Monday afternoon from 1er May 2023 will remain anchored in the memories of many Charlevoisiennes and Charlevoisiens. The watersheds of the tributaries of the Gouffre River would have poured phenomenal amounts of water to swell its flow to such an extent that it reached 429 m3/s.
Everyone saw catastrophic scenes: the trailers crashed under the bridge over the Rivière des Mares, the low wall that split near Ménard Street causing unprecedented flooding in the area. Unprecedented ? Catastrophic? Phenomenal? But that’s not what science tells us.
Data taken from the Center d’expertise hydrique du Québec, which monitored the Rivière du Gouffre:
– April 1968: 544m3/s
– April 1973: 513m3/s
– July 1976: 578m3/s
– May 2023: 429m3/s
We knew so well that the risk existed that a low wall was erected in the town centre, that the houses in the area for the most part have a ground floor 1.3 m from the ground and that (to the great displeasure of the victims ) insurers do not cover flooding since it is a known flood zone. Even the small slope in an easterly direction on Leclerc, des Cèdres and St-Joseph streets indicates the alluvial terrace of the river’s “centenary” flood.
Our political institutions must, at all levels, review their regulations. The area of freedom of watercourses must be considered within legal frameworks. Buildings near watercourses must be substantial or prohibited.
The two deaths are the consequence of political inaction in this direction. The residence where the tragedy occurred is in a flood zone, literally less than 100 m from the inner bank of a bend in the Rivière du Gouffre, the first zone flooded by a stream, just like the Ménard sector. Leclerc–St-Joseph, as well as the Eustache pit sector where a meander cut is in progress.
I don’t blame anyone. No actor in the community allowed these constructions with a Machiavellian design, most of the victims were not even aware of the risk. But now is the time to change our behaviors and make the right decisions, backed by science. Talk to any geomorphologist, nothing about what happened on the 1er last May is not of the order of the “phenomenal”, on the contrary. We just tend or feel like forgetting quickly.
Climate change will increase the frequency and intensity of precipitation events. We will continue to have heavy snow cover in the summits, and the watersheds of the Rivière du Gouffre will continue to respond quickly to these rains, especially in the spring when the ground is already waterlogged.
Hoping that Christopher and Régis did not leave us for nothing.