In this study, the hydrochemical evolution and qualitative deterioration of Gorganrud River water were investigated in a distance of approximately 100 km from the northern margin of the Alborz highlands to Gorgan Gulf. For this purpose, the analysis results of elven phy
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In this study, the hydrochemical evolution and qualitative deterioration of Gorganrud River water were investigated in a distance of approximately 100 km from the northern margin of the Alborz highlands to Gorgan Gulf. For this purpose, the analysis results of elven physicochemical parameters related to four hydrometric stations over a ten-year statistical period were used. Gibbs, Stiff, Piper, Durov diagrams as well as five saturation indices for carbonate, sulfate and chloride minerals were used to study the hydrochemical evolution of the river. Water quality changes in drinking (using Schoeller Diagram), agricultural (using Wilcox Diagram), and industrial (using corrosion indices) sectors along the Gorganrud River were also investigated. In this study, F test and hierarchical cluster analysis were used to analyze the variance of data and the number of factors affecting water hydrochemistry, respectively. The results showed that rock-water reaction, evaporation, and Gorgan Gulf saline water intrusion are the most important factors controlling the river water chemistry. Also, the water dominant type of Gorganrud River at the highlands margin is bicarbonate and as it enters the plain, it tends to reach full maturity, the type of sodium chloride. At all stations, river water is supersaturated with respect to calcite and dolomite but it is under saturated respect to anhydrite, gypsum and halite. However, evaporite minerals saturation increases in the flow direction. The quality of water for drinking and agriculture is suitable at the margins of highlands and as it enters the plain and the path to the Gorgan Gulf decreases sharply. According to the statistical analysis results, the most changes in physicochemical parameters are obtained between the Lazoure Station at the highlands margin and the Qazaghli Station in the middle part of the plain and after that no significant changes were observed between the quality parameters until Gorganroud outlet.
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