A flood plain is the land area that will flood under conditions of a storm event that has a 1% chance of occurring in any given year. This translates to a 26% chance of flooding within the life of a 30-year mortgage and a 67% chance of flooding within a span of 100 years. You may have also heard it called the "100-year flood plain," which is also sometimes referred to as the Special Flood Hazard Area (SFHA) or base flood. The National Flood Insurance Program's flood plain management regulations must been forced within the SFHAs by a community as a condition of participation in the flood insurance program.