Computation method of instream ecological flow based on physical habitat simulation

The principles and methods of instream ecological flow based on the PHABSIM (Physical Habitat Simulation model) are introduced, and the middle reach of the Yangtze River is used as a case study for the calculation of minimum and optimal ecological flow. The differences between the result of physical habitat simulation and that of the traditional hydrological methods were compared and analysed to verify the rationality of the habitat model. The results of the physical habitat simulation show that during the spawning periods of four major Chinese carp species, from April to June, the minimum ecological flow of the middle reach of Yangtze River is 4570 m(3)/s, and the optimal ecological flow is 12000-15500 m(3)/s. These results are within the scope of the value calculated by traditional hydrological methods, and seem to be more reasonable. The conclusions of this paper could provide suggestions for fish habitat protection and water resources management, and references for ecological regulation of the Three Gorges Project and Gezhouba dam.