The Cryosphere, 8, 537–546, 2014 Open Access www.the-cryosphere.net/8/537/2014/ doi:10.5194/tc-8-537-2014 The Cryosphere © Author(s) 2014. CC Attribution 3.0 License. Near-surface permeability in a supraglacial drainage basin on the Llewellyn Glacier, Juneau Icefield, British Columbia L. Karlstrom1, A. Zok2, and M. Manga2 1Department of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305, USA 2Department of Earth and Planetary Science, 307 McCone Hall, University of California at Berkeley, Berkeley, CA 94720, USA Correspondence to: L. Karlstrom (
[email protected]) Received: 10 October 2013 – Published in The Cryosphere Discuss.: 4 November 2013 Revised: 4 February 2014 – Accepted: 13 February 2014 – Published: 27 March 2014 Abstract. Supraglacial channel networks link time vary- 1 Introduction ing melt production and meltwater routing on temperate glaciers. Such channel networks often include components of both surface transport in streams and subsurface porous In the ablation zone of glaciers and ice sheets, surface flow through near-surface ice, firn or snowpack. Although meltwater channelizes and thermally erodes the icy sub- subsurface transport if present will likely control network strate. This flowing meltwater localizes to form supraglacial transport efficacy, it is the most poorly characterized compo- streams if melt production exceeds the transport capacity of nent of the system. We present measurements of supraglacial near-surface ice, firn or snowpack. Supraglacial melt trans- channel spacing and network properties on the Juneau Ice- port links surface melt to subglacial hydrologic systems field, subsurface water table height, and time variation of through englacial drainage (Fountain and Walder, 1998), so hydraulic characteristics including diurnal variability in wa- temporal variations in the rate and volume of supraglacial ter temperature.