33°49'30"N

33°49'N

33°48'30"°N

Prepared in cooperation with the
City of Atlanta,
Georgia

aUSGS

science for a changing world

84°26'30"W 84°26'W 84°25'30"W 84°24'30"W

Base from U.S. Geological Survey High-Resolution
Orthoimagery for the Atlanta, Georgia Urban Area, 2007
Transverse Mercator projection

State Plane Coordinate System, Georgia West, FIPS 1002
North American Datum of 1983 (NAD 83)

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Map EXPLANATION
as COUNTN: Flood-inundation area
nzggga0n i 307 y Model boundary
Y 02336490 @ USGS streamgage and identifier
WY 023363004 usGs streamgage and NWS
N AANGI forecast site and identifiers
{ —> Direction of surface-water flow

84°24'W 84°23'30"W 84°23'W

Scientific Investigations Map 3189
Sheet 19 of 50

Pamphlet accompanies map

84°22'30"W

4,000 FEET
}

oto

Disclaimer for Flood-Inundation Maps

Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. The USGS provides these maps “as-is” for a quick reference, emergency
planning tool but assumes no legal liability or responsibility resulting from the use of this information.

Uncertainties and Limitations for Use of Flood-Inundation Maps

Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some uncertainty is associated with these maps. The flood boundaries shown

were estimated based on water stages (water-surface elevations) and streamflows at selected USGS streamgages. Water-surface elevations along the stream reaches were estimated by
steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the USGS streamgage(s). The hydraulic model reflects the
land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing as of March 2011. Unique meteorological factors (timing and distribution of precipitation)
may cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations in the water-surface elevations and inundation
boundaries shown. Additional areas may be flooded due to unanticipated conditions such as: changes in the streambed elevation or roughness, backwater into major tributaries along a
main stem river, or backwater from localized debris or ice jams. The accuracy of the floodwater extent portrayed on these maps will vary with the accuracy of the digital elevation model
used to simulate the land surface. Additional uncertainties and limitations pertinent to this study are described in the document accompanying this set of flood inundation map plates.

If this series of flood-inundation maps will be used in conjunction with National Weather Service (NWS) river forecasts, the user should be aware of additional uncertainties that may
be inherent or factored into NWS forecast procedures. The NWS uses forecast models to estimate the quantity and timing of water flowing through selected stream reaches in the
United States, These forecast models (1) estimate the amount of runoff generated by precipitation and snowmelt, (2) simulate the movement of floodwater as it proceeds downstream,
and (3) predict the flow and stage (water-surface elevation) for the stream at a given location (Advanced Hydrologic Prediction Service [AHP] forecast point) throughout the forecast
period (every 6 hours and 3-5 days out in many locations). For more information on AHPS forecasts, please see: hitp://water: weather.gov/ahps/pcpn_and_river_forecasting,pdf.

Flood-Inundation Map of Peachtree Creek in Atlanta, GA, Corresponding to a Gage Height of 23.0 Feet and an Elevation of 787.2 Feet (NAVD 88)
at U.S. Geological Survey Streamgage Peachtree Creek at Atlanta, GA (02336300), and a Gage Height of 29.4 Feet and an
Elevation of 766.0 Feet (NAVD 88) at U.S. Geological Survey Streamgage Chattahoochee River at GA 280, near Atlanta, GA (02336490)

U.S. Department of the Interior
U.S. Geological Survey

1,000 METERS.

wetting,

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Prepared in coordination with the

National Weather Service
http://water. weather gov/ahps/pcpn_and_river_forecasting.pdf

was

Suggested citation:

Musser, J.W, 2012, Flood-inundation maps for Peachtree Creek
from the Norfolk Southern Railroad bridge to the Moores Mill

Road NW bridge, Atlanta, Georgia: U.S. Geological Survey Scientific
Investigations Map 3189, 9 p. pamphlet, 50 sheets; available

online only at http://pubs.usgs.gov/sim/3189/.