Three 100-year floods in five years? How can that happen? What is a 500-year flood?
“100-year” and “500-year” is really misleading and not the best way to communicate the risk.
It doesn’t mean it’ll happen “once in 100 years” or once in 500 years”.
For a 100-year flood it means there’s a 1% chance it could happen EVERY year.
For a 500-year flood it means there’s a 0.2% chance it could happen EVERY year.
While the statistics aren’t high… they’re based on a recurrence interval. The current flood is a 500-year flood event. The Corps of Engineers has a flood map which shows potential inundation areas for 1% and 0.2% areas. This map is slightly different from the FEMA Flood Risk Map and communicates more of the percentage chance of experience inundation and different levels.
-Garrett
