EAR-PF: Revisiting Megafloods: Insights From Glacial Isostatic Adjustment on Flood Size, Flow Routes, and Climate Response

EAR-PF：重温特大洪水：冰川均衡调整对洪水规模、水流路线和气候响应的见解

• 批准号: 1900756
• 负责人: Tamara Pico
• 金额: $ 17.4万
• 依托单位: Pico, Tamara
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900756&HistoricalAwards=false
• 关键词: EAR; PF; Revisiting; Megafloods; Insights

Dr. Tamara Pico has been awarded an NSF EAR Postdoctoral Fellowship to investigate the influence of glacial isostatic adjustment on late Pleistocene catastrophic flooding to improve our understanding of the timing and routing of mega-floods. The work will be conducted at the California Institute of Technology and Oregon State University. During the last ice age, 22,000 to 14,000 years ago, dozens of catastrophic mega-floods from an ice-dammed Glacial Lake Missoula scoured the landscapes of Idaho and eastern Washington, forming what are known as the Channeled Scablands. These glacial lake outbursts are the largest known floods on Earth. Reconstructing the magnitude of these events informs our understanding of how floods shape Earth's landscapes and relate to abrupt changes in climate. Over the period of flooding, ice sheet melting caused crustal deformation with rates of about 10 mm/yr, which is orders of magnitude above regional tectonic uplift rates, resulting in a substantially different regional topography relative to today. This process of glacial isostatic adjustment has been neglected in prior estimates of flood volumes or discharge, introducing a potentially large error, which has not yet been quantified. This study will provide a more accurate estimates of total discharge during flood events which in turn will help quantify the response of the ocean and broader climate system to mega-floods. In addition, the research will help inform for outburst flood planning by studying the nature of past catastrophic flooding and the stability of ice sheets in response to climate change. The PI has extensive leadership and outreach experience in women in science and underrepresented minority groups and will continue a committed involvement in these communities. Outburst mega-floods from glacial Lake Missoula, occurring from 22,000 to 14,000 years ago, are the largest known floods on Earth. Prior estimates of water volume and flow discharge during these flood events rely on slopes based on modern topography. Over this time period, glacial isostatic adjustment caused crustal deformation with rates of about 10 mm/yr, orders of magnitude above regional uplift rates, and changed local slopes by about 30%. Thus, prior estimates of flood volumes include a potentially large error, which has not yet been quantified. Furthermore, over the interval of Missoula flooding, patterns of uplift and subsidence due to glacial isostatic adjustment evolved significantly, and this reshaping of topography may explain observed changes in flood routing over time. This proposal, within disciplines of Geomorphology and Geophysics, seeks to investigate the influence of glacial isostatic adjustment on the Channeled Scablands landscape as it developed over the course of Missoula mega-flood events. Three interconnected goals for this project are proposed: (1) reconstruct drainage path evolution across the interval of flood events in response to glacial isostatic adjustment; (2) accurately estimate flood discharge using slopes corrected for glacial isostatic adjustment; and (3) connect the response of ocean, and broader climate system, to newly-refined estimates of total freshwater flux. Glacial isostatic adjustment simulations will be performed to predict paleo-topography and paleo-slopes in the Channeled Scablands. Flood drainage pathways and flood discharge estimates will be calculated using the resulting topography corrected for glacial-isostatic adjustment. Finally, these new estimates of freshwater flux will be compared to the geochemical record of sediment cores collected off the Oregon coast, to assess the response of the ocean's biological system to mega-flood events. The proposed research, which transcends multiple scales by using glacial-isostatic adjustment modeling to connect geomorphic processes to both small and large wavelength features of the mantle's response to ice loading, ultimately linking local short-lived outburst flooding to longer global climate changes.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.

Tamara Pico 博士获得了 NSF EAR 博士后奖学金，以研究冰川均衡调整对晚更新世灾难性洪水的影响，以提高我们对特大洪水发生时间和路线的了解。这项工作将在加州理工学院和俄勒冈州立大学进行。在 22,000 至 14,000 年前的最后一个冰河时期，来自冰坝米苏拉湖的数十次灾难性特大洪水冲刷了爱达荷州和华盛顿州东部的景观，形成了所谓的“渠道式Scablands”。这些冰川湖溃决是地球上已知的最大洪水。重建这些事件的严重程度有助于我们了解洪水如何塑造地球景观以及与气候突变的关系。在洪水期间，冰盖融化导致地壳变形，其变形速度约为每年 10 毫米，比区域构造抬升速度高出几个数量级，导致区域地形与今天有很大不同。先前对洪水量或流量的估计中忽略了冰川均衡调整的过程，从而引入了潜在的巨大误差，但尚未量化。这项研究将对洪水事件期间的总流量进行更准确的估计，从而有助于量化海洋和更广泛的气候系统对特大洪水的响应。此外，该研究还将通过研究过去灾难性洪水的性质以及冰盖应对气候变化的稳定性，为突发洪水规划提供信息。 PI 在科学界女性和代表性不足的少数群体方面拥有丰富的领导和外展经验，并将继续致力于参与这些社区。米苏拉冰川湖爆发的特大洪水发生于 22,000 至 14,000 年前，是地球上已知的最大洪水。先前对这些洪水事件期间水量和流量的估计依赖于基于现代地形的坡度。在此期间，冰川均衡调整导致地壳变形速度约为每年 10 毫米，比区域抬升速度高出几个数量级，并改变了局部坡度约 30%。因此，先前对洪水量的估计存在潜在的较大误差，但尚未量化。此外，在米苏拉洪水期间，由于冰川均衡调整而导致的隆起和下沉模式显着演变，这种地形的重塑可以解释观察到的洪水路径随时间的变化。该提案属于地貌学和地球物理学学科，旨在研究冰川均衡调整对在米苏拉特大洪水事件过程中形成的沟渠Scablands景观的影响。该项目提出了三个相互关联的目标：（1）重建洪水事件期间的排水路径演化，以响应冰川均衡调整； （2）利用冰川均衡调整修正后的坡度准确估算洪水流量； (3) 将海洋和更广泛的气候系统的响应与新近完善的总淡水通量估计联系起来。将进行冰川均衡调整模拟，以预测通道Scablands的古地形和古斜坡。将使用针对冰川均衡调整校正后的地形来计算洪水排水路径和洪水流量估算。最后，这些对淡水通量的新估计将与俄勒冈州海岸附近收集的沉积物岩心的地球化学记录进行比较，以评估海洋生物系统对特大洪水事件的响应。拟议的研究超越了多个尺度，通过使用冰川均衡调整模型将地貌过程与地幔对冰载荷响应的小波长和大波长特征联系起来，最终将局部短暂的爆发洪水与长期的全球气候变化联系起来。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Not a bathtub: A consideration of sea-level physics for archaeological models of human migration

不是浴缸：人类迁徙考古模型中海平面物理学的考虑

• DOI: 10.1016/j.jas.2021.105507
• 发表时间: 2022-01
• 期刊: Journal of Archaeological Science
• 影响因子: 2.8
• 作者: Borreggine, Marisa;Powell, Evelyn;Pico, Tamara;Mitrovica, Jerry X.;Meadow, Richard;Tryon, Christian
• 通讯作者: Tryon, Christian