Base Flood Law and Legal Definition
According to 44 CFR 9.4 [Title 44 -- Emergency Management and Assistance; Chapter I -- Federal Emergency Management Agency, Department of Homeland Security], base flood means “the flood which has a one percent chance of being equalled or exceeded in any given year (also known as a 100-year flood). This term is used in the National Flood Insurance Program (NFIP) to indicate the minimum level of flooding to be used by a community in its floodplain management regulations.”