Selection of suitable aggregation function for estimation of water quality index for the Orontes River

Abstract

This study aims to select the most appropriate aggregation function to determine a preliminary classification of water quality according to special criteria for required use. The Orontes River was taken as a study case as an important water resource, to assess the suitability of its water for various uses by using water quality index. Four main steps were applied to build a water quality index; the first step is selecting parameters using the Delphi technique based on experts' opinion, where 5 parameters of the most important water pollutants were selected, the relative weight of each parameter was determined based on its significance to the final index using the weight criteria method. To standardize the range of pollution indicators, the quality rating curves for each parameter were drawn using regression analysis and extracting equations for the quality rating qi. The final step is aggregation Sub-indicators, about 20 aggregation functions were applied to select the most appropriate aggregation function for assessing the water quality of the Orontes River (ORSI) based on special criteria (Ambiguity, Eclipsing, Constant functional behavior, weight, sensitivity). After comparing the values of the indicators based on the criteria, the results showed that the weighted arithmetic mean (ORSIwa) is the best linear function for assessing the Orontes River water quality by the classifications of the main categories according to the required use.