Seafloor Impact of Human vs Natural Processes: Insights from the North Carolina Shelf following Hurricane Florence
Seafloor Impact of Human vs Natural Processes: Insights from the North Carolina Shelf following Hurricane Florence
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人类与自然过程对海底的影响：佛罗伦萨飓风过后北卡罗来纳州大陆架的见解
DOI：
10.1002/essoar.10505803.1
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Corbett, D.R.
中科院分区：
文献类型：
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作者：
Walsh, J.P.;Chris Freeman, C;Sumners, B.;Corbett, D.R.
美国东部和墨西哥湾沿岸的许多社区正在经历中度至重度侵蚀。北卡罗来纳州海岸管理部确定的十年海岸线侵蚀率表明，北卡罗来纳州超过 65% 的海岸线正在受到侵蚀，其中 20% 的海岸线以每年约 1 m 的速度消失。风暴造成的长期侵蚀和间歇性快速影响促使北卡罗来纳州大多数沿海社区进行海滩养护以缓解影响。令人担忧的一个问题是，人们对近海沙洲（通常是营养来源）如何随着风暴条件和疏浚活动而演变的了解有限。 2018 年 9 月，飓风佛罗伦萨影响了北卡罗来纳州南部和南卡罗来纳州北部，许多社区遭受了加剧的侵蚀。未来，在东海岸和其他地方，为了海滩营养而进行的海上除沙是不可避免的。博格湾（北卡罗来纳州）靠海大陆架上的取土区提供了观察人为和海洋学过程导致的海底变化的机会。飓风“佛罗伦斯”于 2018 年 9 月 14 日上午在北卡罗来纳州威尔明顿附近登陆，等级为 1 级。在登陆之前，该风暴是强大的 2 级飓风，几天前为 4 级飓风。研究区附近大片地区遭遇飓风级大风，产生强大的风暴潮和超过8 m的波浪。鉴于 ODMDS 的水深，预计将进行海底改造。该项目于 2019 年 2 月在北卡罗来纳州博格班克斯近海部分 ODMDS 收集了地球物理数据和沉积物样本。获得了多波束测深、后向散射和地震反射数据以及 24 个沉积物样本。这些数据添加到之前在 2013 年和 2018 年收集的同一地区的数据中。所有收集的样品的粒度分析均已完成。与早期结果相比，对飓风后数据的初步分析表明，自 2018 年 3 月上次调查以来，海底已经重塑，可能是为了应对飓风佛罗伦萨。 ODMDS 的宽圆顶形状仍然存在，但形态发生了明显的变化。在较浅的区域，大沙波（波峰大致南北向，波长 20-30 m）与早期测绘不同。尽管进行了显着的改造，2013 年疏浚的人为痕迹仍然留在了海景上。
Many communities along the East and Gulf coasts of the United States are experiencing moderate to severe erosion. Decadal shoreline erosion rates determined by the North Carolina Division of Coastal Management indicate that >65% of the NC shoreline is eroding, with 20% losing shore at ~1 m per year. Chronic long-term erosion and episodic rapid impacts from storms have encouraged most coastal NC communities to conduct beach nourishments for mitigation. One concern is that there is limited knowledge of how offshore sand shoals – often sources for nourishments – are evolving in response to storm conditions and dredging activity. In September 2018, Hurricane Florence impacted southern NC and northern SC, and many communities experienced enhanced erosion. Future offshore sand removal for beach nourishment is inevitable here and elsewhere along the East Coast. A borrow area on the continental shelf seaward of Bogue Inlet (NC) offers an opportunity to see how the seabed is changing as a result of anthropogenic and oceanographic processes. Hurricane Florence made landfall as a Category 1 near Wilmington, NC on the morning of September 14, 2018. Prior to making landfall the storm was a powerful Category 2 hurricane, down from Category 4 status days prior. Hurricane-force winds were experienced over a large region, yielding powerful storm surge and waves over 8 m near the study area. Given the water depths of the ODMDS, seabed reworking was anticipated. The project collected geophysical data and sediment samples over a portion of the ODMDS offshore of Bogue Banks, NC in February 2019. Multibeam bathymetry, backscatter and seismic reflection data were obtained along with 24 sediment samples. These data add to previously collected data over the same area in 2013 and 2018. Grain-size analysis has been completed on all collected samples. Preliminary analysis of the post-hurricane data in comparison to earlier results indicate that the seabed has been reshaped since the last survey in March 2018, likely in response to Hurricane Florence. The broad dome-shape of the ODMDS remains, however, there is conspicuous morphological change. In shallower areas large sand waves (crests oriented roughly N-S, wavelength 20-30 m) differ from earlier mapping. Despite notable reworking, the anthropic signature of dredging in 2013 remains on the seascape.