It happened in July 2016. A flash flood roared through Ellicott City, Maryland, killed two people and caused tens of millions of dollars in damages to the historic buildings along Main Street. The experts said it was one of those rare 1,000-year flood events. The city set about the job of rebuilding. It takes a long time – often years – for a community to recover from a devastating flood.
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| Ellicott City in the 2016 flood. |
Then last May, while Ellicott City was still getting over the 2016 disaster, it happened again, another one of those “extremely rare" 1,000-year floods.
For something that has only a 0.1% chance of happening in any given year, there are a lot of those floods going around lately. There have been nine 1,000-year events since 2010 in the United States. Three of them took place in the first seven months of 2016. In the likely event we'll have more of them, it will be important to make a distinction between 1,000-year floods and 1,000-year rains. A record rain does not necessarily result in a record flood. It depends on things like how fast and relentlessly the rain falls, how much moisture plants and soils can absorb, and how much impermeable surfaces a city has. It was concrete, asphalt and rooftops that made the damage in Houston so severe during Hurricane Harvey last fall.
Read the post from blogger Bill Becker - “Snakes, Rats & Floating Corpses.”
