RAPID: Characterizing Inundation and Sediment Transport Associated with Hurricane Michael: A Modern Analog for Paleo-Hurricane Reconstructions

目前对飓风活动调节驱动机制的理解受到飓风发生的短暂仪器记录的严重阻碍。基于沿海池塘和沼泽中沉积的冲积层的代用记录提供了一种方法，可以扩展我们对数千年前飓风袭击的认识。这些古记录使我们能够阐明飓风活动的千年和百年尺度模式，并探索驱动飓风活动变化的机制。其中一些重建是从佛罗里达州的狭长地带发展起来的，并将我们对该地区飓风活动的了解扩展到了4000多年前。然而，需要有充分文献记载的现代类似物来帮助解释长期记录。2018年10月，飓风迈克尔在佛罗里达州的狭长地带登陆，为研究与四级飓风袭击有关的冲积沉积物的特征提供了机会。这项研究将检查佛罗里达州博尔德角三个沿海天坑池塘的沉积学和景观变化，这个地方距离飓风迈克尔登陆的中心大约100公里。这项工作将使用从池塘中提取的新沉积物岩心的海拔数据和材料，并将这些信息与以前从同一池塘中进行的长期沉积学研究记录的结果进行比较。这项研究的结果将有助于限制过去几千年来在该地区留下沉积物的史前事件的特征。这项工作的广泛影响包括增加联邦灾害机构、保险公司、海岸管理人员和社区对佛罗里达狭长地带大风暴袭击的概率和时间的了解，这将有助于更好地制定土地和灾害规划。影响还包括研究生培训和通过讲座和与社区领袖对话进行的公众宣传。后一种外联具有很强的项目媒体报道潜力。由于这些强风暴事件在时间和空间上的仪器记录有限，目前对在几十年和更长时间尺度上驱动飓风活动变化的原因了解不足。海岸沉积环境中保存的冲积层等地质代用物为研究史前飓风变动性提供了重要工具。这项研究包括收集基于无人机的航空数据和土地调查，以检查风暴及其风暴潮造成的地貌和海拔变化。它还涉及在佛罗里达州狭长地带的秃头点收集沉积物岩心，距离墨西哥海滩不到100公里，2018年10月，飓风“迈克尔”的风眼登陆了墨西哥海滩。沉积物取样和调查将在先前研究过的三个沿海天坑池塘进行：Little Tucker， Mullet和Shotgun。本研究收集的数据将与这三个站点的基线数据进行比较，其中一些数据包括2010年进行的激光雷达（光探测和测距）飞机高程测量。飓风迈克尔沉积物岩心将被采集，样品将被检查粒度、事件层沉积和碎屑组成。它们还将被检查以测试从海底撕裂的微化石，如有孔虫。后一种数据将提供关于风暴期间海底波浪/潮汐侵蚀和海洋沉积物运输的程度和力量的见解。需要解决的问题包括：风暴强度以及如何在地质记录中记录风暴强度，以及风暴需要到达一个地点多近才能导致事件层沉积。对现代类似物的研究，如飓风迈克尔留下的沉积物，对于能够正确解释这个和其他地方的沉积物记录至关重要。它还将提供该地区强风暴事件的长期重建，以及可能更广泛适用的研究结果和方案。通过描述三个目标研究地点的淹没水平和沉积物运输程度，该项目将能够更好地解释过去4000年来佛罗里达狭长地带沉积的强飓风/风暴事件的性质。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。

Current efforts to understand the driving mechanisms responsible for modulating hurricane activity are significantly hampered by a short instrumental record of hurricane occurrence. Proxy records based on overwash layers deposited in coastal ponds and marshes provide a means of extending our knowledge of hurricane strikes back thousands of years. These paleo-records allow us to elucidate millennial and centennial scale patterns in hurricane activity and explore the mechanisms that drive changes in hurricane activity. Several of these reconstructions have been developed from the Panhandle of Florida and have extended our knowledge of hurricane activity in the area back more than 4000 years. However, well documented modern analogs are needed to help interpret the long term records. The landfall of Hurricane Michael on the panhandle of Florida in October 2018 provided an opportunity to investigate the character of overwash deposits associated with a category 4 strike. This research will examine sedimentological and landscape changes at three coastal sinkhole ponds on Bald Point, Florida, a location that is about 100 km from the center of where Hurricane Michael came ashore. The work will use elevation data and material from new sediment cores, taken from the ponds, and compare this information to results from longer term sedimentological records of previous studies from the same ponds. Results of this research will help constrain the character of prehistoric events that left deposits in the region over the past several millennia. Broader impacts of the work include increasing knowledge for use by federal disaster agencies, insurance companies, coastal managers, and communities about the probability and timing of major storm strikes on the Florida panhandle which should assist in better land and disaster planning. Impacts also include graduate student training and public outreach via lectures and conversations with community leaders. The latter outreach has strong potential for project media coverage.There is presently an insufficient understanding of what drives variability of hurricane activity on multidecadal and longer timescales due to the limited, in time and space, instrumental record of these strong storm events. Geologic proxies such as overwash layers preserved in coastal depositional settings provide an essential tool for examining hurricane variability in prehistory. This research involves the collection of drone-based aerial data and land surveys to examine geomorphic and elevation changes resulting from the storm and its storm surge. It also involves the collection of sediment cores on Bald Point on the Florida panhandle within 100 km of Mexico Beach where the eye of Hurricane Michael came ashore in October of 2018. Sediment sampling and surveys will be carried out at three coastal sinkhole ponds that have been previously studied: Little Tucker, Mullet, and Shotgun. Data collected in this study will be compared with the baseline data from these three sites, some of which includes LIDAR (LIght Detecting and Ranging) aircraft elevation surveys taken in 2010. Hurricane Michael sediment cores will be taken and samples will be examined for grain size, event-bed deposition, and clast composition. They will also be examined for the tests of microfossils, like foraminifera, ripped from the seabed. The latter data will provide insights into the extent and force of seabed wave/tide erosion and marine sediment transport during the storm. Questions to be addressed include: storm intensity and how that is recorded in the geological record and how close a storm needs to come to a site to result in event-bed deposition. Studies of modern analogs, such as the deposits left behind by Hurricane Michael, are essential for being able to correctly interpret the sediment record at this and other localities . It will also provide long-term reconstruction of strong storm events in the area and findings and protocols that may be applicable more widely. By characterizing the level of inundation and degree of sediment transport to the three targeted study sites, the project will be able to better interpret the nature of strong hurricane/storm events deposited over the last 4 millennia on the Florida panhandle.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.