Drones help monitor accelerating erosion along N.W.T.'s Arctic coastlines
3D imagery to help scientists track and understand climate change-driven coastal changes
Researchers are using drones as a better, cheaper way to monitor accelerating erosion along N.W.T.'s Arctic coastlines.
Dustin Whalen, a physical scientist with the Geological Survey of Canada, says in the past they used old aerial photographs, satellite imagery, on-the-ground measurements and GPS techniques to track coastal change but none of those techniques give a 3D image or a sense of height.
In 2004, researchers got that kind of data using airborne LIDAR — a type of remote sensing using lasers — but it was expensive.
"Twelve years later we're able to use drones for a fraction of the cost to get the exact same data we would have spent hundreds of thousands of dollars on years ago," he said.
Drones can also get pictures of places that are difficult or unsafe to access, like slumping sediments below jutting cliffs.
In the summer of 2016, Whalen's team at the Geological Survey of Canada studied the shores of Pelly Island, Hooper Island and Pullen Island off the Mackenzie Delta, Toker Point and Atkinson Point along the Tuktoyaktuk peninsula, and at Cape Bathurst. They were looking at ice-rich cliffs five metres or higher, located in the path of the region's dominant winds and waves.
Whalen's team made 50 20- to 30-minute drone excursions and took 70,000 photos.
"It's really not that hard to fly the drone," he said. "You can run it from an iPad."
They directed it where they wanted it to go, but otherwise the drone was largely autonomous.
"At one point it was raining and the drone told us it was getting wet and was going to return home now," he said.
The photos are then put through a rendering software to create up-to-date 3D images of the shores. This can take days or weeks.
"Because there's so many 2D pictures all overlapped on each other taken from different angles, it's able to reconstruct the 3D sort of mosaic of it. It's able to give it structure."
Scientists are seeing an acceleration of coastal change in the area, he says. From the 1950s to the mid-1990s, erosion appeared to be stable on N.W.T.'s Arctic coast. After the mid-1990s, the rate of erosion sped up, even doubling in some areas.
At Pelly Island this summer, researchers measured 40 metres of change in one season.
"The change we're seeing is driven by climate," Whalen said.
Warmer air temperatures are leading to thawing permafrost, less sea ice and earlier spring break-up. That means the shorelines are being hit by waves and storms for longer periods than in the past.
More erosion from the shores means more sediment in the water and that could have potential effects on aquatic ecosystems and human activities, Whalen said. In Tuktoyaktuk, residents often travel the channel to the east of the island.
"If we're depositing more and more sediment into the water column, how is that affecting the water depths in that navigation channel?" he asked.
Whalen said the detailed imagery can help researchers understand the processes at work as well as help plan erosion mitigation efforts.
The researchers hope to continue their drone shoreline studies next summer.
