Narges Khatoon Dowlatabadi - Ph.D Student of Water Resources, Faculty of Aburaihan, University of Tehran
Hedieh Ahmadpari - M.Sc. Student of Irrigation and Drainage, Faculty of Aburaihan, University of Tehran
Feridon Radmanesh - Associate Professor, Department of Water Resources Engineering, Shahid Chamran University of Ahvaz

Environmental flow requirement (EFR) are important to maintain rivers, especially in developing countries same as Iran. The EFR was analyzed for the Halil River, Kerman, Iran. In this study, the EFR has been assessed by the sing Flow Duration Curve (FDC) shifting method and Global Environmental Flow Calculator software (GEFC). Accordingly, this study simulated monthly stream flow (1964-2016: 53 years) for natural conditions based on Hossein-abad hydrometric station. The GEFC software was used with the simulated flow time series to calculate EFR for different environmental management classes (EMCs). The EFR conditions of rivers are defined by six environmental management classes (A, B, C, D, E and F). Rivers which fall into classes C to F would normally be presented in densely populated areas with multiple man-induced impacts. A poor ecosystem conditions (classes E and F) are sometimes not considered acceptable from the management perspective and the management intention is always to move toward to the acceptable classes through river rehabilitation measures. The results illustrated that the quantities of the EFR for Classes A, B, C, D, E and F were 53.2, 30.4, 18.4, 11.8, 7.7, and 4.9 percent ratio the average annual flow, respectively. It should be mentioned that the average annual flow is 299.5 MCM, in Halil River. Therefore, the EMC- C (maintaining the minimum ecological conditions of the river) was proposed due to consideration of the hydro-ecological conditions of the river. Consequently, the EFR is about 55.18 MCM (18.4% of the annual average flow) in the Halil River.

EFR, Halil River, FDC, GEFC, EMCs