基于DRASTIC模型优化的地下水污染风险评价研究

Assessment of groundwater contamination risk based on improved DRASTICmodel

地下水污染风险评价是地下水污染防治的方法之一,但传统的地下水污染风险评价仅考虑了自然条件因素,未考虑人类活动影响.因此,本文提出一种地下水脆弱性与污染荷载结合的评价方法,通过引入土地利用类型指标对DRASTIC模型进行优化,从毒性、释放可能性和可能释放量3个方面定量评价污染源荷载;同时,构建了基于DRASTIC模型优化的地下水污染风险评价指标体系,并以西部半干旱地区西宁市为例,在宏观尺度上评价该地区地下水污染风险,并通过地下水脆弱性和污染源荷载叠加,研究了该区域地下水污染风险.结果表明,研究区地下水脆弱性整体偏低,污染风险水平较低;较高脆弱性和高脆弱性区域主要分布在湟水河河谷两侧,占比约23%,该区域地下水埋深浅,含水层厚度薄;此外,工业污染源的潜在污染风险最高,高荷载区占评价区域总面积的0.272%;较高风险和高风险区面积为293.96 km^(2),占总面积的3.84%,主要分布在湟中区东部和城东区南部.本研究结果可为后续地下水污染防治重点区划等工作提供科学依据和参考.

The risk assessment of groundwater contamination could prevent and control groundwater contamination.However,traditional risk assessment of groundwater contamination only considers natural conditions without considering the impact of human activities.Therefore,we proposed an assessment method combining groundwater vulnerability and pollution load.By introducing the indicators of land-use type,we optimized the DRASTIC model with the quantitative evaluation of pollution source load from three aspects:toxicity,release possibility and possible release amount.The risk assessment index system of groundwater contamination was constructed on the optimization of DRASTIC model.Taking a semi-arid region in the west China,Xining City,as an example,the risk of groundwater contamination was assessed at a macro scale.The research results indicated that the overall vulnerability of groundwater in the study area was relatively low,and the level of pollution risk was relatively low.High vulnerability areas were mainly distributed on both sides of the Huangshui river valley,accounting for about 23%.The groundwater depth in this area was shallow,and the thickness of the aquifer was thin.In addition,the potential industrial pollution risk was the highest,and the high load areas were accounted for 0.272%of the total assessed area.The area of high-risk areas was 293.96 km^(2),accounting for 3.84%of the total area,which was mainly distributed in the eastern part of Huangzhong district and the southern part of Chengdong district.The results of this study could provide scientific basis for the subsequent groundwater pollution prevention and control.