The Linkage of Glacier Sliding and Hydrology on the Kennicott Glacier, Alaska

阿拉斯加州肯尼科特冰川冰川滑动与水文的联系技术描述。正如sger资助的一项旨在推广阿拉斯加的试点研究所显示的那样？正如Kennicott冰川作为一个天然实验室一样，每当它们的水文系统不够发达，无法容纳来自融水或排水湖泊的水时，冰川就会滑动。SGER研究论文中提出的概念模型被广泛引用来解释格陵兰岛的新观测结果。理解冰川滑动的关键是，冰川下的水文系统总是处于一种短暂的状态；水的输入变化很大，水文系统的渠化和非渠化部分的水力效率也是如此。拟建的研究团队由一位具有冰川实地考察和水文-滑动联系分析经验的地貌学家和一位研究断层和喀斯特系统的水文的水文学家组成，这两者都与冰川水文有关。滑动问题。该团队将把肯尼科特冰川的实地考察与数值模型联系起来，以对不断演变的水文系统及其引发的基础滑动形成严格的理解。任务1)肯尼科特冰川野外实验。这个40公里长，4公里宽的冰川是研究水文和冰川运动之间联系的理想场所。它的水文系统每天都受到干扰，每年夏天都会发生一次重大的春季事件，每年都会发生一次突发洪水。几个冰川侧湖和小型冰川湖作为天然的气压计，记录了流域网络的季节演变和溃决洪水的通道。该研究将记录冰川的昼夜、季节和洪水相关的水输入和输出，以及相关的滑动响应。gps获取的冰速将记录水平和垂直位移场，这些位移场在每日、季节和洪水时间尺度上变化数倍。这些数据集将作为水文-滑动联系模型的严格测试案例。任务2)冰下水文数值模拟。在Kennicott冰川的新老数据和一维水文滑动模型的启发下，将开发不同复杂程度的水文模型。基于网络和网格的2D分布式数值模型将具有动态孔径几何形状和水力特性，允许从分布式孔径转换到分布式孔径。与腔??般的水管吗?由时间和空间变化的熔体输入引起的行为。这些模型将预测水平和垂直冰运动的时空格局，以及水文系统的可测量特征，包括出口的溶质浓度。它们将立即用于诊断2006年试点研究的结果，并将在实地工作阐明整个年度周期时加以改进。更广泛的意义。冰川通过冰的变形和在冰川床上的滑动将冰运下山谷。冰川研究的动力部分来自这样一个事实，即冰川和冰盖的冰的损失对冰川流域的海平面和水资源都产生了深远的影响。虽然冰川学家了解冰的变形，但对冰的滑动却知之甚少。此外，由于冰川只有通过滑动才能侵蚀其移动的景观，因此要了解主导许多国家公园的冰川景观，就需要了解滑动是如何起作用的。冰川滑动的变化显然与融水进入冰川的季节性和每日输送有关，但冰川中水系统的状态与这种滑动之间的联系尚不清楚；不存在基于物理的滑动模型。最近格陵兰冰盖冰川出口的加速滑动已被证明模拟了在高山冰川上观察到的季节性滑动历史，使高山冰川成为一个适当的和更便宜的实验室，用于探索可能导致冰盖海平面上升的水文滑动联系。拟议中的研究将利用阿拉斯加入口处肯尼科特冰川壮观的自然实验室。这里是弗兰格尔圣伊莱亚斯国家公园。这项研究将产生冰川滑动和冰川水文状态演变的详细数据集，这将指导滑动理论模型的发展。本研究中的数值模型利用了冰川床上的冰-岩接触和断层上的岩石-岩石接触之间的类比。在这两种情况下，界面都是粗糙的，有斑驳的接触和间隙；在这两种情况下，界面的滑动都是由高压推动的。本研究中构建的模型将捕捉到不断演变的冰下水文系统的全部复杂性，包括从地表和排水湖泊中快速输入的促进滑动的水，以及用于调节滑动的反馈。

The linkage of glacier sliding and hydrology on the Kennicott Glacier, AlaskaTechnical description. As shown in a SGER-funded pilot study designed to promote Alaska?s Kennicott Glacier as a natural laboratory, glaciers slide whenever their hydrologic system is insufficiently developed to accommodate water inputs, either from melt or from a draining lake. The conceptual model suggested in a paper from the SGER study is being cited extensively to explain new observations in Greenland. The key to understanding the sliding of a glacier is that the hydrologic system beneath a glacier is always in a state of transience; water inputs vary widely, as do the hydraulic efficiencies of the channelized and unchannelized portions of the hydrologic system. The proposed research teams a geomorphologist with experience in both glacial fieldwork and analysis of the hydrology-sliding connection, with a hydrologist whose research includes the hydrology of faults and karst systems that are both pertinent to the glacial hydrology?sliding problem. The team will link fieldwork on Kennicott Glacier with numerical models to develop a rigorous understanding of the evolving hydrologic system and the basal sliding that it inspires. Task 1) Kennicott Glacier field experiment. This easily accessible 40-km long, 4-km wide glacier is ideal to study the connection between hydrology and glacial motion. Its hydrologic system is perturbed diurnally, by a major spring event each summer, and by an annual outburst flood. Several side-glacier and small supra-glacial lakes serve as natural manometers to document seasonal evolution of the drainage network, and passage of the outburst flood. The research will document the diurnal, seasonal, and flood-related inputs and outputs of water from