Spatial-temporal Change Characteristics of Precipitation over the Key Region of Three Gorges Reservoir

Wang Miao; Zhou Yuehua; Ren Yongjian; Fang Sida

doi:10.16765/j.cnki.1673-7148.2017.01.006

Abstract：Based on the 1961-2012 daily precipitation data of 261 stations over the key region in the Three Gorges Reservoir,which after the quality controls,the characteristics and changing trend of precipitation especially May-September were analyzed by using statistical diagnostic methods such as linear trend estimation,FFT smoothing method and other statistical methods.The results indicated that the average annual precipitation over the region was 992.9 mm.During the recent 52 years,the annual precipitation exhibited a remarkable downward trend of-16.2 mm per decade,which tended to reduce all over the area after 2000 especially the Yibin-Chongqing and the least in Jinsha River.The spatial pattern showed more in the east and less in the west and the high value center was located in the southeast of Min river.In addition,the precipitation during May-September which was the whole supply for the water storage accounted for 75.6 percent of that in the whole year.The precipitation in this stage decreased significantly by-12.2 mm per decade in average and the decreasing trend was notable over the intersection of the Min River,Tuo River and Yibin-Chongqing.The precipitation in May-September appeared a distribution pattern of more in middle-north and less in south before 1970s,but after 1970s,it was less in middle-north and more in south.The heavy storm and extreme precipitation showed a increasing trend.The change of the precipitation over the region before and after impoundment was mainly reflected in the transformation of the spatial distribution pattern.