RAPID - Impacts of Hurricane Florence on Coastal and Inner Shelf Environments: Onslow Bay, North Carolina

飓风佛罗伦萨是2018年9月的一场巨大风暴，在外海岸的北卡罗来纳州造成了严重的海岸侵蚀。与风暴有关的降雨事件在沿海和内陆地区造成了前所未有的洪水，影响了向沿海海洋的泥沙输送。此外，飓风还产生了2至3米的风暴潮。水位上升，加上巨大和持续的海浪能量，对沿海岛屿和海湾造成严重侵蚀，并可能对整个大陆架的沉积物和海底形态造成影响。该研究项目收集了熊岛、昂斯洛海湾和博格班克斯地区离岸和岛后泻湖地区的地球物理测量和沉积物取心数据，这些数据具有时间性。这些调查将在风暴前为同一地区的研究进行的调查和取心的同一地点进行，以了解佛罗伦萨对这些环境的影响。收集和分析新数据的目的是评估风暴对以下方面的影响：(1)整个地区的侵蚀和沉积；(2)沙资源(位置、体积等)的变化；(3)不同环境中微化石和沉积物类型的变化；(4)在地层记录中保留和识别这一风暴信号的可能性。了解内部陆架和沿海过程及其对飓风佛罗伦萨等高能量风暴事件的反应，对于准确计算海滩营养的沙量、了解此类事件发生后沙子的去向以及预测应对海平面上升和风暴影响的海岸侵蚀速度非常重要。这将有助于我们了解沙子资源的弹性，而沙子资源对该地区和美国外滩沿岸的海滩营养至关重要。这项工作的更广泛影响包括研究生和本科生培训，以及与北卡罗来纳州吊床海滩州立公园的工作人员共享数据和信息，这可能有助于公园的管理，以及其他沿海资源管理人员。2018年9月，飓风佛罗伦萨严重影响了北卡罗来纳州恐惧角和哈特拉斯角之间的沿海地区，持续风速为每小时50至90英里，阵风超过每小时100英里。它还在一般的小潮汐区域产生了8米的显著海浪高度，峰值周期为15至17秒。飓风还在北卡罗来纳州昂斯洛湾中部造成了2至3米的风暴潮，并持续了几个潮汐周期。这些浅水波的平均内陆架深度约为15m，具有巨大的能量，对内陆架、岸面、堰塞岛和进水口环境的侵蚀、泥沙输移和沉积产生了极大的影响。这些影响在最近获得大量地质和地球物理风暴前数据的地点很明显。这些风暴前的数据将作为在佛罗伦萨之后在相同地区收集的测量的基线。将收集地球物理数据(多波束水深测量和Chirp海底数据)以及内陆架和岸面的沉积物取心/采样。通过比较风暴前后的结果，可以评估(1)该地区的侵蚀和沉积；(2)内大陆架海滩营养沙资源分布的变化；(3)对古环境和古风暴研究很重要的有孔虫组合的变化；(4)评估生存潜力和识别地层记录中的风暴信号。该奖项反映了NSF的法定任务，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，认为值得支持。

Hurricane Florence was an immense 2018 September storm that caused significant coastal erosion in North Carolina on the Outer Banks. Rainfall events associated with the storm caused unprecendented flooding in coastal and inland locations that impacted sediment delivery to the coastal ocean. In addition, the hurricane generated a storm surge of 2 to 3 meters. Elevated water levels combined with the tremendous and sustained wave energy caused substantial erosion to coastal islands and inlets and likely impacted sediments and the morphology of the seafloor across the continental shelf. This research project collects time-critical, ephemeral data consisting of geophysical surveys and sediment coring in the offshore and back island lagoonal parts of the Bear Island, Onslow Bay, and Bogue Banks areas. These surveys will be taken in the same location of surveys and coring done for studies in the same areas prior to the storm to understand the impacts of Florence on these environments. Goals of the collection and analysis of the new data are to assess the impact of the storm on: (1) erosion and sedimentation throughout the region; (2) changes to the sand resources (location, volume, etc.); (3) changes to the types of microfossils and sediments in the various environments and; (4) the potential for retaining and identifying this storm signal in the stratigraphic record. Understanding inner shelf and coastal processes and their response to high energy storm events like Hurricane Florence is important for accurately calculating sand volumes for beach nourishment, understanding where sand goes following such an event, and forecasting coastal erosion rates in response to sea-level rise and storm impacts. This will aid in our understanding of the resiliency of sand resources which are vital for beach nourishment in this region and all along the Outer Banks of the United States. Broader impacts of the work include graduate and undergraduate student training and the sharing of data and information with Hammocks Beach State Park personnel in North Carolina which may aid in management of the park, as well as other coastal resource managers. Hurricane Florence severely impacted the coastal region of North Carolina between Cape Fear and Cape Hatteras in September of 2018 with sustained winds of 50 to 90 mph with gusts exceeding 100 mph. It also generated significant wave heights of 8 meters with peak periods of 15 to 17 seconds in a generally microtidal area. The hurricane also caused a storm surge of 2 to 3 meters in central Onslow Bay, North Carolina that was sustained over several tidal cycles. With an average inner continental shelf depth of about 15 m in Onslow Bay, these shallow water waves possessed tremendous energy that greatly influenced erosion, sediment transport, and deposition on the inner continental shelf, the shoreface, and barrier island and inlet environments. These impacts were manifest in a location where substantial geological and geophysical pre-storm data were recently acquired. These pre-storm data will serve as a baseline for measurements collected post-Florence in the same areas. Both geophysical (multibeam bathymetric surveys and CHIRP subbottom data) and sediment coring/sampling on the inner shelf and shoreface will be collected. Comparison of the pre- and post-storm results allow assessment of (1) erosion and sedimentation in the area; (2) changes in the distribution of beach nourishment sand resources on the inner continental shelf; (3) changes to foraminiferal assemblages which are important for paleoenvironmental and paleo storm studies; (4) assessment of the potential for survival and identification of storm signals in the stratigraphic record.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.