Geomorphic Response of Glacial Decoupling in Alpine Regions in Response to Climate Warming: Icy Debris Fans and Early Paraglacial Landscape Evolution

高山地区冰川脱钩对气候变暖的地貌响应：冰碎屑扇和早期冰缘景观演化

• 批准号: 1224720
• 负责人: R. Craig Kochel
• 金额: $ 27.56万
• 依托单位: Bucknell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1224720&HistoricalAwards=false
• 关键词: Geomorphic; Response; Glacial; Decoupling; Alpine

In recent decades, the impacts of climate warming have been especially significant in alpine glaciated regions. Many valley glaciers have decoupled from high-level icecaps to expose major escarpments now experiencing rapid mass wasting by processes dominated by ice, including ice avalanching, rockfalls, icy debris flows, and slush avalanches. This project will conduct the first detailed study of a suite of dynamic ice-dominated landforms (here termed icy debris fans) that are evolving at the base of these escarpments. Previous studies of deglaciating landscapes, formed during periods known as paraglacial, have described rapid development of alluvial fans and talus cones, however, the influence of ice-dominated mass wasting processes on landform evolution has mostly gone unrecognized. Research will occur at study sites in Alaska and New Zealand that provide maximum variety of morphogenetic settings and temporal stages needed to develop an accurate evolutionary model for landforms associated with icy debris fans. This research will focus on field investigations aimed at deciphering the depositional processes that form icy debris fans, the influence of catchment morphometry on fan morphology, and distinguishing sedimentological characteristics of icy fans compared with similar landforms not dominated by ice. By using a novel combination of ground-based LiDAR mapping surveys, time-lapse photography, and remote-control aircraft, we will quantify variations in the rates and volumes of depositional processes and morphology of fans formed in different settings through time. Surficial sedimentological data and subsurface geophysical surveys will document the sedimentary architecture of icy debris fans. Once integrated, these datasets will yield important constraints on the formation and evolution of icy debris fans and hold implications for evaluating landscape evolution through time, including distinguishing the deposits of icy debris fans from related but more thoroughly studied landforms such as alluvial fans and talus cones. Recent climate warming has had major impacts on glaciers delivering ice from high-level icecaps to lower elevation valley glaciers. Warming has resulted in decoupling of many valley glaciers from their source icecaps, thereby exposing major bedrock escarpments. These escarpments are highly unstable and characterized by extreme erosional processes dominated by ice ? such as ice avalanches, icy debris flows, slush avalanches, and rockfall. Rapidly-forming landforms known as icy debris fans dominate this newly-forming landscape immediately following deglaciation where hundreds of catastrophic ice avalanches and icy debris flows are common during summer weeks. This research directly addresses several key scientific problems linked to modern global warming and will advance research methods of landform analysis in rugged alpine environments by developing a novel methodology involving time-lapse photography, ground-based radar imaging, and remote-controlled aircraft. Given that icy debris fans are newly discovered landforms, our research holds promise for providing new perspectives on the nature of landform evolution in deglaciating alpine environments. The anticipated outcomes will have direct implications towards improving assessment of geohazards and watershed management in deglaciating alpine settings. Specifically, results will provide a better understanding of changes in sediment and water flux downstream, improving our understanding of hazards and safety in back country areas of national parks in Alaska and New Zealand. As glaciers continue to melt and thin in alpine environments, a wide range of glacial hazards are expected to increase, including rockfalls, breakout floods from ice dams, and ice avalanches. Icy debris fans will become more prevalent as slopes become increasingly unstable. Better characterization of the nature and frequency of these poorly understood processes and landforms will help mitigate the impacts of these hazardous phenomena that are affecting increasingly larger geographic regions.This project is supported by the Geomorphology and Land Use Dynamics Program, NSF's Office of International Science and Engineering, and EAR's Education and Human Resources program.

近几十年来，气候变暖的影响在高山冰川地区尤为显著。许多山谷冰川已经从高水平的冰盖中分离出来，暴露出主要的悬崖，这些悬崖现在正在经历由冰主导的过程，包括冰崩落，岩崩，冰泥石流和雪泥雪崩。 该项目将对这些悬崖底部不断演变的一套动态冰主导地貌（这里称为冰碎屑扇）进行首次详细研究。以前的研究冰川消退景观，形成于被称为paraglacial时期，描述了冲积扇和岩屑锥的快速发展，然而，冰为主的质量消耗过程对地貌演化的影响大多没有得到承认。 研究将在阿拉斯加和新西兰的研究地点进行，这些研究地点提供了为与冰碎片扇有关的地貌开发准确的演变模型所需的最大种类的形态发生背景和时间阶段。 这项研究将侧重于实地调查，旨在破译的沉积过程，形成冰碎屑扇，集水形态对风扇形态的影响，并区分沉积学特征的冰扇相比，类似的地形不占主导地位的冰。 通过使用一种新颖的地面激光雷达测绘调查，延时摄影和遥控飞机的组合，我们将量化沉积过程的速率和体积以及随时间推移在不同环境中形成的风扇形态的变化。表层沉积学数据和地下地球物理调查将记录冰碎屑扇的沉积结构。 一旦整合，这些数据集将产生重要的约束条件的形成和演变的冰碴扇，并持有通过时间来评估景观演变的影响，包括区分存款的冰碴扇相关的，但更彻底的研究地貌，如冲积扇和岩屑锥。最近的气候变暖对冰川产生了重大影响，冰川将冰从高海拔冰盖输送到低海拔山谷冰川。气候变暖导致许多山谷冰川与其源头冰盖脱钩，从而暴露出主要的基岩悬崖。这些悬崖是高度不稳定的，其特点是极端侵蚀过程占主导地位的冰？例如冰崩、冰碎屑流、雪泥崩和落石。快速形成的地貌被称为冰碎屑扇，在冰川消退后立即主导着这一新形成的景观，在夏季的几周里，数百次灾难性的雪崩和冰碎屑流是常见的。这项研究直接解决了与现代全球变暖有关的几个关键科学问题，并将通过开发一种涉及延时摄影、地基雷达成像和遥控飞机的新方法，推进崎岖高山环境中地形分析的研究方法。 鉴于冰碎屑扇是新发现的地貌，我们的研究有望为冰川消退高山环境中地貌演化的性质提供新的视角。预期成果将对改善冰川消退高山环境中地质灾害评估和流域管理产生直接影响。具体而言，研究结果将提供更好的了解沉积物和水通量下游的变化，提高我们对阿拉斯加和新西兰国家公园偏远地区的危害和安全的理解。随着冰川在高山环境中继续融化和变薄，预计各种冰川灾害将增加，包括岩崩、冰坝决堤和雪崩。随着斜坡变得越来越不稳定，冰屑扇将变得更加普遍。更好地描述这些知之甚少的过程和地貌的性质和频率将有助于减轻这些危害现象的影响，这些危害现象正在影响越来越大的地理区域。