‘500-Year Flood’ Could Happen Again Sooner Than You Think. Here’s Why.
"In the aftermath of Hurricane Harvey, President Trump tweeted that the storm had brought a “once in 500 year flood” to Houston, and expressed support for relief efforts. His words suggested the kind of catastrophic event that hadn’t been seen in the area for five centuries. But parts of Houston saw “500-year flooding” just last year. And in 2001, Tropical Storm Allison also delivered severe flooding to the area."