Assessing the hydrochemical evolution of surface waters in Halilrood basin: The use of physicochemical parameters and multivariate statistical techniques

The Halilrood River is the most important river in the Kerman province and plays an important role in supplying the water needs. Thus, the study of this river quality has a particular importance. This study investigates the hydrochemical evolution of surface waters in Halilrood river basin using chemical analysis of water samples in 12 hydrometric stations. The commonly used hydrochemical methods and statistical techniques were used to this aim. Hydrochemical diagrams such as Piper diagram and series plots were used to evaluate the water quality changes along the river course. The PHREEQC code was used to investigate the interaction between the rocks, sediments and river water. The saturation indexes were calculated for the most important dissolved minerals in river water. Also, the multivariate statistical techniques such as cluster analysis and factor analysis were used to determine factors affecting river water quality. The results of this study show that the total dissolved solids in the river water increases from the highlands to the plains (Due to the dissolution of the rocks and sediments in the river course). Based on the results of this study, the dissolution of rocks and sediments in river water, precipitation and surface evaporation are the most important factors affecting the surface waters quality in the study area.