Water Quality Assessment Based on Combined Multi-Criteria Decision-Making Method with Index Method

This work presents combined approach to water quality assessment based on both Water Quality Indices (WQI) and Multi-Criteria Decision-Making (MCDM) methods. Using weights from the official WQI calculation algorithm, the model for MCDM was formed and presented on the case of the Danube River water quality in Serbia. By applying PROMETHEE method, locations of potential environmental risk were determined and ranked according to the quality of water. Using its visual modeling option GAIA, the most dominant variables that affect the quality of water at certain locations were identified as polluting parameters (suspended matter, BOD-5, total N, NH4-N and PO4-P). Concentrations of identified pollutants were compared with limits of both EU and national recommendations so the actual water quality of the river was determined. The results showed that although WQI analysis indicated good and very good water quality, extension with MCDM methods revealed that there is a significant excess in values of PO4-P and E.coli at almost every location on the course of the river, as well as in values of total N and NH4-N. Proposed combined approach could serve to engineers and decision makers involved in water quality management in creating more detailed reports on water quality while facilitating the process of decision-making in the choice of selection of particular locations with critical water quality, where appropriate measures for remediation of pollution should be taken.