Integration of geophysical, ground surface, and remote sensing methods to identify ice features in discontinuous permafrost near Fairbanks, Alaska

Wednesday, 17 December 2014: 5:15 PM
Thomas A Douglas1, Kevin Bjella1, Christopher A Hiemstra1, Stephen D Newman2, John Anderson3, Jarrod Edwards3, Steven A Arcone2, Anna M Wagner1, Robyn Barbato2, Jacob Berkowitz4 and Elias J Deeb2, (1)U.S. Army Cold Regions Research and Engineering Laboratory Alaska, Fairbanks, AK, United States, (2)U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH, United States, (3)Remote Sensing and Fluorescence Spectroscopy Lab, Richmond, VA, United States, (4)U.S. Army Environmental Laboratory, Vicksburg, MS, United States
Ground ice features such as ice wedges, segregation ice, and thermokarst cave ice are present in the subsurface in a variety of spatial scales and patterns. Accurately identifying the character and extent of these ice features in permafrost terrains allows engineers and planners to cost effectively create innovative infrastructure designs to withstand the changing environment. We are assembling a holistic view of how a variety of surficial and standoff geophysical measurements can be combined with classic ground based measurements to delineate subsurface permafrost features. We are combining horizontal geophysical measurements; borehole mapping; multispectral and radar remote sensing; airborne and ground-based LiDAR; snow, soil, and vegetation mapping; and subsurface thermal measurements and modeling at three field sites in discontinuous permafrost of Interior Alaska. Our sites cross transects representing upland and lowland permafrost and a variety of soil and vegetation compositions. With our measurements we identified and mapped a 300 meter wide swath of ice rich frozen peat at one of our lowland field sites. The high ice content was confirmed with borehole measurements. This ice rich permafrost region yields higher electrical resistivity values than the nearby permafrost and is associated with anomalously low seasonal thaw depths compared to other sites nearby. Surface soils in the ice rich region have high soil moisture contents, low redox potential (30-100 mV), and elevated soil microbial activity. The ice rice region yields low phase changes from paired interferometric synthetic aperture radar measurements collected in late spring and late summer. One interpretation of this result is that the ice rich area experiences minimal summer season subsidence. Taken in total, our results suggest the ice rich peat region has distinct surface signatures and subsurface geophysical characteristics that may be extrapolated to other areas to identify ice rich permafrost in the subsurface.