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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 4 | Copyright
The Cryosphere, 12, 1461-1478, 2018
https://doi.org/10.5194/tc-12-1461-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 20 Apr 2018

Research article | 20 Apr 2018

Subglacial drainage patterns of Devon Island, Canada: detailed comparison of rivers and subglacial meltwater channels

Anna Grau Galofre1, A. Mark Jellinek1, Gordon R. Osinski2, Michael Zanetti3, and Antero Kukko4 Anna Grau Galofre et al.
  • 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver (BC), Canada
  • 2Department of Physics and Astronomy, University of Western Ontario, London (ON), Canada
  • 3Department of Earth Sciences and Centre for Planetary Science and Exploration, University of Western Ontario, London (ON), Canada
  • 4Center of Excellence in Laser Scanning Research, Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute Geodeetinrinne 2, Masala, Finland

Abstract. Subglacial meltwater channels (N-channels) are attributed to erosion by meltwater in subglacial conduits. They exert a major control on meltwater accumulation at the base of ice sheets, serving as drainage pathways and modifying ice flow rates. The study of exposed relict subglacial channels offers a unique opportunity to characterize the geomorphologic fingerprint of subglacial erosion as well as study the structure and characteristics of ice sheet drainage systems. In this study we present detailed field and remote sensing observations of exposed subglacial meltwater channels in excellent preservation state on Devon Island (Canadian Arctic Archipelago). We characterize channel cross section, longitudinal profiles, and network morphologies and establish the spatial extent and distinctive characteristics of subglacial drainage systems. We use field-based GPS measurements of subglacial channel longitudinal profiles, along with stereo imagery-derived digital surface models (DSMs), and novel kinematic portable lidar data to establish a detailed characterization of subglacial channels in our field study area, including their distinction from rivers and other meltwater drainage systems. Subglacial channels typically cluster in groups of  ∼ 10 channels and are oriented perpendicular to active or former ice margins. Although their overall direction generally follows topographic gradients, channels can be oblique to topographic gradients and have undulating longitudinal profiles. We also observe that the width of first-order tributaries is 1 to 2 orders of magnitude larger than in Devon Island river systems and approximately constant. Furthermore, our findings are consistent with theoretical expectations drawn from analyses of flow driven by gradients in effective water pressure related to variations in ice thickness. Our field and remote sensing observations represent the first high-resolution study of the subglacial geomorphology of the high Arctic, and provide quantitative and qualitative descriptions of subglacial channels that revisit well-established field identification guidelines. Distinguishing subglacial channels in topographic data is critical for understanding the emergence, geometry, and extent of channelized meltwater systems and their role in ice sheet drainage. The final aim of this study is to facilitate the identification of subglacial channel networks throughout the globe by using remote sensing techniques, which will improve the detection of these systems and help to build understanding of the underlying mechanics of subglacial channelized drainage.

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Water accumulated at the base of ice sheets is the main driver of glacier acceleration and loss of ice mass in Arctic regions. Previously glaciated landscapes sculpted by this water carry information about how ice sheets collapse and ultimately disappear. The search for these landscapes took us to the high Arctic, to explore channels that formed under kilometers of ice during the last ice age. In this work we describe how subglacial channels look and how they helped to drain an ice sheet.
Water accumulated at the base of ice sheets is the main driver of glacier acceleration and loss...
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