Application Hydrological methods for estimating River Environmental water rights (Case Study of Gorganroud River)

Water resource development plans (such as dams) has the numerous environmental effects, which altering the natural regime of river and river flow reduction is the most important. One of the most important environmental challenges in water resources planning is river water rights estimation affected by natural variables, understanding the importance of protecting water resources, variety biological and ecosystems related to river flow. Environmental flows is meaning time, quality and amount of required current to protect freshwater, estuarine ecosystems, human welfare and livelihoods related to water. The main aim of this study is estimation of environmental water right Gorganrood river (Aq Qala station) based on 33-year period, using hydrological methods Tennant, Tessman, aquatic base flow, flow duration curve and duration curve change in different months of years. The results show that at least the Gorganrood river flow (Aq Qala station) to provide environmental flows using the above methods, respectively should equal to 27/2, 8/1, 51/5, 47/4 and 33/3 (class C) cubic meters per second. This study has shown that in the absence of information on the ecological, hydrological indices can be used for preliminary estimation of environmental flows.