Habitat Simulation Technique as a Powerful Tool for Instream Flow Needs Assessment and River Ecosystem Management

Abstract

Instream flow needs (IFN) assessment studies are performed to provide guidelines for stream water management and to assess the impacts of different water projects such as weirs, dams and stream diversions on the available fish habitat. The physical habitat simulation is one of the IFN assessment methods and also a powerful tool in management of river ecosystem that has not become a common method in many countries, yet. The main aim of the present research is representing the ability of habitat simulation technique in river ecosystem management. Delichai stream in Tehran province in Iran is selected as the case study. Based on the results habitat simulation technique has considerable ability for dynamic assessment of IFN and river habitat evaluation along the longitudinal and latitudinal cross sections and it can also present the spatial habitat suitability distribution in various months of the year dynamically. IFN assessment with habitat simulation technique has advantages related to other methods like that of the Tennant method and wetted perimeter method and creates the least discussion between river environmental managers and stakeholders. In the study stream of this research due to the variation of ecological condition for the target species, three different values for IFN in various months of the year were estimated and it was seen that the habitat near the stream bank requires more protection and restoration projects.