Collaborative Research: Geomorphic legacy of megaflood deposits on river processes and form, Eastern Himalaya

合作研究：喜马拉雅东部大洪水沉积物对河流过程和形态的地貌遗产

• 批准号: 2220335
• 负责人: Karl Lang
• 金额: $ 20.96万
• 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: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2220335&HistoricalAwards=false
• 关键词: Collaborative; Research; Geomorphic; legacy; megaflood

Earth and other planetary landscapes contain a record of both past and present surface processes. During colder climate periods thousands of years ago, glacial ice and debris episodically dammed rivers, leading to catastrophic floods of a magnitude not seen on Earth today. Such “megafloods” left an indelible signature on landscapes across nearly every continent, and geologists rely on rare flood deposits to reconstruct how megafloods have shaped the landscapes we see today. This project focuses on unique flood deposits from the eastern Himalayan mountains, using new observations, measurements, and computer modeling to study how catastrophic flood events contribute to the evolution of a steep, high-relief mountain landscape. This project also uses the fascinating story of megafloods to develop publicly accessible K-12 educational materials that integrate scientific discovery with Indigenous Knowledge and will support training of multiple graduate and undergraduate students. The results of this work will help to more accurately interpret the origin of the landscapes seen on both Earth and Mars today – as well as to better predict hazards from similarly catastrophic anthropogenic analogues, such as flooding after the failure of a dam. Prior megaflood research has focused on the impact of dam-burst megaflood discharges (10^6 m3/s) on bedrock channel erosion. This project will further explore the role of megaflood deposition on the long-term (10^3 yr) evolution of bedrock rivers. The project team will focus on a well-documented example of megaflood deposition along the Yarlung-Siang-Brahmaputra river system in the eastern Himalaya to: 1. determine the source, depositional age and grain size distribution of flood deposits using cutting-edge analytical tools, 2. develop a process-based numerical model to predict first-order changes to a bedrock river channel following abrupt flood aggradation, and 3. search for a unique topographic signature of megaflood processes by comparing the morphology of eastern Himalayan river channels with and without a history of megaflooding. These findings will illuminate how intermontane sediment deposition by megafloods governs river valley evolution. Ultimately, the results have the potential to change the way sediment deposition is considered in numerical models of eroding mountainous landscapes and will provide new insight into the role of infrequent, high-magnitude flood events in shaping landscapes on both Earth and Mars.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.

地球和其他行星地貌包含了过去和现在的地表过程的记录，在数千年前的寒冷气候时期，冰川和碎片偶尔会堵塞河流，导致当今地球上从未见过的灾难性洪水。几乎每个大陆的景观都留下了不可磨灭的印记，地质学家依靠罕见的洪水沉积物来重建特大洪水如何塑造我们今天看到的景观。该项目还利用喜马拉雅山脉东部的沉积物，利用新的观测、测量和计算机模型来研究灾难性洪水事件如何导致陡峭、高浮雕山地景观的演变，并利用特大洪水的迷人故事来开发可公开获取的 K。 -12 份教育材料将科学发现与本土知识相结合，并将支持对多名研究生和本科生的培训。这项工作的结果将有助于更准确地解释当今地球和火星上所见景观的起源。更好地预测危险先前的特大洪水研究主要集中于溃坝特大洪水流量（10^6 m3/s）对基岩河道侵蚀的影响。大型洪水沉积对基岩河流长期（10^3 年）演化的影响 该项目团队将重点研究沿线的大型洪水沉积实例。喜马拉雅东部的雅鲁藏布江-雅鲁藏布江水系：1. 使用尖端分析工具确定洪水沉积物的来源、沉积年龄和粒度分布，2. 开发基于过程的数值模型来预测一级变化洪水突然加剧后的基岩河道，以及 3. 通过比较有和没有特大洪水历史的喜马拉雅东部河道的形态，寻找特大洪水过程的独特地形特征。将阐明特大洪水造成的山间沉积物如何控制河谷演化，最终，这些结果有可能改变侵蚀山地景观数值模型中考虑沉积物沉积的方式，并将为罕见的高强度洪水的作用提供新的见解。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

The Erosional and Depositional Potential of Holocene Tibetan Megafloods Through the Yarlung Tsangpo Gorge, Eastern Himalaya: Insights From 2D Hydraulic Simulations

喜马拉雅东部雅鲁藏布江峡谷全新世西藏特大洪水的侵蚀和沉积潜力：来自二维水力模拟的见解

• DOI: 10.1029/2021jf006498
• 发表时间: 2022-04-29
• 期刊: Journal of Geophysical Research: Earth Surface
• 作者: Susannah M. Morey;K. Huntington;Michael D. Turzewski;Mahathi Mangipudi;David R. Montgomery
• 通讯作者: David R. Montgomery