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Old 07-14-2013, 05:20 PM   #4018
octothorp
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Originally Posted by Burninator View Post
This is the map to The City of Calgary's Floodway / Flood Fringe. It looks like these maps are before this flood. I'm pretty these maps are based on the 100 year flood and they look pretty close to the maps the AB government just put out. I am also pretty sure that a 100 year flood is not a flood that occurs once every 100 years, but rather the worst flood in the last 100 years. So that flood could have occurred in 1913 or 2013, or even multiple times in between. I too haven't heard if this was a 100 year flood or not.
My understanding is actually quite different: that when the phrase '100 year flood' is used, it means a flood that has a 1% chance of happening in a given year. A '50 year flood' would have a 2% chance, a '500 year flood' would have a 0.2% chance of happening in a given year. I'm not sure of that, but most technical articles I've read since the flood occurred have seemed to use this distinction. So basically, it's a model for probability, not a model of history.
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