EXPLANATION

USGS office

Streamflow at one or more USGS streamgages exceeded the given annual exceedance probability

1 percent (100 year)0.5 percent (200 year)0.2 percent (500 year)

GEORGIA

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

Epic Flooding in Georgia, 2009Metropolitan Atlanta—September 2009 Floods• TheepicfloodsexperiencedintheAtlantaareainSeptember2009wereextremelyrare.EighteenstreamgagesintheMetropolitanAtlantaareahadfloodmagnitudesmuchgreaterthantheestimated0.2-percent(500-year)annualexceedanceprobability.

• TheFederalEmergencyManagementAgency(FEMA)reportedthat23countiesinGeorgiaweredeclareddisasterareasduetothisfloodandthat16,981homesand3,482businesseswereaffectedbyfloodwaters.Tenliveswerelostintheflood.Thetotalestimateddamagesexceed$193million(H.E.Longenecker,FederalEmergencyManagementAgency,writtencommun.,November2009).

• OnSweetwaterCreeknearAustell,Ga.,justnorthofInterstate20,thepeakstagewasmorethan6feethigherthantheestimatedpeakstageofthe0.2-percent(500-year)flood.FloodmagnitudesinCobbCountyonSweetwater,Butler,andPowderSpringsCreeksgreatlyexceededtheestimated0.2-percent(500-year)floodsforthesestreams.

• InDouglasCounty,theDogRiveratGa.Highway5nearFairplayhadapeakstagenearly20feethigherthantheestimatedpeakstageofthe0.2-percent(500-year)flood.

• OntheChattahoocheeRiver,theU.S.GeologicalSurvey(USGS)gageatViningsreachedthehighestlevelrecordedinthepast81years.Gwinnett,DeKalb,Fulton,andRockdaleCountiesalsohadrecordflooding.

South Georgia March and April 2009 Floods• TheMarchandApril2009floodsinSouthGeorgiaweresmallerinmagnitudethantheSeptemberfloodsbutstillcausedsignificantdamage.

• Noliveswerelostinthisflood.Approximately$60millioninpublicinfrastructuredamageoccurredtoroads,culverts,bridgesandawatertreatmentfacility(JosephT.McKinney,FederalEmergencyManagementAgency,writtencommun.,July2009).

• FlowattheSatillaRivernearWaycross,exceededthe0.5-percent(200-year)flood.FlowsatsevenotherstationsinSouthGeorgiaexceededthe1-percent(100-year)flood.

Fact Sheet 2010–3107 October 2010

Measuring Sweetwater Creek floodflow over Interstate 20 near Atlanta, Georgia. Photo by Alan M. Cressler, USGS.

Altamaha Regional Park, Glynn County, Georgia, April 14, 2009. The water is 3 feet deep. Photo by Alan M. Cressler, USGS.

USGS Role During the Floods• OneoftheprimarymissionsoftheUSGSisthemeasurementanddocumentationofthemagnitudeandextentofhydrologichazards,suchasfloods,droughts,andhurricanestormsurge.

• InGeorgia,theUSGSmaintainsanetworkofmorethan300stream-gagesthatprovidedatainrealtimeviatheInternet.Datafromthesestreamgagesareusedbylocal,State,andFederalofficialsfornumerouspurposes,includingpublicsafety,NationalWeatherService(NWS)floodforecasting,andtoaidemergencymanagementofficialsinmakinginformeddecisionsbefore,during,andafterfloodevents.

• Duringthesetwofloodevents,USGSpersonnelmademorethan100discretefloodmeasurements,performedextensiveongoinganalysisofratingsandfloodfrequency,collectedwater-qualitysamplesinfloodedareas,andprovidedroutingbriefingstoUSGSHeadquarters,NWS,localgovernmentofficials,andthepress.

