The Federal Emergency Management Agency's National Flood Insurance Program (NFIP) delineates areas subject to a one-percent annual chance (or 100-year) for flooding. These areas are delineated as "Special Flood Hazard Areas" (SFHAs). FEMA categorizes riverine and some coastal SFHAs as A or AE Zones." In riverine areas A Zones are determined using hydrologic and hydraulic numerical models. In coastal areas, A Zones are determined using coastal storm surge models, or tide gage analyses based on long-term tide gage records. Another type of SFHA, found exclusively in coastal areas, is called the V or VE Zone. V Zones are determined using the same coastal storm surge analyses to define Coastal A Zones, with the exception that the landward boundary of the V Zone is generally determined by the inland limit of significant wave action, high velocity waters, or the inland toe of the primary frontal dune. NFIP floodplain management regulations are enforced in SFHAs, and mandatory purchase of flood insurance is required for federally-backed mortgages for buildings located in SFHAs