Numerical Simulation of Dissolved Oxygen Concentration in the Downstream of Three Gorges Dam

Strong colliding between the flow discharged from spillway and the water-body in the stilling basin will produce a lot of air bubbles in the downstream of the Three Gorges Dam. Bubble mass transfer will be dominant and can cause total dissolved gas (TDG) supersaturation. Elevated TDG levels can have an adverse effect on aquatic organisms in the form of gas bubble trauma (GBT). TDG concentration is changed with distance from the spillway crest and depending on hydraulic and operating conditions. Dissolved oxygen (DO) transport model is developed in this paper and used to simulate the physical processes of gas transfer coupled with the air-water two-phase mixture flow model. Supersaturated DO concentration in the water-body downstream along with distance is successfully calculated during spillage when the water level is 139m in the Three Gorges reservoir.