Numerical modelling of subglacial water flow under a visco-elastic glacier-ice cover
Year: 2025
Type: conference-abstract
Abstract: We present a model for water flow at the base of a glacier implemented with the Elmer/Ice Open-Source Finite-Element Software. The model describes subglacial water flow in connection with the emptying of basal water bodies and the subglacial propagation of glacial outburst flood (jökulhlaup) fronts using a visco-elastic model for the overlying glacier combined with a turbulent thin-sheet model for water flow. The visco-elastic model is based on Maxwell-elements1 combining linear elasticity with the non-linear viscous behaviour described by Glen's ice-flow law, and, by introducing a pressure variable, allowing for incompressibility of the material. The dynamics of the subglacial ice–water interface is implemented as fluid–structure interaction (FSI), utilizing artificial compressibility. The coupled visco-elastic, thin-sheet model aims to represent the propagation of rapidly- and slowly-rising subglacial floods2, many of which are inferred from remote-sensing and in-situ observations to involve lifting of the glacier from its sole over large areas3. Dynamically similar subglacial ice–water interactions may be involved in widespread, propagating ice-velocity and surface-elevation disturbances that have been observed by remote sensing during subglacial drainage events in Greenland4 and Antarctica5, indicating that the dynamics of jökulhlaups may have wider implications for glacier dynamics in general. We will demonstrate the coupled model with simple synthetic examples. The visco-elastic model can simulate the observed geometry of ice-surface depressions formed by the collapse of basal water cupolas and conduits, for which we present simulation results with comparison to observed ice-surface depressions at Vatnajökull ice cap, Iceland.References1Zwinger, T., Nield, G. A., Ruokolainen, J., and King, M. A.: A new open-source viscoelastic solid earth deformation module implemented in Elmer (v8.4), Geosci. Model Dev., 13, 1155–1164 (2020).2 Jóhannesson, T. Propagation of a subglacial flood wave during the initiation of a jökulhlaup. Hydrol. Sci. J., 47, 417–434 (2002).3 Magnússon, E., & 13 others. New insights into the development of slowly rising jökulhlaups from the Grímsvötn subglacial lake, Iceland, deduced from ICEYE SAR images and in-situ observations. EGU General Assembly 2024, EGU24-18204, https://doi.org/10.5194/egusphere-egu24-18204.4 Maier, N., Andersen, J.K., Mouginot, J., Gimbert, F., & Gagliardini, O. Wintertime supraglacial lake drainage cascade triggers large-scale ice flow response in Greenland. Geophys. Res. Lett., 50(4), p.e2022GL10 (2023).5Neckel, N., Franke, S., Helm, V., Drews, R., & Jansen, D. Evidence of cascading subglacial water flow at Jutulstraumen Glacier (Antarctica) derived from Sentinel-1 and ICESat-2 measurements. Geophys. Res. Lett., 48(20), p.e2021GL094472 (2021).
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4408438017