Hydrologic modeling of a perennial firn aquifer in southeast Greenland

• Published in: Journal of glaciology Vol. 69; no. 275; pp. 607 - 622
• Main Authors: Miller, Olivia, Voss, Clifford I., Solomon, D. Kip, Miège, Clément, Forster, Richard, Schmerr, Nicholas, Montgomery, Lynn
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-06-2023
• Subjects: Advection; Aeration zone; Aquifer recharge; Aquifers; Climate change; Energy balance; Energy transfer; Energy transport; Firn; Glacier hydrology; Glaciers; Global warming; Groundwater; Groundwater flow; Hydraulics; Hydrologic models; Hydrology; Ice sheets; ice-sheet modelling; Lakes; melt – surface; Meltwater; Phase change; Physics; polar firn; Recharge; Saturation; Simulation; Snow; Snowmelt; Surface energy; Surface energy balance; Surface properties; Surface temperature; Temperature; Transport; Water flow; Greenland; ice-sheet modelling; melt – surface; polar firn; Glacier hydrology
• ISSN: 0022-1430; 1727-5652
• DOI: 10.1017/jog.2022.88

A conceptual model, based on field observations and assumed physics of a perennial firn aquifer near Helheim Glacier (southeast Greenland), is evaluated via steady-state 2-D simulation of liquid water flow and energy transport with phase change. The simulation approach allows natural representation of flow and energy advection and conduction that occur in vertical meltwater recharge through the unsaturated zone and in lateral flow within the saturated aquifer. Agreement between measured and simulated aquifer geometry, temperature, and recharge and discharge rates confirms that the conceptual field-data-based description of the aquifer is consistent with the primary physical processes of groundwater flow, energy transport and phase change. Factors that are found to control simulated aquifer configuration include surface temperature, meltwater recharge rate, residual total-water saturation and capillary fringe thickness. Simulation analyses indicate that the size of perennial firn aquifers depends primarily on recharge rates from surface snowmelt. Results also imply that the recent aquifer expansion, likely due to a warming climate, may eventually produce lakes on the ice-sheet surface that would affect the surface energy balance.