EVIDENCE FOR CHANGING FLOOD RISK IN NEW ENGLAND SINCE THE LATE 20TH CENTURY
EVIDENCE FOR CHANGING FLOOD RISK IN NEW ENGLAND SINCE THE LATE 20TH CENTURY
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DOI：
10.1111/j.1752-1688.2008.00277.x
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发表时间：
2009-04-01
影响因子：
2.4
通讯作者：
Collins, Mathias J.
中科院分区：
文献类型：
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作者：
Collins, Mathias J.
近几十年来，人类影响最小的流域的长期流量记录显示出区域和国家尺度上流量增加的趋势，特别是对于低流量分位数，如年最小流量和年中值流量。高流量分位数的趋势不太清楚，尽管最近的研究表明，在过去的世纪，美国本土的降水量增加，主要是由于日降水量分布的上10百分位事件的频率和强度增加，特别是在东北部。本研究调查了新英格兰流域28个长期年洪水系列的趋势，主要是自然径流。洪水系列平均为75年一遇，持续到2006年。通过非参数Mann-Kendall检验，25个系列显示出上升趋势，其中40%（10）具有统计学显著性（p < 0.1）。此外，23个研究仪表的平均标准化偏离系列表明，在新英格兰的洪水震级增加发生在1970年左右的一个步骤的变化。这一时间与北大西洋涛动低频变率的相位变化大致同步，北大西洋涛动是一种显著的高层大气环流模式，已知会影响沿着美国东海岸的气候变率。当受影响的流量记录用于洪水频率分析时，应考虑可识别的水文气候变化。洪水序列的特殊处理可以改善分析，并提供更好的估计洪水量级和频率下的主要水文气候条件。
Long-term flow records for watersheds with minimal human influence have shown trends in recent decades toward increasing streamflow at regional and national scales, especially for low flow quantiles like the annual minimum and annual median flows. Trends for high flow quantiles are less clear, despite recent research showing increased precipitation in the conterminous United States over the last century that has been brought about primarily by an increased frequency and intensity of events in the upper 10th percentile of the daily precipitation distribution - particularly in the Northeast. This study investigates trends in 28 long-term annual flood series for New England watersheds with dominantly natural streamflow. The flood series are an average of 75 years in length and are continuous through 2006. Twenty-five series show upward trends via the nonparametric Mann-Kendall test, 40% (10) of which are statistically significant (p < 0.1). Moreover, an average standardized departures series for 23 of the study gages indicates that increasing flood magnitudes in New England occurred as a step change around 1970. The timing of this is broadly synchronous with a phase change in the low frequency variability of the North Atlantic Oscillation, a prominent upper atmospheric circulation pattern that is known to effect climate variability along the United States east coast. Identifiable hydroclimatic shifts should be considered when the affected flow records are used for flood frequency analyses. Special treatment of the flood series can improve the analyses and provide better estimates of flood magnitudes and frequencies under the prevailing hydroclimatic condition.