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4. Landslides and Permafrost
12 Mile Creek slide: located 10 km south
of Carmacks, this slide initiated in 2002 as
a massive debris flow that traveled down
the length of 12 Mile Creek at speeds of up
to 40 km/hr. Approximately 250 000 m3
of material was transported downslope
toward an important salmon spawning ground
in the Nordenskiold River. Exposure of
permafrost in the source area has caused
ongoing retreat of the headscarp and continued
sedimentation into the Nordenskiold River.
Ground and air temperatures are being monitored
at this site and InSAR remote sensing will be used
to monitor ground deformation throughout the
summer of 2006. Geophysical resistivity surveys
will also be conducted to study local permafrost
conditions.
Distribution, Nature and Impacts of Landslides and Permafrost - Related Terrain Hazards
Terrain destabilization by landslides and permafrost degradation are becoming a major concern in Yukon in recent years, driven by uncertainty surrounding the distribution and nature of permafrost and the effects of climate change on landslide processes. In particular, the influence of climate change on the occurrence of forest fires, glacial retreat, and permafrost degradation is of prime importance to terrain stability. Continued efforts to characterize these issues are required to support impending development, infrastructure maintenance and land-use planning within communities and along infrastructure corridors.
The purpose of this project is to improve our overall understanding of the geomorphological processes that contribute to terrain hazards in southern and central Yukon, primarily in relation to permafrost degradation. The role of forest fire, permafrost and climate change will be focused upon, and monitoring of several failures will be initiated or continued from previous years using both remote sensing and on-site instrumentation. The potential impacts of these hazards on water quality, fish habitat and infrastructure development are also being considered.
For more information on this project, please contact Panya Lipovsky email
Project Components
A) Monitoring of permafrost-related landslides:
Long-term monitoring of the following landslides will contribute to our understanding of permafrost-controlled landslides, including their seasonal activity, sediment transport mechanisms, and responses to the current climate regime. This in turn provides a basis for predicting frozen ground responses to future climate change.
Monitoring techniques include air and ground temperature logging and morphological surveys using total station surveying or high-precision GPS. Most of the landslides below will also be monitored using InSAR (interferometric synthetic aperture radar) remote sensing during the summer of 2006. InSAR is capable of measuring subcentimetre vertical changes in ground deformation. This work has been made possible through the European Space Agency and CCORE Engineering (St. John's, Newfoundland). These agencies have funded the remote sensing monitoring in order to demonstrate InSAR's ability to detect permafrost-related ground deformation.
Magundy slide: located 10 km SouthEast
of the eastern end of Little Salmon Lake,
this slide is classified as a large bimodal flow.
As frozen material thaws at the headscarp,
it is transported away by mudflows that
have traveled up to 2 km downslope.
Ground and air temperatures are being
monitored at this site, as is the retreat of
the actively thawing headscarps. InSAR
remote sensing analysis will be used to
monitor ground deformation throughout
the summer of 2006.
(The slide is 300 m wide at the top of the
photo. View is to the south).
B) Inventory of landslides and their impacts in the Pelly River watershed
Selkirk First Nation has raised concerns about dramatically deteriorated water quality in the Pelly River in recent years which is believed to be linked to increased frequencies of landslides in the watershed, particularly in response to permafrost degradation and climate change. There are concerns that this could negatively impact fisheries, wildlife and public safety in their traditional territory. A reconnaissance-level landslide inventory will be initiated this summer to further investigate these issues.
C) Alaska Highway geotechnical borehole database and related studies
A large volume of permafrost and surficial geology information (stratigraphy, texture, and ice character and content) exists in geotechnical logs from boreholes drilled along the Alaska Highway over the last 30 years. In 2005, the YGS began to compile Yukon Highways borehole logs into a digital GIS-compatible database. Over 4000 boreholes were entered into the database along a 200-km stretch of the Alaska Highway between Beaver Creek and Kluane Lake. Data compilation will be continued this summer to extend the range of the database eastward to Whitehorse. Ultimately, this data will be extremely useful for a variety of planning purposes within the Alaska Highway corridor, including modeling thaw settlement potential and mapping the distribution of permafrost in greater detail than currently exists. This project is being undertaken in collaboration with the Geological Survey of Canada and will contribute to a nation-wide permafrost database.
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