The populated areas of Quebec are increasingly prone to landslides due to climate change. As many as 19,000 homes are under surveillance as they are located in government-listed high-risk areas.
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The large landslide that swept away a residential home at the base of a cliff in the La Baie district of Saguenay on June 13 forced the evacuation of 76 homes in the same area. Unfortunately, some owners will never be able to return to their homes because the risks are too high.
To date, 41 municipalities manage sectors located in the heart of areas prone to landslides. According to The protocolno fewer than 19,000 homes and more than 1,000 commercial units are currently in these areas across Quebec, not to mention community infrastructure, institutional buildings and resorts.
These dwellings are mostly built on “sensitive” clay soils, which tend to move when disturbed.
The government ensures that these places are monitored and preventive measures are implemented.
These natural events, which are affecting Quebec’s built heritage and the safety of its population, are expected to increase at an accelerated rate due to the climate crisis, experts say.
“Indeed, the vegetation is changing, just like the soil,” explains Alain Bourque, executive director of Ouranos, a consortium for regional climatology and climate change adaptation.
According to the Canadian Geoscience Education Network, river erosion and increased water pressure in the ground can trigger subsidence “particularly during heavy rainfall or rapid snowmelt.”
“That means a shift that should have happened perhaps in 2085 could happen now. We can imagine that by 2100 there will be many more people who will experience landslides because the ground has become unstable.
This phenomenon is in addition to human activities, “such as excavation and construction work,” which typically act as the primary trigger or exacerbating factor in landslides.
“Everyone wanted a nice view from the top of the embankments,” emphasizes Professor Emeritus Serge Leroueil. “Back then we knew less about the risk. »
Geotechnician Mr. Leroueil thinks it is “plausible” that climate change is increasing the risks. Increased precipitation can cause ground movement, he says, but he adds nuance; these are mostly “superficial”.
For its part, the Ministry of Public Security is ensuring that its analysis and monitoring now includes climate-related risks.
“Advances in research into the effects of climate change on certain types of landslides now make it possible to take these parameters into account,” stresses Marie-Josée Montminy of the Ministère de la Sécurité publique.
NUMBER OF NON-SLIP PROPERTIES IN QUEBEC
19,000 residential units
1000 business areas
- A building can contain multiple units
- The number of dwellings built in restricted areas may change over time
- The risk levels associated with landslides vary within the same stress zone. The probability of being affected by a landslide decreases the farther away you are from an embankment.
Sources: Departments of Municipal Affairs and Housing, Public Safety, Natural Resources and Transport
VERY PRECIOUS TO THE STATE
Over the past decade, Quebec has spent $71 million on financial assistance programs for landslide victims and conducting ground movement prevention efforts. “Under the emergency relief programs, a total of more than $32 million has been paid to individuals, rental property owners and businesses related to ground movement files,” said the spokesman for the Ministry of Public Safety (MSP). , Marie-Josee Montminy. In addition, 13 landslide prevention projects valued at $39 million have been completed or will be completed by 2025.
HUNDREDS OF INCIDENTS
For the past five years, an average of 182 landslides have been registered each year, particularly in densely populated regions. Reports are identified by the ministry as “possible threats to life or property.” Movements mostly take place outside of the areas shown on the government map. In the past 10 years, a total of 369 individual cases have been opened under the homeowner’s financial assistance programs. On average, $87,000 was paid per file. Public infrastructure such as roads are also victims of these settlements.
The Ministry of Public Security ensures that a risk analysis for the built environment is carried out by its experts to “ensure safe rural development”. The government determines the vulnerable zones, which are then disseminated through mapping in the urban environment. “This makes it possible to identify situations of concern where mitigation measures are deemed necessary. Depending on the situation, financial support can be offered to the community and affected citizens to rectify the situation,” explains MSP spokeswoman Marie-Josée Montminy. Municipalities are obliged to integrate it into their development plan. Quebec may request changes for public safety reasons.
NO DEPRECIATION… FOR THE FIRST TIME
In 2018, Quebec City’s Altus Group conducted a study of the market value of land in La Baie located within landslide stress zones. Conclusion: There was no significant impact on the selling price. The panoramic view and the quality of the materials are the winning elements. In several cases, however, the location certificate did not clearly state the inclusion of housing in the zone, as did the property advertisements, which emphasized the view. “If market participants … ignore the possibility of slippage occurring, the impact on prices may be skewed,” the report states.
According to the list of buildings located in landslide-prone restricted areas, the main high-density buildings are senior residences and housing cooperatives. For example, the Chartwell Domaine Cascade residence in Shawinigan has 265 units and is in a red zone, according to the Department of Energy. In Alma, the CHSLD Isidore-Gauthier can also be found in one of the risk areas. Resorts, such as the Chalets sur le Fjord in L’Anse-Saint-Jean, are also located in these areas, as well as institutional buildings such as schools and day care centers.