RAPID: Hurricane-induced Shelf Sediment Transport and Deposition after Hurricane Ida in 2021

RAPID：2021 年飓风艾达后飓风引起的陆架沉积物输送和沉积

• 批准号: 2203111
• 负责人: Kehui Xu
• 金额: $ 8.24万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-11-15 至 2023-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2203111&HistoricalAwards=false
• 关键词: RAPID; Hurricane; induced; Shelf; Sediment

Hurricane Ida was a very destructive Category 4 storm that made landfall at Elmer’s Island and Caminada Headlands, Louisiana on 29 August 2021, bringing storm surge and waves of 13 feet, not seen since Hurricane Katrina. The importance of the role of these large storms on shelf sediment transport and the effect of these events on coastal change has become apparent in recent years. With improvements in instrumentation and technology, more field studies have been conducted to measure sediment transport processes on offshore continental shelves during storm events. However, due to the unpredictability of storm paths and the difficulties and expense in obtaining measurements, there is still a lack of field data. During this project, samples will be obtained in two dredge pits, which are used to replenish beaches after these storms, to test the overarching hypothesis that hurricanes play a major role in redistributing sediment on the continental shelf and likely produce massive sediment deposition in dredge pits and extensive mass wasting of the dredge pit walls. Dredge pits may be a sustainable resource for this sand in Louisiana, but their efficacy as sediment traps requires an understanding of their long-term evolution and marine processes along the continental shelf. Data collection is time-sensitive because of the goal of capturing the post-hurricane sediment on the continental shelf and within the two dredge pits. The project supports the training of undergraduate and graduate students at sea.While it is readily known that continental shelves can be energetic environments, there is a lack of marine observational data for sediment transport and deposition that occurs during and immediately after major hurricanes. In particular, the sediment fluxes of bed and suspended loads can increase one to two orders of magnitude during hurricanes. However, these deposits may be obliterated by subsequent events. Dredge pits serve as excellent recorders of post-hurricane sediment deposition and can provide natural capture basins on continental shelves that record these major events. This project will result in a post-hurricane quantification of sediment transport and stratigraphy of the South Pelto and Sandy Point dredge pits as well as multiple stations east and west of Hurricane Ida along the 10-m isobath on the inner Louisiana shelf. A comparison will be made between the pre- and post-hurricane conditions by leveraging historical data over the past seven years (2014 to 2021). Hurricane conditions often cause mass wasting and submarine landslides in coastal environments, which pose a hazard to existing critical infrastructure on the continental shelf, such as renewable wind energy and telecommunication infrastructure. It is also likely that Hurricane Ida triggered dredge pit wall collapse and outward migration, possibly posing a major hazard to hurricane-impacted platforms and pipelines in the vicinity.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.

飓风艾达是一场极具破坏性的四级风暴，于2021年8月29日在路易斯安那州埃尔默岛和卡米纳达岬登陆，带来自卡特里娜飓风以来从未见过的风暴潮和13英尺的海浪。近年来，这些大风暴对大陆架沉积物迁移的重要作用以及这些事件对海岸变化的影响已变得十分明显。随着仪器和技术的改进，进行了更多的实地研究，以测量风暴期间近海大陆架上的沉积物输运过程。然而，由于风暴路径的不可预测性以及获取测量数据的困难和费用，仍然缺乏实地数据。在本项目期间，将在两个用于在风暴后补充海滩的挖泥坑中采集样本，以检验以下总体假设：飓风在重新分配大陆架上的沉积物方面发挥了重要作用，并可能在挖泥坑中产生大量沉积物沉积和大量浪费挖泥坑壁。疏浚坑可能是一个可持续的资源，这种沙子在路易斯安那州，但其功效作为沉积物陷阱需要了解其长期演变和海洋过程沿着大陆架。数据收集具有时间敏感性，因为目标是收集大陆架上和两个挖掘坑内飓风后的沉积物。该项目支持对本科生和研究生进行海上培训，虽然众所周知，大陆架可能是充满活力的环境，但缺乏关于大飓风期间和之后沉积物迁移和沉积的海洋观测数据。特别是，在飓风期间，河床和悬浮物的沉积物通量可增加一到两个数量级。然而，这些沉积物可能会被随后的事件所抹去。疏浚坑是飓风后沉积物沉积的极好记录器，可以在大陆架上提供记录这些重大事件的天然捕获盆地。该项目将对飓风后南佩尔托和桑迪角疏浚坑以及飓风“艾达”沿着路易斯安那内陆架10米等深线以东和以西的多个监测站的沉积物迁移和地层进行量化。将利用过去七年（2014年至2021年）的历史数据对飓风前后的情况进行比较。飓风条件往往在沿海环境中造成大量浪费和海底滑坡，对大陆架上现有的关键基础设施，如可再生风能和电信基础设施构成危险。飓风Ida也有可能引发疏浚坑壁坍塌和向外迁移，可能对附近受飓风影响的平台和管道构成重大危险。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。