Moving Beyond the 100-Year Flood: Redefining Flood Policies for Human Time Scales

In 1968, Congress passed the National Flood Insurance Act as part of a comprehensive program of floodplain management. Flood damages had been rising rapidly in the U.S.; thus the National Flood Insurance Program (NFIP) was created to "reduce future flood damage" for individuals and communities, in return for communities taking the lead in imposing nonstructural flood control (www.fema.gov/nfip/intnfip.htm). In this manner, the federal government would "shar[e] the risk of flood losses" with Americans living in flood-prone areas (U.S. Code, Title 42, Section 4001). Of course, flood risk needs to be quantified and flood plains delineated ìn order to assess insurance premiums. The Federal Insurance Administration (FIA), part of the Federal Emergency Management Agency (FEMA), which administers the NFIP, produces maps of participating NFIP communities that show which areas in the communities face flood risk. The Special Flood Hazard Area (SFHA) maps show "the area of land that would be inundated by a flood having a one-percent chance of occurring in any given year" (www.fema.gov/nfip/intnfip.htm). The flood with a one-percent chance of occurrence in any given year is also popularly known as the "100-year flood." This standard was adopted in the early 1970s in order to standardize areas of risk between communities. Within the 100-year flood plain, development may take place, but must comply with local flood plain ordinances, which, in turn, must comply with federal requirements. The SFHA standard "constitutes a reasonable compromise between the need for building restrictions to minimize potential loss of life and property and the economic benefits to be derived from floodplain development".