ABSTRACT: Permafrost and climate change: importance for municipal and transportation infrastructures.

CGRG Bibliography of Canadian Geomorphology
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The presence of permafrost (i.e. soil or rock at temperatures below the freezing point of water) is one of the key factors that make the Arctic highly sensitive to climate change. A warmer climate leads to greater depths of thaw in summer (the active layer depth) with the consequence that the surface of the ground settles. Increased thaw depth also destabilizes slopes and accelerates down slope soil movements such as gelifl uxion or even triggers landslides. The thawing of permafrost often gives way to the formation of hollows and lakes which are termed thermokarst lakes. Those changes affect both natural environments, with major ecological impacts, and built environments, with potentially damaging consequences for buildings and transportation infrastructures. In Nunavik and Nunatsiavut, the climate warming that occurred since 1992 resulted in a general increase of 1.5 °C in near surface ground temperatures (4 m deep) and lead to major changes in the abundance of discontinuous permafrost. The impacts also affected roads and runways since they were not designed to face the ongoing climate warming and, also, because the importance of local effects was ignored such as the impacts of infrastructures on snow cover and soil drainage. Over the same period, the northern population increased by 10% generating an important need for newhousing construction. The communities are expected to expand over permafrost terrain in the coming years. Existing infrastructures such as roads and airports will have to be stabilized and expanded while some new ones may be required. The approach used to support community adaptation and expansion consists principally in producing high resolution maps of permafrost conditions integrating data from numerous sources such as drilling, geophysics, thermistor cables, and laboratory analyses of permafrostsamples. Numerical simulations of ground thermal regime and active layer changes until 2050 are made to assess how the terrain will evolve and choose the best building foundation designs adapted for each terrain conditions. This information is compiled into GIS systems and then transferred and discussed with community representatives, involved ministries (Municipal affairs, Transports) and other stakeholders to orient policies and decisions.

Bibliography of Canadian Geomorphology