Modifying the analysis made by water quality index using multi-criteria decision making methods

Abstract Groundwater should be considered as the most important drinking water resource in arid/semi-arid regions such as Karaj, Iran. Provision of drinking water with a preeminent quality is, accordingly, a real matter of concern in these regions. Despite being an essential factor for rating of under exploitation water wells, Water Quality Index (WQI) entails conflicting issues. As a result, Multiple-criteria decision making (MCDM) models, such as Technique for order preference by similarity to ideal solution (TOPSIS), Compromise Programing (CP) and Ordered Weighted Averaging (OWA) operators were adopted to alleviate contradictions involving WQI index. In the current paper, compromise programming was utilized assuming p = 1&2 and the average value of ranks attained from all the above MCDMs (Averaged value rating) was correspondingly cited as a rating reference. Putting the above MCDM models into practice, ultimately, led to striking variations not only in the rankings but in category of water wells. It was clarified that compromise programming when p values are assumed to be 1 and 2 (CP (p = 1) & CP (p = 2)), TOPSIS and OWA could be recognized as proper techniques to eliminate contradictions involving ranking by WQI index.