Groundwater feedbacks on ice sheets and subglacial hydrology

TL;DR

This study models how sedimentary basins beneath ice sheets influence glacier dynamics, revealing that groundwater interactions can either promote or hinder ice flow and potentially accelerate retreat.

Contribution

It introduces an idealised model incorporating sedimentary basins into glacier hydrology, highlighting their impact on ice sheet behavior and retreat dynamics.

Findings

Groundwater exfiltration promotes glacier sliding.

Sedimentary basins lead to thicker, slower ice.

Exfiltration can accelerate ice retreat during retreat phases.

Abstract

The dynamics of many of Antarctica's glaciers are modulated by a hydrological system at the base of the ice. Sedimentary basins beneath the ice bed contribute to the water budget in this hydrological system by discharging or taking up water. However, sedimentary basins are not included in most current models of ice dynamics, and little is known about their effect. In this paper we develop an idealised model of a glacier whose sliding is coupled to a subglacial hydrological system, which includes a sedimentary basin. We find that groundwater discharge (exfiltration) and recharge (infiltration) are controlled by the shape of the ice sheet and of the sedimentary basin, and that exfiltration promotes sliding whereas infiltration hinders it. Overall, the presence of a sedimentary basin leads to thicker and slower-flowing ice in the steady state. We also find that, when the ice sheet is undergoing retreating, groundwater exfiltration can lead to a positive feedback which accelerates this retreat. Our results shed light on the potential role and importance of Antarctic sedimentary basins, and how these might be incorporated into existing models of ice and subglacial hydrology.