment Methods And Applications

Tianjin is a typical resource-based water shortage city.Groundwater plays an important supporting role in the development of urban economy.However,with the development of urbanization,industrialization and agriculture,groundwater resources have been over-exploited.The groundwater environment is facing serious pollution threats,which is gradually transferring from shallow groundwater to deep groundwater.Once groundwater resources are contaminated,the cost of recovery is very expensive.Therefore,to protect groundwater resources,principles of “taking prevention as the main,with treatment combined” should be adopted.Groundwater pollution risk assessment can identify the potential of groundwater contamination in different areas.Based on this,high-risk areas.can be identified.It has great reference values for the selection of groundwater source,control of groundwater pollution,and plan of land usage.(1)This article analyzed go deeper into the existing research results of groundwater pollution risk assessment.The situations of groundwater hydrogeological conditions,development and utilization,water quality distribution and pollution distribution in Tianjin were collected.The data used for research of groundwater pollution risk assessment was obtained.The groundwater pollution risk evaluation index system was constructed,from the vulnerable of groundwater,the load of pollution and the value of groundwater function.(2)Based on the principle of variance maximization,the combination method of subjective weight and objective weight was proposed.Then,based on fuzzy mathematics theory and the combined weight method,the evaluation model of groundwater vulnerability,the evaluation model of pollution load and the evaluation model of groundwater value function.(3)Respectively,using two representative international groundwater pollution risk assessment system: U-N system and W-P system,the evaluation model of groundwater vulnerability,the evaluation model of pollution load and the evaluation model of groundwater value function were combined.(4)Taking the shallow groundwater of Tianjin as study case,.the original data of each evaluation index was extracted by ArcGIS 10.2,U-N system evaluation model and W-P system evaluation model were applied,respectively.Results derived from U-N system evaluation showed that the level of groundwater pollution was between 4.07 and 7.23.The medium risk areas covered over 70% including Jixian,Wuqing,Baodi,Ninghe,Jinghai and outer suburb areas.The higher pollution risk areas were mainly distributed in the Binhai and the part areas of Beichen,Dongli,Jinnan,Xiqing.These region had the common characteristics that economy was developed,raw sewage was more,population density was higher,and pollution load was higher.Results derived from W-P system showed that the level of groundwater pollution is between 4.40 and 6.43.The medium risk was over 80% including central and southern most of the region in the research of Tianjin.Slightly higher risk areas were located in the Binhai,Jinnan,the small area of Xiqing,Wuqing,Baodi,Jixian.Binhai and the small areas of the suburbs.In these regions,economy was developed,raw sewage was more,population density was higher,and pollution load was higher.In Wuqing,Baodi and Jixian,the value of groundwater is large,non-point sources pollution was the main the more pollution form.In conclusion,The evaluation system of U-N system and W-P system had affected the results of groundwater pollution risk.The impact of groundwater value on groundwater pollution risks is highlighted in the W-P system.The U-N system was more comprehensive.It was suitable for the evaluation of groundwater pollution in Tianjin.