Impacts of Three Gorges Dam on Regional Circulation: A Numerical Simulation

Abstract

AbstractThe Three Gorges Dam (TGD) is the largest hydropower project in the world. The resulting Three Gorges Reservoir (TGR) extends 660 km along the waterway of the Yangtze River in surrounded by complicated terrain. The dam and its impounded reservoir has triggered large‐scale land use and land cover change, which can potentially impact the environment and climate significantly. In this study, the impact of the TGD on regional‐scale circulation is explored through high‐resolution simulation using the weather research and forecast model. It is found that the construction of the TGD has little influence on the near‐surface temperature in the TGR region even when extreme hot weather occurs in the region. The numerical experiments performed in this study indicate that the construction of the TGD can alter the atmospheric circulation on the regional scale when the weak southeasterly wind in the lower troposphere prevails in the region. Due to the blocking effects of the TGD and the expanding water surface area of the TGR, the low‐level southeasterly flow is turned into northeasterly and southeasterly flows before reaching the dam, leading to an anomalous cyclone over 112–115°E, 33–34°N, and an anomalous anticyclone over 110–112°E, 28–29°N. It is also found that the anomalous cyclone can evidently enhance precipitation locally under some special atmospheric conditions. This study suggests that the impact of the TGD can be amplified due to the complicated terrain in the surrounding areas of the TGD.