The effects of gotvand olia dam impoundment on the water quality of karun river

Gotvand olia dam is the highest embankment dam in Iran. this dam is the last dam  built on the Karun River before entering khuzestan plain in gotvand area. the main worry of the analyst before the gotvand dam impoundment, has been the dissolution of the anbal salt in the reservoir of the dam and affected the karun water at the bottom of the dam. the aim of this study was checking the effects of gotvand dam impoundment on the water quality of karun river during the years 2001 to 2016 at the gotvand section. in this research, non-parametric tests of Mann-Kandal and Pettit were used to evaluate the trend and determine the break point and the SDI index was used to calculate the hydrological drought of time series. The results showed that in recent years the salinity of the karun river has increased. the main cause is the decrease of river flow from the water year 2007-2008 and continuation until now. Therefore, increasing salinity of the karun river has started three years before the dam impoundment. As a result, the dam impoundment has not changed the quality of water in the gotvand regulatory dam.