洪泽湖流域洪涝灾害演变趋势及其与El Nio事件关系

为分析洪泽湖流域洪涝灾害在千年尺度序列上的演变趋势，采用统计历史洪涝记录的方法，分析了气候变化背景下洪涝灾害的响应过程，探讨了洪泽湖流域洪涝灾害同El Nio事件的关系。结果表明：近1 000 a来洪泽湖流域洪涝灾害的频度总体是趋于上升的，这种变化趋势同气候变化的趋势是一致的。研究结果显示：公元1000~1400年洪涝记录偏少，同我国东部地区尤其是中世纪暖期出现的一次200 a以上的干旱化过程有较好的对应性。1400~1800年是洪泽湖流域洪涝的多发期，这一事实同我国东部1550~1850年小冰期期间总体偏湿的环境特征相一致。分析洪涝灾害变化同El Nio事件对应性关系表明：在El Nio事件年及其次年是洪泽湖流域洪涝的多发年份。这可能是由于El Nio事件通过改变西太平洋副高的强度与位置，以及大气环流形势而引起的降水异常所致。了解洪泽湖流域洪涝的演变趋势及其同El Nio的关系对于长期防灾减灾策略具有重要的参考意义。

CHANGING TRENDS OF FLOODS AND ITS RELATIONSHIP WITH EL Nio EVENT IN HONGZE LAKE CATCHMENT|CHINA

Statistically collected historical flood records in different archives are analyzed to detect the flooding trend on a millennium scale in Hongze lake catchment，and floods responding to the climate change and its relationship with the El Nio events are identified.Results show that the frequency of the flood disaster has a generally upward trend in Hongze lake catchment，which suggests a good accordance to the trend of the climate change in the last millennium.During the periods of 1000~1400，records of flood are relatively lower，which reveals a direct response to the climate change during the Medieval Warm Period，in which an over 200 years drought period is detected.Similarly，during the periods of 1400~1800，records of floods are higher，demonstrating a close accordance to the climate change in the Little Ice Age from 1550 to 1850 which showed a relatively wetter environment in eastern China.Also，the contrasting relations between the floods and the El Nio events reveal that，big flood disasters are possible to occur in the year of the El Nio events and the year after the El Nio events in Hongze Lake catchment.The strength and location of the subtropical high in the western Pacific Ocean region and the changed atmospherical circulation caused by the El Nio events，which resulted in the abnormal excess precipitation in Hongze Lake catchment，can possibly serve as the physical mechanism of this phenomenon.Understanding this information may be of great help to flood mitigation and to effective decision making for long term flood management strategies in this area.