Abstract
Chinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. The model was evaluated with velocity measurements, and the results were determined to be in good agreement. By inverting the 2016–2019 field monitoring results, the model shows that the preferred velocity range for Chinese sturgeon spawning is 0.6–1.5 m/s. Velocity fields of different opening modes of the generator units were simulated with identical discharge. The suitable-velocity area was maximal when all units of Dajiang Plant of Gezhouba Dam were open. For discharges below 12,000 m3/s, most of the area was suitable; for discharges above 12,000 m3/s, the suitable area rapidly decreased with increasing discharge. A comparison of suitable areas under high-flow showed that at discharges of 12,000–15,000 m3/s, opening 11–13 units on the left side was optimal. For discharges above 15,000 m3/s, all units should be open. We used these results to recommend a new operation scheme to support the conservation of Chinese sturgeon.
Highlights
Chinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground
A previous study has shown that the Chinese sturgeon actively selects flow velocity conditions that are beneficial to its habitat and r eproduction[8], and flow velocities exceeding the maximum tolerable velocity of the fish affect the normal h abitat[9]
There were 92 Chinese sturgeon signals from 2016 to 2019, which were identified with the Dual-Frequency Identification Sonar (DIDSON) dual-frequency video sonar system
Summary
Chinese sturgeon (Acipenser sinensis) is a critically endangered species, and waters downstream from Gezhouba Dam are the only known spawning ground. To optimize the velocity conditions in the spawning ground by controlling the opening mode of Gezhouba Dam generator units, a mathematical model of Chinese sturgeon spawning ground was established in FLOW-3D. A numerical modelling study retrieved the flow field during historical detection days and concluded that the suitable velocity range of Chinese sturgeon was 1.1–1.7 m/s14. In a hydrodynamic simulation of the spawning ground of Chinese sturgeon, the authors concluded that the most suitable velocity range was 0.97–1.48 m/s15 In another numerical modelling study, researchers simulated the water level and velocity by a two-dimensional (2D) hydraulic model and found that a velocity of 1.06–1.56 m/s was suitable for the spawning of Chinese sturgeon[16]. The optimal scheme of different generating units of Gezhouba Dam was simulated and analysed to form recommendations for alternative release procedures to support the reproduction of the sturgeon
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