Mapping shows how climate change can flood low-lying areas in BC

The researcher overlaid data on web-based maps to show how much lower-lying areas may be covered by water under different climate change models

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Low-lying areas in major cities like Vancouver and Montreal could be flooded with flooding for the next 80 years under different climate change scenarios, suggests a map of floods developed by a researcher from Western University.


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The maps, created by engineering professor Slobodan Simonovic, are a visual distillation of nearly 150,000 reference documents – including current and historical data on precipitation and snowmelt, topographic analyzes, urbanization factors that prevent effective drainage and a range of climate projections.

Simonovic superimposed the data on web-based maps to show potential future floods – how much of an area is covered by water – as well as how often and how significant floods could be.

The maps, which show flood impacts in a standardized way across Canada, identify areas where rivers are most likely to overflow, including the Assiniboine and Red Rivers, which converge on Winnipeg and the Fraser Valley, which run through Vancouver.


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Simonovic said other vulnerable streams are found in parts of northern Ontario, Quebec and British Columbia, the Mackenzie River in the Northwest Territories and much of the island of Montreal.

One of his goals was to show the public the impact of floods due to climate change.

“It basically means more land will be flooded, more land will be underwater during these extreme events,” he said, adding that 30 percent more of Canada could be flooded by 2100, with an increase in flood depth of up to 60 percent.

“Of course, it is not everywhere in the country. There are some areas that are higher risk than others, but an overall increase up to that level is a very important message.”

Users of the maps can search by zip code and reset neighborhoods or compare current 100-year flood zones with those predicted during worst, middle or best cases of climate change in 60 and 80 years from now.


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Simonovic, an award-winning flood expert, said understanding the location and extent of flood risk can help insurers, engineers, homebuilders, conservationists and governments at all levels plan better policies and stronger flood protection.

He said the next steps for his project are to expand the mapping to include coastal floods and fine-tune projections to even smaller grids with larger neighborhood details.

His mapping work was funded through a collaboration grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) and Chaucer Syndicate, a group representing insurance companies across Canada.

“The message is definitely that we need to rethink, better prepare and reassess the risk in key locations,” Simonovic said, adding that about four million Canadians now live in flood-prone areas.

“Our work is a step towards a better understanding that these consequences of climate change are significant in Canada.”



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