Proposing a Quality Index for Rivers of Iran

Rivers are water resources which are exposed to different amounts of pollutants. Therefore having awareness of qualitative variation of rivers is necessary. Using water quality indices is one of the methods for analysis of water quality. In this study, kind and weight of the variables included in the valid national and international water quality indices are examined statistically. Then, the performance index curves of the variables are produced based on the various standards and guidelines. In the next stage, using the Delphi method 9 variables are selected as the effective variables for water resources in Iran and their weights are determined based on the analytical hierarchy process. Curves with high correlation coefficient are fitted to the quality values proposed by the specialists and geometric average function is employed for combination of sub indices and calculating the final value of the quality index. The value of the proposed quality index is calculated for the Karoun river and is compared with the other quality indices. According to the obtained results, interpretation of water quality in the Karoun river based on the presented new quality index differs from the other quality indices.