Investigation on the geochemistry of formations of Gotvand-olya dam reservoir and its influence on the quality of water in reservoir

Gotvand-Olya Dam is located near Gotvand City, 25 km north of Shooshtar city in Khozestan province. The present research aimed at investigation on the influence of outcrop formations in the reservoir on the water quality (concentration of anions and cations, TDS, EC, and concentration of heavy metal strontium) at three levels of 150, 200, and 250 m. The results showed that Gachsaran and Mishan formations release the highest concentrations of anions and cations to the water in all three levels respectively. Concentration of strontium was especially high in the Gachsaran formation which is justified by the significant correlation between strontium and basic and sulfate environments. According to the effect of solubility rate of the Gachsaran formation in the levels of 150 and 200 m on the water quality after filling the dam, EC of water was estimated to be 36632 and 28872 S/cm respectively which is classified as very high saline water. The results have also shown that the salinity drops significantly at the level of 250 m and the water at this level is classified as high saline water. In the case of the effect of the Mishan formation, the classification of water in the three levels are the same as Gachsaran formation, only EC at the level of 200 m is more than the two other levels.