Regional climate change after the commissioning of the Three Gorges Dam: a case study for the middle reaches of the Yangtze River

ABSTRACT: The Three Gorges Dam (TGD) has caused hydrological regime changes in the region downstream of the dam. Based on meteorological station data, this study focused on regional climate changes by evaluating several climatic factors in the middle reaches of the Yangtze River and investigated the mutation time of the number of high and low temperature days using the Mann-Kendall (MK) test. We also examined the vegetation response to regional climate change and variations induced by this in the land surface temperature, utilizing the enhanced vegetation index (EVI) and land surface temperature (LST) images, respectively. The study defined 3 stages related to the construction and commissioning time of the TGD. The regional climate before and after the commissioning of the TGD displayed opposite trends in temperatures, including daily mean, maximum and minimum temperatures. Temperatures tended to decrease in the northern portion of the study area, and increase in the southern portion of the study area. MK test results indicated that the mutation times of the number of high and low temperature days occurred around the time that the dam began commissioning to regulate the water flow. Precipitation decreased in the study area, particularly in the Dongting Lake region and its surrounding areas. Vegetation coverage generally increased in most of the southern study area in response to the change in climate. Moreover, the LST trends in the different regions were affected by the changes in vegetation.