%0 Journal Article %T Impacts of the Golestan and Voshmgir Dams on Indicators of Hydrologic Alterations in the Gorganroud River Using Range of Variability Approach %J Iranian journal of Ecohydrology %I Faculty of New Sciences and Technologies, University of Tehran %Z 2423-6098 %A Daiechini, Fatemeh %A Vafakhah, Mehdi %A Moosavi, Vahid %D 2020 %\ 09/22/2020 %V 7 %N 3 %P 595-607 %! Impacts of the Golestan and Voshmgir Dams on Indicators of Hydrologic Alterations in the Gorganroud River Using Range of Variability Approach %K Climate Variables %K Flow regime %K Indicators of Hydrologic Alterations %K trend %K Environmental Water Requirement %R 10.22059/ije.2020.301564.1320 %X Dam construction as one of the methods in water resources management, is among the most important man-made structures along rivers that can make major hydrological changes in the river regime and ultimately in the entire drainage basin and surface flow adjustment. Therefore, the quantitative evaluation of hydrological changes caused by human activities such as dam construction is very important. Therefore, the purpose of this study is the statistical analysis of the indicators of hydrologic alterations affected by the Golestan and Voshmgir dams in the periods before and after the construction of these dams using the IHA software version 1.7. To do this, Gonbad and Ghazaghli hydrometric stations in downstream of Golestan Dam were considered to analyze the effect of Golestan dam and Agh Ghala hydrometric station to analyze the effect of Voshmgir dam. Also, in order to investigate the climate change situation in the study area, the trend of climatic Variables i.e. precipitation, temperature and evapotranspiration were evaluated using Mann-Kendall test and Sen’s slope. Then, the changes of 33 hydrological indicators in five main groups (magnitude-duration-timing-frequency- rate of change) before and after the construction of Golestan and Voshmgir dams were calculated using Range of Variability Approach (RVA) approach. According to the results of trend analysis, precipitation and temperature had an increasing trend while evapotranspiration hand a decreasing trend. Based on the indicators of group one (Magnitude), it can be concluded that average monthly discharge in the period after the construction of Golestan Dam has decreased compared to the period before the construction of the dam in Gonbad and Ghazaghli hydrometric stations. While the average monthly discharge has increased after the construction of the Voshmgir Dam except from March to June. For the indicators of group two (minimum and maximum discharges), it can be stated that all flow indicators except 3-, 7-, and 30-day minimum flow indicators and 1-, 3-, 7-day maximum flow indicators in Gonbad hydrometric station and 1- and 3-day  minimum flow indicators  and  3-day maximum flow indicators in Ghazaghli hydrometric station have decreased after the Golestan dam construction. While all flow indicators except 1-, 3-, 7-day maximum flow indicators in Agh Ghala hydrometric station have increased after the Voshmgir dam construction. Finally, it can be concluded that flow regime changes can pose significant threats to plant and animal species (aquatic and wildlife) and lead to adverse environmental effects. It should be noted that the variation in the hydrologic indicators is mainly influenced by dam construction and the change of climate variables has also been influential in this regard, and the separation of affecting factors need to be considered in further studies. %U https://ije.ut.ac.ir/article_77566_a822d19395137996d28d930eb52b3d5e.pdf