Collaborative Research: RAPID: The fate of landslide-derived sediment following tropical cyclones: a case study of Hurricane Fiona in Puerto Rico

合作研究：RAPID：热带气旋后滑坡沉积物的命运：波多黎各飓风菲奥娜的案例研究

• 批准号: 2301378
• 负责人: Karl Lang
• 金额: $ 2.46万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2023-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2301378&HistoricalAwards=false
• 关键词: Collaborative; Research; RAPID; fate; landslide

From September 18-20, 2022 Hurricane Fiona delivered more than 64 cm of rainfall to the island of Puerto Rico. This excessive precipitation caused mass wasting and flooding across the island, similar to the effects of Hurricane María in 2017. Both events represent extraordinary opportunities to study the impact of tropical cyclones on the evolution of a high relief, tropical landscape. This project will support two deployments of scientists and equipment to collect time-sensitive and perishable data from two catchments in southern Puerto Rico strongly impacted by mass wasting after the hurricane. Using these catchments as a model study area the investigators will: 1. survey the topography of landslide deposits, scars, and post-landslide river aggradation using drone-based structure-from-motion photogrammetry; 2. collect samples of river sediment downstream of landslide areas for grain size analysis and cosmogenic nuclide tracing of landslide-derived sediment, 3. monitor and record the movement of still-unstable landslides and actively aggrading river channels with time-lapse cameras. The project will be collaborative with co-investigators based in Puerto Rico and coordinated in concert with federal and local scientists working in hazards assessment and prevention. Field work deployments will engage at least 3 graduate and 3 undergraduate students.For more than sixty years, geologists have debated the contribution of large, yet infrequent storm events to the long-term evolution of eroding landscapes. For large storms like tropical cycles, the immediate geomorphic impact to tropical landscapes may be obvious: mass wasting and flooding. However, the extended response of tropical landscapes to the storm event is often more complex, and measurement of landscape response requires repeated observations across a catchment area, beginning immediately after the storm event. This project supports collection of time-sensitive and perishable data to explore three hypotheses concerning the response of a tropical landscape to landslides and flooding caused by a tropical cyclone. Specifically, the investigators will address the questions: 1. Where (and why) do storm events destabilize hillslopes? by surveying landslide scars and deposits in-person, monitoring still-unstable hillslopes with time-lapse cameras, and mapping landslides regionally with remotely-sensed imagery; 2. How do river networks adjust to an influx of landslide-derived sediment? by measuring channel aggradation/erosion patterns with repeat drone-based topographic surveys and direct tracking of coarse sediment transport using time-lapse images of channels downstream of landslide areas; and 3. What is the residence time of landslide-derived sediment in a tropical landscape? by repeated measurement of cosmogenic radionuclide concentrations in river sediment to detect changes in the flux of landslide-derived sediment over the following year.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.

2022 年 9 月 18 日至 20 日，飓风菲奥娜给波多黎各岛带来了超过 64 厘米的降雨量，过量的降水导致全岛出现大规模浪费和洪水，类似于 2017 年飓风玛丽亚造成的影响。这两起事件都带来了非凡的机遇。研究热带气旋对高地势热带景观演变的影响该项目将大力支持科学家和设备的两次部署，以从波多黎各南部的两个集水区收集时间敏感且易腐烂的数据。调查人员将利用这些流域作为模型研究区域： 1. 使用基于无人机的运动结构摄影测量技术来调查滑坡沉积物、伤痕和滑坡后河流加积的地形；收集滑坡区下游河流沉积物样本，进行滑坡沉积物的粒度分析和宇宙成因核素示踪，3. 监测和记录仍不稳定的滑坡运动和积极侵蚀的河流该项目将与波多黎各的联合研究人员合作，并与从事危害评估和预防工作的联邦和当地科学家协调一致。实地工作部署将吸引至少 3 名研究生和 3 名本科生。六十多年来，地质学家一直在争论大型但罕见的风暴事件对侵蚀地貌的长期演变的贡献，对于热带周期这样的大型风暴，对热带地貌的直接影响可能是显而易见的：质量。然而，热带景观对风暴事件的长期响应通常更为复杂，景观响应的测量需要在风暴事件发生后立即开始在整个流域进行重复观测。具体而言，研究人员将利用易腐烂的数据来探索有关热带景观对热带气旋引起的山体滑坡和洪水的反应的三个假设：1.通过调查山体滑坡痕迹和风暴事件在何处（以及为何）破坏山坡的稳定？现场沉积物，用延时摄像机监测仍然不稳定的山坡，并用遥感图像绘制区域滑坡图； 2. 河流网络如何通过测量河道侵蚀/侵蚀模式来适应滑坡沉积物的流入？重复基于无人机的地形调查，并使用滑坡区域下游通道的延时图像直接跟踪粗沉积物的输送；以及 3. 通过重复测量，滑坡产生的沉积物在热带景观中的停留时间是多少？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。