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2008 Alaska Park Science Symposium
October 14, 2008
Thermokarst Distribution in the Noatak Basin, Alaska: Increased Frequency and Correlations with Local and Regional Landscape Variables
Andrew Balser1, Breck Bowden2, Jeremy Jones3, Michael Gooseff4, Diane Sanzone5, Aurora Bouchier6, Tara Whitesell7, Kumi Rattenbury8
1Institute of Arctic Biology, University of Alaska Fairbanks, 1332 Virginia Ct. #1, Anchorage, AK, 99501, USA, Phone 907-947-7612, fnawb@uaf.edu
2Rubenstein School of Environment & Natural Resources, University of Vermont, 304 George D. Alken Center, 81 Carrigan Drive, Burlington, VT, 05405, USA, Phone 802-656-2513, Fax 802-656-8683, wbowden@zoo.uvm.edu
3Institute of Arctic Biology, University of Alaska Fairbanks, USA
4Pennsylvania State University, USA
5Environmental Studies Group, BP Exploration (Alaska), Inc., 900 East Benson Boulevard, Anchorage, AK, 99519-6612, USA, Phone 907-564-4857
6Department of Geology and Geologic Engineering, Colorado School of Mines, USA
7National Park Service, USA
8National Park Service, USA
In arctic regions, climate warming is leading to permafrost melting and wide-scale ecosystem alteration. A prominent pathway of permafrost loss is through thermokarst processes, which includes the catastrophic loss of soil structure and rapid subsidence. Regional-scale distribution of thermokarst features is poorly documented throughout the Arctic, and correlations with landscape variables are not well understood. The Noatak Basin in northwestern Alaska's Brooks Range mountains harbors a transitional landscape from arctic and alpine tundra to boreal forest within a 7,000,000 acre watershed. Field investigations augmented by photogrammetric measurements from 2005 to 2007 revealed patterns in the distribution of classifiable thermokarst failure types in the Noatak Basin, and provided data on the physical and chemical impacts these features have on aquatic systems. Distinct thermokarst classes show significant relationships with local site variables such as slope and vegetation, and with regional variables including lithology, glacial geology and landcover. Frequency of thermokarst features has increased markedly in several core study areas in the Noatak Basin within the past 30 years. Analysis of current and historical aerial photographs shows two to three fold increases in number of features present, and in total surface area of landscape affected. The core study areas are spread along a gradient from the upper to lower Noatak Basin covering a number of major land cover types. The majority of these features occur in headwaters of Noatak tributaries and can have marked impacts on small headwater streams, which have less capacity to buffer the effects of disturbance. These studies show that thermokarst processes and effects, especially in headwater regions, have been vastly under-reported in the Noatak Basin. These findings suggest that similar phenomena may be under-reported in other permafrost regions as well, due in part to the logistical difficulty of conducting quantitative surveys in remote areas with rugged topography.
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