The quantity and type of ground ice control the terrain response to climate change, especially in areas with ice-rich permafrost. For example, ice-rich permafrost thaw in flat terrain commonly results in subsidence of the ground surface and ponding; on hillslopes, ground ice melt can initiate landslides or gullying.
Ground ice occurs in different forms and accumulates due to a variety of processes. Segregated ice forms as lenses or layers due to the migration of unfrozen water toward colder ground and subsequent freezing. Wedge ice accumulates when permafrost ground cracks due to extreme cold. In spring, water fills the crack and freezes, forming an ice vein. Repeated cracking, infilling, and freezing forms large wedges of ground ice over centuries to millennia. Glacier ice may become buried by sediment and preserved as large ice bodies in permafrost. Hydraulic pressure in unfrozen aquifers can also cause the formation of injection ice in permafrost. Given the various types of processes involved in its formation, ground ice content is controlled by several factors including surficial geology, climate, glacial history, vegetation, and moisture conditions.
| name | source | data type | spatial domain | spatial resolution | temporal coverage | time step | data format | |
|---|---|---|---|---|---|---|---|---|
| Circum-Arctic Map of Permafrost and Ground-Ice Conditions, Version 2 | NSIDC | Map, manual delineation | Global | Polygons from 1:10,000,000 paper map | Variable | None | Shapefiles | details |
| Ground ice map of Canada | NRCan | Map, manual and heuristic rules | Canada | Polygons from 1:5,000,000 digital maps | Late 20th century | None | GeoTIFF; WMS | details |
| Permafrost Map of Canada | NRCan | Map, manual delineation | Canada | Polygons from 1:7,500,000 map | None | None | details | |
| Permafrost Information Network | NRCan | Station data | Canada | Point data | Variable,1953-2009 | None | None | details |
| N.W.T. Permafrost Database | Northwest Territories Geological Survey/GNWT | Station data | NWT | Point data | Variable | None | CSV | details |
| Permafrost and ground ice conditions of northwestern Canada | NRCan | Map, manual delineation | Northwest Canada | 1:1,000,000 | None | None | details | |
| Yukon Permafrost Database | Yukon Geological Survey/Yukon Government | Station data | Yukon | Point data | Variable | None | None | details |
3.4.3.1 Data sources
Circum-Arctic Map of Permafrost and Ground-Ice Conditions, Version 2: https://nsidc.org/data/ggd318. (Brown et al., 2002). Northern hemisphere representation of ground ice conditions. The relative abundance of visible ground ice in the upper 10-20 m is estimated in percent volume (>20 percent, 10-20 percent, <10 percent, and 0 percent for areas with thick overburden; and >10 percent, <10 percent for areas with thin overburden).
Ground ice map of Canada https://doi.org/10.4095/330294. National-scale modelling of segregated, wedge, and relict (buried glacier) ice. Modelling methodology described in O’Neill et al. (2019). The modelling uses an expert-system (rules-based) approach that employs datasets on surficial materials, paleovegetation, deglacial history, and modern permafrost distribution. GeoTIFF data layers are accessible on NRCan’s GEOSCAN repository and WMS are available.
Permafrost map of Canada (Heginbottom et al., 1995). The Permafrost map of Canada, published in the 5th Edition (1978 to 1995) of the National Atlas of Canada, is a 1:7,500,00 map showing permafrost zones and ground ice information. The legend includes ground ice represented as the % by volume of visible ice in the upper 10-20 m of ground as with the IPA map. The classes include high (>20%), medium (10-20%), low (<10%) and nil (0%). The geospatial data is not currently (21 July 2021) available on a public portal, but digital files have been prepared and will be available shortly on Open Maps.
Permafrost Information Network (https://pin.geosciences.ca/en/map ) The Permafrost Information Network (PIN) is a web portal in early development to access permafrost-related information from the Geological Survey of Canada (Natural Resources Canada). Currently, the portal includes records from ~14,000 geotechnical boreholes from northern Canada. These borehole logs contain information related to ground ice such as: descriptions of visible ground ice, gravimetric moisture content, and in some cases, excess moisture content. The borehole logs also include useful information for permafrost thermal modelling applications, such as the % fractions of sand/silt/clay for many boreholes. PIN also displays the ground ice mapping layers of O’Neill et al. (2019 and 2022).
