Changing landscapes by damming: the Three Gorges Dam causes downstream lake shrinkage and severe droughts

The world’s largest dam—the Three Gorges Dam (TGD)—has been in operation for more than 10 years. While the recent shrinkage of large lakes and increased severe droughts in the downstream have been subjectively ascribed to TGD, empirical support based on thorough analysis is still lacking, leaving a gap for ecologists to quantify the TGD impacts on the surrounding landscapes. This study aims to quantify the impacts of TGD water impoundment on downstream landscapes in terms of lake shrinkage and severe droughts. We have incorporated the recent findings and conducted a comprehensive analysis based on long-term datasets and contrasting scenarios with and without the presence of TGD. The datasets were constructed from hydrological measurements, a hydrodynamic model, and satellite data retrieval techniques. Here we show that, in addition to natural variations due to climatic conditions, TGD water impoundment has indeed weakened river’s ability in preventing backflows from its connected lakes directly contributed to their shrinkage. The impoundment substantially increased the intensity and severity of droughts downstream, and may have produced a cluster of impacts on the changing landscape. Our finding provides needed information for assessing TGD’s impacts on environmental services in the region, and raises serious concerns with the ongoing large-scale hydraulic project—China’s South-to-North Water Transfer Project—which will further reduce the flow of the Yangtze River.