A new UBC-led study shows that safeguarding key natural ecosystems across Canada can help reduce flood risks for more than half of the country’s urban areas at high risk for flooding.
The research reveals that preserving the most important five per cent of watersheds—about 201,000 square kilometres or two per cent of Canada’s land—can significantly reduce rainwater runoff, protect homes and livelihoods, and safeguard croplands.
“This is the first national study to assess the role of Canadian ecosystems in flood prevention and to identify where conservation could have the greatest impact,” said Dr. Matthew Mitchell, an assistant professor in the faculty of forestry and the faculty of land and food systems.
Nature: the flood shield
Upstream watersheds near cities such as Vancouver and Toronto play an important role in protecting 3.7 million people living in floodplains and another 20.1 million nearby—more than half of Canada’s population.
Using global data, Dr. Mitchell and his colleagues analyzed how land types like forests, wetlands and riparian zones absorb water and reduce runoff.
These natural systems prevent downstream flooding, improve water quality and support wildlife, while reducing reliance on costly infrastructure like dams.
“Nature-based solutions are highly effective for managing flood risks, and this study shows exactly where conservation can make the biggest impact,” said Dr. Mitchell.
Conservation priorities across Canada
The study identified key ecosystems in B.C. that are critical for flood prevention:
Beyond B.C., the researchers recommend the following conservation priorities:
Canada has committed to protect 30 per cent of its lands by 2030, yet only eight per cent of the most flood-critical ecosystems are currently protected. The researchers call for stronger conservation policies and funding to prioritize these high-impact areas.
“This research makes it clear that conserving nature isn’t just about biodiversity—it’s also about protecting communities and making cities more resilient to climate change,” said Dr. Mitchell.
The study, published recently in Ecosystem Services , offers a global roadmap for integrating nature-based solutions into urban planning and flood management.
Ecosystem Services
Data/statistical analysis
Not applicable
Flood prevention benefits provided by Canadian natural ecosystems
1-Dec-2024