An impressive landslide in Centre-du-Québec is a reminder of the importance of being careful near the banks, especially when it has been raining heavily, as in the past few days.
“There are often small landslides, but a slab of this size is a first,” says Frédérick Marcotte.
The firefighter was dispatched Thursday to Rang de la Chaussée, in Saint-Léonard-d’Aston, to find that agricultural land and part of a maple grove had fallen into the Nicolet River.
Fortunately, no one was injured in the event. Two buildings are still at risk of collapse, according to Mr. Marcotte.
Experts from Quebec Public Security will soon be on site to assess the extent of the damage.
At the place where the subsidence took place, “the Nicolet River is very incised, very hollow. There are very steep embankment slopes,” explains geomorphologist Pascale Biron.
An embankment is a very sloping land, developed by earthworks, construction of a road, for example.
High risk
The municipality of Saint-Léonard-d’Aston is part of the Saint-Laurent lowlands, an area where several landslides occur annually, some of them fatal.
“There is a fairly high risk because there is clay soil. This Ice Age legacy has left fine deposits. Everything in this sector is therefore very vulnerable,” says the professor at Concordia University.
This type of incident generally occurs in the spring, when the snow melts. The soils, already waterlogged, are then more sensitive to heavy rains such as those experienced last week.
It’s hard to say whether climate change will exacerbate the problem of landslides, which are already a major issue in the province, according to Ms.me Biron.
On the other hand, if the heavy rains in the spring become more and more frequent, Quebec might experience more.
Solutions
In order to limit the number of subsidences, it would therefore be important to keep the landslide risk maps up to date and to prohibit the addition of weight at the top of the slopes, warns Mme Biron.
“But it’s almost impossible to say that we will avoid all landslides in Quebec. It’s part of the natural phenomena. We have to live with that, ”she concludes.
In 2017, Quebec had experienced a record number of 351 ground movement files listed by the Ministry of Transport.
