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TitleIcings in the Great Slave region (1985-2014), Northwest Territories, mapped from Landsat Imagery
AuthorMorse, P D; Wolfe, S A
SourceGeological Survey of Canada, Open File 7720, 2014, 38 pages,
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatreadme
File formatpdf; rtf; shp; xml
ProvinceNorthwest Territories
NTS85G/14; 85G/15; 85G/16; 85H/13; 85I/04; 85I/05; 85I/11; 85I/12; 85I/13; 85I/14; 85J; 85K/01; 85K/02; 85K/07; 85K/08; 85K/09; 85K/10; 85K/15; 85K/16; 85N/01; 85N/08; 85O; 85P/03; 85P/04; 85P/05; 85P/06; 85P/10; 85P/11
AreaGreat Slave Lake; Yellowknife
Lat/Long WENS-117.0000 -113.0000 63.8333 61.8333
Subjectsgeophysics; surficial geology/geomorphology; remote sensing; satellite imagery; ice; ice sheets; ice thicknesses; ice movement; ice conditions; transportation
Illustrationslocation maps; photographs; satellite images; histograms; tables; flow charts; plots
Natural Resources Canada Library - Ottawa (Earth Sciences)
ProgramLand-based Infrastructure, Climate Change Geoscience
LinksMetadata - Métadonnées
Released2014 11 28
AbstractIcings are sheet-like masses of layered ice that form over the winter by freezing of successive flows of water on the ground surface or on top of river or lake ice. Because icings can negatively impact the performance of seasonal and all-season roads, they are a transportation risk in the Arctic. Therefore, maps of their occurrence and reoccurrence provide important geoscience information required for development and transportation infrastructure planning. In this study, threshold values of band ratios were used to derive a set of icing maps from Landsat image time series of images (1985 - 2014), located within the Slave Geological Province (WRS-2 Path 47/Row 16). The icings maps were generated using image data acquired in late-spring when the region is largely snow-free, but ice bodies remain. A water mask created from summer image data was used to differentiate frozen water bodies so any remaining ice was considered to be land-fast, and thus icings formed from winter overland flow of water. Icing occurrence and reoccurrence maps were generated by overlaying the successive icing distribution maps in a Geographic Information System. This Open File contains digital, georeferenced icing data.
Summary(Plain Language Summary, not published)
We report on icings mapped in permafrost terrain within different terrain types in the Great Slave Region, Northwest Territories. Icings are sheet-like masses of layered ice that form over the winter by freezing of successive flows of water on the surface. Icings are a potential hazard to northern ice roads and all-weather roads, decreasing the number of days of operational use. This case study demonstrates a new mapping technique utilizing a 30-year archive of Landsat satellite imagery. For each year of data we map icings from a late-spring image, and then successive maps are overlain in a Geographic Information System to determine the total distribution of icings and their reoccurrence intervals. Nearly 5,500 icings were mapped, with icing density and dynamics varying distinctly by regional terrain type. We provide geoscientific data much needed in this region to reduce risks for land-based transportation infrastructure, and demonstrate a technique that may be used to map icings throughout the north.