Description: What is a Flood Insurance Rate Map (FIRM)?A Flood Insurance Rate Map (FIRM) is an official map of a community on whichFEMA has delineated both the special hazard areas and the risk premium zonesapplicable to the community.What flood hazard zones are shown on the FIRM andwhat do they mean?Several areas of flood hazard are commonly identified on the DFIRM andFIRM. One of these areas is the SFHA, which is defined as the area that wouldbe inundated by the flood event having a 1 percent chance of being equaled orexceeded in any given year. The 1-percent-annual-chance flood is also referredto as the “base flood.” SFHAs are labeled as Zone A, Zone AO, Zone AH, ZonesA1–A30, Zone AE, Zone 99, Zone AR, Zone AR/AE, Zone AR/AH, Zone AR/AO,Zone AR/A1–A30, Zone AR/A, Zone V, Zone VE, and Zones V1–V30. Moderateflood hazard areas, labeled Zone B, are also shown on the FIRM or DFIRM and arethe areas between the limits of the base flood and the 0.2-percent-annual-chanceflood. The areas of minimal flood hazard, which are the areas outside the SFHAand higher than the elevation of the 0.2-percent-annual-chance flood, are labeledZone C. On new and revised maps, Zone X is used in place of Zones B and C. Anunshaded Zone X holds the same meaning as the labeled Zone B. A shaded ZoneX can mean any of the following: the area is in the 0.2 floodplain; is protectedby a levee; is subject to inundation by a flood event having a 1 percent chance ofreaching less than a 1.0-foot depth; is subject to inundation by a 1-percent-annualchanceflood within an area of less than 1 square mile; or is subject to inundationby a 1-percent-annual-chance flood determined using future conditions. Thedefinitions for the various flood hazard areas are below.Zone V: Primary frontal dunes and areas along coasts subject to inundation bythe 1-percent-annual-chance flood event with additional hazards associated withstorm-induced waves. Because detailed coastal analyses have not been performed,no BFEs or flood depths are shown. Mandatory flood insurance purchaserequirements apply.Zones VE and V1–V30: Primary frontal dunes and areas along coasts subject toinundation by the 1-percent-annual-chance flood event with additional hazardsdue to storm-induced velocity wave action. BFEs derived from detailed hydrauliccoastal analyses are shown within these zones. Mandatory flood insurancepurchase requirements apply. Zone VE is used on new and revised maps in place ofZones V1–V30.Zone A: Areas subject to inundation by the 1-percent-annual-chance flood event.Because detailed hydraulic analyses have not been performed, no BFEs or flooddepths are shown. Mandatory flood insurance purchase requirements apply.Zones AE and A1–A30: Areas subject to inundation by the 1-percent-annual-chanceflood event determined by detailed methods. BFEs are shown within these zones.Mandatory flood insurance purchase requirements apply. (Zone AE is used on newand revised maps in place of Zones A1–A30.)Zone AH: Areas subject to inundation by 1-percent-annual-chance shallow flooding(usually areas of ponding) where average depths are 1–3 feet. BFEs derived fromdetailed hydraulic analyses are shown in this zone. Mandatory flood insurancepurchase requirements apply.Zone AO: Areas subject to inundation by 1-percent-annual-chance shallow flooding(usually sheet flow on sloping terrain) where average depths are 1–3 feet. Averageflood depths derived from detailed hydraulic analyses are shown within this zone.Mandatory flood insurance purchase requirements apply.Zone A99: Areas subject to inundation by the 1-percent-annual-chance flood event,but which will ultimately be protected upon completion of an under-constructionFederal flood protection system. These are areas of special flood hazard whereenough progress has been made on the construction of a protection system, suchas dikes, dams, and levees, to consider it complete for insurance rating purposes.Zone A99 may be used only when the flood protection system has reachedspecified statutory progress toward completion. No BFEs or flood depths areshown. Mandatory flood insurance purchase requirements apply.Zone AR: Areas that result from the decertification of a previously accreditedflood protection system that is determined to be in the process of beingrestored to provide base flood protection. Mandatory flood insurance purchaserequirements apply.Zones AR/AE, AR/AH, AR/AO, AR/A1–A30, and AR/A: Dual flood zones that,because of the risk of flooding from other water sources that the flood protectionsystem does not contain, will continue to be subject to flooding after the floodprotection system is adequately restored. Mandatory flood insurance purchaserequirements apply.Zones B, C, and X: Areas identified in a community’s FIS as areas of moderate orminimal hazard from the principal source of flood in the area. However, buildingsin these zones could be flooded by severe, concentrated rainfall coupled withinadequate local drainage systems. Local stormwater drainage systems are notnormally considered in a community’s FIS. The failure of a local drainage systemcreates areas of high flood risk within these rate zones. Flood insurance is availablein participating communities but is not required by regulation in these zones.Zone X is used on new and revised maps in place of Zones B and C.Zone D: Unstudied areas where flood hazards are undetermined, but floodingis possible. No mandatory flood insurance purchase requirements apply, butcoverage is available in participating communities.
Copyright Text: Federal Emergency Management Agency (FEMA)