Evaluation of Irrigation Water Quality by Data Envelopment Analysis and Analytic Hierarchy Process-Based Water Quality Indices: the Case of Aksaray City, Turkey

In this study, two water quality indices (AHP-IWQI and DEA-IWQI) based on Data Envelopment Analysis and Analytic Hierarchy Process have been produced in order to evaluate the water quality of surface waters used in agricultural irrigation. Depending on the efficiency scores of indices, two different water quality classification systems, which are composed of four suitability categories, have been defined. The 10 different alternatives and a total of 13 sub-criteria classified under 3 main criteria groups were used in the establishment of a hierarchical structure. For the sub-criteria, efficiency scores for electrical conductivity and sodium adsorption ratio having the highest efficiency score were calculated as 0.214 and 0.148, respectively. The results obtained from the indexes were compared with the results of the United States Salinity Laboratory and Wilcox diagrams. The comparative results of the predictions by AHP- and DEA-based indexes show that the accuracy ratio of the DEA-IWQI is higher than of the AHP-IWQI.