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Twentieth century storm activity and sea level rise along the United States coast and their impact on shoreline position

机译：二十世纪美国沿海的风暴活动和海平面上升及其对海岸线位置的影响

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摘要

Coastal storms and sea level changes play important roles in coastal landform evolution. Long records (60--90 yr) of hourly water level from tide gauges and historical shoreline position data (100--150 yr) from NOS T-sheets and vertical airphotos along the U.S. East Coast were used to investigate the temporal and geographic changes in storm activity during this century, storm impact on beaches, post-storm recovery processes, and applicability of the Bruun rule.;Three storm indices based on hourly storm surge data: count, duration, and integrated intensity (area under the storm surge curve that is above two standard deviations for the entire surge record) from 10 tide gauges along the U.S. East Coast do not show any discernible secular trend during the 20 th century. There are, however, significant interdecadal variations in storminess. There was more storm activity (number) and intensity (duration and magnitude) during the mid- to late 1950s and early 1960s, but that storminess was comparable to that experienced in the early 1930s and 1990s.;Northeaster indices exceed that of hurricanes in number, duration, and integrated intensity along the U.S. East Coast. Extratropical storms dominate the coast from Virginia northward, while the influence of hurricanes increases southward.;Beach erosion is not only related to storm severity but also to whether the storm is coincident with spring tides. A storm erosion damage index (inner product of storm surge and tide) was developed. The spatial distribution of the storm erosion damage index, including the effects of both storm tides and waves, shows that the Delmarva coast suffers the most severe storm impact; the New Jersey and Long Island, NY coasts experience considerable storm- induced erosion; the New England coast undergoes relative light storm erosion hazard; the coast from southern North Carolina to the northern Florida experiences the lightest storm impact.;Great storms cause a quantum level of beach erosion in only several days. However, beaches appear to recover to positions consistent with their long-term erosion trend regardless of storm severity. This suggests that storms have little effect on long-term beach erosion, but more pre- and post-storm data are clearly needed.;There is a significant correlation between sea level rise and long-term beach erosion at erosional areas not influenced by inlets and coastal engineering projects. The shoreline retreat rate averages about 150 times that of sea level rise. The Bruun rule is well satisfied at these areas, indicating that it is appropriate to use the Bruun rule to predict the potential beach erosion in response to sea level rise.;Most beaches along the U.S. East Coast are influenced by tidal inlets. Changes in sediment supply induced by inlet activity play a dominant role in determining long- term shoreline changes. Sea level change is only a secondary effect in these areas, and its influence cannot be discerned in areas of rapid shoreline changes because of inlets. However, beach erosion caused by sea level rise is inexorable, while down-drift erosion induced by inlets can be mitigated by natural and artificial sand by-passing. It will become ever more difficult to protect fixed coastal development as active profiles migrate landward in response to sea level rise.
机译：沿海风暴和海平面变化在沿海地貌演变中起着重要作用。利用潮汐计的每小时水位的长期记录（60--90年）和来自NOS T型表的垂直海岸线位置数据（100--150年）和沿美国东海岸的垂直航拍照片来调查时间和地理变化在本世纪的风暴活动中，风暴对海滩的影响，风暴后的恢复过程以及Bruun规则的适用性;基于每小时风暴潮数据的三个风暴指数：数量，持续时间和综合强度（风暴潮曲线下的面积）在整个20世纪，从10个潮汐仪获得的数据（整个潮汐记录的两个标准差以上）都没有显示任何明显的长期趋势。但是，暴风雨年代际变化很大。 1950年代中期至1960年代初和1960年代初，风暴活动（数量）和强度（持续时间和强度）有所增加，但暴风雨可与1930年代和1990年代初的暴风雨相提并论。 ，持续时间和综合强度在美国东海岸。温带风暴主宰着弗吉尼亚州以北的沿海，而飓风的影响则向南增加。海滩侵蚀不仅与风暴的严重性有关，而且与风暴是否与春季潮汐同时发生有关。开发了风暴侵蚀破坏指数（风暴潮和潮汐的内积）。风暴侵蚀破坏指数的空间分布，包括潮汐和海浪的影响，表明德尔马瓦海岸遭受的风暴影响最为严重。新泽西州海岸和纽约州长岛沿岸经历了暴风雨造成的侵蚀；新英格兰海岸遭受了相对轻微的暴风雨侵蚀。从北卡罗来纳州南部到佛罗里达州北部的海岸受到的风暴影响最轻。；大风暴仅在几天内就造成了量子级的海滩侵蚀。但是，无论风暴的严重程度如何，海滩似乎都能恢复到与其长期侵蚀趋势一致的位置。这表明风暴对长期的海滩侵蚀影响不大，但显然需要更多的风暴前和风暴后数据;在不受进水口影响的侵蚀区域，海平面上升与长期海滩侵蚀之间存在显着相关性和沿海工程项目。海岸线的平均撤退速度约为海平面上升速度的150倍。这些区域的Bruun规则非常令人满意，这表明使用Bruun规则预测海平面上升引起的潜在海滩侵蚀是适当的。;美国东海岸的大多数海滩都受到潮汐进口的影响。入口活动引起的沉积物供应变化在确定长期海岸线变化中起主要作用。在这些地区，海平面变化只是次要影响，在因进口而海岸线快速变化的区域中，其影响是无法分辨的。但是，由海平面上升引起的海滩侵蚀是不可避免的，而通过自然和人造沙的绕行可以减轻由进口引起的向下漂移侵蚀。随着海平面上升，活跃的剖面向陆地迁移，保护沿海固定发展将变得越来越困难。

著录项

  • 作者

    Zhang, Keqi.;

  • 作者单位

    University of Maryland, College Park.;

  • 授予单位 University of Maryland, College Park.;
  • 学科 Geography.;Geology.;Physical geography.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 266 p.
  • 总页数 266
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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