There is an underground threat lurking down the road outside of Whitehorse.

It is relentless, ruthless and, unless drastic measures are taken, inevitable.

When you hit the Alaska Highway, many of the northern Yukon communities will be cut off from Whitehorse, as will Whitehorse’s only connection to neighboring Alaska.

That’s why Fabrice Calmels, president of research in permafrost and geoscience at Yukon University, has peppered the area around it with sensors. He hopes he can give governments an early warning of the threat long before the ground starts to shake under his feet.

The threat is called permafrost depression. It occurs when the permanently frozen layer of soil that underlies large swaths of Canada north of the 60th parallel begins to thaw.

When that layer contains a lot of water in the form of ice (in Canada, it does so more often) and that ice melts, the soil often can no longer bear the weight above it.

When that happens, it can cause roads to buckle or buckle. It can even cause sinkholes to open in the middle of a road.

And when depressions do occur, there is often a chain reaction: more permafrost is exposed to the air, accelerating the thaw, and the fall becomes an uncontrolled process.

To be fair, the threat, located about 21 miles west of the Whitehorse airport by road, is more of a tortoise than a hare.

It has moved 69 meters in the last five years and is now 37 meters from the road. But it has picked up the pace recently. Over the past summer, fueled in part by a two-week period of weather above 30 C, it has moved a whopping 18 meters.

If you continue at your current average pace, which is not a given, you will cross the road in two to three years. The Yukon Department of Roads and Public Works is already looking for ways to mitigate the problem.

They’re considering everything from diverting the road to finding ways to keep the permafrost cool to digging to replace and stabilize the soil under the road.

The problem, says Idrees Muhammad, the department’s design and construction manager, is that all of those options are expensive, part of the cost of trying to build on permafrost.

Fabrice Calmels, a professor of research in permafrost and geosciences at Yukon University, stands on the side of a permafrost fall in the Yukon in this photo from the May brochure.

The Calmels sensors are the first stage of an early warning system for falling permafrost, which he is developing in collaboration with his mentor, Michel Allard, a professor emeritus at the University of Laval, who has similar sensors installed at three airports in communities. remote areas of Nunavik in the north. Quebec for the same purpose.

“Permafrost touches everything,” says Calmels. “It has always been difficult to build on permafrost.”

Everything that is built on permafrost today incorporates measures designed to minimize the impact of that layer becoming unstable. Houses built on permafrost are built on the ground to allow air to pass under them and keep the permafrost frozen. Roads cost five times more to build and maintain in permafrost than non-permafrost terrain because they must compensate for possible ground movement due to changes in the permafrost layer.

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But most of that technology relies on a relatively stable climate, Calmels says, one in which there is a thermal balance between infrastructure, air temperature and permafrost temperature.

“But if our (global) temperature is increasing, then it becomes much more difficult.”

When the alert system is complete, scientists hope to be able to automatically analyze the data coming from those sensors, predict whether thawed permafrost could cause a fall that could threaten those sites, and automatically send an alarm to those who need to know. about those things.

Those warnings would come on two levels, Calmels says. The first, detecting smaller movements and temperature changes in the permafrost, would warn officials that there is a possibility of a dip occurring in the near future. The second level, a massive movement or loss of a sensor, would indicate that a fall, or sinkhole, had just occurred, giving officials a chance to close the affected roads.

Calmels sensors, some deployed in wells drilled in the permafrost, measure soil temperature at various depths every hour, air temperature, soil moisture and precipitation.

They also include inclinometers, which can be used to produce information about whether the ground is moving, how much and how fast it is moving, and about its movement relative to other layers.

His team also examines the depression from the air, using GPS markers and a drone to track its movement.

All the data goes to a data logger, which then sends the information to a nearby substation called a gateway. In the case of the Alaska Highway crash, that entrance is in the place of a farmer about a kilometer away.

From the gateway, the information is uploaded via the Internet to a central computer at Laval University in Quebec City. There, an algorithm, now in the final stages of development, analyzes the raw data and determines if there is a danger of a disorder occurring in the near future.

There is evidence that this system works. For the past year, Calmels placed sensors directly in front of the Alaska Highway depression and, using the data it collected, was able to predict the next part of the depression six days before it actually happened.

Over time, the entire system will be automated, and if the algorithm determines that an alarm should be triggered, it will automatically be sent through an email distribution list to whoever needs to know.

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The project, funded in part by the federal and territorial governments, is carried out in collaboration with Laval University.

Michel Allard, a professor emeritus at the University of Laval, looks at one of his sensors deployed at Salluit in Nunavik in this photo from the 2016 brochure.

In Quebec, Allard de Laval has placed similar sensors near the airports of three Nunavik communities – Salluit, Tasiujaq and Inukjuak – to monitor whether any changes in the permafrost could cause runways to buckle.

Here, Allard is also concerned that melting permafrost will generate landslides, a process similar to depressions in the Yukon, but occurring on a steeper slope.

When the permafrost layer thaws, the layer of soil on top of it, the active layer, which is frozen and remade perennially, can loosen and begin to slide. Scientists call it an “active layer shedding failure.”

“The idea is: how can we assess the risk of a landslide occurring in the future?” he says. “By what method can we make an alert system that tells, for example, the mayor, civil security organizations that, if the weather continues as it does now, the risk of landslides will begin.”

Those kinds of warnings are vitally important in the far north of Quebec. There are 14 Inuit communities in Nunavik, all of which rely solely on their airports for supply once the seasons change and the ice closes off access to shipments.

Once the Allard and Calmels warning system is up and running, all three airports will receive a short notice of changes in permafrost that could affect airport runways. Allard says he has already been talking to the government about expanding that alert system to the other 11 communities.

And it is no exaggeration to believe that the early warning system they have developed can be adapted to other areas without permafrost.

For example, with sufficient study, the sensor network and automated alert system could be applied to slopes in British Columbia, warning officials there when a mud or rock slide could be imminent and sending a widespread alarm when it is. done. That’s a warning that could have come in handy during last week’s floods and landslides in southern British Columbia that killed at least one person and trapped hundreds of people on its roads.

“This is not that complex, you know,” says Allard. “The key system is the data logger and (local) communication. And those systems are widely available and can be deployed anywhere in the world.

“So if some landslide specialist wants to send a signal, the system can be installed on their instrumentation and put into use.”

Allard expects the automatic alert system to be up and running by next summer.



Reference-www.thestar.com

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