Permafrost geosystem assessment at the Beaver Creek Road experimental site (Alaska Highway, Yukon, Canada)

Thesis (M.S.) University of Alaska Fairbanks, 2013An experimental site testing a range of engineering techniques for mitigating permafrost degradation along the Alaska Highway has been established in 2008 at Beaver Creek (Yukon, Canada). Based on the hypothesis that permafrost has a distinctive sensitivity to climate and terrain conditions at a local scale, a geosystem approach, which considers a set of components (e.g. permafrost, embankment, vegetation, hydrology and hydrogeology) and accounts for dynamics within a system, was applied to obtain a better understanding of local permafrost conditions and changes within the system. Therefore, this assessment, for ultimately measuring performance of the mitigation techniques, integrated the permafrost conditions, in terms of cryostratigraphic units and soil properties, with local climate, natural terrain and embankment conditions. The author, who participated in the site establishment, its baseline investigations and monitoring programs, presents here the baseline geosystem studies at the Beaver Creek Road Experimental Site with an emphasis on permafrost.Chapter 1. Introduction -- Chapter 2. Study area background -- 2.1. The Alaska Highway -- 2.2. Geology -- 2.3. Climate, drainage, and vegetation -- 2.4. Permafrost -- 3. Permafrost cryostratigraphy and material properties -- 3.1. Introduction -- 3.2. Methodology -- 3.2.1. Ground ice and soil description -- 3.2.2. Permafrost geotechnical properties -- 3.2.3. Thermal regime -- 3.3. Results -- 3.3.1. Permafrost cryostratigraphy -- 3.3.1. Unit 1 (0 to ~0.5-1.0 m deep) --3.3.1.2. Unit 2 (~0.5-1.0 to ~6.5.-9.0 m deep) -- 3.3.1.3. Unit 3 (~6.5.-9.0 to ~11.0-15.0 m deep) -- 3.3.1.4 Unit 4 (~11.0-15.0 m to>̲ 16 m deep) -- 3.3.1.5. network of buried ice-wedges (2.5 m to>̲ 10.7 m deep) -- 3.3.2. Permafrost geotechnical properties -- 3.3.2.1 Unit 1 (0 to ~0.5-1.0 m deep) -- 3.3.2.2. Unit 2 (~0.5-1.0 to ~6.5-9.0 m deep) -- 3.3.2.2.1 Sub-unit 2A (~0.5-1.0 to 2.0 m deep) -- 3.3.2.2.2 Sub-unit 2B (~2.0 to 4.0 m deep) -- 3.3.2.2.3 Sub-unit 2C (4.0 to ~6.5-9.0 m deep) -- 3.3.2.3 Unit 3 (~6.5-9.0 to ~11.0-15.0 m deep) -- 3.3.2.4 Unit 4 (~11.0-15.0 m to>̲ 16 m deep) -- 3.3.3 Ground thermal regime -- Chapter 4. Climatic and natural terrain conditions -- 4.1. Introduction -- 4.2. Methodology -- 4.3. Results -- 4.3.1 Terrain settings -- 4.3.2. Air temperatures -- 4.3.3. Wind speed and direction -- 4.3.4. Snow -- 4.3.5. Near surface ground temperatures -- Chapter 5. Road embankment conditions -- 5.1. Introduction -- 5.2. Methodology -- 5.2.1. Microtopography measurements for embankment geometry -- 5.2.2. Subsurface investigations of road embankment -- 5.2.3. Representation of road embankment data -- 5.2.3.1. Validation of data -- 5.2.3.2. Digital elevation model (DEM) -- 5.3. Results -- Chapter 6. Synthesis of knowledge -- 6.1. Local environment factors -- 6.2. Cryofacies analysis for engineering purposes -- 6.3. Road embankment and permafrost thermal regime -- 6.4. Conclusions -- References -- Appendices