Use of the hydraulic method to estimate the minimum environmental flow for a part of Duab Samsami River

Surface water withdrawals in recent years to meet the diverse needs of human, such as drinking, agriculture and industry, has endangered the functioning and health of the river ecosystem. Harvesting water from the river may be harmless to the river ecosystem, but, in order to properly exploit the rivers and prevent excessive harvesting, the environmental requirements of the river must be determined. There are various hydraulic, hydrological, and comprehensive methods for determining the environmental needs. In this research, the environmental demand of the Duab Samsami River (located in Koohrang, Chaharmahal and Bakhtiari) was calculated from the hydrologic method of the Tennant and the two methods of hydraulic slope and maximum curvature. The results showed that the maximum curvature method had better estimation than the curve slope method. The proposed flow of Tennant method cannot meet the needs of the river in dry months of year. In this study, the discharge rate of 0.94 cubic meters per second for the months of July to December and the amount of 3.82 cubic meters per second for the months of January to June was proposed as the minimum environmental requirement of the Duab Samsami River.