Extreme rainfall and flooding in Alberta could result in one of the most costly natural disasters in Canadian history — and it may not be an isolated event.
Flooding in southern Alberta that occurred in 2005 was then considered a one-in-100-years disaster, yet the heavy rains this week that have led to flooding in Banff, Canmore, Calgary and south toward Lethbridge have caused more widespread damage than the previous event.
According to Jason Thistlethwaite, director of the Climate Change Adaptation Project at the University of Waterloo, the flood signals a trend toward more extreme weather events.
“You’ve had two floods that arguably fall into that one-in-100-year, one-in-200-year probability occur within eight years,” Thistlethwaite said. “That speaks to a trend climate change scientists have been predicting for a long time now.”
Natural disasters, particularly that impact highly populated areas, don’t occur frequently in Canada — a fortunate fact about the country, Thistlethwaite said.
But rising global temperatures are resulting in more water evaporating and being held in the atmosphere, fuelling heavy downpours.
“A warmer climate doesn’t necessarily mean you’ll see more rainfall. What we think is likely happening is that warmer climate creates conditions for more frequent and intense rain events,” he explained.
More rain over time isn’t problematic; however, in small burst it can be devastating.
“Rain that falls at a very intense rate over a short period of time in a small area is incredibly dangerous,” Thistlethwaite said.
These events are incredibly difficult to predict — with no more than a few days warning — and the infrastructure that exists in most urban areas aren’t designed to withstand floodlike conditions.
“The problem is we’ve allowed for developments in these 100-year floodplains,” Thistlethwaite said, adding that existing safeguards such as reservoirs aren’t always enough to withstand extreme events.
“In hindsight there’s a pattern that we’re starting to see that as these flooding events become more frequent we have to really improve our flood defences,” he said.
He said better planning needs to be done in developing around these areas. More research is also needed to understand how climate change may affect the 100-year floodplain areas around water sources — whether the areas are getting larger — as floods occur more often.
The best protection for individuals and families is to ensure that everyone has a 72-hour emergency preparedness plan outlining what they do when an extreme weather event occurs, how to contact other friends and family and ensure they have supplies readily available.
“Don’t take the environments around you for granted, don’t assume it’s going to remain static,” Thistlethwaite said.
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