海安地区近1000年来的气候变化与洪灾

对海安地区史志资料作了搜集与整理,利用Mann-Kendall法对该区1951年以来汛期总量与夏季最高温作了突变检测分析,以对该区近1000年来洪旱灾害的发生规律做一探讨.结果表明,小冰期时期湿润与波动剧烈的气候条件是研究区频繁发生水灾的一个重要因素,同时研究区地势低平,极易遭受水灾、热带风暴及海潮涨溢的影响.MK突变检验表明,研究区汛期总量的突变发生时间大致在20世纪60年代中期,而历年夏季最高温序列在20世纪90年代中期发生突变,具体时间大致在1993年左右.汛期总量在20世纪90年代以前呈波动下降趋势,但在其后汛期径流量又呈上升趋势;夏季最高温在20世纪90年代以前呈波动下降趋势,而在其后呈波动上升趋势,夏季最高温与汛期总量变化趋势相一致.夏季极端高温事件发生概率的增大可能导致洪灾事件的增多,因而在未来气候持续变暖的情景下,研究区乃至长江下游防洪抗灾任重而道远.

Climatic changes and flood events since 1000 aBP in the Hai'an region

Wide collection was performed on the historic records of climatic changes and flood events in the Hai'an region. Mann-Kendall methods was applied to explore the jump transition of the flood runoff and extreme high summer temperature. The research results indicated that the humid and fluctuating climatic changes of the Little Ice Age periods were the driving factors of the frequently-occurring flood disasters. Low-lying terrain of the study region made it prone to the flood disaster, tropic storm and high tide.Calculation results from Mann-Kendall method demonstrated that the jumping point of the flood runoff changes was in the middle of 1960's and that of the extreme summer temperature changes was in the middle of 1990's, the exact jump point was in 1993. Flood runoff had descending trend before 1990's and ascending tendency after 1990's; the extreme high summer temperature had descending trend before 1990's and ascending tendency after 1990's. This result showed that the changing trend of flood runoff matched that of the extreme high summer temperature in the study region.Under the climatic warming scenario,the occurrence probability of the extreme high summer temperature will be increasedg and which will raise the appearance of flood events.