NWT Permafrost Database Permafrost and ground ice conditions are available through borehole data compiled from geotechnical datasets. Datasets represent geotechnical data from industry, construction of linear infrastructure and government, and academic research projects. Borehole logs contain information related to ground ice such as: fractions of sand/silt/clay, volumetric ice content, in some cases excess ice content and descriptions of visible ice. (Contact Niels Weiss: niels_weiss@gov.nt.ca)
Permafrost and ground ice conditions of northwestern Canada (Heginbottom and Radburn, 1992) The mapping provides a qualitative assessment of ground ice abundance in northwestern Canada at 1:1,000,000 scale. The assessment is based mainly on previous surficial geological and geomorphological mapping sources at scales of 1:100,000 to 1:250,000.
Yukon Permafrost Database (Release imminent; contact Derek Cronmiller: Derek.Cronmiller@yukon.ca) Compilation of about 15,000 boreholes including several compilations: The Alaska Highway Borehole Database (8818 holes) compiled by the Yukon Geological Survey in 2010, based on logbooks 1970–1990. The boreholes were drilled approximately every 100 m down centerline, averaging 6 m deep; approximately 1/3 record some form of permafrost. HPW-TEB GINT/Holebase (1743 holes) 2011–2019. EBA GINT (4408 holes) compilation from contracts carried out up to 2010. Mineral Industry (380 holes) from Western Copper-Casino, BMC Minerals-Kudz Ze Kayah, Clinton Creek Mine. Additionally, the Permafrost Information Network (PIN) has 633 sites for Yukon that are not included in this compilation.
3.4.3.2 Strengths and Limitations of Datasets
Station data (boreholes): Sources of ground ice information include compilations of geotechnical borehole logs. Point-scale borehole records provide direct and spatially explicit observations and are thus valuable for the characterization of local ice conditions. However, the type and detail of ground ice information vary depending on the purpose of the geotechnical drilling campaign. For example, some records may include only a visual description of ice conditions, whereas others may include measurements of ice content.
Modelling/mapping: Ground ice mapping products provide estimates of ground ice content over large areas, informed by available field information on ground ice and extrapolations to areas with similar environmental conditions. Given the general lack of ground ice information over much of the Canadian landmass for calibration and validation and the coarse resolution of basemaps used for mapping and modelling, these can provide only a rough estimate of average ground ice conditions within the map units. The ground ice information for Canada from the IPA map and Permafrost map of Canada is based on extrapolation of expected ground ice conditions to a basemap of large physiographic regions. The recently published Ground ice map of Canada uses a more detailed national-scale surficial geology dataset as a basemap. This provides a more detailed depiction, but in some regions, the abundance of frost-susceptible sediments is underrepresented compared to bedrock, which affects the spatial accuracy of the modelling/mapping (Wolfe et al., 2021). Nonetheless, these products are the only available information suitable for use in spatial modelling.
References – Subsurface Ice Content
Brown, J., O. Ferrians, J.A. Heginbottom, and E. Melnikov, 2002: Circum-Arctic Map of Permafrost and Ground-Ice Conditions, Version 2. Boulder, Colorado USA, NSIDC: National Snow and Ice Data Center, doi.org/10.7265/skbg-kf16.
Heginbottom, J.A., M.A. Dubreuil, and P.T. Harker, 1995: Canada - Permafrost. In The National Atlas of Canada, Natural Resources Canada, doi.org/10.4095/294672.
Heginbottom, J.A., and L.K. Radburn, 1992: Permafrost and Ground Ice Conditions of Northwestern Canada / Conditions relatives au pergélisol et à la glace de sol du Nord-Ouest du Canada. Geological Survey of Canada, doi.org/10.4095/183822.
O'Neill, H.B., S.A. Wolfe, and C. Duchesne, 2019: New Ground Ice Maps for Canada Using a Paleogeographic Modelling Approach. The Cryosphere, 13(3), 753-773, doi.org/10.5194/tc-13-753-2019.
O'Neill, H.B., S.A. Wolfe, and C. Duchesne, 2022: Ground Ice Map of Canada. Geological Survey of Canada, https://doi.org/10.4095/330294.
Wolfe, S.A., H.B. O'Neill, and C. Duchesne, 2021: A Ground Ice Atlas of Canada. Geological Survey of Canada, doi.org/10.4095/328115.