A Comparative Study of Water Quality Indices for Karun River

Water quality is an important factor for preservation of human life and aquatic ecosystem. In rivers, water quality is affected by the environment, climate condition, seasonal variation, land-use, natural and man-made pollution of watershed. Considering growth of water use for different consumptions and discharge of pollutions in rivers, several water quality parameters are usually monitored along rivers in different periods. However, there is a need to combine results of such measurements in the form of composite indices which are understandable to decision makers and general public. For this purpose, some indices for classification of water quality in rivers have been applied world wide recently. In this paper, two Water Quality Indices (i.e. National Science Foundation of the USA and Council of Ministers of Environment of Canada) were trialed for the case of Karun River system which is the most important river of Iran. These indices were calculated using existing data and their variations have been analyzed and compared in 9 stations, located along the river, for different periods. Results showed that application of these simplified indices was satisfactory for the educational case study and could be replicated for other communities in Iran.