Water Quality Assessment of Gheshlagh River Using Water Quality Indices

Document Type : Original Articles


1 Department of Environmental Engineering, Faculty of Environment, University of Tehran

2 Department of Environmental Pollutant, Environmental Sciences Research Institute, University of Shahid Beheshti


Comprehensive information and knowledge about the quality of water resources plays a very important role in preservation plans for water resource management. One of the engineering methods used to assess river water quality conditions without mathematical and statistical complexity is water quality indices. In this method, different water quality parameters are analyzed and interpreted in a river water quality assessment study. It is one of the most important parts of river quality monitoring plans in which the qualitative indices are converted to a single and dimensionless number. Water quality classification is undertaken on the basis of the value of the indices comparing with a predefined rated scale. In this study, a monitoring plan is achieved for the 18 stations located along with Gheshalgh River in Kurdistan province in Iran. Water quality assessment has been conducted using two NSF quality indices of general water use and the British Columbia index for drinking and agricultural consumption. Based on the results obtained from these indices, water of this river has the worst quality due to agricultural use downstream of the wastewater treatment plant of Sanandaj city. Its condition is degraded up to the discharge point of Morghe Par slaughterhouse due to the assimilation capacity of the river. In this location water quality is acceptable for drinking purposes and most of the stations have appropriate conditions except for Dare Kuleh and the downstream station which are on the border. Results indicate that the degree of influence of urban pollutant sources such as entry of urban wastewater and also of a landfill leachate brook is high, especially in the Gheshlagh bridge area up to the tributaries.