Preprints
https://doi.org/10.5194/tc-2020-319
https://doi.org/10.5194/tc-2020-319

  20 Nov 2020

20 Nov 2020

Review status: this preprint is currently under review for the journal TC.

Sensitivity of subglacial drainage to water supply distribution at the Kongsfjord basin, Svalbard

Chloé Scholzen1, Thomas V. Schuler1, and Adrien Gilbert2 Chloé Scholzen et al.
  • 1Department of Geosciences, University of Oslo, Norway
  • 2Université Grenoble-Alpes, CNRS, IGE, Grenoble, France

Abstract. By regulating the amount, the timing and the location of meltwater supply to the glacier bed, supraglacial hydrology potentially exerts a major control on the evolution of the subglacial drainage system, which in turn modulates sliding. Yet the configuration of the supraglacial hydrological system has received only little attention in numerical models of subglacial hydrology so far. Here we apply the two dimensional subglacial hydrology model GlaDS to a Svalbard glacier basin with the aim of investigating how the spatial distribution of meltwater recharge affects the characteristics of the basal drainage system. We design four experiments with various degrees of complexity in the way that meltwater is delivered to the subglacial drainage model. Our results show significant differences between experiments in the early-summer transition from distributed to channelized drainage, with discrete recharge at moulins favouring channelization and driving earlier rise in basal water pressure. Otherwise, we find that water input configuration only poorly influences subglacial hydrology, which is controlled primarily by subglacial topography. All experiments fail to develop channels of sufficient efficiency to substantially reduce summertime water pressures, which we impute to small surface gradients and short melt seasons. The findings of our study may be extended to most Svalbard tidewater glaciers with similar topography and low meltwater recharge. The absence of efficient channelization implies that the dynamics of tidewater glaciers in the Svalbard archipelago may be sensitive to future long-term trends in meltwater supply.

Chloé Scholzen et al.

 
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Chloé Scholzen et al.

Chloé Scholzen et al.

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Short summary
We use a 2D model of water flow below the glaciers in Kongsfjord, Svalbard, to investigate how different ways of surface-to-bed meltwater transfer affect subglacial hydraulic conditions. The latter are important for the sliding motion of glaciers, which in some cases exhibits huge variations. Our findings indicate that the glaciers in our study area undergo substantial sliding because water is poorly evacuated from their base, with limited influence from the surface hydrology.