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. Subglacial meltwater channels (N-channels) are attributed toerosion by meltwater in subglacial conduits. They exert a major control onmeltwater accumulation at the base of ice sheets, serving as drainagepathways and modifying ice flow rates. The study of exposed relict subglacialchannels offers a unique opportunity to characterize the geomorphologicfingerprint of subglacial erosion as well as study the structure andcharacteristics of ice sheet drainage systems. In this study we presentdetailed field and remote sensing observations of exposed subglacialmeltwater channels in excellent preservation state on Devon Island (CanadianArctic Archipelago). We characterize channel cross section, longitudinalprofiles, and network morphologies and establish the spatial extent anddistinctive characteristics of subglacial drainage systems. We usefield-based GPS measurements of subglacial channel longitudinal profiles,along with stereo imagery-derived digital surface models (DSMs), and novelkinematic portable lidar data to establish a detailed characterization ofsubglacial channels in our field study area, including their distinction fromrivers and other meltwater drainage systems. Subglacial channels typicallycluster in groups of ∼ 10 channels and are oriented perpendicular toactive or former ice margins. Although their overall direction generallyfollows topographic gradients, channels can be oblique to topographicgradients and have undulating longitudinal profiles. We also observe that thewidth of first-order tributaries is 1 to 2 orders of magnitude largerthan in Devon Island river systems and approximately constant. Furthermore,our findings are consistent with theoretical expectations drawn from analysesof flow driven by gradients in effective water pressure related to variationsin ice thickness. Our field and remote sensing observations represent thefirst high-resolution study of the subglacial geomorphology of the highArctic, and provide quantitative and qualitative descriptions of subglacialchannels that revisit well-established field identification guidelines.Distinguishing subglacial channels in topographic data is critical forunderstanding the emergence, geometry, and extent of channelized meltwatersystems and their role in ice sheet drainage. The final aim of this study isto facilitate the identification of subglacial channel networks throughoutthe globe by using remote sensing techniques, which will improve thedetection of these systems and help to build understanding of the underlyingmechanics of subglacial channelized drainage.

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