海河流域干旱特征与旱涝交替降雨事件概率分析

在气候变化影响下,极值事件频发,旱涝交替加快。以海河流域42个代表性气象站点1963~2013年的逐日降雨资料为基础,使用SOM神经网络算法,对气象站点进行聚类分区,选取连续无雨日干旱评价方法确定海河流域干旱等级,在此基础上采用Pearson-Ⅲ频率曲线对干旱之后的最大降雨量进行保证性分析,计算不同等级干旱发生后降雨强度达到中到大雨及大到暴雨的概率。结果表明,随着年内干旱发生次数的增加,降雨频次在减小,降雨强度明显增强,海河流域极大可能同时遭受旱涝灾害。研究结果可为海河流域旱涝事件的应对提供有力支撑。

Analysis of drought characteristic and rainfall frequency during alternative drought and flood in Haihe River Basin

Under the impact of climate change, extreme events occur frequently and the alternative speed of drought and flood gets faster. Based on the daily rainfall data of 42 stations in Haihe River basin from 1963-2013, we divided the basin into four sub-regions (region A, region B, region C, region D) by cluster analysis of meteorological stations using self-organizing map (SOM) neural network method. The number of consecutive rainless days was used to identify the drought magnitudes and the maximum daily precipitation after a drought period was analyzed with the Pearson-III frequency curve, then the frequencies of the moderate to heavy rain and heavy to torrential rain after different levels of drought were analyzed. The results indicated that with the increase of drought events, rainfall frequency decrease, but rainfall intensity increases obviously and the Haihe River basin may suffer flood and drought disasters at the same time. The conclusion can provide a strong support to cope with the drought and flood events in the Haihe River Basin.