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TitreCCGP land-based project: advances and challenges in geoscientific research and monitoring
AuteurMorse, P D; Wolfe, S A; Zhang, Y; Kokelj, S V
SourceNorthwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2015, 2015 p. 72-73 (Accès ouvert)
LiensOnline - En ligne (complete volume, pdf, 1.98 MB)
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20150323
ÉditeurCommission géologique des Territoires du Nord-Ouest
Réunion43rd Annual Yellowknife Geoscience Forum; Yellowknife; CA; Novembre 24-26, 2015
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf (Adobe® Reader®)
ProvinceTerritoires du Nord-Ouest
SNRC85I/13; 85I/14; 85P/03; 85P/04; 85P/05; 85P/06
Lat/Long OENS-114.0000 -113.0000 63.5000 62.7500
Sujetspergélisol; glace fossile; milieu hydrologique; climat; végétation; tourbières; sediments; températures au sol; analyses thermiques; établissement de modèles; régimes des eaux souterraines; qualité de l'eau; flux thermique; météorologie; changement climatique; forêt; incendie de forêt; glaçages; géologie des dépôts meubles/géomorphologie; géologie de l'environnement; hydrogéologie
ProgrammeGéosciences de changements climatiques, Infrastructures terrestres
Diffusé2015 11 01
Résumé(disponible en anglais seulement)
The 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.
Résumé(Résumé en langage clair et simple, non publié)
Le projet de RNCan axé sur les infrastructures terrestres du programme géosciences pour les changements climatiques (PGCC) fournit une expertise géoscientifique sur les conditions hydrogéologique de base et sur celles du pergélisol pour la région North Slave, Territoire du Nord-Ouest. La zone de pergélisol discontinu et abondant se retrouve principalement dans les milieux forestiers où les sédiments non-consolidés sont riches en glace. Le pergélisol est près de 0 °C et les sols en terrain naturel et perturbé montrent des signes de dégradation. En réponse aux changements climatiques, l¿étendue du pergélisol sera restreinte de façon sporadique aux tourbières. La présence de 5500 aufeis (géorisque en saison hivernale) cartographiés est contrôlée par la température hivernale de l¿air et les précipitations survenues au cours de l¿autonome précédent, mais dépend également des conditions variables de la géologie. Afin d¿évaluer les impacts, de nouvelles recherches portant sur la cartographie de la glace de sol, la modélisation tridimensionnelle et l¿interaction entre l¿hydrogéologie et le développement des aufeis doivent être développées.
GEOSCAN ID297383