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NATURAL RISKS AND FREQUENCY OF DEBRIS FLOWS IN AKSHAYUK PASS (NUNAVUT, CANADA)

DOUCET, ANNICK  University of Ottawa.
Lauriol, Bernard  University of Ottawa.

Akshayuk Pass in Auyuittuq National Park is located in the Eastern Canadian Arctic (Baffin Island). This national park has many debris flows, which can be hazardous to the safety of tourists. These debris flows are a moving mass of rock fragments, soil, and mud, with more than half of the particles being larger than sand size. Thirty-two debris flows have been studied between Summit Lake and Overlord Peak. The objectives of this study is to evaluate the active frequency periods of these debris flows and to date their activities. Also, this study provides information concerning the potential natural risk for hikers and park’s infrastructures.

The lichenometric approach is based on size/age correlations of the lichen Rhizocarpon geographicum. This method of dating is based on the measurements of the longest axis of individual thalli. Each boulder surface was searched to measure every single thalli until 150 measurements per quadrat was reached. A comparison can then be established between two techniques: (1) maximum thalli measurement and (2) mean of the ten largest thallus measured. The age and frequency result of debris flows were statistically analyzed.

The results from this study indicate that (1) debris flows were more active 450 and 1000 years ago, (2) presently they are very active in spring when ice and snow melt and (3) they are a source of hazards for the tourists during this season.

In conclusion, debris flows are more active during periods of climatic warming. The phenomenon is explained by the fact that ice and snow melting are important during these periods and produce large quantity of water on slopes.


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