Skip Navigation LinksFlood Plain Data

The State of Georgia is in the process of updating the City’s Flood Insurance Rate Maps (FIRM) as part of FEMA’s Flood Map Modernization Program. The updates have been performed because more accurate topographic information is available which allows the maps to more accurately show flood hazards. The project has reached the point where new preliminary floodplain limits have been established. 


The following link provides a way to show the location of your property with respect to the flood hazards on an interactive map. You can enter your address and use the two buttons in the upper left hand corner to display Effective Flood Zones (currently adopted floodplain limits) and Preliminary Flood Zones (which are scheduled to be adopted in November 2012).

Floodplain terms

Flood (also Flooding)

A general and temporary condition of partial or complete inundation of normally dry land areas. For flood insurance claim purposes, two or more structures must be inundated before flood damage will be covered.


Federal Emergency Management Agency (FEMA)
The Federal Emergency Management Agency - a former independent agency that became part of the Department of Homeland Security in March 2003 - is tasked with responding to, planning for, recovering from and mitigating against disasters. The agency's mission is: to lead America to prepare for, prevent, respond to and recover from disasters with a vision of "A Nation Prepared."


Channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 100-year flood discharge can be conveyed without increasing the elevation of the 100-year flood by more than a specified amount (1 foot in most states).


100-year flood

The flood having a 1-percent chance of being equaled or exceeded in any given year; also known as the base flood. The 1-percent annual chance flood, which is the standard used by most Federal and state agencies, is used by the National Flood Insurance Program (NFIP) as the standard for floodplain management and to determine the need for flood insurance. A structure located within a special flood hazard area shown on an NFIP map has a 26 percent chance of suffering flood damage during the term of a 30-year mortgage.


100-year floodplain

This is the boundary of the flood that has a 1-percent chance of being equaled or exceeded in any given year. Officially termed the 1-percent annual chance floodplain.


Flood Insurance Rate Map (FIRM)
The insurance and floodplain management map produced by FEMA that identifies, based on detailed or approximate analyses, the areas subject to flooding during a 1-percent-annual-chance (100-year) flood event in a community. Flood insurance risk zones, which are used to compute actuarial flood insurance rates, also are shown. In areas studied by detailed analyses, the FIRM shows BFEs to reflect the elevations of the 1-percent-annual-chance flood. For many communities, when detailed analyses are preformed, the FIRM also may show areas inundated by 0.2-percent-annual-chance (500-year) flood and regulatory floodway areas.


Flood Profile
A cross-sectional drawing showing the contiguous cross sections along a stream, with ground elevations and potential flood elevations plotted.


Below you will find the City of Dunwoody Floodplain Boundary Changes presentation from the Public Information Meeting held May 17, 2012.

City of Dunwoody Floodplain Boundary Changes 


If you would like more information on the Map amendment process click the link below:

FEMA Letters of Map Amendment (LOMA) and Letter of Map Revision based on Fill (LOMR-F) links