Hydrologists and Floodplain Managers don't like to hear a term like "100-year flood" because, scientifically, it is a misinterpretation of terminology that leads to a misconception of what a 100-year flood really is.
Instead of the term "100-year flood" we would rather describe this hydrologic event as a flood having a 100-year recurrence interval. In other words, a flood of that magnitude has a 1 percent chance of happening in any year.
|
Recurrence intervals and probabilities of occurrence |
Recurrence interval,
in years |
Probability of occurrence in
any given year |
Percent chance of occurrence in
any given year |
100 |
1 in 100 |
1 |
50 |
1 in 50 |
2 |
25 |
1 in 25 |
4 |
10 |
1 in 10 |
10 |
5 |
1 in 5 |
20 |
2 |
1 in 2 |
50 |
|