Researchers with Natural Resources Canada’s Geological Survey of Canada (GSC) glaciology section recently completed an airborne Lidar survey of the Columbia Icefield, and are looking forward to interpreting the findings. 

The survey, designed by NRCan glaciology section head Dr. Mike Demuth, working with the Canadian Consortium of Lidar Environmental Applications Research (C-CLEAR), took place in early August as part of a C-CLEAR partnership survey flown across Canada to various sites, including the Canadian Rockies. 

Flying in three transects at 4,600 metres (15,000 feet), the aircraft flew over the centre of the icefield on the Saskatchewan Glacier, the southern flanks of Mount Columbia and then around to the northwest to pass over the North Twin, Mount Snow Dome and Castleguard Glacier. On its final pass, the plane passed over the Bush River Glacier, then over the site of NRCan’s glacier research camp at the base of Snow Dome from last April before exiting the area over the Athabasca Glacier. 

As it flew, a laser scanner swept back and forth taking measurements that will allow the researchers to calculate elevation change by comparing this data to historical digital elevation models. From the difference between the two, glaciologists will know where and how much thinning and/or thickening of ice has occurred on the icefield. 

The LIDAR — light detection and ranging — equipment is configured into an airborne laser terrain mapper, or ALTM. The equipment then works much like radar using light instead of radio waves.

Ideally, Demuth said, the measurements would be taken by sweeping the scanner back and forth along the terrain, much the way a combine overlaps its tracks to gather every bit of grain, but budget constraints allowed for only the three transects to be recorded.

Flying at an airspeed of 100 knots, the aircraft was required to made rudder turns to keep the plane as level as possible so as not to lose the GPS lock. 

“If it were to make banked turns when getting lined up for each transect, there is a risk of losing the lock on the GPS satellites telling us where the Lidar system is in a spatial sense, and this would be bad,” Demuth explained. “So what the pilot does is fly the wings level during the turns, and ‘skids’ the aircraft around. It sounds simple enough, but it takes a lot of skill behind the wheel.”

The data gained from this Lidar survey will be used in conjunction with measurements Demuth and his team of researchers conducted in April to determine the current volume of the icefield, as part of how glaciologists from the GSC, with support from the Canadian Space Agency and Parks Canada, are using technology to conduct a complete analysis of the volume of ice contained in the 223-square-kilometre Columbia Icefield. 

“The work we did in the spring was to start measuring the current volume of the icefield,” Demuth explained. “This latest effort is to start measuring the volume change — the container versus the shell of the container.”