ZHAO Zi-hao, JIANG Xiao-dong, YANG Shen-bin
Due to special underlying surface properties, large water bodies have impacts on local water thermal cycle and climate. The Three Gorges Project is the world's largest water conservancy project. In the present research, we analyzed systematically the characteristics of climate change in the Three Gorges Reservoir over the past 66 years and the impacts of water storage on local climate by means of climate tendency rate and CVM test. Results demonstrated that the local temperature of the Three Gorges Project has declined after impoundment, affecting an area of 299.83 km2 near the dam, reaching 12.65 km away from the dam. The temperature of Zigui station, which is the closest to the dam, changed abruptly in 1997. The average annual temperature of Zigui two decades after the impoundment was 1.15 ℃ lower than that before the impoundment. Local precipitation has increased, affecting an area of 2 914.88 km2, reaching 109.15 km away from the dam. The precipitation of Zigui station also changed abruptly in 1997, and the average precipitation of Zigui two decades after the impoundment increased by 245.90 mm compared with that before the impoundment. Water storage also led to the rise of local relative humidity. Zigui and Xingshan witnessed abrupt changes in relative humidity in 1997 and 2003, respectively, of which the former rose by 5.29% two deades after the impoundment. The number of sunshine hours reduced, affecting the nearby area of 2 045.66 km2, extending 41.06 km away from the dam. The sunshine hours of Zigui changed abruptly in 2002, reducing by 33.87 hours compared with that two decades before the impoundment. In conclusion, water storage in the Three Gorges Reservoir has had a small scope of influence on meteorological elements, affecting an area of only 75.27 km2 on all the elements; only Zigui station experienced abrupt changes in all the elements during water storage.
