Ensemble MCDM Approach to Determine Priorities of Parameters for WQI

Priorities of different water quality parameters are required to be determined for the calculation of Water Quality Indices. The procedures of determining priorities (importance) to the parameters are often subjective and preferential. The present study proposes an objective and non-preferential method to determine the priorities of water quality parameters to calculate Water Quality Index. Relative importance of the parameters were determined on the basis of important criteria like hazard potential, utility, cost, and citation frequency using Multi-Criteria Decision-Making methods like Analytic Hierarchy Process, Fuzzy Logic Decision-Making, and their combinations. Different Water Quality Indices (MCDM WQI) were developed from the priority values of the parameters, determined by each of the methods applied. A case study was performed in Tripura, India to validate those Water Quality Indices. Sensitivity analysis, statistical analysis, and comparison with an established Water Quality Index (NSF WQI) were performed for each of the indices developed. The MCDM WQIs were found to be close to NSF WQI (less than 2% deviation) and also follow similar patterns. The Hybrid AHP-FLDM method was found to be closest to NSF WQI (0.29% deviation) among the methods used. Thus, the MCDM WQI is successful in representing the overall water quality.