CGRG Bibliography of Canadian Geomorphology
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Author : Gosselin, P.; and Allard, M.
Date : 2010.
Title : Severe permafrost degradation due to major fluvial thermoerosion event.
Publication : 7th Annual ArcticNet Scientific Meeting. December 15-17, 2010. The Westin Ottawa, Ottawa,Ontario.
Issue : Programme.
Page(s) : 123.
Abstract
In June 2008, the community of Pangnirtung was seriously impacted by an extreme peak discharge of the Duval River following an intense rainy storm event. In a matter of several hours, the bouldery main channel was overdeepened by nearly 10 m while thermal and mechanical erosion acted simultaneously for undercutting permafrost river banks, expanding thermo-erosional niches up to 30 m. Eventually, the weight of the undercutted banks exceeded the resistive strength of the permafrost and major collapses occurred. The two bridges were permanently impaired which resulted in a limited access to some vital services such as drinkable water distribution and sewage transport. The Hamlet had to declare a state of local emergency. This event shows how climate change and more specifically, extreme climatic events can trigger landscapes hazards, raising safety concerns and infrastructures issues in northern communities. In pursuance of developing a more resilient community, this study in three steps will focus on understanding the process of thermal erosion and on assessing the potential risk of reoccurrence of high magnitude fluvial events in Pangnirtung. First of all, in order to understand the past long-term hydrologic variability, radiocarbon dating of organic material found in fossil alluvial sequences will allow determining if a flood frequency trends exists. Then, with the objective of understanding the role of the main parameters involved during thermal erosion, mathematical equations develop by Randriamazoaro et al (2007) and Fortier et al (2007) will be used. The main parameters, i.e. discharge, water temperature, ice content and ground temperature, were measured during fi eld work done in 2009 and 2010. Moreover, a simple numerical simulation made with TempW should enhance the representativeness of the mathematical approach. Finally, a potentiel frequency of reoccurrence of extreme peak discharge likely to cause destructive thermoerosion events in the future will be determined using climate simulations at high resolution extracted from the Canadian Regional Climate Model (CRCM).
Bibliography of Canadian Geomorphology