Subglacial blister evolution in the event of supraglacial lake drainage

Meltwater lakes on the surface of the Greenland Ice Sheet are forming at higher altitudes due to atmospheric warming. They can often drain suddenly (within hours) by evacuating water through crevasses in the ice. This water then spreads along the ice-bedrock interface, resulting in hydraulic jacking on the order of metres. The effect of such events on the wider subglacial drainage system is poorly understood, and current models of the large-scale subglacial drainage system are unable to resolve these high volumes of fluid being injected over short time scales.

We present a mathematical model for the radial expansion of a subglacial ‘blister’ both during and after injection from a supraglacial lake. The model incorporates both turbulent and laminar water flow, both of which are found to be significant over different time and length scales. We also include a novel formulation for the fluid ‘leak-off’ to represent the decay of the blister volume as the injected water drains into the wider subglacial drainage system. This model can be used as a buffer to regularise numerical formulations of the larger-scale subglacial network.