Application of variable fuzzy sets method in comprehensive evaluation of water quality

Under systematic view,a comprehensive evaluation model for water quality was established based on variable fuzzy sets method,and the water quality evaluation was converted from the qualitative assessment to a quantitative one.The method can scientifically and reasonably determine membership degrees and relative membership functions of water quality indexes at level interval.Weights of indexes can be obtained by binary comparison and quantification based on the importance of indexes.By calculating the characteristic value of each level,water quality of the Yongding River in Beijing was evaluated using the variable fuzzy sets method,which showed that the proposed method was feasible.