Estimation of Environmental Flow Indicators in the Downstream of Golestan and Voshmgir Dams

According to the results of the trend test, the changes in climatic variables have often been in an increasing trend in precipitation and temperature and a significant increasing or decreasing trend in evapotranspiration. The results also showed that peak discharge of high current pulses rates in Gonbad, Ghazaghli and Agh Ghala hydrometric stations are 28, 38 and 30.5 m3/s with a frequency of zero-, two- and one-day in the period after the construction of dams, respectively. The peak discharge indicator of small floods in Gonbad, Ghazaghli and Agh Ghala hydrometric stations are 46, 107 and 149.8 m3/s with a frequency of zero-day, respectively, Golestan and Voshmgir dams have been caused a decreasing trend in this indicator due to self-regularity of the dams. Finally, according to the large Flood indicators, it can be concluded that in Gonbad and Ghazaghli stations, peak discharge of the large floods indicator with a flow rate of zero m3/s has a decreasing trend and in Agh Ghala station with a flow rate of 274 m3/s shows a decreasing trend. Finnally, due to self-regulatory effect of Golestan and Voshmgir dams dams have been caused low monthly changes and large and small floods and in the most months of the year, the flow discharge is lower in the periods after the construction of the dams. The results of this analysis can be used the decision-making on sustainable water resources management issues for future watershed management plans.