关键词: 三峡水库, 降雨, 时间分布, 高度变化, 坡向差异, 水体效应

Abstract: According to the daily rainfall data of 10 weather stations around the dam area of the Three Gorges Reservoir from 1992 to 2002, the ratio method is used to extend the shortrange data, then the comparing and regressive methods are adopted to analyze the variation of rainfall, rain days, heavy rain and heavy rain days with time(within a year, yearly) and topography(height, slope) . It is revealed that it is obvious with dry winter, more rain in summer and autumn, and increasing rainfall in recent years around the dam area of the Three Gorges Reservoir. Compared with Wuhan, there is more rain days but fewer heavy rain days; rainfall, rain days, heavy rain and heavy rain days increased with height; because of the blocking and augmenting effect of mountain on air flow, there is more rain and rain days in the south part of the river (in correspondence to the north slope) than in the north part (in correspondence to the south slope); the water body can restrain raining progress near the reservoir, and it is more obvious at night than in daytime, in the strong rainfall process than in the weak rainfall process.It should be highly regarded that there is more rain at higher mountainous place than in lower maintain valley, and that will magnify with more water deposit in the reservoir, which will lead to more geological disasters around the dam area of the Three Gorges Reservoir.

Key words: the dam area of the Three Gorges Reservoir, rainfall, temporal distribution, the rainfall difference with heights the rainfall difference with slopes, the effect of water body