the glacier, and the associated sliding response over two full years. GPS-derived ice speeds will document the horizontal and vertical displacement fields, which vary by several-fold on daily, seasonal and flood timescales. These data sets will serve as a rigorous test case for models of the hydrology-sliding link. Task 2) Numerical modeling of subglacial hydrology. Inspired by both old and new data on the Kennicott Glacier, and a working 1D hydro-sliding model, hydrologic models of differing complexity will be developed. Network and grid-based 2D distributed numerical models will have dynamic aperture geometry and hydraulic properties that allow transitions from distributed ?linked cavity? to ?conduit-like? behaviors resulting from temporally and spatially variable melt inputs. The models will predict spatial and temporal patterns of horizontal and vertical ice motion, and measurable features of the hydrologic system, including solute concentrations at the outlet. They will be immediately employed to diagnose the results from the 2006 pilot study, and will be refined as the full annual cycle is illuminated by the field efforts. Broader significance. Glaciers transport ice down their valleys both by deformation of the ice and by sliding against their beds. Glacial research is motivated in part by the fact that the loss of ice from glaciers and ice sheets profoundly impacts both sea level and water resources in glaciated watersheds. While glaciologists understand the deformation of ice, sliding remains poorly understood. In addition, as only by sliding do glaciers erode the landscape over which they move, understanding of glacial landscapes that dominate many national parks requires knowledge of how sliding works. Variations in glacier sliding are clearly linked to the seasonal and daily delivery of meltwater into the glacier, but the linkage between the state of the water system in the glacier and this sliding remains unclear; no physically-based model of sliding exists. Recent acceleration of sliding of glacial outlets from the Greenland Ice Sheet has been shown to mimic the seasonal sliding history observed on alpine glaciers, making alpine glaciers an appropriate and less expensive laboratory to probe the hydrology-sliding connection that may drive sea level rise from ice sheets. The proposed research will make use of the spectacular natural laboratory of the Kennicott Glacier at the entrance to Alaska?s Wrangell St. Elias National Park. The research will generate a detailed data set of glacier sliding and of the evolving hydrologic state of the glacier that will guide the development of theoretical models of sliding. Numerical models in this research take advantage of the analogy between the ice-rock contact at the bed of a glacier and the rock-rock contact across a fault. In both cases, the interface is rough, with patchy contacts and gaps; and in both cases, sliding at this interface is promoted by high water pressures. Models constructed in this study will capture the full complexity of the evolving subglacial hydrologic system, including rapid inputs of water from the surface and from draining lakes that promote sliding, and feedbacks that serve to regulate the sliding.