Glaciers, Erosion, and Climate Change in the Himalaya Mountains

喜马拉雅山脉的冰川、侵蚀和气候变化

• 批准号: 0952352
• 负责人: Bernard Hallet
• 金额: $ 22.5万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952352&HistoricalAwards=false
• 关键词: Glaciers; Erosion; Climate; Change; Himalaya

Erosion plays an important role in the development of the Himalaya Mountains, and is generally controlled by the interplay among tectonics, topography and climate that govern mountain building. Little is known, however, about rates of erosion at the heavily glaciarized crest of the range, and there is no consensus on whether glaciers accelerate or impede erosion in the region. This project will determine contemporary erosion rates for the Khumbu basin, at the foot of Mt Everest, through a detailed examination of the fluxes of ice and rock debris in this drainage basin. These fluxes will be determined on three time scales: during the 2-year duration of this project, ~60 years and ~10,000 years. Contemporary fluxes of ice and debris will be determined from analyses of digital topography and satellite images, existing glaciological and geomorphologic data, and field studies. These will reveal the debris advected with the ice and accumulating in the lower reaches of the glacier, and the debris that exits Khumbu Glacier through the proglacial stream. Mass balance and runoff will be modeled through the last six decades using available global climate data. Historical data documenting the glacier surface profile, surface velocities and debris cover will also guide modeled estimates of debris and ice fluxes through this period. Estimates will be made of the volume of the massive debris edifice that formed in the lower Khumbu valley since the last major glacial advance about 10,000 years ago to determine the volume of debris derived from the upper Khumbu basin. This will be accomplished using satellite imagery, digital elevation models, and available radar and gravity surveys. The erosion rate averaged over this time span can be calculated from this debris volume by accounting for the fraction of sediment evacuated fluvially during this period on the basis of the measurements of contemporary sediment flux in the Khumbu proglacial stream.This study will advance knowledge of the interactions between snow and debris that sustain massive low-latitude glaciers and shape high mountains. Glaciers are common featues of mountain ranges around the world, and this study will document their role in erosion and mobilization of sediment. This project wiil also help evaluate two important issues: how climate change may affect glaciers in the Himalaya and the probable consequences for the vast population dependent on the major rivers that emanate from the glaciers in the Himalaya and Tibet. These consequences include 1) an initial increase in runoff due to the accelerated melting followed by diminishing supplies of fresh water from the dwindling glaciers, and 2) an increasing threat of floods from ice-dammed lakes formed by rapid glacier retreat.

侵蚀在喜马拉雅山脉的发展中起着重要的作用，通常受控制造山运动的构造、地形和气候之间的相互作用的控制。 然而，人们对该山脉严重冰川化的山顶的侵蚀速率知之甚少，而且对于冰川是否加速或阻碍该地区的侵蚀也没有共识。 该项目将通过详细研究珠峰山脚下昆布流域的冰和岩屑通量，确定该流域目前的侵蚀率。 这些通量将在三个时间尺度上确定：在本项目的2年期间、~60年和~ 10，000年。 将通过分析数字地形和卫星图像、现有的冰川和地貌数据以及实地研究来确定冰和碎片的当代通量。这些将揭示与冰平流并在冰川下游积累的碎片，以及通过冰前流离开昆布冰川的碎片。 将利用现有的全球气候数据对过去六十年的物质平衡和径流进行建模。记录冰川表面轮廓、表面速度和碎片覆盖的历史数据也将指导对这一时期碎片和冰通量的模拟估计。 将对大约10 000年前最后一次重大冰川推进以来在昆布河谷下游形成的大量碎片建筑物的体积进行估计，以确定昆布盆地上游产生的碎片的体积。这将利用卫星图像、数字高程模型以及现有的雷达和重力测量来完成。根据测量库姆布冰前溪流中当代沉积物通量的基础上，通过计算该时期河流排出的沉积物比例，可以根据该碎片体积计算出该时间跨度内的平均侵蚀速率。这项研究将推进雪和碎片之间的相互作用的知识，这些碎片维持了大量低纬度冰川并塑造了高山。 冰川是世界各地山脉的共同特征，这项研究将记录它们在侵蚀和沉积物移动方面的作用。该项目还将有助于评估两个重要问题：气候变化如何影响喜马拉雅山脉的冰川，以及对依赖喜马拉雅山脉和西藏冰川发源的主要河流的广大人口可能产生的后果。 这些后果包括：（1）由于冰川加速融化，径流量最初增加，随后来自冰川萎缩的淡水供应减少，以及（2）冰川快速退缩形成的冰坝湖泊造成的洪水威胁增加。