Impact of Quaternary megafloods on erosion of the Tsangpo River gorge, southeastern Tibet

在过去十年中，人们再次就地震、山体滑坡和洪水等极端事件在长期侵蚀和景观演变中的作用展开辩论。然而，这一领域的进展从根本上受到限制，因为很难在人类的时间尺度上观察极端事件，并将其与百万年平均侵蚀率测量相联系。该项目通过结合实地、实验室和计算机建模方法，帮助弥合差距，以调查地球上侵蚀最快的自然景观之一西藏东南部史前特大洪水遗留的第一个直接证据。 该项目将综合冰川湖存款年表、洪水沉积物的实地观察和年代测定、不同量级水流沉积物的来源数据以及洪水事件的计算机模拟，以便：（1）建立洪水水力学、滑坡触发、静水沉积物沉积和洪水灾害模型;（2）将洪水条件与侵蚀过程联系起来，并评估特大洪水集中侵蚀峡谷的程度;（3）开始限制巨型气候事件发生的时间和频率，以便更好地了解它们与气候的关系以及对长期侵蚀的影响。 最后，这种新的化学“指纹”洪砂（使用锆石U-Pb年龄）研究侵蚀过程的方法将提高我们对河流切割和岩石隆起，青藏高原边缘演化之间可能的反馈的理解，以及冰川-间冰期时间尺度上气候和侵蚀之间的联系。 该模型研究将通过评估该地区水电站大坝开发的洪水危害来造福社会。 该项目涉及华盛顿大学、美国地质调查局和印度一个灾害管理机构之间的合作。 研究生和本科研究生将接受现场，实验室和计算机建模方法的培训。为了促进K-12 STEM教育在少数民族服务的高中，研究人员和学生将与教师合作，为华盛顿大学的推广计划，摇滚出制定一个关于洪水和巨型森林侵蚀的课程和活动。 此外，研究结果将通过华盛顿大学的外联和高中方案、印度灾害管理人员、大学课程、会议和出版物广泛传播。 该项目由地貌学和土地利用动力学以及国际科学与工程计划共同支持。

The last decade has seen a resurgence of debate over the role of extreme events such as earthquakes, landslides and floods in long-term erosion and landscape evolution. Yet progress in this area is fundamentally limited by the difficulty of observing extreme events on human timescales and linking them to million-year average erosion rate measurements. This project helps bridge the gap by combining field, laboratory and computer modeling approaches to investigate the first direct evidence of the legacy of prehistoric megafloods in one of the most rapidly eroding natural landscapes on Earth, southeastern Tibet. This project will integrate glacial lake deposit chronologies, field observations and dating of flood deposits, provenance data for sediments deposited in different magnitude flows, and computer simulations of flood events to (1) model flood hydraulics, landslide triggering, slackwater sediment deposition and flood hazard; (2) relate flood conditions to erosion processes and evaluate the extent to which megafloods focus erosion in the gorge; and (3) begin to constrain the timing and frequency of megaflood events to better understand their relationship to climate and impact on long-term erosion. Ultimately, this novel approach of chemically "fingerprinting" flood sands (using zircon U-Pb ages) to investigate erosion processes will improve our understanding of possible feedbacks between river incision and rock uplift, Tibetan plateau margin evolution, and links between climate and erosion on glacial-interglacial timescales. The modeling study will benefit society by evaluating flood hazard associated with hydropower dam development in the region. The project involves collaborations among the University of Washington, US Geological Survey, and a disaster management agency in India. Graduate and undergraduate research students will be trained in field, laboratory, and computer modeling methods. To promote K-12 STEM education in minority-serving high schools, the researchers and students will work with a teacher to develop a lesson and activity on floods and megaflood erosion for the University of Washington outreach program, Rocking Out. Additionally, research findings will be disseminated broadly through University of Washington's outreach and high school programs, Indian disaster management personnel, university courses, conferences and publications. This project is jointly supported by the Geomorphology and Land Use Dynamics and International Science and Engineering programs.