基于海河流域30个气象站点1960-2014年的气象数据,计算各站历年逐日的综合气象干旱指数(CI)值,并对等级划分标准进行修正,统计了近55 a各站点出现的干旱过程,对海河流域干旱的持续时间、强度、发生频率和覆盖面积百分率进行了分析,揭示了海河流域干旱的变化特征。结果表明:(1)近55 a海河流域干旱严重程度趋于上升且发生范围广泛。该流域干旱持续时间和干旱强度均呈增加的趋势。海河流域的干旱在四季均有发生,其中冬旱最为严重,夏旱严重程度较低。(2)海河流域干旱程度呈现出高频低强度、低频高强度的空间分布特征。干旱持续时间和干旱强度在空间上均表现为南高北低的分布规律,而年干旱发生频率呈现出北高南低的分布规律。
Along with the intensifying global warming,drought disasters become increasingly serious,which has restricted the sustainable development of the economy and society. In this paper,based on the meteorological data of 30 meteorological stations from 1960 to 2014 in Haihe Basin,China,a comprehensive meteorological drought index was calculated and modified. By using CI index,the drought processes of each station were confirmed one by one,and the occurrence frequencies,scopes,duration and intensity of the meteorological droughts were computed and analyzed to reveal the characteristics of droughts in the Haihe Basin. Results indicated as follows:(1)The severity of the drought showed a rising trend,and the occurrence of drought was wide in the Haihe Basin. The drought duration and intensity showed a continuous growth tendency. Droughts occurred in all seasons. Droughts in winters were the worst and the situations in summer were relatively better.(2)Droughts in the Haihe Basin featured a"high frequency-low intensity"and"low frequency-high intensity"spatial distribution characteristics. In space,the drought duration and intensity decreased from south to north. Whereas the annual occurrence frequencies of the meteorological drought decreased from north to south in the Haihe Basin. For the arid area,it is far from enough that the former is confined to the warming and drying,and the occurrence of drought.The innovation point of this paper was to analyze the severity and occurrence of drought by using the modified comprehensive meteorological drought index as the drought index. This paper provided a theoretical basis for the monitoring,assessment and early warning.