Subglacial hydrology modeling predicts high winter water pressure and spatially variable transmissivity at Helheim Glacier, Greenland

Abstract Water pressure beneath glaciers influences ice velocity. Subglacial hydrology models are helpful for gaining insight into basal conditions, but depend on unconstrained parameters, and a current challenge is reproducing elevated water pressures in winter. We eliminate terms related to englacial storage, opening by sliding, melt due changes the pressure-melting-point temperature, create minimalist version of Hydrology And Kinetic, Transient Interactions (SHAKTI) model, apply this model Helheim Glacier east Greenland explore winter base state subglacial drainage system. Our results suggest that meltwater produced at bed alone supports active with large areas preferential pathways, using continuum approach allows transitions between flow regimes. Transmissivity varies spatially over several orders magnitude from 10 −4 3 m 2 s −1 , regions weak transmissivity representing poorly connected Bed topography controls location primary high rates occur along steep valley walls. Frictional heat sliding dominant source melt; different approaches calculating shear stress produce significantly discharge.