【摘要】 基于1960—2016年乌江流域41个气象站的逐日降水观测资料,利用线性倾向估计、滑动平均、累积距平等方法计算趋势系数和气候趋势,分析了研究时段内乌江流域年暴雨等级面雨量、年平均最大日降水量、年平均极端持续强降水次数和对应降水量的时空分布特征,分析表明:(1)乌江流域年暴雨等级面雨量和日数呈显著增加趋势(均通过α=0.05显著性水平检验),而暴雨强度呈不显著性增加趋势;5—10月各旬暴雨等级面雨量及日数变化基本一致,5月中旬至8月上旬呈单峰型分布,暴雨强度呈波动增减分布。(2)近57 a乌江流域年平均最大日降水量年代际变化比较明显。(3)乌江流域发生极端持续强降水年平均次数呈不显著的减少趋势,但极端持续强降水量呈不显著的增加趋势。采用耿贝尔极值Ⅰ型分布法计算了乌江流域5个代表站不同重现期日最大降水量值,发现不同站点日极端最大降水量重现期水平差异明显,重现期时间尺度存在临界点,约为50 a。更多还原

【Abstract】 Based on the daily precipitation observation data at 41 meteorological stations in the Wujiang River basin from 1960 to 2016, temporal and spatial distribution characteristics of the annual mean surface rainfall, the annual mean maximum daily precipitation, and the number and precipitation amount of the annual mean extreme precipitation in the Wujiang River basin during the study period were analyzed. The analysis shows the following results.(1) The annual rainfall and the number of raining days in the Wujiang River basin showed a significant increasing trend(both passed the 0.05 reliability test), while the intensity of the rainstorm showed no significant increase. The rainfall and the number of days of rainstorms from May to October were basically the constant. From mid-May to early August, there was a unimodal distribution; the intensity of rainstorm first increased and then decreased.(2) In the past 57 years, the annual mean maximum daily precipitation in the Wujiang River basin did not show significant linear variation, but the interdecadal changes were more obvious.(3) The mean annual number of extreme persistent heavy rainfall in the Wujiang River basin showed an insignificant decrease, but the extreme persistent heavy precipitation showed an insignificant increase. The maximum daily precipitation at five representative stations in Wujiang River basin was calculated using the Gumbel extreme value I distribution method. It was found that there was a critical point of 50 a in the time scale of the return period.更多还原