Abstract:

The construction of Three Gorge Dam (TGD) in the end of upper reach of the Yangtze River result in a great beltshape of Three Gorge Reservoir (TGR) in China. Based on the daily meteorological data from 1961 to 2010,the linear climate trends of temperature,precipitation over the TGR were analyzed. The climate variability of the Yangtze River was also investigated to be compared with that of TGR area.The results showed that the temperature was increasing over TGR area,and the precipitation showed obvious decadal variability with a clear decline in rainfall amount after 2001.All the trend and variability of TGR area were in phase with those of the Yangtze River basin,indicating that the climate change of TGR area was under climate background of a wider area.Generally speaking,after the reservoir constructed and impounded,the water area enlarged greatly,and the possible influence on regional climate might stretch from a few miles to hundreds of mile depending on the form of the reservoir and local topography.The Three Gorge Reservoir is a long and narrow reservoir,thus the climate effect is supposed as not obvious as a round one.By the observational data analysis of contrast of temperature changes of areas which were near and far away from the TGR,the temperatures of areas near the reservoir got warmer in winter but got cooling in summer.Analysis with the use of a regional climate model simulation showed that,the reservoir only had a significant effect on the temperature above the water,but the effect on temperature of lands which were close to water decreased dramatically.However,there was no obvious change after TGR impoundment and the impact of TGR on precipitation was not as clear as that on temperature.The impact range of the TGR on the nearby climate was no more than the distance of  20 km.However there was still great uncertainty of the climate models.Numerical models simulation results need more observation data to be validated.It was observed more extreme weather/climate events in recent decades around the globe.Severe droughts occurred just near the TGR area,such as the SichuanChongqing Drought in summer of 2006,the severe Southwest Drought in winter of 2009/2010.Previous studies have revealed that a close relationship between these extreme weather/climate events and the large scale of atmospheric circulation abnormal in East Asia,the changes in Arctic sea ice cover and sea surface temperature,and the QinghaiTibetan Plateau thermal anomaly.Specific geographical environment,particular climate conditions as well as the impact of human activities in the TGR area lead to a great significance of understanding the climate characteristics and climate effect of TGR area.Therefore,it is needed to make continuous climate monitoring and make further impact assessment research in TGR area