流域平均降水量

对流域历年平均降水量序列最大熵谱分析表明存在3.6年的显著周期和5.7年的次周期。

Spectrum Analysis and Maximum Entropy Spectrum Analysis of precipitation show 3.6,5.7 years period and the evaporation has no significant period .

结果表明：黄河流域多年平均降水量的地区分布既受天气系统的制约，又受地形等地理环境的影响，造成明显的地区性差异；

The results showed that the distribution of long year average precipitation in the Yellow River Basin had an obvious regional difference , which was influenced not only by the weather system , but also by the topography and geographical environment .

小波分析结果表明，嘉陵江流域气温存在42年的变化周期。流域年平均降水量倾向率为-8.801mm/10a，降水量呈下降趋势，特别是秋季降水量减少最为显著。

The wavelet analysis showed that the temperature change period is about every 42 years and the annual average precipitation decreased by 8.8mm per a ten-year period , with more obvious decrease in the fall seasons .