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

飓风艾达是一场极具破坏性的4级风暴，于2021年8月29日在路易斯安那州的埃尔默岛和卡米纳达岬角登陆，带来了自卡特里娜飓风以来从未见过的风暴潮和13英尺高的海浪。近年来，这些大风暴在陆架沉积物运输中的重要作用以及这些事件对海岸变化的影响已变得明显。随着仪器和技术的改进，人们开展了更多的实地研究，以测量风暴事件期间近海大陆架上的沉积物运输过程。然而，由于风暴路径的不可预测性以及获得测量的难度和费用，仍然缺乏现场数据。在这个项目中，将在两个疏浚坑中获得样本，用于在这些风暴后补充海滩，以测试飓风在大陆架沉积物的重新分配中起主要作用，并可能在疏浚坑中产生大量沉积物沉积和疏浚坑壁的大量浪费的总体假设。疏浚坑可能是路易斯安那州这种沙子的可持续资源，但它们作为沉积物陷阱的功效需要了解它们的长期演变和大陆架沿岸的海洋过程。数据收集是时间敏感的，因为目标是捕获飓风后大陆架和两个疏浚坑内的沉积物。该项目支持在海上培训本科生和研究生。虽然人们很容易知道大陆架可能是高能环境，但缺乏在大飓风期间和之后立即发生的沉积物运输和沉积的海洋观测数据。特别是，在飓风期间，河床和悬浮物的泥沙通量可以增加一到两个数量级。然而，这些沉积物可能被随后的事件所湮没。疏浚坑是飓风后沉积物沉积的优秀记录者，可以在大陆架上提供自然捕获盆地，记录这些重大事件。该项目将对飓风后的沉积物运输和南佩尔托和桑迪点的疏浚坑以及飓风艾达东部和西部沿路易斯安那州内大陆架10米等深线的多个站点进行定量分析。将利用过去7年（2014年至2021年）的历史数据，对飓风前和飓风后的情况进行比较。飓风条件经常在沿海环境中造成大规模浪费和海底滑坡，这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害。飓风“艾达”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威胁。该奖项反映了美国国家科学基金会的法定使命，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。

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.