Developing environmental indices based on fuzzy set theory and evidential reasoning

Environmental indices (EI) are used as a communication tool to describe overall status of the environmental systems. Due to the uncertainty in the process of determination of EI, a fuzzy evidential method is proposed in this paper. First, the data collected from different sources are modeled as fuzzy numbers. Second, a method to transform fuzzy variables into basic probability assignments is developed based on the similarity measure between generalized fuzzy numbers. Then conflict data is efficiently combined based on the distance measure of evidences. At last, a real example to determine water quality indices is used to illustrate the efficiency of the proposed method.