Temperature changes in Three Gorges Reservoir Area and linkage with Three Gorges Project

The Three Gorges Project (TGP) is one of the largest hydroelectric projects throughout the world. It has brought many benefits to the society but also led to endless debates about its environmental and climatic impacts. Monitoring the spatiotemporal variations of temperature in the Three Gorges Reservoir Area (TGRA) is important for understanding the climatic impacts of the TGP. In this study, we used remote sensing-based land surface temperature (LST) and ground-measured air temperature data to investigate temperature changes in the TGRA. Results showed that during the daytime in summer, LST exhibited significant cooling (1-5 degrees C) in the downstream region of the reservoir, whereas LST during the nighttime in winter exhibited significant warming (1-5 degrees C) across the entire reservoir. However, these cooling and warming effects were both locally constrained within 5km buffer along the reservoir. The changes in air temperature were consistent with those in LST, with 0.67 degrees C cooling in summer and 0.33 degrees C warming in winter. The temperature changes along the reservoir not only resulted from the land-water conversion induced by the dam impounding but were also related to the increase of vegetation cover caused by the ecological restoration projects. Significant warming trends were also found in the upstream of TGRA, especially during the daytime in summer, with up to 5 degrees C for LST and 0.52 degrees C for air temperature. The warming was caused mainly by urban expansion, which was driven in part by the population resettlement of TGP. Based on satellite observations, we investigated the comprehensive climatic impacts of TGP caused by multiple factors.