Increasing Flash Floods in a Drying Climate over Southwest China
Increasing Flash Floods in a Drying Climate over Southwest China
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DOI：
10.1007/s00376-018-7275-7
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发表时间：
2018-06
影响因子：
5.8
通讯作者：
C. Xiao;P. Wu;Lixia Zhang;R. Clark
中科院分区：
文献类型：
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作者：
C. Xiao;P. Wu;Lixia Zhang;R. Clark
在全球变暖的世界里，亚热带地区通常会变得更干燥，而热带和中高纬度地区会变得更潮湿。与此相适应，如果年平均降水量减少，中国西南地区（北纬25°）预计将变得越来越容易发生干旱。然而，尽管有这一趋势，水分供应的时间分布变化实际上可能导致该区域极端降雨量的增加，该区域的气候特点是有明显的旱季和雨季。使用每小时和每天的测量观测，自1971年以来的降雨强度变化进行了检查，在该地区的142个地点的网络。从分析中可以看出，旱季的变化可以忽略不计，但雨季的变化呈现出明显的下降趋势[-2.4%（10年）-1]，特别是在过去15年[-17.7%（10年）-1]。然而，在最潮湿的5%小时内，事件的强度似乎在整个期间稳步增加[1.4%（10年）-1]，与政府最近的干旱和洪水统计报告相吻合。如果相反的趋势是气候变暖的结果，那么可以合理地预期，这种矛盾的趋势将继续下去，相关地区未来几十年发生山洪暴发的风险将增加。
In a globally warming world, subtropical regions are generally expected to become drier while the tropics and mid–high latitudes become wetter. In line with this, Southwest China, close to 25°N, is expected to become increasingly prone to drought if annual mean precipitation decreases. However, despite this trend, changes in the temporal distribution of moisture supply might actually result in increased extreme rainfall in the region, whose climate is characterized by distinct dry and wet seasons. Using hourly and daily gauge observations, rainfall intensity changes since 1971 are examined for a network of 142 locations in the region. From the analysis, dry season changes are negligible but wet season changes exhibit a significantly strong downward trend [−2.4% (10 yr)−1], particularly during the past 15 years [−17.7% (10 yr)−1]. However, the intensity of events during the wettest of 5% hours appears to steadily increase during the whole period [1.4% (10 yr)−1], tying in with government statistical reports of recent droughts and flooding. If the opposing trends are a consequence of a warming climate, it is reasonable to expect the contradictory trend to continue with an enhanced risk of flash flooding in coming decades in the region concerned.