However, a low risk of flooding does not mean there is no risk of flooding. Areas with a low to moderate hazard are shown as Zone X. BFEs may differ dramatically within a small area, because waves can diminish in size over a short distance upon encountering obstructions or steep ground. Changes in flood zones and BFEs can have a significant impact on building requirements and flood insurance costs. On flood maps in coastal communities, Zone AO usually marks areas at risk of flooding from wave overtopping, where waves are expected to wash over the crest of a dune or bluff and flow down into the area beyond.īase Flood Elevations (BFEs) in these flood zones vary along the coast and with distance inland. Zone AO is used to map areas at risk of shallow flooding during a base (1%-annual-chance) flood, where water with average depths of 1 to 3 feet flows over sloping ground. Zones with a letter grade of A or V are considered high-risk areas with a one in four chance of flooding during a 30-year mortgage period. Zone AE indicates areas that have at least a 1%-annual-chance of being flooded, but where wave heights are less than 3 feet. FEMA gives each zone a letter grade based on the type and likelihood of flooding. These practices are intended to improve the chance of a home safely weathering a flood event. What constitutes a high risk flood area High risk flood areas are known as SFHAs (Special Flood Hazard Areas). To address the added wave hazard, more stringent building practices are required in Zone VE, such as elevating a home on pilings so that waves can pass beneath it, or a prohibition to building on fill, which can be easily washed away by waves.

Fema high risk flood zone