摘要：Total dissolved gas (TDG) can be easily induced in high dams spilling. It will create adverse effects for fishes. Generally, the hydropower stations built on the embranchment are smaller and the supersaturation of TDG is much lower than the main stream. According to this, a separated region at the confluence, which will become the refuge for fish to survive the supersaturated TDG, can be formed with lower TDG concentration under appropriate structural measures. In this study, a numerical simulation is established to the simulation region which is 5 km downstream the river from discharge structures. Under the condition of tunnel-spillway flood discharging in a hydropower station, the study especially focuses on the hydraulic characteristics and distribution of supersaturated TDG at the confluence. Coupled with the simulation on hydrodynamics, the distribution of TDG under different structural measure conditions are simulated, including setting up longitudinal embankments and water-blocking piles. At last, considering the feeding ground hydraulic requirements of the fish, which is paid significant attention, the study analyses the effectiveness of the refuge region created before. The result shows that the case with 2 water-blocking piles and longitudinal embankments of 200 m length can effectively increase the area of the refuge for fish to avoid the adverse effects of TDG supersaturation. Besides, the simulation of adopting sturctural measures can satisfy the hydraulic conditions of the concerned fish as well. This study provides new directions and references to construct shelter for fishes against the detrimental effects of supersaturated TDG.
