中文摘要：

采用Hilbert—Huang变换对雅鲁藏布江干支流上的10个水文站1956—2000年天然径流资料进行分析，探讨了雅鲁藏布江流域年径流变化的近似周期及其演变趋势。研究结果表明，雅鲁藏布江全流域范围内存在约3、6～8、9、11～13、16～17及22～24a的近似周期。同时研究还发现，雅鲁藏布江干支流在20世纪60年代左右径流量较大，但在进入60年代中后期之后，年径流量呈逐渐减小的趋势，这种趋势在80年代附近达到极小值，此后径流量逐渐回升，并在90年代后逐渐进入相对丰水期。

英文摘要：

This study applied the Hilbert-Huang Transform （HHT） in the multiple-time-scales analysis of annual runoff series in the Yarlung Zangbo River. With the measured annual runoff data from 1956 to 2000 in the Yarlung Zangbo River, the Intrinsic Mode Function （IMF） and Hilbert spectrum were used to extract hydrological time series periods and the evolution trends of the natural annual runoff. The results showed that the annual runoff periods of the Yarlung Zangbo River include 3, 6 - 8, 9, 11 - 13, 16- 17 and 22 -24 years, respectively. It indicated that the annual runoff of the main and tributary of the Yarlung Zangbo river had an obvious decline trend during 1960s and reached the minimum in 1980s. since then, the annal runoff increased and a relatively wet season occurred in 1990s.