The St. François River cuts through Drummondville, creating steep valley slopes made of marine clay and till. These deposits are prone to erosion and sudden saturation during spring thaws. Heavy rainfall events, common in the region, can trigger fast-moving debris flows that threaten infrastructure near the river corridor. We combine field reconnaissance with numerical modeling to map initiation zones and runout paths. Before modeling, we often run a groundwater infiltration test to understand how quickly water enters the slope. That data feeds directly into the stability analysis.
In Drummondville's clay slopes, debris flow often follows a 50 mm rainfall event within 24 hours. Timing is everything.