RAPID: The nature and physics of the Montecito debris flows of January 9, 2018, increasing community resiliency to debris flow hazards

泥石流造成了广泛的破坏，造成了人命和基础设施的损失，仅在过去10年里，太平洋沿岸和太平洋西北部就发生了几起重大悲剧。2018年1月9日，美国加利福尼亚州圣巴巴拉县蒙特西托村发生三起大型泥石流，造成21人死亡，390多栋房屋和商业建筑被毁或受损，当地所有交通中断数周。这些水流是由加州历史上最大的野火托马斯大火后几天的强降水造成的。研究表明，在受火灾影响的更广泛地区，托马斯大火造成的泥石流危害可能会持续2年或更长时间。泥石流对蒙特西托社区的影响增加了，因为公众和地方灾害管理官员都对泥石流的物理性质和导致泥石流的条件缺乏清楚的了解。通过图书馆、市政厅会议和当地报纸上的文章与公众直接互动，应有助于教育居民了解区域地质环境、使用和理解具体术语（用“泥石流”代替听起来更温和的“山洪”或“泥石流”）；并灌输对这些快速移动的载石泥浆的危险的现实认识，以及通过立即关注应急管理指令来自我保护的必要性。它还应该完善这些指示，使其成为明确的强制性疏散警告，而不是非强制性建议。目前对自然泥石流的物理性质和流面剖面的认识主要是基于对残余泥石流沉积物的解释。然而，要了解任何单一泥石流的物理特性，都需要收集重要的泥石流数据，而这些数据往往会在几个月到几年内从地质记录中消失。Morell， Dunne和Keller将通过收集时间敏感的现场数据来约束与2018年1月9日Montecito事件相关的物理泥石流过程的关键方面，这些数据包括峰值流量的高度和流动方向，侵蚀和沉积源物质的体积，以及泥石流沉积物的沉积特征，以及了解源区，峰值速度，流变学以及大型泥石流的脉动，膨胀和冲刷所需的关键数据。通过绘制三条受影响流域泥石流沉积物的详细地图和横截面，该项目将描绘出事件沉积物的范围和性质、导致泥石流和大范围破坏的地表流动物理特性，为同一地区近期可能发生的事件做好准备。它将评估泥石流移动巨石的能力，并试图确定未来泥石流的情景和预警系统。该项目利用裸地激光雷达数据（由圣巴巴拉县提供）作为野外工作的基础地图，以及泥石流发生后几天的航空照片（由Geomni公司提供）。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。

Debris flows have caused widespread destruction and loss of human life and infrastructure, with several major tragedies unfolding just in the past 10 years along the Pacific coast and Pacific northwest. On January 9, 2018, three large debris flows in the village of Montecito, Santa Barbara County, California, killed 21 people, destroyed or damaged over 390 homes and commercial buildings, and closed all local traffic for several weeks. The flows were caused by intense precipitation in the days following the Thomas Fire, the largest wildfire in California history. Research suggests the debris flow hazards posed by the Thomas fire may continue for 2 or more years in the wider area affected by the fire. The impact of the debris flows on the Montecito community was increased because both the public and local hazard management officials lacked a clear understanding of the physics of debris flows and the conditions that lead to them. Direct interactions with the public through library Town Hall meetings and articles in the local newspapers should help to educate residents as to the regional geologic setting, the use and understanding of specific terminology ("debris flow" instead of the more benign-sounding "flash flood" or "mudslide"), and to instill a realistic understanding of the danger of these rapidly moving boulder-laden slurries and the need for self-preservation through immediate attention to emergency management instructions. It should also refine those instructions to be unequivocal mandatory evacuation warnings rather than non-mandatory suggestions.Current understanding of the physics of natural debris flows and flow-surface profiles is largely based on interpretation of remnant debris flow deposits. However, understanding the physics of any single debris flow requires the collection of important flow data that are often erased from the geologic record within months to several years. Morell, Dunne and Keller will constrain critical aspects of physical debris flow processes associated with the Jan 9, 2018 Montecito event by collecting time-sensitive field data as to the height and flow direction of the peak flow, the volume of eroded and deposited source material, and the sedimentary character of debris flow deposits, key data needed to understand the source regions, peak velocity, rheology, and the runout, bulking, and scouring of large debris flows. By constructing detailed maps and cross-sections of the debris flow deposits along the three affected drainages, the project will delineate the extent and nature of the event deposit, the surface flow physics that caused the debris flow and the widespread destruction, in preparation for potential near-future events from this same area. It will assess the power of the debris flows to move boulders and attempt to determine scenarios for future flows and warning systems. The project leverages bare-earth LiDAR data (supplied by the county of Santa Barbara) for use as base maps for field work, and aerial photos flown several days after the debris flows (supplied by the company Geomni).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.