The Impact of Permafrost and Ice Thermodynamics on Ice Marginal Hydrology of Polythermal Glaciers

The complex thermodynamics of polythermal glaciers complicates their hydrology. The hydrology of two adjacent glaciers on Bylot Island, Canada are compared as the impact of the thermal and hydrological structure of the glacier ice and surrounding permafrost results in very different hydrological regimes. Surveys of long-abandoned and still-active hydrological conduits within the two glaciers and surrounding ice- cored permafrost demonstrates the complexity of water flow from the sub/englacial systems out into the proglacial system. The formation and long-term preservation of a proglacial icing results from steady state flow from one of the glaciers through a hydrothermal talik within the ice marginal permafrost. The hydraulic conductivity of the talik limits water flow resulting in breaches through "cold" marginal ice and catastrophic outburst flooding. Seasonal and inter-annual ground-penetrating radar surveys of the adjacent glacier indicate that while the thermal structure of the glacier has been fairly constant, the liquid water content within the glacier changes seasonally as the ice matrix drains. Subglacial drainage and conduits preserved within the ice-cored moraines, have resulted in a very different hydrological character than the other glacier. The comparison of these two glaciers demonstrates the complexity that can be found in close proximity given slight differences in the hydrothermal structure of glaciers and surrounding permafrost.