Subglacial drainage dynamics

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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.