The decadal decline of CO2 emissions from a large ephemeral lake in China

The influence of natural hydrological factors on CO2 evasion from lakes has been widely studied. However, the long-term effects of man-made hydraulic infrastructures are not yet well understood. Here, we examined the multi-year (1961 - 2016) trend of the CO2 budget for Poyang Lake, a large ephemeral lake in China. Poyang Lake is situated downstream of the Three Gorges Dam (TGD), the world’s largest human-made hydraulic infrastructure. Using a combination of eddy covariance observations and artificial neural network modeling, we show that following the development of TGD in 2003, CO2 emissions of Poyang Lake significantly decreased by 77% (0.18 Tg C) compared with the pre-TGD period. The TGD can explained 21% of the CO2 flux decrease during impoundment period. The results imply that the TGD and other hydropower infrastructures potentially decrease the CO2 emission of lakes naturally connected or surrounded with Yangtze River in the middle and lower reaches.