Assessment of Environmental Flow Requirements for Four Major Chinese Carps in the Lower Reaches of the Jinsha River, Southwest China

An appropriate environmental flow (AEF) is one of the necessary conditions for fish spawning. The operation cascade reservoirs in lower reaches Jinsha River has changed discharge process downstream, which turn directly affected spawning habitat fishes. Determining how to quantitatively evaluate impact different outflows from Xiangjiaba Reservoir on four major Chinese carp species downstream area a key problem that must be solved immediately. Yibin section was selected as study area, and velocity water depth were measured. A physical simulation model (PHABSIM) used analyze main hydrodynamic affect quantify weighted usable (WUA) fishes based Reservoir. Hydrodynamic suitability curves established observed data 2012 2020, two-dimensional developed using triangular grid obtain distribution characteristics habitat. Then, AEF range obtained outflow-WUA relationship. results showed during period 0.6–1.3 m/s, most 0.9–1.0 3.0–18.0 m, 9.0–12.0 m. Additionally, 2,000–4,500 m 3 /s, optimal was, /s. research provide scientific basis ecological River.