全球变暖、长江水灾与可能损失

GLOBAL CLIMATIC WARMING, THE YANGTZE FLOODS AND POTENTIAL LOSS

全球大幅度变暖,使得水循环加快,蒸发和降水增强。长江中下游地区在20世纪90年代已呈现出明显增温趋势,达到0.2～0.8℃,最大增温区域在长江三角洲地区。降水在长江流域中下游地区增加明显,增加值为5%～20%。20世纪90年代是继50年代后,长江流域性洪水灾害高发的10年。长江流域是我国经济发展的核心地区,对长江流域725个县洪水灾害脆弱性分析结果表明,近1/3的地区是洪水灾害高脆弱性地区。按照1998年社会经济状况,若遭遇1954年型、1991年型、1996年型和1998年型的洪水时,洪水灾害造成的可能损失分别为589、55、70和196亿美元。气候模拟预测表明,21世纪长江流域地区的增温可能达到2.7℃,导致降水可能增加10%,径流可能增加37%。在全球变暖的趋势,以及区域社会经济可持续发展造成不透水面积增大和单位经济价值升高的共同影响下,长江流域发生相当于1870年、1954年和1998的千年、百年和20年一遇洪水的可能性增大,甚至可能发生超过上述频率的特大洪水。

A rapid, highamplitude global climatic warming would speed global water cycle and strengthen rainfall and evaporation. Mean temperature in 1990s increases 0.2～0.8℃ comparing on the temperature between 1951 and 1980. High temperature increases in the Yangtze Delta. Annual precipitation increases more that 5%～20% in 1990s than the value between 1951 and 1980. At the Yangtze river catchment 5 heavy floods were happened in the 1990s. As the Yangtze river catchment plays an important role in the economic development in China, potential loss to floods increase very quickly. Based on the value of production in 1998, potential losses will be 58 900, 5 500, 7 000 and 19 600 million US dollar if the 1954, 1991, 1996 and 1998 floods would be happened. Based on regional climate model developed from National Climate Centre, increase of greenhouse gases like CO2 will lead to increase of about 2.7℃ of annual mean temperature in the Yangtze river catchment, it is projected to estimate the increase of 10% precipitation and 37% runoff. It is conclusion that the possibility of heavy floods like the types of 1998, 1954 and 1870 would happen in future as the impact of climatic warming and increasing urbanized area due to fast economic development. 