New study projects 300% increase in landslides in Vancouver’s North Shore Mountains

Click to play video: 'Study warns for more, larger landslides' Study warns for more, larger landslides
A new report based on historical data from Metro Vancouver and new modelling suggests mountainous regions could be in for more and larger landslides as climate change and more rainfall affect the landscape over the next century – Oct 29, 2021

Shallow landslides in Vancouver’s North Shore Mountains are projected to increase in frequency by 300 per cent until the end of this century, a new study has found.

The Vancouver-based BGC Engineering’s estimate comes from new climate modelling and analysis of Metro Vancouver’s historical landslide database.

It’s nearly four times more than what the consulting firm had previously projected — similar research in 2009 led to an estimated increase of 10 per cent from the number of landslides in the past 30 years.

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“When we did the study in 2009, we had inferior models to the ones we have now,” explained BGC principal engineering geoscientist Matthias Jakob.

“As well, we looked at changes in the average landslide magnitude and found that also could go up by as much as 50 per cent.”

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The findings are important, he added, because landslides can impact not only urban infrastructure, but rural infrastructure like pipelines, railways and roads as well. They can also damage critical watersheds and sensitive ecosystems.

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The new study examined the possible frequency, magnitude and intensity of future landslides and debris flow in the North Shore Mountains, and how climate change may impact them.

While some effects of climate change, such as changes in temperature or precipitation, are simpler to measure, it’s much more complicated to tie a link between climate change and landslides, said Jakob.

“It is very important to understand these third, or higher-order effects of climate change on the Earth’s surface processes,” he told Global News. “Understanding what will happen in the future is very important because the past may no longer be a key to the future.”

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Read more: Massive landslide on B.C.’s central coast created its own seismic event: geologist

The study was unable to definitively link the likelihood of increased landslides to climate change.

Metro Vancouver’s database showed a doubling in landslide frequency since 1981, it said, but before that, recording was “sporadic,” so it’s possible the increase may be linked to better record-keeping.

Nevertheless, Metro Vancouver is preparing for the possibility of increased precipitation and landslides according to the division manager for environment and water services.

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“On the water-supply side, the potential for increased landslides over time is certainly being considered in long-term planning associated with the water infrastructure,” said Jesse Montgomery.

“Vancouver as a region is very fortunate in having a large area of reasonably undisturbed wilderness as their water supply.”

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Jakob said it’s up to all levels of government to adequately fund risk mitigation, such as updated community plans, added warning systems and new infrastructure to protect existing developments.

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