Identification of river water quality using the Fuzzy Synthetic Evaluationapproach

Proper identification of water quality conditions in a river system based o n limited observations is an essential task for meeting the goals of enviro nmental management. Various classification methods have been used for estim ating the changing status and usability of surface water in river basins. H owever, a discrepancy frequently arises from the lack of a clear distinctio n between each water utilisation mode, the uncertainty in the quality crite ria employed and the vagueness or fuzziness embedded in the decision-making output values. Owing to inherent imprecision, difficulties always exist in some conventional methodologies when describing integrated water quality c onditions with respect to various chemical constituents, biological aspects , nutrients, and aesthetic qualities. This paper presents a comparative stu dy using three fuzzy synthetic evaluation techniques to assess water qualit y conditions in comparison to the outputs generated by conventional procedu res such as the Water Quality Index (WQI). Based on a set of data collected at seven sampling stations, a case study for the Tseng-Wen River system in Taiwan was used to demonstrate their application potential. The findings c learly indicate that the techniques may successfully harmonise inherent dis crepancies and interpret complex conditions. A further, newly developed fuz zy synthetic evaluation approach described in this paper might also be usef ul for verifying water quality conditions for the Total Maximum Daily Load (TMDL) program and be helpful for constructing an effective water quality m anagement strategy. (C) 2001 Academic Press.