Quantification of environmental impact of water pollutants using fuzzy comprehensive model

This paper proposes a fuzzy logic model to evaluate Water Quality Index (WQI) by taking into consideration both freshwater of Mandovi River and seawater intrusion into the river. Pollutant (viz. Fluoride, Nitrate, Nitrite, Chloride, BOD, and TDS) concentrations are treated as variables, making this a multivariate problem. The variables are ranked based on their Indian standard limits, and numeric weights are obtained for each variable. Pollutant concentrations are translated into fuzzy membership values depending on the significance of each pollutant. Based on conditional rules developed using the weights, the aggregate effect of the pollutants is obtained, which then translates into linguistic attributes. This model not only categorizes water quality as good or bad but gives a quantitative comparative judgment on water quality. The results ensure that borderline cases are dealt with in a more user-friendly manner to provide a comprehensive status on water quality, an edge over the previous research.