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

目前理解调节飓风活动的驱动机制的努力受到飓风发生的短暂工具记录的严重阻碍。基于海岸池塘和沼泽中沉积的溢流层的代理记录为我们提供了一种将飓风袭击的知识延伸到数千年前的方法。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。其中几个重建是从佛罗里达州的狭长地带发展而来的，将我们对该地区飓风活动的了解延长到4000多年前。然而，需要有充分证据的现代类比来帮助解释长期记录。2018年10月，飓风迈克尔在佛罗里达州狭长地带登陆，为调查与4级袭击有关的溢流沉积物的特征提供了机会。这项研究将研究佛罗里达州Bald Point的三个沿海天坑池塘的沉积学和地貌变化，该位置距离飓风迈克尔登陆的中心约100公里。这项工作将使用来自池塘的新沉积物岩芯的高程数据和材料，并将这些信息与同一池塘以前研究的较长期沉积学记录的结果进行比较。这项研究的结果将有助于限制史前事件的特征，这些事件在过去数千年里在该地区留下了沉积物。这项工作的更广泛影响包括增加供联邦灾害机构、保险公司、沿海管理人员和社区使用的关于佛罗里达州狭长地带发生重大风暴袭击的可能性和时间的知识，这应该有助于更好的土地和灾害规划。影响还包括研究生培训和通过讲座和与社区领导人的对话进行公共宣传。由于这些强风暴事件在时间和空间上的工具记录有限，目前对飓风活动在数十年和更长时间尺度上变化的驱动因素了解不足。保存在沿海沉积环境中的溢流层等地质指标为研究史前飓风的变异性提供了必要的工具。这项研究涉及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高程变化。它还涉及在佛罗里达州狭长地带的Bald Point上收集沉积物岩芯，距离墨西哥海滩不到100公里，2018年10月，飓风迈克尔的眼睛在墨西哥海滩登陆。沉积物采样和调查将在三个以前研究过的沿海天坑池塘进行：小塔克、穆莱特和猎枪。这项研究收集的数据将与这三个地点的基线数据进行比较，其中一些包括2010年进行的LIDAR(光探测和测距)飞机高度调查。将采集飓风迈克尔的沉积物岩心，并对样品进行粒度、事件床沉积和碎屑成分的检查。他们还将接受从海床上挖出的微化石的测试，比如有孔虫。后者的数据将提供对风暴期间海底波浪/潮汐侵蚀和海洋沉积物输送的程度和力量的深入了解。需要解决的问题包括：风暴强度和如何将其记录在地质记录中，以及风暴需要离现场多近才能导致事件床沉积。对现代类似物的研究，如飓风迈克尔留下的沉积物，对于能够正确解释该地区和其他地区的沉积物记录至关重要。它还将提供对该地区强风暴事件的长期重建，以及可能更广泛适用的调查结果和方案。通过表征三个目标研究地点的淹没程度和泥沙输送程度，该项目将能够更好地解释过去4000年来在佛罗里达州狭长地带沉积的强烈飓风/风暴事件的性质。该奖项反映了NSF的法定使命，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，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.