Assessment quality of Karoon River and its branches in Chaharmahal and Bakhtiari Province

The chemical component of surface waters is usually very different due to contact to different geological formations, relation with other surface and groundwater resources. Solution rate of minerals and ions in river water depends on discharge. The aim of this investigation is to identify chemical components of Karoon River and its main branches in Chaharmahal and Bakhtiari Province of Iran and to determine the main factors affecting water quality. For this purpose, the location of Karoon River and main branches was determined using the ARC GIS software. We used results of chemical analysis of physiochemical parameters measured in 9 hydrometric stations in river course up to 2010 and classified using SPSS software. Hydrogeochemistry and hydrochemistry analysis applied for the Chemistry, AquaChem and Aq.QA softwares. In each station, water quality was determined for drinking and irrigation by considering the water quality standards such as Wilcox and Schoeller diagrams which are generally locating in suitable water class. The water type in most stations is Ca-HCO3 and in some of them is Na-Cl. According to the results of correlation coefficients between different chemical parameters and geological analysis, the lithology of formations in the river course is the main factor in water quality change, which causes the extreme decrease of water quality in some area such as Mavarz station. Finally, by analysis of drainage network limited to Karoon River and branches, suitable quality sanctum 1500 meter was considered an area of each different formation was calculated.