January 13, 2012

Washmawapta Glacier Retreat, British Columbia

Posted by Mauri Pelto

The West Washmawapta Glacier and Washmawapta Icefield are located in the Vermillon Range in British Columbia. They are in a basin between Limestone Peak and Helmet Peak. The West Washmawapta is a cirque glacier and has been the focus of detailed studies of its dynamics and runoff in recent years. The study of its dynamics (Sanders et al, 2010) measured velocities of 3-10 meters/year, pretty typical for a cirque glacier of this size, and had a maximum depth of 185 m, a bit deeper than usual. The runoff study (McGregor, 2007) and Dow et al (2011)examined streamflow below the glacier and found that peak flow was at 2100 hours, several hours after peak melting. They conclude that this indicates a well developed subglacial drainage system. Sanders et al (2010) noted that West Washmawapta Glacier lost 30% of its area from 1949-2007. A comparison of Google Earth imagery from 2002 (top) and 2007 (middle) and Landsat imagery from 2009(bottom) identifies changes in the two glacier in the last decade. For the West Washmawapta Glacier in 2002 the glacier ended in contact with two proglacial lakes (Point A-C) and a lake that is just forming at Point B. The retreat is from 30-50 meters in this five year span. In the 2009 Landsat the Lake at Point C is well separated from the glacier. For Washmawapta Icefield, does not really deserve the icefield title, has lost a lower former glacier section that was in contact with Elizajan Lake, green arrow. The purple areas point to two prominent bedrock features that indicate retreat of 30 meters over the five year time span. The problem for both glacier is the insufficient size of the accumulation area. In 2009 the image is from August 20th, a month left in the melt season and only 40% of the glaciers are snowcovered. An alpine glacier like these needs at least 55% snowcover to be in equilibrium. The 2007 imagery in from July and the accumulation area is at 65%, by September of 2007 the extent was down to 35%. Now if you are still not sated, the video on the West Washmawapta Glacier project illustrates the amount of hard work and good humor that is essential to complete such a field project is quite a treat.