关键词: 雅鲁藏布江中游河谷, 降水量, 时间尺度, 周期, 小波分析, 植被恢复

Abstract: Based on daily precipitation data of four weather stations from 1957 to 2007 in the middle reaches of Yarlung Zangbo River, the characteristics of precipitation and its cycle were analyzed at different time scales by climate tendency rate and wavelet analysis. The results show that the minimum precipitation occurs in 1980s. Mean annual precipitation from 2000 to 2007 is roughly equal to that in 1990s or 1960s. Inter-decadal and annual variations of precipitation are similar in summer and autumn. Annual precipitation increases from 1957 to 2007, while it is not significant. Annual precipitation cycles are obvious with 3 years, 8-11 years and 30 years, especially 11 years. The increasing trend of precipitation is the most obvious in spring, while it is not significant in autumn and winter. Precipitation takes on the decreasing trend in summer. Spring precipitation could supply soil water during drought and prevent desertificated land spread. For time scales and cycles of seasonal precipitation, precipitation will be high in spring at 20-30 years time scale and low in summer and autumn at 8-12 years time scale after 2007. Winter will become transition period of precipitation amount from the low to the high at 20-30 years time scale.