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[en] The present state of sub-sea permafrost modeling does not agree with certain observational data on the permafrost state within the East Siberian Arctic Shelf. This suggests a need to consider other mechanisms of permafrost destabilization after the recent ocean transgression. We propose development of open taliks wherever thaw lakes and river paleo-valleys were submerged shelf-wide as a possible mechanism for the degradation of sub-sea permafrost. To test the hypothesis we performed numerical modeling of permafrost dynamics in the Dmitry Laptev Strait area. We achieved sufficient agreement with the observed distribution of thawed and frozen layers to suggest that the proposed mechanism of permafrost destabilization is plausible.
[en] A high resolution three-dimensional sub-regional scale (104 km"2) density-dependent, discretely fractured groundwater flow model with hydro-mechanical coupling and pseudo-permafrost was developed from a larger 5734 km"2 regional-scale groundwater flow model of a Canadian Shield setting. The objective of the work is to determine the sensitivity of modelled groundwater system evolution to the hydro-mechanical parameters. The discrete fracture dual continuum numerical model FRAC3DVS-OPG was used for all simulations. A discrete fracture network model delineated from surface features was superimposed onto an approximate 790 000 element domain mesh with approximately 850 000 nodes. Orthogonal fracture faces (between adjacent finite element grid blocks) were used to best represent the irregular discrete fracture zone network. Interconnectivity of the permeable fracture zones is an important pathway for the possible migration and subsequent reduction in groundwater and contaminant residence times. The crystalline rock matrix between these structural discontinuities was assigned mechanical and flow properties characteristic of those reported for the Canadian Shield. The variation of total dissolved solids with depth was assigned using literature data for the Canadian Shield. Performance measures for the sensitivity analysis include equivalent freshwater heads, environmental heads, linear velocities, and depth of penetration by conservative non-decaying tracers released at the surface. A 121 000 year North American continental scale paleo-climate simulation was applied to the domain with ice-sheet histories estimated by the University of Toronto Glacial Systems Model (UofT GSM). Hydro-mechanical coupling between the rock matrix and the pore fluid, due to the ice sheet normal stress, was included in the simulations. The flow model included the influence of vertical strain and assumed that areal loads were homogeneous. Permafrost depth was applied as a permeability reduction to both three-dimensional grid blocks and fractures that lie within the time varying permafrost zone. Values of ice sheet normal stress and proglacial lake depth from the UofT GSM were applied to the sub-regional model as surface boundary conditions using a freshwater head equivalent to the normal stress imposed by the ice sheet at its base. The sensitivity of glacial meltwater penetration to different conceptualizations of hydro-mechanical properties were investigated. (author)
[en] This report provides the results of a research project that investigated the use of codes and standards in terms of their potential for fostering adaptation to the future impacts of climate change on built infrastructure in Canada's north. This involved a literature review, undertaking key informant interviews, and a workshop where key stakeholders came together to dialogue on the challenges facing built infrastructure in the north as a result of climate change and the role of codes and standards to help mitigate climate change risk. In this article, attention is given to the topic area of climate data and information requirements related to climate and climate change. This was an important focal area that was identified through this broader research effort since adequate data is essential in allowing codes and standards to meet their ultimate policy objective. A number of priorities have been identified specific to data and information needs in the context of the research topic investigated: There is a need to include northerners in developing the climate and permafrost data required for codes and standards so that these reflect the unique geographical, economic, and cultural realities and variability of the north; Efforts should be undertaken to realign climate design values so that they reflect both present and future risks; There is a need for better information on the rate and extent of permafrost degradation in the north; and, There is a need to improve monitoring of the rate of climate change in the Arctic. (author)