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TitreInfrastructure and climate change impacts on ground thermal regime, Iqaluit International Airport, Nunavut
AuteurLeBlanc, A -M; Oldenborger, G A; Sladen, W E; Allard, M
SourceArctic Change 2014, poster abstracts; 2014 p. 102-103
Année2014
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140226
RéunionArctic Change 2014; Ottawa; CA; décembre 8-12, 2014
Documentlivre
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNunavut
SNRC25N/09; 25N/16
Lat/Long OENS-69.0000 -68.0000 64.0000 63.6667
Sujetsclimat arctique; fluctuations climatiques; regimes thermiques; pergélisol; températures au sol; géologie des dépôts meubles/géomorphologie; Quaternaire
ProgrammeInfrastructures terrestres, Géosciences de changements climatiques
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
It is now common knowledge that climate change may threat the integrity of northern infrastructures and should be considered in the design of infrastructures on permafrost. For transportation infrastructure, the structure itself, snow accumulation and water ponding along embankments will also influence the ground thermal regime. In the context of climate change, it is useful for planned or newly built infrastructure to differentiate between the effects of climate warming and anthropogenic factors on the permafrost thermal regime. In 2010, a joint study was initiated between the Canada-Nunavut Geoscience Office, Natural Resources Canada and Centre d'etudes nordiques of Universite Laval to investigate permafrost sensitivity and terrain conditions within the Iqaluit International Airport area. The airport has a history of terrain stability problems and is now entering a major improvement phase. Ground surface temperature sensors have been used to monitor the surface microclimate on embankment slopes, undisturbed ground, stream channels or ditches, and areas with different thicknesses of snow cover. Combined with historical data since the construction of the airport and other geotechnical information, the ground surface temperatures were used to support numerical modeling. A two-dimensional cross-section between the runway and what is now the main apron of the new terminal building is used to show the separate and combined impacts of climate change, snow accumulation, and the infrastructure itself on the ground thermal regime. Initially, the past and current ground temperature distributions are simulated using the cooling (1946-1992) and the warming (1993-2014) trends in the air temperature record as well as the change in surface conditions that have occurred since 1946. Then different case scenarios over a 30 years period were simulated to assess the future ground temperature distribution: 1) new embankment material to extend the current apron, 2) use of insulation within the embankment, and 3) climate warming trends of 0.5°C and 1.0°C per decade. Results of past and current ground temperatures are in agreement with observed ground temperature changes. The impact on the ground thermal regime due to the new embankment material, without climate trends, depends on the ground temperature distribution and surface conditions prior to the embankment construction. The addition of Styrofoam insulation results in permafrost warming by a few tenths of degree Celsius at depth while the ground temperatures closer to the surface decreases and the permafrost table moves upward just underneath the insulation. In general, warming trends cause the permafrost to be warmer at depth while remaining colder close to the surface compared to the preconstruction condition. At a location where thick snow cover existed at the toe of the old apron embankment, the combined impact of new embankment (with or without insulation) and climate warming leads to a permafrost temperature similar to the pre-construction conditions at 15 m depth. Over years, the simulations indicate an increase in active layer thickness after an initial move upward within the new embankment. Resultscan be used by northern transportation infrastructure managers to better understand the causes behind the thermal changes of permafrost.
Résumé(Résumé en langage clair et simple, non publié)
Dans un contexte où de nouvelles infrastructures sont planifiées ou construites au moment où le climat est en changement, il devient utile de différencier entre les effets du réchauffement climatique et des facteurs anthropiques sur le régime thermique du pergélisol. Une étude a été initiée en 2010 sur la sensibilité du pergélisol et les conditions de terrain à l'aéroport d'Iqaluit. Par le biais de la modélisation numérique, les impacts isolés et combinés des changements climatiques, de l'accumulation de neige et des nouvelles infrastructures sur le régime thermique du sol sont simulés. L'impact de la mise en place de matériaux de remblai sur le régime thermique du sol dépend des conditions de surface avant la construction. Au cours des 30 prochaines années, l'augmentation de la température du sol et de l'épaisseur de la couche active sont simulée. Ces augmentations surviennent après un refroidissement initial du pergélisol près de la surface et une remontée de la couche active dans le nouveau remblai. Les résultats peuvent être utilisés par les gestionnaires d'infrastructures de transport nordiques afin de mieux comprendre les causes des changements thermiques du pergélisol.
GEOSCAN ID295210