River basin

Active streamgage

EXPLANATION

Altamaha

Chattahoochee

Coosa–Tallapoosa

Flint

Ochlockonee

Ogeechee

Satilla–St. Marys

Savannah

Suwannee

Tennessee

#*

Augusta

Columbus

0 20 40 MILES

0 20 40 KILOMETERS

Clinch

Worth

SumterCrisp

Miller

Macon

Marion

Randolph

Warren

Calhoun

Evans

Dougherty

Sem

inol

e

Web

ster

Schley

Ware

Burke

Clinch

Wayne

Laurens

Hall

Early

Floyd

WorthCoffee

Bulloch

Charlton

Emanuel

Long

Camden

Dodge

Screven

Decatur

GradyThomas

Troup

Tift

Liberty

Wilkes

Harris

Irwin

Cobb

Jones

Appling

Polk

Sumter

Dooly

Gilmer

Bibb

Colquitt

Telfair

Bartow

Rabun

Walker

Fannin

Carroll

Mitchell

Talbot

Coweta

Echols

Union

Taylor

Wilcox

Elbert

Pike

Greene

Stewart

Hart

Henry

Pierce

Upson

Crisp

Heard

Clay

Putnam

Bacon

Walton

Gordon

Miller

Jackson

Butts

Lee

Fulton

Bryan

Glynn

Brooks

Macon

Bake

r

Berrien

Lowndes

Washington

JasperHancock

Marion

Twiggs

Jefferson

Monroe

ToombsChatham

Brant

ley

Jenkins

Effingham

GwinnettM

urra

y

Wilkinson

Mcintosh

Cook

Morgan

Randolph

Cherokee

Houston

White

Terrell

Mer

iwet

her

Turner

Banks

Atkinson

Warren

DeKalb

Lumpkin

Oglethorpe

Newton

Paulding

Dade

Johnson

Madison

Wheeler

JeffDavis

Richmond

Lincoln

Pulaski

Columbia

Baldwin

Calhoun

Ben Hill

Evans

Crawford

Lanier

Lamar

Franklin

Whi

tfiel

d

Pickens

Dougherty

Candler

Forsyth

McDuffie

Haralson

Chattooga

Sem

inol

e

Dawson

Towns

Fayette

Haber

sham

Peach

Oconee

Web

ster

Bleckley

Schley

Douglas

Spalding

TreutlenMuscogee

Barrow

Quitman

Stephens

Catoosa

Mon

tgom

ery

TaliaferroC

layt

on

Clarke

Chattahoochee

Glascock

Rockd

ale

Tattnall

82°

84°

34°

32°

#*

#*

#*

#*

#*

#*

#*#* #* #*

#*#*#*#*

#*

#*

#*#*

#*#*

#*

#* #*#*

#*#*#*

#*

#*

#*#*

#*

#*

#*

#*

#*#*#*

#*

#*

#*#*#*#*#*

#* #*

#*

#*#*#*

#*

#*#*

#*#*#*

#*#*#*

#*

#*#*

#* #*

#*

#*#*

#*#*

#*

#*

#*#* #*

#*#*

#*

#*

#*

#*#*

#*

#*#*

#*#*#*

#*

#*

#* #*

#*

#*

#*

#*

#* #*

#*#*

#*

#*

#*

#*

#*#*

#*

#*

#*

#*

#*

#*#*

#*

#*

#*

#*

#*#*

#*#*

#*#*#*#*#*#*#*

#*#*#*

#*

#*#*#*#*#*#*#*

#*#*#*#*

#*#*#*#*#*

#*#*#*#*#*

#*#*#*#*#*#*

#*#*

#*#*#*

#*#*

#*

#*

#*#*#*

#*#*

#*

#*

#*

#*#*#*

#*#*

#*

#*#*

#*

#*

#*#*

#*#*

#*#*#*

#*

#*

#*

#*

#*

#*

#*

#*

#*

#*

#*

#*

#*

#*#*

#*

#*#*

#*#*

#*

#*

#*

#*

#*

#*#*#*

#*#*#*

#*#*#*

#*

#*#*#*#*

#*#*

#*#*

#*#*#*#*#*#*

#* #*#*#*

#*

#*#*

#*

#*

#*#*

#*#*#*#*

#*#*#*

#*#*

#*#*#*#*#*#*#*#*

#*

#*

#*

#*

#*

#*

#*

#*#*

#*

10

100

1,000

10,000

100,000

September 2009 flood is greater than the 0.2 percent (500 years) annual exceedance probability flood.

19 20 21 22 23 24 25September

Disc

harg

e, in

ft3 /s

02392975 Noonday Creek at Shallowford Road, near Woodstock, Georgia

1 percent AEP

5,000

10,000

15,000

20,000

25,000

30,000

35,000

19 20 21 22 23 24

Estim

ated

25

September 2009 flood exceeded the 0.2 percent (500 years) annual exceedance probability flood. Streamgage was inundated which resulted in loss of continuous data. USGS personnel were at the site and measured the peak streamflow.

0

September

Disc

harg

e, in

ft3 /s

02337000 Sweetwater Creek near Austell, Georgia

September 2009 flood about equal to the 0.2 percent (500 years) annual exceedance probability flood. Streamgage was inundated which resulted in loss of continuous data. The peak streamflow was determined from high water marks.

02207120 Yellow River at Ga. 124, near Lithonia, Georgia

19 20 21 22 23 24 25September

Disc

harg

e, in

ft3 /s

100

1,000

10,000

100,000

Dashed whereestimated

September 2009 flood magnitude is about equal to the 0.5-percent (200-year) AEP flood.

September 2009 flood is between the 1 and0.5 percent (100 and 200 years) annual exceedance probability flood.

Disc

harg

e, in

ft3 /s

02336000 Chattahoochee River at Atlanta, Georgia

19 20 21 22 23 24 25September

1,000

10,000

100,000

02327500 Ochlockonee River near Thomasville, Georgia

AprilMarch25 30 4 9 14 19 24 29

Disc

harg

e, in

ft3 /s

1,000

100

10,000

100,000

02226500 Satilla River near Waycross, Georgia

AprilMarch25 30 4 9 14 19 24 29

Disc

harg

e, in

ft3 /s

1,000

100

10,000

100,000

September 2009 flood magnitude greatly exceeded the 0.2-percent (500-year) AEP flood.

September 2009 flood magnitude is between the 1- and 0.5-percent (100- and 200-year) AEP flood.

September 2009 flood magnitude exceeded the 0.2-percent (500-year) annual exceedance probability (AEP) flood.

By Anthony J. Gotvald and Brian E. McCallum

Design and layout by Caryl J. Wipperfurth

http://ga.water.usgs.govhttp://www.usgs.gov

For more information contact:USGS Georgia Water Science Center3039 Amwiler Road, Suite 130Atlanta, Georgia 30360telephone: 770–903–9100

April 2009 flood magnitude is about equal to the 0.5-percent (200-year) AEP flood.

April 2009 flood magnitude is between the 1- and 0.5-percent (100- and 200-year) AEP flood.