Expansion rate and geometry of floating vegetation mats on the margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA

Earth Surface Processes and Landforms
By: , and 

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Abstract

Investigations on the northern Seward Peninsula in Alaska identified zones of recent (<50years) permafrost collapse that led to the formation of floating vegetation mats along thermokarst lake margins. The occurrence of floating vegetation mat features indicates rapid degradation of near-surface permafrost and lake expansion. This paper reports on the recent expansion of these collapse features and their geometry is determined using geophysical and remote sensing measurements. The vegetation mats were observed to have an average thickness of 0.57m and petrophysical modeling indicated that gas content of 1.5-5% enabled floatation above the lake surface. Furthermore, geophysical investigation provides evidence that the mats form by thaw and subsidence of the underlying permafrost rather than terrestrialization. The temperature of the water below a vegetation mat was observed to remain above freezing late in the winter. Analysis of satellite and aerial imagery indicates that these features have expanded at maximum rates of 1-2myr-1 over a 56year period. Including the spatial coverage of floating 'thermokarst mats' increases estimates of lake area by as much as 4% in some lakes. ?? 2011 John Wiley & Sons, Ltd.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Expansion rate and geometry of floating vegetation mats on the margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA
Series title Earth Surface Processes and Landforms
DOI 10.1002/esp.2210
Volume 36
Issue 14
Year Published 2011
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Earth Surface Processes and Landforms
First page 1889
Last page 1897