%0 Conference Proceedings
%T Airborne electromagnetic mapping of subsurface permafrost (Invited) [abs.]
%A Abraham, J.D.
%A Minsley, B.J.
%A Cannia, J.C.
%A Smith, B.D.
%A Walvoord, M.A.
%A Voss, C.I.
%A Jorgenson, T.T.
%A Wylie, Bruce K.
%A Anderson, L.
%E in
%B Fall Meeting
%D 2011
%V Fall Meeting Abstracts
%7 5-9 December 2011
%I American Geophysical Union
%C Washington, D.C.
%@ http://www.agu.org/meetings/fm11/waisfm11adv.html
%G FY 2012
%F Abraham_etal2011
%O exported from refbase (http://eros.usgs.gov/refbase/show.php?record=23325), last updated on Fri, 21 Sep 2012 11:59:54 -0500
%X Concerns over the impacts of climate change have recently energized research on the potential impacts thawing permafrost may have on groundwater flow, infrastructure, forest health, ecosystems, energy production, CO2 release, and contaminant transport. There is typically little knowledge about subsurface permafrost distributions, such as thickness and where groundwater-surface-water connections may occur through taliks. In June of 2010, the U.S. Geological Survey undertook an airborne electromagnetic (AEM) survey in the area of Fort Yukon, Alaska in order to map the 3-D distribution of permafrost and provide information for the development of groundwater models within the Yukon River Basin. Prior to the development of these models, information on areas of groundwater-surface water interaction was extremely limited. Lithology determined from a borehole drilled in Fort Yukon in 1994 agrees well with the resistivity depth sections inferred from the airborne survey. In addition to lithology, there a thermal imprint appears on the subsurface resistivity values. In the upper 20-50 m, the sections show continuous areas of high electrical resistivity, consistent with alluvial gravel deposits that are likely frozen. At depth, unfrozen gravel deposits have intermediate-to-high resistivity; frozen silts have intermediate resistivity; and unfrozen silts have low resistivity. Under the Yukon River and lakes where the subsurface is not frozen, zones of moderate resistivity intermix with areas of low resistivity. The areas of loess hills on the margins of the Yukon Flats have very-high electrical resistivity, indicating higher ice content, and are associated with the some of the greatest thickness of permafrost in the survey area. This work provides the first look into the 3-D distribution of permafrost in the areas around Fort Yukon and is a demonstration of the application of AEM to permafrost mapping. The AEM survey provides unprecedented 3-D images of subsurface electrical properties that reveal changes in lithology and the presence or absence of permafrost. These geophysical data fill an important gap between sparsely sampled boreholes, regional hydrogeologic measurements, and remote sensing data. Interpretations of the AEM data are being integrated with other remotely sensed data to supply critical hydrogeological information needed for developing an improved understanding of groundwater-surface-water interactions in permafrost terrains. More specifically, the interpretations of the AEM data help to refine groundwater flow models in the Yukon Flats Basin. Because of the success of this study we now know that there are many other uses for this data. For example, airborne surveys can provide baseline data for estimating the 3-D distribution of permafrost that can be compared to future surveys in order to estimate volumetric changes over time.
%K airborne
%K Alaska
%K application
%K area
%K basin
%K change
%K climate
%K climate change
%K CO2
%K conference abstracts
%K data
%K development
%K ecosystem
%K flats
%K flow
%K forest
%K geophysical data
%K groundwater
%K ice
%K image
%K impact
%K infrastructure
%K interpretation
%K knowledge
%K lake
%K map
%K mapping
%K measurement
%K model
%K permafrost
%K production
%K properties
%K regional
%K remote sensing
%K research
%K river
%K river basin
%K surveys
%K terrain
%K thawing
%K thermal
%K water
%K Yukon River basin
%U http://www.agu.org/meetings/fm11/waisfm11adv.html