Base Flood
Plain-English definition and practical context.
Definition: Base Flood | (None commonly used)
pronunciation: base flud
A Base Flood is the flood level that has a one percent annual chance of occurring in any given year.
You may also see this described as the “1-percent-annual-chance flood” or the “100-year flood.” It does not mean a flood happens only once every 100 years. It means there is a 1% chance of that flood level happening in any single year.
This term matters because it is used to map flood risk and set standards used in floodplain management and insurance rating.
Sources & Authority
Sources for Base Flood
Defines “Base flood” as “the flood having a one percent chance of being equalled or exceeded in any given year.”