Englacial drainage structures in an East Antarctic outlet glacier

Thomas Schaap,Christian Schoof,Michael J Roach,Bernd Kulessa,Sue Cook,Leo E Peters

doi:10.1017/jog.2019.92

Abstract

AbstractGround-penetrating radar data acquired in the 2016/17 austral summer on Sørsdal Glacier, East Antarctica, provide evidence for meltwater lenses within porous surface ice that are conceptually similar to firn aquifers observed on the Greenland Ice Sheet and the Arctic and Alpine glaciers. These englacial water bodies are associated with a dry relict surface basin and consistent with perennial drainage into an interconnected englacial drainage system, which may explain a large englacial outburst flood observed in satellite imagery in the early 2016/17 melt season. Our observations indicate the rarely-documented presence of an englacial hydrological system in Antarctica, with implications for the storage and routing of surface meltwater. Future work should ascertain the spatial prevalence of such systems around the Antarctic coastline, and identify the degree of surface runoff redistribution and storage in the near surface, to quantify their impact on surface mass balance.

Highlights

Englacial channels represent current and relict flow pathways for meltwater through the body of a glacier (Gulley and others, 2009)
We propose that the Channel Lake basin was drained through the englacial pathways imaged by our Ground-penetrating radar (GPR) surveys
Our GPR data acquired along sub-parallel profiles on Sørsdal Glacier (Fig. 1) provide compelling evidence for the presence of englacial voids filled with water, or air pockets above water, at depths typically exceeding 5 m but

Summary

Introduction

Englacial channels represent current and relict flow pathways for meltwater through the body of a glacier (Gulley and others, 2009). Systems which form by this mechanism are characterised by meandering channels with a low gradient and occasional step-pools. This mechanism requires the downcutting rate of the stream to be higher than the ablation rate of the surrounding ice, with this mechanism being most common in regions of low surface ablation and high stream flow rates (i.e. high surface slope and large catchment areas), and has typically been observed in glaciers at high latitude (Gulley and others, 2009; Vatne and Irvine-Fynn, 2016; Benn and others, 2017)

Methods

Results

Discussion

Conclusion