SPECIAL FLOOD HAZARD AREAS (SFHA) - The 1% annual chance flood (100-year flood), also known as the base flood, is the flood that has a 1% chance of being equaled or exceeded in any given year. The SFHA is the area subject to flooding by the 1% annual chance flood. Areas of SFHA in Graham County include Zones A, AE, AO. The Base Flood Elevation (BFE) is the water-surface elevation of the 1% annual flood.
FEMA Special Flood Hazard Areas (SFHA)
Areas determined to be outside the 0.2% annual chance of flood
Zone X (500 Year)
Areas of 0.2% annual chance of flood
No Base Flood Elevation determined
Base Flood Elevation determined
Zone AE Floodway
The flood-way is the channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights.
Zone AO Depth 1'
Flood depths of 1 foot (usually sheet flow on sloping terrain)
Zone AO Depth 2'
Flood depths of 2 feet (usually sheet flow on sloping terrain)