Subglacial drainage dynamics

冰川和冰盖是未来海平面上升的关键。冰川也在区域上发挥着关键作用，特别是在加拿大北部，因为它们重塑了地貌，并通过储存和分流水影响了水资源的可获得性。冰流是冰川行为的关键部分：更快的冰流往往会导致更薄、更小的冰川。然而，人们对冰川快速流动的一些最戏剧性的例子--冰川涌动--的控制却知之甚少。冰川涌动是由冰川床上水压的突然变化引起的冰川的快速推进。所有的冰川，不仅仅是那些涌动的冰川，都会受到底部加压水的影响，因为这会削弱冰床之间的接触，并促进快速滑动。控制冰川床上水的压力水平的物理机制还没有完全被理解。拟议的研究将把一项有针对性的实地工作计划与先进的定量地球物理技术结合起来，绘制并量化育空地区圣埃利亚斯山脉涌浪型冰川底部的融水排水系统的演变。我们将利用这些数据开发新的冰下排水数值模型，以了解涌流和其他快速冰川流动现象背后的物理原理。利用拟建的场地靠近一个冰川堰塞湖的优势，我们还将对该湖爆发的洪水进行研究。这样的洪水可能会给冰川化地区带来重大自然灾害。在这样的洪水中，洪水在产生潜在破坏性影响之前被引导到冰川下面，所涉及的物理原理类似于驱动冰川下破坏性较小的排水的物理原理。我们的研究旨在量化洪水是如何触发的，从而最终如何预测洪水的发生和规模。

Glaciers and ice sheets hold the key to future sea level rise. Glaciers also play a crucial role regionally, particularly in the Canadian north, as they reshape the landscape and affect the availability of water resources through storing and diverting water. Ice flow is a key part in the behaviour of glaciers: faster flow tends to lead to thinner and smaller glaciers. Yet controls on some of the most dramatic examples of fast glacier flow, glacier surges, are poorly understood. Glacier surges are rapid advances in a glacier that are caused by an abrupt change in water pressure at its bed. All glaciers, not only those that surge, are affected by pressurized water at their base, as this weakens the ice-bed contact and facilitates fast sliding. The physics that controls the level of pressurization of water at the glacier bed is only incompletely understood. The proposed research will combine a targeted field work program with advanced quantitative geophysics techniques to map and quantify the evolution of the melt water drainage system at the base of a surge-type glacier in the St Elias Mountains, Yukon Territory. We will use these data to develop novel numerical models of subglacial drainage in order to understand the physics behind surges and other fast glacier flow phenomena. Capitalizing on the proximity of the proposed field site to a glacier-dammed lake, we will also conduct a study of the outburst floods produced this lake. Such floods can present major natural hazards in glacierized areas. Flood waters in such floods are routed under the glacier before emerging to potentially destructive effect, and the physics involved are similar to those that drive less disruptive drainage under glaciers. Our research will aim to quantify how floods are triggered and therefore how their occurence and size can ultimately be predicted.