Strange Floods: The Upper Tail of Flood Peaks in the United States
Strange Floods: The Upper Tail of Flood Peaks in the United States
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DOI：
10.1029/2018wr022539
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发表时间：
2018-09
影响因子：
5.4
通讯作者：
J. Smith;Alexander A. Cox;M. Baeck;Long Yang;P. Bates
中科院分区：
文献类型：
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作者：
J. Smith;Alexander A. Cox;M. Baeck;Long Yang;P. Bates
我们通过分析来自8，000多个美国地质调查局（USGS）流量测量站的年度峰值观测值，并通过对产生最极端洪水的风暴的水文气象分析，来研究洪峰分布的上尾。我们重点关注上尾比的分布，上尾比定义为河流测站记录洪水的峰值流量除以样本10年洪水量级。1903年6月14日的赫普纳风暴是俄勒冈州东部沿沿着形成的一场冰雹风暴的产物，该地区主要是融雪洪水。在美国，创纪录的洪峰与年度洪峰分布较大之间的一个鲜明对比是洪水发生的季节性，创纪录的洪水反映了暖季雷暴系统的更大贡献。山区地形和强对流降水是极端上尾比洪峰形成的重要地理和水文气象要素。美国地质调查局河流测站上尾比值的分布不依赖于流域面积，这一结果与基于极值理论的定标结果一致。降尺度模拟与天气研究和预报模型被用来检查风暴环境的1903年赫普纳风暴，沿着与其他两个记录的洪峰附近的蓝山东部俄勒冈州从美国地质勘探局杂项洪水记录，1956年7月迈耶斯峡谷洪水和1965年7月巷峡谷洪水。
We examine the upper tail of flood peak distributions through analyses of annual peak observations from more than 8,000 U.S. Geological Survey (USGS) stream gaging stations and through hydrometeorological analyses of the storms that produce the most extreme floods. We focus on the distribution of the upper tail ratio, which is defined as the peak discharge for the flood of record at a stream gaging station divided by the sample 10‐year flood magnitude. The 14 June 1903 Heppner storm, which produced an upper tail ratio of 200, was the product of a hailstorm that formed along the Blue Mountains in eastern Oregon, a region dominated by snowmelt flooding. A striking contrast between record flood peaks and the larger distribution of annual flood peaks in the United States is in the seasonality of flood occurrence, with record floods reflecting a much stronger contribution from warm season thunderstorm systems. Mountainous terrain and intense convective rainfall are important elements of the geography and hydrometeorology of extreme upper tail ratio flood peaks. The distribution of upper tail ratio values for USGS stream gaging stations does not depend on basin area, a result which is consistent with scaling results based on extreme value theory. Downscaling simulations with the Weather Research and Forecasting model are used to examine the storm environment of the 1903 Heppner storm, along with two other record flood peaks near the Blue Mountains of eastern Oregon from the USGS miscellaneous flood record, the July 1956 Meyers Canyon flood and the July 1965 Lane Canyon flood.