基于模糊综合优化模型的地下水质量评价

在应用模糊综合评判法进行地下水水质评估中,存在地下水质量标准与方法要求的分级标准不匹配以及隶属度绝对化的问题。文中在模糊综合评判法的基础上,引入相对隶属度概念表征评价指标与水质标准间的模糊关系,从而建立起模糊综合优化模型。应用该模型对青岛市大沽河地下水源地水质状况进行评价和分析对比,研究结果表明,地下水质量标准符合优化模型对评判标准类型的要求,克服了传统模型存在的标准不兼容问题。指标实测值介于某中间等级时,该等级与左右相邻等级的相对隶属度值均大于0。与绝对的隶属度分布相比,优化模型拓展了指标在各等级隶属度的分布,真实反映了其相对的特征。水源地南部地区(监测井S1和S3)地下水的总硬度、溶解性总固体与其他特征污染物的含量均超过Ⅳ类水质标准,优化模型判定的水质等级也为Ⅳ类水,评价结果符合研究区的实际情况,表明优化模型是可靠的。

Groundwater quality assessment based on optimization of fuzzy synthetic evaluation

Fuzzy synthetic evaluation method can be problematic when it is applied to groundwater quality assessment due to absolutization of membership degree or mismatch between national groundwater quality standard and classification criteria required by fuzzy synthetic evaluation. Here, we created an optimized fuzzy synthetic evaluation model to solve these problems. We introduced the concept of relative membership degree for establishing a dynamic fuzzy relationship between evaluation index and groundwater quality standard. Furthermore, we used the optimized model to analyze and assess the groundwater quality of the Dagu River Basin in Qingdao for validation. The results show that the national groundwater quality standard satisfied the requirements of evaluation criteria type in the optimized model. The optimized model solved the incompatibility problem in the traditional model. When the measure index fell in a mid-grade interval, the relative membership degrees for this and two adjacent grades were greater than 0. Compared with the absolute distribution of membership degree, the optimized model expanded the distribution over different grades and reflected the relative and dynamic characteristics of the distribution. The overall hardness and total concentration of dissolved solids and other characteristic pollutants exceeded the threshold value for grade IV groundwater quality standard in the southern area (monitoring wells S1 and S3), in agreement with the optimized model assessment. Thus we have verified the reliability of the optimized model.