| 摘要: |
| 近期在很多地方洪水越来越频繁且破坏性更大.20世纪90年代以来全球大洪水造成社会经济财产巨大损失,30次大洪水每次总损失额均超过10×108美元.1990-1998年的9a时间的大洪水爆发的次数比1950-1985年期间Ma大洪水次数还要多.近年来中国大陆也遭受了若干重大洪水灾害(包括1996和1998年两次大的财产损失).与气候变率和变化相关的洪水灾害和易爆发程度的显著增加,这是当前最紧迫的问题.随着气温升高大气中持水量也增加,因此大规模强度的降水的可能性也增大.己观测到高而集中的大降水事件而且这种趋势在未来气候变暖条件下可能增加,大降水事件的增加是洪灾增加的必然条件.当然也有一些其它的非气象因素加剧洪灾的发生,比如土地利用变化(森林砍伐、城市化)导致土壤持水能力下降,径流系数增加;此外,人类占据了洪泛区,可能导致洪水损失增大.另外物质财富在洪泛区的积聚也导致了洪灾损失增加.毫无疑问,由于人类活动和气候的共同作用,未来洪水风险在很多地方可能增加.洪水易爆发程度被认为是暴露系数和调节能力的函数,而且在许多地方所有这些变量都可能增加.而随着暴露系数比人类调节能力增加快,因此洪水易爆发程度增大.然而,要完全从径流变化中区分气候因素导致的强烈自然变率还是直接的人为环境变化是很困难的.由于使用不同的假定情景和不同的气候模型,得到的未来环境的预测结果差异也很大.IPCC第三次评估报告中广泛讨论了气候变化与洪水之间的关系.IPCC第三次评估报告警告说,在东亚季风区非常湿润的季风季节出现的可能性非常大,进而会导致相应地区洪水风险增加.本文总结了迄今为此可收集到的有关长江洪水的资料.利用一些案例来分析研究未来假定情景下气候对水文的影响,并对东亚地区的模拟结果进行了讨论. |
| 关键词: 全球变暖 长江 洪水风险 |
| DOI：10.18307/2003.sup19 |
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| 基金项目: |
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| Flood Risk Growth under Global Change-Yangtze Floods in Perspective |
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Zbigniew W. KUNDZEWICZ1,2
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1.Potsdam Institute for Climate Impact Research(PIK), Potsdam, Germany;2.Research Center for Agricultural and Forest Environment, Polish Academy of Sciences, Poznan, Poland
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| Abstract: |
| Recent floods have become more abundant and more destructive than ever in many regions of the globe. Catastrophic floods observed since 1990 all over the world have led to record-high material damage, with total losses exceeding one billion US dollars in each of over 30 events. The number of great flood disasters in the nine years 1990-1998 was higher than in the three-and-half decades 1950-1985, together. A significant part of these recent losses (including the two highest material damages on record, in 1996 and 1998) have been observed in China. The immediate question emerges as to the extent to wiiich a sensible rise in flood hazard and vulnerability can be linked to climate variability and change. As the water-holding capacity of the atmosphere grows with temperature, the potential for intensive precipitation also increases. Higher and more intense precipitation has been already observed and this trend is expected to increase in the future, warmer world. This is a sufficient condition for flood hazard to increase. Yet there are also other, non-climatic factors exacerbating flood hazard, such as land-use change (deforestation, urbanization) leading to the reduction of water storage potential and increase of the runoff coefficient. Humans have been driven to occupy unsafe areas, thereby increasing the loss potential. Growing wealth has been accumulated in flood-endangered areas. There is no doubt that in the fiiture, flood risk is likely to grow in many places, due to a combination of anthropogenic and climatic factors. Vulnerability to floods can be regarded as a function of exposure and adaptive capacity, and all these entities have been increasing in many areas. The vulnerability grows, as exposure increases faster than the adaptive capacity. Yet, it is difficult to disentangle the climatic component of the river flow series from the strong natural variability and direct, man-made, environmental changes. There is a large difference between results obtained for the Mure conditions by using different scenarios and different models. Links between climate change and floods have found extensive coverage in the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC). The findings in the IPCC TAR material warn of a considerable increase of the risk of a very wet monsoon season in Asian monsoon region. This presentation examines the available information on the floods on the Yangtze observed in the past-to-present. Further, it will review a sample of available studies on hydrological impacts of future climate scenarios. Results of modeling of future conditions in East Asia will be discussed. |
| Key words: Global Change Yangtze River Flood risk |
