RAPID: Observations of Sediment Scour and Deposition in the Vicinity of Ports and Harbors from the 11 March 2011 Japan Tsunami

RAPID：2011 年 3 月 11 日日本海啸期间港口附近沉积物冲刷和沉积的观测

• 批准号: 1240385
• 负责人: Robert Weiss
• 金额: $ 7.39万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1240385&HistoricalAwards=false
• 关键词: RAPID; Observations; Sediment; Scour; Deposition

Weiss/113534/Texas A&MThe magnitude 9 March 11, 2011 Japanese earthquake spawned a trans-oceanic tsunami causing significant effects throughout the Pacific. While the tsunami outside of Japan was not catastrophic, there were localized pockets of considerable damage, particularly in ports, harbors, and marinas. Protective barriers around ports and harbors, such as breakwaters, do effectively reduce the effects of everyday wind waves. However, with tsunamis, the energy is focused at the gaps in these barriers, typically the harbor entrance channel. This focusing leads to extreme currents, turbulence, and significant sediment transport. It is the overarching theme of this proposal to observe, document, and understand the tsunami-driven hydrodynamic and sedimentological effects near ports and harbors and compare the tsunami inundation characteristics in inhabited areas throughout the Pacific.This grant supports an interdisciplinary, coastal impact survey of the tsunami that focuses on Pacific islands and other selected far field locations to reconstruct the tsunami characteristics, as well as sediment dynamics during the event. Engineering evaluation and sedimentary studies are jointly done in and near harbors, ports, and coastal infrastructure to provide a comprehensive assessment of this event. In the vicinity of infrastructure the team determines the runup, inundation distance, and flow depth. During the engineering evaluation, the team measures scouring around infrastructure, if accessible, and interviews eyewitnesses about the timeline of tsunami arrival, inundation dynamics, and the hydrodynamics in ports, harbors, and marinas as a consequence of the tsunami. Discussion with local harbormasters and captains provides information about regions and severity of underwater scour and deposition. In uninhabited areas or areas with minimum influence of infrastructure on the tsunami inundation dynamics, the team determines the tsunami damage and flood-zone characteristics and compares these finding with data near coastal structures. The team also determines the characteristics of generated deposits or erosion from the tsunami. For deposits they measure the extent, thickness, grading trends, and take samples for grain-size analysis. If the soil material permits, they dig an exploratory trench to look for deposits from past tsunamis.Combined with surveys already completed by the PIs along the US West coast, this compilation of data and observations is the most comprehensive for a tsunami affecting all scales of modern maritime infrastructure from small boat marinas to large commercial ports.This interdisciplinary RAPID proposal will incorporate engineering characterization of tsunami damage and the flood zone with investigations of the tsunami deposits and erosion. The interdisciplinary character of the survey has the potential to transform how reconnaissance tsunami field surveys will be carried out in the future due to a more coherent and consistent assessment of man-made and natural environments. Sedimentologic studies will also bring a geoscientific perspective to the data that will result in a more complete characterization of tsunami event, potentially taking the paleo-tsunami record into account. If the skill to look back into geologic history to estimate tsunami intensity and extreme-event recurrence from sediment deposits existed, the implications for efficient hazard planning are tremendous. Furthermore, with some knowledge of the capacity of a tsunami to transport and scour sediment near coastal infrastructure, we should be able to better design for and mitigate these damaging impacts.

2011年3月11日日本发生的9级地震引发了跨洋海啸，对整个太平洋造成了重大影响。虽然日本以外的海啸不是灾难性的，但局部地区造成了相当大的破坏，特别是在港口、港口和码头。港口周围的防护屏障，如防波堤，确实有效地减少了日常风浪的影响。然而，在海啸中，能量集中在这些屏障的缝隙上，通常是港口入口通道。这种聚焦导致了极端的水流、湍流和大量的沉积物运输。观察、记录和理解海啸对港口附近的水动力和沉积学影响，并比较整个太平洋居民区的海啸淹没特征，是本提案的首要主题。这笔赠款支持对海啸进行跨学科的沿海影响调查，重点关注太平洋岛屿和其他选定的远场地点，以重建海啸特征，以及海啸期间的沉积物动态。工程评估和沉积研究是在港口、港口和沿海基础设施内及其附近共同进行的，以提供这次事件的全面评估。在基础设施附近，团队确定了坡度、淹没距离和水流深度。在工程评估期间，团队测量了基础设施周围的冲刷情况，如果可以使用，并采访了目击者，了解海啸到达的时间、淹没动力学以及海啸造成的港口、港口和码头的水动力学。与当地港长和船长的讨论提供了有关水下冲刷和沉积的区域和严重程度的信息。在无人居住的地区或基础设施对海啸淹没动态影响最小的地区，研究小组确定海啸破坏和洪水区特征，并将这些发现与沿海建筑附近的数据进行比较。该小组还确定了海啸产生的沉积物或侵蚀的特征。对于沉积物，他们测量范围、厚度、分级趋势，并采集样品进行粒度分析。如果土壤材料允许，他们会挖一条勘探沟，寻找过去海啸留下的沉积物。结合pi在美国西海岸已经完成的调查，这一数据和观测汇编是海啸影响从小型游艇码头到大型商业港口的所有规模的现代海上基础设施的最全面的。这个跨学科的RAPID方案将把海啸破坏和洪水区的工程特征与海啸沉积物和侵蚀的调查结合起来。由于对人为环境和自然环境的评估更加连贯一致，这次调查的跨学科性质有可能改变今后海啸实地调查的方式。沉积学研究还将为这些数据带来地球科学的视角，这将导致对海啸事件更完整的描述，可能会考虑到古海啸记录。如果能够回顾地质历史，从沉积物中估计海啸强度和极端事件的重现，那么对有效的灾害规划的影响将是巨大的。此外，了解海啸在沿海基础设施附近运输和冲刷沉积物的能力后，我们应该能够更好地设计和减轻这些破坏性影响。