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TitleCCGP land-based project: advances and challenges in geoscientific research and monitoring
AuthorMorse, P DORCID logo; Wolfe, S AORCID logo; Zhang, YORCID logo; Kokelj, S V
SourceNorthwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2015, 2015 p. 72-73 Open Access logo Open Access
LinksOnline - En ligne (complete volume, pdf, 1.98 MB)
Alt SeriesEarth Sciences Sector, Contribution Series 20150323
PublisherNorthwest Territories Geological Survey
Meeting43rd Annual Yellowknife Geoscience Forum; Yellowknife; CA; November 24-26, 2015
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®)
ProvinceNorthwest Territories
NTS85I/13; 85I/14; 85P/03; 85P/04; 85P/05; 85P/06
AreaNorth Slave Region
Lat/Long WENS-114.0000 -113.0000 63.5000 62.7500
Subjectssurficial geology/geomorphology; environmental geology; hydrogeology; permafrost; ground ice; hydrologic environment; climate; vegetation; peatlands; sediments; ground temperatures; thermal analyses; modelling; groundwater regimes; water quality; heat flow; meteorology; climate change; permafrost degradation; thermal degradation; forests; forest fires; tundra; icings; geological hazards; surface temperatures; terrain sensitivity
ProgramClimate Change Geoscience, Land-based Infrastructure
Released2015 11 01
AbstractThe Climate Change Geoscience Program (CCGP) land-based project of Natural Resources Canada provides geoscientific expertise on environmental baseline conditions. Primary research, monitoring, and modelling supports informed decision making for resource development and land use. This project provides new geoscientific knowledge to improve our understanding of the distribution and nature of permafrost and seasonal hydrological conditions in the North Slave.
Our research indicates most permafrost is associated with forest areas, rather than only with peatlands that characterize just 2% of the regional area. Extensive discontinuous permafrost conditions (65% of the regional area) relate primarily to the extent of unconsolidated ice-rich fine-grained sediments, with annual mean ground temperatures ranging from -1.4 °C to 0.0 °C. Monitored permafrost temperatures commonly illustrate thermal degradation in both natural and disturbed terrain. Modelling indicates substantial reductions of permafrost extent driven by climate-change, with a gradual transition by AD 2100 to isolated permafrost retained primarily within peatlands, and that on average, fire accelerates permafrost disappearance by 5 years, though permafrost in forest areas more sensitive to fire than in tundra and peatlands. Icings, a geohazard indicative of winter hydrological conditions, develop over the winter by freezing successive overflows of groundwater to the surface, and we mapped 5500 in the study region. Mapped icings indicate the extent of groundwater springs in the region, information useful for hydrological monitoring of seasonal ground water flow and chemistry. Regional interannual variation is driven by winter warming intervals and antecedent autumn precipitation, but this is moderated by geological conditions that vary intra-regionally. Future icings may develop less frequently due to decreasing winter warming intervals, but increasing autumn rainfall may increase icing density in areas dominated by bedrock outcrop.
Overall, our key finding is that substantial changes in permafrost and seasonal hydrological conditions are likely to occur naturally within the lifetime of many projects. Understanding the direct impacts from those changes requires future research to address a number of challenges. Driven by surface temperature change, the rate of permafrost degradation is regulated by surface organic layer thickness, but also by ground ice content, which also determines the degree of terrain sensitivity to thaw with indirect effects related to water quality and catchment-scale hydrology. However, unlike organic layer thickness, ground ice conditions are poorly understood. In reality, degradation of discontinuous permafrost is also driven by changes in heat flow adjacent to and beneath permafrost bodies, thus permafrost modelling should explicitly consider 3-D boundary conditions. Soil moisture strongly influences heat flow and ground temperatures, but the dynamic relations are not well quantified. Icing activity is likely affected by regional meteorological differences, but at present this variation cannot be accounted for due to a lack of field data for validation. Finally, the physical process linking winter air temperature warming to overflow is not known, but this understanding would greatly assist with prevention and mitigation measures.
Summary(Plain Language Summary, not published)
The Climate Change Geoscience Program (CCGP) land-based project of NRCan provides geoscientific expertise on permafrost and winter hydrological baseline conditions in the North Slave, NWT. We found extensive discontinuous permafrost relates primarily to forests on unconsolidated fine-grained sediments. Permafrost temperatures are very warm, and natural and disturbed terrain show signs of thermal degradation. With climate change, permafrost extent may reduce to isolated permafrost within peatlands. Winter air temperature and antecedent autumn rainfall, moderated by variable geological conditions, drive interannual variation of the 5500 icings (winter geohazards) we mapped. To assess the impacts of changing baseline conditions, new research must address several challenges including ground ice mapping, 3-D modelling, and process studies of soil moisture dynamics and icing development.

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