84°06'W 84°05'W 84°04'W 84°03'W

34°03'N

34°02'N

SUWANEE ROAD

LAWRENCEVILLE 

MARTIN FARM 

MCGINNIS FERRY ROAD

BUFORD HIGHWAY

PEACHTREE INDUSTRIAL BOULEVARD

NOBLIN RIDGE 

0 1,000 2,000 3,000 4,000 FEET

0 500 1,000 METERS

DRIVE

ROAD

Map area

GWINNETT

COUNTY

Chattahoochee

River

Suwanee

Cr

GEORGIA

02334485

SWEG1

Suggested citation:

Musser, J.W., 2012, Flood-Inundation Maps for Suwanee Creek from the Confluence of Ivy Creek to the Noblin Ridge

Drive Bridge, Gwinnett County, Georgia: U.S. Geological Survey Scientific Investigations Map 3220, 8 p. pamphlet,

19 sheets; available online only at http://pubs.usgs.gov/sim/3220/.

Scientific Investigations Map 3226

Sheet 11 of 19

Pamphlet accompanies map

Prepared in cooperation with

Gwinnett County,

Georgia

Prepared in coordination with the

National Weather Service

http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf

U.S. Department of the Interior

U.S. Geological Survey

Base from High-Resolution Orthoimagery for Gwinnett County, 2010

Transverse Mercator projection

State Plane Coordinate System, Georgia West, FIPS 1002

North American Datum of 1983 (NAD 83)

Flood-Inundation Map of Suwanee Creek in Gwinnett County, GA, Corresponding to a Gage Height of 12.0 Feet and an 

Elevation of 921.9 Feet (NAVD 88) at U.S. Geological Survey Streamgage Suwanee Creek at Suwanee, GA (02334885)

02334885

SWEG1 NORFOLK SOUTHERN RAILROAD

USGS streamgage and 

 NWS forecast site 

 and identifiers

EXPLANATION

Model boundary

Flood-inundation area

02334485

SWEG1

Direction of surface-

 water flow

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 by 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 October 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 [AHPS] 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: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf.

Chattahoochee River