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Rogue Earth: Alberta Floods

4 Factors that Led to the 2013 Flood of Floods in Southern Alberta
By Nicole O’Brien

Alberta made headlines back in 2013 after rising floodwaters wreaked havoc on the city of Calgary and several communities in the southern region of the province.   The devastating flood cut off dozens of communities and prompted the largest evacuation in Canada in more than 60 years. Approximately 10,000 Albertans were told to leave their homes.

Up until the 2016 Fort McMurray wildfire, this was considered to be the costliest natural disaster Canada had ever seen, with an estimated cost of $5 billion in property damage.
So what led to the flooding?  A combination of factors created “perfect” conditions for the massive flooding, including weather, geography, and infrastructure. Here is what led to one of the biggest disasters in Alberta’s history:
  1. Heavy Rainfall
According to Environment Canada, 68 mm of rain fell in Calgary within 48 hours, but it was the rainfall across the eastern slopes of the Rockies that set off the intense flooding that followed. Some areas were pummelled by 200 millimeters of rain- more rainfall in a few hours than those areas’ average in months.
  1. Delayed Snow Melt
Back in 2012, snow hit Southern Alberta beginning early October and didn’t stop until mid-April. The mountain snowpack in May 2012 was immense, over one meter in some places. Several days of thunderstorms drenched the snow-packed ground, preventing the vast amounts of water from being absorbed.  Once the rainfall and melting snow hit the rivers, levels rose rapidly. The Bow River spiked to 10 times its normal flow rate.
  1. Geography and Infrastructure
Most major cities are historically located along watersheds, which were once trade routes. But these older locations, like New York, New Jersey, and Alberta, are now at risk. Dr. Brent Ward, a geology professor at Simon Fraser University, said the infrastructure in Albertan cities is inadequate to handle increased construction in the floodplain. “We can try to protect these structures with a series of levees or some sort of floodways, but eventually these things will fail.”
  1. Climate Change
Alberta hydrologist John Pomeroy told CTV News that in the past 100 years there has been “immeasurable change” in the type of rainfall that reaches the Prairies, with larger volumes of rain and less snow.  “The rain themselves could not have been prevented, though I suspect they’re a manifestation of our changing climate,” he said.

The flooding in 2013 was considered to be a ‘1 in 100 year’ event. These 100-year floods have roughly a 1 percent chance of occurring in any given year, demonstrating just how rare this event was. The last time anything like this happened was in 1995.  

Marking the fifth anniversary of this catastrophic super flood, Discovery’s newest original Canadian documentary Alberta Floods: Rogue Earth re-examines the events of June 2013 and the resilience of Albertans who recovered from one of the province’s worst natural disasters. Watch it now on!
Sources: CTV News | Environment Canada | The Weather Network | Alberta Ministry of Environment and Parks
Photo One: Aftermath of the 2013 flood along Cougar Creek in Canmore QMI Agency| Calgary Herald
Photo Two: Todd Korol | Reuters