Evaluation of the Water Quality of Soufi Chai by Shannon Entropy and AHP Methods

Evaluation of the changes in river water quality plays key role in sustainable management of surface water resources. This study evaluates the river water quality of Sofi Chai River using the water quality index (WQI) from 1972 to 2016. Shannon's Entropy Method and Analytical Hierarchy Process (AHP) have been used to determine the relative weight of water quality parameters and then these parameters have been compared with the weights provided by the World Health Organization (WHO). Qualitative parameters of Electrical Conductivity (EC), acidity (pH), Total Dissolved Solids (TDS), calcium (Ca2+), bicarbonate (HCO3-), sulfate (SO42-), chloride (Cl-), magnesium (Mg2+) and sodium (Na+) have been used to evaluate the water quality of Soufi Chai River. The results of this study show TDS and EC in AHP and sodium, chlorine and sulfate in the Entropy Method are the most effective parameters on the water quality of Soufi Chai River. The average of Water Quality Indicator calculated by the weighting methods such as entropy, AHP and standard weighting of the WHO during the period of 1972 and 2016 are 13, 38 and 16, accordingly, which indicates that the water quality of Soufi Chai River is excellent.