In Savannah there are six zones: A, AE, AH, VE, X, and X_500.
Most of the City is in the X and X_500. The X zone, “Low Risk”, is considered above the 100 and 500 year floodplains. The lightly shaded X or X_500, “Moderate Risk”, is above or protected from the 100 year floodplain, but may have up to a foot of water in a 500 year storm event.
The A, AH and AE Zones are the flood zones which are common in Savannah. These areas are in the “High Risk” area and are prone to flood with rising water in both the 100 year and the 500 year storms. Structures have a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage. An unnumbered “A” zone means that no Base Flood Elevation (BFE) above Sea Level has yet been determined. “AE” means a base flood elevation has been determined. For example, “AE-15" means that the lowest finished floor elevation of the structure must be at or above 15 NAVD 1988 because that is where the predicted flood water will rise. Zone AH indicated shallow flooding, usually in the form of a pond, with an average depth ranging from 1 to 3 feet. All new construction must be constructed above the designed base flood elevation (DBFE). Also, in this zone the “50% rule” applies.
The VE Zones are the most dangerous flood zones. VE zones are in the “High Risk” area and will experience rising waters, severe winds and wave action greater than three feet. Homes in this area are on the south side of Savannah along the Forest and Vernon Rivers. To protect against wave scouring and frontal velocity, structures must be elevated so that the lowest horizontal structural member (floor joist) is above the designed base flood elevation (DBFE). Such construction usually means placing the structure on piles (pilings), and these pilings must also be anchored to resist flotation, collapse and lateral movement due to the combination effects of wind and water loading forces of the 100 year storm. A registered professional engineer or architect must develop, review and certify the structural design, specifications and plans. The 50% Rule also applies here too.
The Coastal A Zone: is a term that is used to draw a distinction between coastal V zones and inland A Zones, and to highlight similarities between V Zones and A Zones in coastal areas. A building in this area is subject to breaking wave heights between 2.9 feet and 1.5 feet. Building damage in Coastal A Zones is consistent with those observed in V Zones, not riverine A Zones. The City has not mapped the Coastal A zone at this time.