Climatic control of Mississippi River flood hazard amplified by river engineering
Climatic control of Mississippi River flood hazard amplified by river engineering
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DOI：
10.1038/nature26145
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发表时间：
2018-04-05
期刊：
影响因子：
64.8
通讯作者：
Donnelly, Jeffrey P.
中科院分区：
文献类型：
--
作者：
Munoz, Samuel E.;Giosan, Liviu;Donnelly, Jeffrey P.
在过去的一个世纪里，世界上许多主要河流都进行了改造，以缓解洪水、发电和商业航行(1)。对密西西比河水系的工程改造改变了河流的泥沙水平和河道形态(2)，但这些改造对洪水风险的影响仍有争议(3-5)。探测和确定河流流量变化具有挑战性，因为在建立减轻洪水的基础设施之前，仪表式径流记录往往太短，无法评估自然水文变化的范围。这里我们表明，密西西比河下游洪水灾害的多年代际趋势受到气候变化动力模式的强烈调制，特别是厄尔尼诺-南方涛动和大西洋十年振荡，但在过去的一个世纪里，人工信道化(限制在拉直的水道)大大放大了洪水的幅度。我们的结果基于对过去500年洪水频率和规模的多代理重建，结果显示，百年一遇的洪水(任何一年都有1%的机会被超过的洪水)的规模在这五个世纪里增加了20%，其中约75%的增加归因于河流工程。我们的结论是，人类对密西西比河水系的改变与气候变化的动态模式相互作用，将目前的洪水风险提高到了过去五个世纪以来前所未有的水平。
Over the past century, many of the world's major rivers have been modified for the purposes of flood mitigation, power generation and commercial navigation(1). Engineering modifications to the Mississippi River system have altered the river's sediment levels and channel morphology(2), but the influence of these modifications on flood hazard is debated(3-5). Detecting and attributing changes in river discharge is challenging because instrumental streamflow records are often too short to evaluate the range of natural hydrological variability before the establishment of flood mitigation infrastructure. Here we show that multi-decadal trends of flood hazard on the lower Mississippi River are strongly modulated by dynamical modes of climate variability, particularly the El Nino-Southern Oscillation and the Atlantic Multidecadal Oscillation, but that the artificial channelization (confinement to a straightened channel) has greatly amplified flood magnitudes over the past century. Our results, based on a multi-proxy reconstruction of flood frequency and magnitude spanning the past 500 years, reveal that the magnitude of the 100-year flood (a flood with a 1 per cent chance of being exceeded in any year) has increased by 20 per cent over those five centuries, with about 75 per cent of this increase attributed to river engineering. We conclude that the interaction of human alterations to the Mississippi River system with dynamical modes of climate variability has elevated the current flood hazard to levels that are unprecedented within the past five centuries.