Analysis of reservoir water quality using fuzzy synthetic evaluation

A general methodology for fuzzy synthetic evaluation is developed and illus trated with a case study of trophic status assessment for Fei-Tsui Reservoi r in Taiwan. The historical data base was collected from the management age ncy of Fei-Tsui Reservoir from 1987 to 1996. In fuzzy synthetic evaluation, the classification is determined by a matrix operation of the weighted vec tor with the fuzzy evaluation matrix. After all individual membership funct ions of evaluated factors have been determined, the fuzzy evaluation matrix can be established. The weighted vector is determined by the analytic hier archy process method (AHP). The results of this investigation show that the long-term change of water quality and the overturn phenomena cannot be obs erved with the Carlson index from 1987 to 1992 but is expressed by fuzzy sy nthetic evaluation. Fuzzy synthetic evaluation is better suited than the Ca rlson index to rating the trophic status of self-sustaining lakes. Interpre tation of the results can provide valuable information to decision makers a nd aid reservoir management.