中世纪暖期豫北地区干旱灾害研究

Research on Drought Disasters of North Henan Province during the Medieval Warm Period

当前全球变暖背景下,以洪涝、干旱为代表的极端气候事件发生频率不断增加,由此给人类社会带来的影响也越来越大.因此,探讨现代变暖背景下相关自然灾害的发生规律十分重要.中世纪暖期(900-1300年)是距今最近的一次气候温暖期,研究这一时期自然灾害的发生规律,可为当前全球变暖背景下相关自然灾害的防治提供科学依据.以豫北地区为例,根据历史文献资料,统计了研究区中世纪暖期旱灾的强度等级与时间变化特征,并对中世纪暖期旱灾发生与气候变化的关系进行了探讨.结果表明:豫北地区在901-1300年的400年间,共发生旱灾116次,平均每3.45年发生一次;其中以1级普通旱灾为主,共计发生111次,占旱灾总次数的95.7%;2级大旱灾仅发生5次,占旱灾总次数的4.3%;没有3级特大旱灾发生.在季节分布上,豫北地区该时期发生的旱灾多集中在夏季和春季,其次为秋季,冬季发生次数最少.从整体来看,前期(901-1020年)旱灾发生具有较频繁的波动变化;中期(1021-1200年)旱灾前段发生次数较多,后段发生次数减少;后期(1201-1300年)豫北地区旱灾发生次数同样先增后降,但在末期又有所增加.旱灾的这一整体发生情况与该区气候的波动变化密切相关.

Under background of global warming,the frequency of extreme weather events,represented by floods and droughts,is increasing,and their impacts on human society are also growing.So it is very important to explore regularity of related natural disasters occurring in the future.The Medieval Warm Period（MWP）is the last warm period from nowadays,and studying the occurrence regularity of natural disasters during this period could provide scientific basis for the disaster prevention in the future.Taking the North Henan Province as a case area,through the statistics and analysis of historical documents during the MWP（i.e.901-1300）,the ranks,temporal changes and the climatic background of drought disasters during the MWP were studied.The result indicates that there were116 times of droughts during the MWP,approximately once every 3.45 years on average.The overwhelming majority of drought disasters were slight ones,which accounted for 95.7% of the total,followed by severe ones with percent of 4.3%,there was no very severe droughts during the MWP.The droughts had obvious seasonaldifference and the droughts occurring in summer and spring were the most,then followed by autumn,the winter was the least.Variation of droughts could be divided into three periods：there was a frequent and fluctuant in the early phase between 901-1020;in the middle phase,the droughts first rose then fell from 1021 to 1200;the later phase also had a similar change to the middle one but with an uptrend in the end.The above overall changes of droughts during the MWP were closely related to climate changes in the north Henan area.