Investigation of Water Quality of Chehelchay River Using IRWQIsc Index

Rivers water quality study can be a great help to water-resource management and planning. This study was conducted to investigate the water quality of Chehelchay River using the IRWQISC.

In this study, water samples were collected from seven different stations along Chehelchay River during a period of 6 months. In order to use IRWQISC, the physicochemical and biological some parameters were measured. After calculating the IRWQISC values for each station, the changes in the IRWQISC values were investigated along river. Then, the results of IRWQISC were compared drinking water and agriculture water standards.

The results of this study showed that Chehelchay River water was situated in a relatively good quality category based on the IRWQISC. IRWQISC diminished in the flow direction from the upstream sampling point to the outlet of basin resulting in a reduction in water quality of river. Results also showed that there is a direct relationship between IRWQISC and the rate of discharge so that the value of IRWQISC increases with increasing the rate of discharge.

The results of this study showed that the average IRWQISC index was better than summer season in spring. Flow changes and IRWQISC index indicate a direct relationship between them, with a slight increase in the rate of fluctuation. Comparison of parameters used in IRWQISC with drinking water and agriculture water standards showed the Chehelchay River water is suitable only for agriculture uses and it cannot be used for drinking purposes. Results showed that water purification must be performed to remove fecal coliform and reduce turbidity of water before using as a drinking water source.