Effects of the Three Gorges Dam on Yangtze River flow and river interaction with Poyang Lake, China: 2003–2008

The Three Gorges Dam (TGD) has been in operation since 2003. Over the operation period from 2003–2008, data have been collected for preliminary evaluations of actual effects of the TGD on the Yangtze River flow and river interactions with downstream lakes and tributaries. These effects are examined in this study, after the climate influence was minimized by comparing hydrological changes between years of similar climate conditions before and after the operation of the TGD. Major results show that the TGD operation has affected the Yangtze River discharge and water level. The significance of these effects varies seasonally and with different locations along the river. The seasonal variation follows the TGD’s seasonal impounding and releasing of water. The magnitude of the effects is dependent on the impounding/releasing rate and the seasonal flow of the river. The most significant effects are confined in the river reach near the TGD and are as great as five times those of sections downstream. The weakening and diminishing of effect of the TGD is primarily because of “dilutions” to the effect by inflows to the Yangtze River from downstream tributaries.