Investigation of Ecohydraulic Indices in Environmental Flow Regime and Habitat Suitability Simulation Analysis using River2D Model with Relying on the Restoration Ecological in Zarrin-Gol River

changing the flow regime of aquatic ecosystems and providing a minimum flow of protection aquatic species. The purpose of this research is to provide the essentials to be prepared tools for the assessment and design of restoration and regeneration projects for Zarrin-Gol river habitats using ecohydraulic and hydromorphological indices based on the habitat suitability simulation. In this regard based on the research framework, after the field studies and the development of the habitat suitability model for the target species, the hydrodynamic simulation of the flow was carried out and eventually the ecological flow regime was extracted. The results showed that River2D model by connecting the flow requirement characteristics of C.Capoeta gracilis and using hydraulic and hydrological relations, would have the maximum and minimum flow regime required to maintain the Zarrin-Gol river ecosystem according to ecological needs in the months of april and october is estimated to order equivalent to 5.09 and 0.89 m3/s, with average 1.79 m3/s (equivalent 84 percent of natural stream of the river). Based on the results of this study, in environmental studies of water resources and river engineering, the two-dimensional hydrodynamic River2D model is able to simulate flow, modeling habitat suitability of target species and predict the dynamics of habitats to protect the proper habitat of fish in river ecosystems. The calculation of the environmental flow can be an appropriate estimate for the ecological response of the river to the morphological changes caused by hydrological processes.