Author(s): Li Ran; Li Jia; Li Ke-Feng; Fengjingjie; Qulu
Linked Author(s):
Keywords: Total dissolved gas; Supersaturation; Field observation; High dam
Abstract: One of the possible negative environmental effects of hydropower stations is the supersaturation of total dissolved gas (TDG) downstream of dams, which can lead to gas bubble disease (GBD) in fish or even death of fish. With more and more high-dam projects put into operation or in construction, the problem has been gradually recognized and paid much attention in recent years in China. By taking the TDG as the main study object, the paper launched the TDG prototype observation on Zipingpu, Three Gorges and Ertan high-dam project in China. The observation results are presented and the factors affecting the TDG generation and dissipation processes are explored in the paper. It demonstrates that the TDG supersaturation phenomenon occurs downstream the high dams when they spill. The supersaturated level and its influential scope differ with the characteristics of the projects and downstream river sections. It is concluded that the discharge rate and the operation pattern are the main factors affecting the generation of the supersaturated TDG, while the main factors affecting the dissipation process of the supersaturated TDG are tributary convergence, water depth and turbulence. The study is helpful for accumulating the experience of TDG prototype observation of high-dam projects in China, and for objectively and impartially evaluating the impact of the supersaturated TDG. It can also provide data and reference for the future study on the TDG supersaturation problem of high-dam projects.
Year: 2009