两阶段模糊法在水质评价中的应用——以嘉善县流域为例

Application of Two-Stage Fuzzy Set Theory to Water Quality Evaluation of Rivers in Jiashan County

采用两阶段模糊法对嘉善县河流水质进行评价,将国家地表水水质标准引入到聚类分析中,依据标准对原始数据进行分段线性归一化,将标准评级后作为模糊聚类中心,对评价对象进行聚类,得到替代原观测值的全局指标IRQ。从空间和时间两方面对所得的全局指标进行分析,分析结果表明嘉善县东南部区域水质污染较北部区域更为严重,年际间水质无明显改善,年内水质优劣比较:丰水期>平水期>枯水期。

Two-stage fuzzy set theory was used to evaluate the water quality of rivers in Jiashan County. Unlike the traditional fuzzy clustering methods, in this study, the original data were first piecewise linearly normalized according to the national surface water quality standards. The standards were rated as fuzzy cluster centers and the objects were classified. Then an overall index, i.e. the river quality index （I RQ）, was constructed to represent the original monitoring data. The results indicated that water pollution in southeast region was more serious than that in the northern region, and the sequence of water quality from good to bad in a year was wet period, flat water period, dry season.