岩溶地区地下水污染风险评价方法探究——以地苏地下河系流域为例

Exploration of risk assessment method towards groundwater contamination in karst region:A case study in Disu underground river system basin

岩溶地下水污染风险评价对岩溶地下水的保护、管理和合理利用具有重要意义。文章总结了近年来国内外地下水污染风险评价方面的研究进展,针对目前评价体系存在的不足,构建了适合岩溶区地下水污染风险评价体系。该方法基于欧洲模式,实现地下水防污性能评价;污染负荷评价则考虑污染物在覆盖层中的衰减过程,利用折减系数实现污染负荷量化;最后,基于GIS空间叠加分析耦合防污性能与污染负荷评价,实现区域地下水污染风险评价。文章以地苏地下河系流域为例,开展岩溶区域地下水污染风险评价,结果表明:区域整体地下水污染风险偏低,地下水中等及以上污染风险区域面积424.41km^2,占研究区总面积的39.03%,主要分布在研究区中东部地苏乡、东庙乡、六也乡局部等人类活动频繁与地苏地下河干流中下游段。地下水污染风险空间分布特征不仅显示了岩性、坡度、岩溶网络发育等自然条件对评价结果的影响,同时也反映了人类活动的影响。地势平缓,岩溶发育程度强烈,加之人类活动频繁是导致区域地下水污染风险较高的原因所在。

Groundwater contamination risk assessment is of great significance in protecting, managing and reasonably utilizing karst groundwater. In this paper, various methods in regards with groundwater contami- nation risk assessment were comparatively reviewed. As a result, a new groundwater contamination risk as- sessment method which is suitable for small karst area was proposed, in view of the disadvantage of the cur- rent methods and based on European model which has often been used to assess the groundwater vulnerabili- ty in a research area. By considering the contaminant attenuation effect, this research focused on the quanti- fication of the reduction coefficient of contaminant load. Moreover, based on GIS spatial analysis, the assess- ment of the environmental risk of groundwater contamination in a research area was performed. To verify the suitability of the method developed, a case study was conducted in Disu karst underground river system. The results show that risk of groundwater contamination in the research area is relatively low. The areal size with moderate and high groundwater contamination risk is 424.41 km2 , accounting for 39.03 % of the total re- search area. The high-risk areas include Disu town, Dongmiao town, Liuye town, with frequent human ac- tivities, and the middle and lower reaches of Disu underground main river stream. Furthermore, for this re- search it is suggested that the spatial characteristics of the groundwater contamination risk in the areas is af- fected not only by the natural factors such as lithology, gradient, development degree of karst and etc. ,but al- so by human activities. High groundwater contamination risk of the region is mainly attributed to the gentle terrain slope, dense karst network and strong human activities