Evaluation of the River Salinity Changes using Hydrochemical Method in Arid Area (Case Study: Namaklan River, Ilam)

In arid and semiarid regions, the water quality of some rivers decreases by salinization while passing through some geological formations. This study aims to find the source of the hydrochemical salinity of Namaklan River. Sampling was performed at 6 points along the Namaklan River for 4 seasons and also from before and after the confluence of Godarkhosh River with the Namaklan River. Namaklan River water type is sodium chloride,and due to the persistence and insignificant changes of these elements in water, the chemical composition of river water is constant along the path, which was analyzed by independent samples t-test in Gachsaran and Aghajari Formations. The results showed that, the concentration of different ions and salts before the confluence is low in the Godarkhosh River while it increases at the point of conjunction. This is due to the arrival of different salts and ions from Namaklan River to Godarkhosh River. So that the amount of EC, SAR and RSC in Namkalan River in January were 336, 75 and 23 times more than before joining to the Godarkhosh River, respectively. Based on the chemical analysis and the existence of specific compounds in water samples, it was found that the source of salinity was the influence of Gachsaran formation, because the minerals and salts in the water of the river correspond to the chemical composition of Gachsaran formation.