基于改进DRASTIC模型的平原河网地区地下水脆弱性评价

Groundwater Vulnerability Assessment in Plain River Network Areas Based on the Improved DRASTIC Model

DRASTIC模型易使用,在国内外地下水脆弱性评价方面得到广泛应用,但平原河网地区地势平坦、地下水埋深浅,DRASTIC模型需根据其特征进行改进,目前应用尚不多见。该研究结合平原河网地区水文地质特征,选取地下水埋深、净补给量、含水层厚度、水力阻力及含水层渗透系数5个指标改进DRASTIC模型,基于GIS软件构建平原河网地区地下水脆弱性评价DRAHC模型,并以上海市为例,进行实例计算与评价。结果表明上海市地下水脆弱性总体较高,"较高"和"高"占全市总面积45.27%,"中等"占33.08%,"低"和"较低"占21.65%。各指标的单参数敏感度分析和地图移除敏感度分析结果显示,有效权重与理论权重大小排序基本一致,每个指标去除均对地下水脆弱性评价结果产生较大影响,说明DRAHC模型在平原河网地区应用的合理性。该研究结果能够为上海市地下水资源管理提供依据,为类似区域地下水脆弱性评价提供参考。

The DRASTIC model is easy to use and has been widely used in groundwater vulnerability assessment at home and abroad.However,in plain river network areas,the DRASTIC model needs to be improved according to the characteristics of flat terrain and shallow groundwater depth,and its application is still limited at present.In this study,combined with the hydrogeological characteristics of plain river network areas,five indexes including groundwater depth,net recharge,aquifer thickness,hydraulic resistance and aquifer permeability coefficient were selected to improve the DRASTIC model.Based on GIS software,DRAHC model for groundwater vulnerability assessment in plain river network areas was constructed,and Shanghai was taken as an example of application for calculation and assessment.The results showed that the vulnerability of groundwater in Shanghai was generally high.According to the classification standard,"high"and"higher"accounted for45.27%of the total area,"medium"accounted for 33.08%,and"lower"and"low"accounted for 21.65%.The results of single parameter sensitivity analysis and map removal sensitivity analysis of five indexes showed that the order of effective weights were basically the same as the theoretical weights,and each index removal had a great impact on groundwater vulnerability assessment,which showed the rationality of DRAHC model applied in plain river network areas.The results can provide a basis for groundwater resource management in Shanghai and a reference for groundwater vulnerability assessment in similar areas.