As the climate crisis looms, an expert’s flood-mapping tool is helping inform Canada’s policy-makers and improve resilience
By Debora Van Brenk BA’86, MA’87
Environmental engineering professor Slobodan Simonovic had hoped his unique Canadian flood-mapping project would draw interest beyond the academic world.
But he had not predicted its impact would unfold in real time when, only days after its release, parts of British Columbia experienced their worst flooding on record.
The interactive site at floodmapviewer.com is the first Canada-wide database that shows how floodplains may become inundated in the next 80 years under various climate change scenarios.
About four million Canadians live in flood-sensitive areas – and they and others will be at increased risk decades from now, the mapping data shows.
“Here in Canada, until now, we haven’t had a nation-wide, standardized way of understanding the vulnerabilities of our own landscapes,” Simonovic noted when the site launched in early November 2021.
His words would quickly prove prophetic as successive days of record rainfall hit the Pacific Northwest, causing damage estimated to be as much as $7.5 billion.
Scores of media outlets drew on Simonovic for expert commentary.
And in the next few weeks, the floodmap’s homepage saw 11 million visits from users in a dozen countries, with 25,000 people taking a deeper dive into the maps.
Simonovic doesn’t view that as a personal victory, but as a clarion call for more good science to make its way into public discourse.
“The extent of interest is just one more indicator that Canada is already experiencing the impacts of changing climate,” said Simonovic, who is also director of engineering studies for the Institute for Catastrophic Loss Reduction.
Simonovic is recognized as one of the world’s most influential climate change scientists, based in part on his high volume of published research, citations by other researchers and policy influence.
has received awards for excellence in teaching, research and outreach, and has published more than 600 professional papers and three textbooks. In 2020, he was named a Fellow of the Royal Society of Canada, and was inducted into the Canadian Academy of Engineering in 2013.
Mapping out data
Nothing like the map tool existed before Simonovic made it his personal commitment to build one to help decision-makers mitigate and adapt to the impact of climate change.
The database and website are a visual distillation of vast amounts of data – including current and historical rainfall and snow-melt run-off data, topographic analyses, hydrodynamic modelling, urbanization and deforestation factors that impede effective drainage, plus a range of climate projections.
Using this data, Simonovic has superimposed on web-based maps current and future flood frequency, flood depths, flood inundation and flow velocity.
Users can search by postal code and zero in on neighbourhoods, or explore specific watersheds to compare current 100-year flood zones to those predicted under worst-, moderate- or best-case climate-change scenarios, decades from now.
“What we used to call 100-year floods in London, Ontario, for example, are taking place now once every 30 years,” he said. “Floods are killing people around the world, and in countries you wouldn’t expect, such as Germany, the U.S. and Japan. A year’s worth of rainfall fell in October 2021, in just three days, in central China.”
In short, what were once unusual events – heavy deluges and unseasonal thaws that over-whelm streets, homes, sewers and dams – will occur more regularly, and several times in a generation.
The maps identify the most vulnerable areas in one-square-kilometre segments, highlighting where rivers are more likely to overflow and by how much.
Even areas that have carefully planned for flooding are vulnerable. Winnipeg, located at the confluence of the Assiniboine and Red rivers, benefits from one of the best floodwater-diversion systems in Canada. Yet, the data forecasts water levels could rise to 4.4 metres above regular flow – 2.5 metres higher than historical peak maximums – unless climate change is slowed or reversed. Such an event would place a severe strain on Winnipeg’s flood-management infrastructure and inundate surrounding areas.
The list of other worrisome areas is long: Vancouver and the Fraser Valley; streams in Northern Ontario and Quebec; much of the island of Montreal; and the Mackenzie and Lower Mackenzie Rivers of Northwest Territories and northern British Columbia.
Simonovic noted the consequences of extreme floods go beyond an increased risk of soaked basements and insurance claims, although they too represent significant cost and impact.
Such flooding directly jeopardizes human lives and kills livestock, he said.
It can crumble bridges, wash away roads and railroads, overwhelm drinking-water and wastewater treatment facilities, destroy sensitive habitat and disrupt ecosystems for generations to come.
Understanding the location and extent of the risk can help insurers, engineers, homebuilders, conservation authorities, and municipal, provincial and federal governments plan better policies and improve Canada’s resilience to flooding, he said.
It’s one reason the Canadian government has committed $63 million over the next three years, through Natural Resources Canada (NRCan) and Environment and Climate Change Canada, to create more detailed flood maps for high-risk areas.
Simonovic is part of that effort. Since the database went live, he has been working with NRCan to transfer his methodology to that department.
He has also been asked by insurance companies to help them use local data and knowledge to develop similar tools for their needs and public use.
What comes next
An August 2021 report from the United Nations International Panel on Climate Change, for the first time, emphasized a much stronger connection between climate change and extreme weather than ever before, Simonovic noted.
His mapping work was funded through a collaborative grant from the Natural Sciences and Engineering Research Council of Canada and Chaucer Syndicate, a group representing insurers of insurance companies across Canada.
Simonovic said the next steps in this project are to expand the mapping to include coastal flooding and fine-tune projections to even smaller grids with greater neighbourhood detail so municipal planning can grow even more precise.