The Northwest Territories Geological Survey, Canada has issued an hazard advisory warning that a small creek valley west of Husky Lake, which lies in the Gwich’ in Settlement Area (GSA) is expected to be impacted by rapid flow of water and debris.
The reason behind this possible hazard is permafrost thaw, which is expected to cause catastrophic lake drainage and potential debris flow in next few months.
“The growth of a permafrost thaw slump will likely cause a small lake to drain catastrophically during 2015, resulting in a flash flood and possibly a debris flow”, the advisory reads.
The lake, which sits on the northern corner of the territory near the community of Fort McPherson, doesn’t carry a name and is a victim of the region’s geology and changing climate.
According to the survey, permafrost in this part of the country packs high percentage of ice in headwalls, which are known to be up to 30 metres thick. That ice has been there since the retreat of the Laurentide Ice Sheet 20,000 years ago.
Problems start when parts of these headwalls are exposed by erosion from wind or rain, which result in ice melts followed by collapse of soil and rock. This collapse exposes more ice, followed by melts and further collapses thereby forming a pattern.
The repetitive ice melts and soil collapse is causing slumps that are getting bigger and bigger as rainfall in the area increases and temperatures warm. There are slumps in the region that are more than a kilometre long and have washed loose millions of cubic metres of rubble.
The lake isn’t a huge one with only a couple of hectares in size and a few metres deep; however, it will send tens of thousands of cubic metres of water crashing down when the last bit of soil holding the lake intact collapses. Though there are no homes or communities in the anticipated flood path, the N.W.T. has issued a warning to steer clear.