A term used by the Federal Emergency Management Agency (FEMA) in the National
Flood Insurance Program (NFIP) to refer to the land area covered by the
floodwaters of the base or 100-year flood (an area of land that has an
approximate 1 percent probability of a flood occurring on it in any given
year). In these areas, the NFIP's floodplain management regulations must be
enforced, and the mandatory purchase of flood insurance applies. Structures
located in SFHAs have a 26 percent chance of suffering flood damage over the
normal 30-year life of a loan, according to FEMA. Structures that are not
located in SFHAs are viewed as less subject to flooding. SFHAs are identified
in flood insurance rate maps (FIRMs).