Modelling the delivery of supraglacial meltwater to the ice/bed interface: Application to southwest Devon Ice Cap, Nunavut, Canada

Abstract

The transfer of surface-generated meltwater to the subglacial drainage system through full ice thickness crevassing may lead to accelerated glacier velocities, with implications for ice motion under future climatic scenarios. Accurate predictions of where surface meltwater accesses the ice/bed interface are therefore needed in fully coupled hydrodynamic ice-sheet models. We present a spatially distributed modelling routine for predicting the location and timing of delivery of surface-derived meltwater to the ice/bed interface through moulins and supraglacial lake drainage. The model is explained as it is applied to the Croker Bay glacial catchment of Devon Ice Cap, Canada. The formation of moulins, drainage of lakes, and the transfer of meltwater through the full ice thickness are modelled for the 2004 and 2006 ablation seasons. Through this case study we assess the model's sensitivity to degree-day factors, fracture toughness, tensile strength and crevasse width, and confirm that parameters influencing the rate at which water fills a crevasse are the most significant controls on the ability of a crevasse to reach the bed. Increased surface melt production, therefore, has the potential to significantly influence the spatial and temporal transfer of meltwater through surface-to-bed connections in a warmer climate.