Study on the Flow Characteristics of Migration Habits and the Instream Flow Required for Ecology Based on Protection Target

It is an important research field of the instream flow required for ecology (IFRE) study to take into consideration of the needs of the ecological protection target for aquatic habitat. Fish are common indicators of aquatic habitat richness, because fish habitat preferences are well described. This paper selected P. altivelis as the ecological protection target in the main channel of the Nanxi River, and analyzes their migration habits terrain and hydrological characteristics in different migration periods. The results show that the hydrological regime and channel form of the Nanxi River is stable, that there are more than 3 times rising flow pulses from March to May, P. altivelis migration period, and 1~2 times rising flow pulses with 10-20 m³/s, which is favorable for fish migration during November to December. The instream flow required for ecology in two important cross-sections of the Nanxi River mainstream was analyzed based on the requirements for migration habitats of P. altivelis. We took maintaining good habitat conditions and meeting the ecological target needs as the goal for the IFRE. And Mike 21 model was used to calculate the habitat area of spawning reach under different discharges to help correct the results of IFRE. The results can provide a reference for the development and utilization of water resources, and be favor of the ecological hydraulics research as a typical case.