近50a来珠江流域降水变化趋势分析

全球气候变化和人类活动影响下，近年来珠江流域降水时空分布变化显著。论文利用珠江流域62 个站点1959—2009 年逐日降水序列，选取Mann-Kendall 统计检验方法和有序聚类法，研究了该流域16 个降水特征指数的趋势变化和变异特征，得到如下结论：①流域全年、春季、冬季降水量呈微弱上升趋势，秋季降水量为稳定下降趋势，夏季降水量无明显变化趋势。夏季降水变化趋势对全年降水变化趋势的空间分布影响最大，春秋次之，冬季最小；②流域春、冬两季降水占全年降水比例呈上升趋势，夏、秋两季降水占全年降水比例呈下降趋势；③流域全年降水日数和小雨日数呈显著下降趋势，中雨日数没有明显变化趋势，大雨、暴雨日数和95 百分位值降水日数均呈上升趋势。全年、小雨和暴雨降水日数显著突变时段发生在20 世纪90 年代初；④流域日平均降水量呈稳定上升趋势，降水时段趋于集中化。

Variation Trend of Precipitation in the Pearl River Basin in Recent 50 Years

Influenced by intensifying human activities and constant changes of global climate, hydrological factors of the Pearl River Basin have been changed significantly. By using the Mann-Kendall trend test method and the sequential cluster analysis, this paper systematically analyzed the trends and mutation of the 16 precipitation indices in the Pearl River Basin. Results indicate that: 1) In the Pearl River Basin, the annual total precipitation, the total precipitations in spring and winter increase faintly, while the precipitation amount in autumn shows a stable decreasing trend. Besides, the precipitation amount in summer does not indicate a significant changing tendency. Meanwhile, the trends of precipitation amount in summer have the greatest impacts on the spatial distribution of the annual total precipitation variations. Additionally, the precipitation amount trend in spring takes the second place, which followed by the precipitation amount trends in autumn and winter. 2) There is a slight increase in the proportions of spring and winter precipitation to annual precipitation, while decreasing trends are found in the proportions of summer and autumn precipitation to annual precipitation in the Pearl River Basin. 3) In the Pearl River Basin, the total numbers of annual rainy days and light rainy days are decreasing significantly, however, the downfall days, torrential rainy days and the 95% percentile of the rainy days distributions tend to increase. Moreover, the significant tendency of light rainy days, torrential rainy days and the 95% percentile of the rainy days distributions have mutations in the early 1990s. 4) In the Pearl River Basin, the mean daily precipitation intensity is increasing stably, and precipitation period is centralizing, which can easily trigger occurrence of floods and droughts.