Field observation of total dissolved gas supersaturation downstream of Ertan high dam

摘要

The problem of total dissolved gas (TDG) supersaturation downstream of high dams and its effects on aquatic life has been recognized and has been paid much attention in China. Field observations were carried out in July 2007, when the Ertan high dam discharge flooded. It shows that TDG supersaturation occurs downstream of the Ertan high dam at the large flood rates. The TDG levels relate closely to the discharge mode. The TDG dissipation rate is slow in Yalongjiang River. The convergence with other branches can speed up the TDG dissipation rate, but deep water depth offers less-effective gas dissipation. The study is of great help for the understanding of the TDG supersaturation problem downstream of high dams, and can also provide the basis and references for further theoretical study.