Epic Flooding in , 2009

Metropolitan Atlanta—September 2009 • The epic floods experienced in the Atlanta area in September 2009 were extremely rare. Eighteen streamgages in the Metropolitan Atlanta area had magnitudes much greater than the estimated 0.2-percent (500-year) annual exceedance probability. • The Federal Emergency Management Agency (FEMA) reported that 23 counties in Georgia were declared disaster areas due to this flood and that 16,981 homes and 3,482 businesses were affected by floodwaters. Ten lives were lost in the flood. The total estimated damages exceed $193 million (H.E. Longenecker, Federal Emergency Management Agency, written commun., November 2009). Measuring Sweetwater Creek floodflow over Interstate 20 near • On Sweetwater Creek near Austell, Ga., just north of Interstate 20, Atlanta, Georgia. Photo by Alan M. Cressler, USGS. the peak stage was more than 6 feet higher than the estimated peak stage of the 0.2-percent (500-year) flood. Flood magnitudes in Cobb County on Sweetwater, Butler, and Powder Springs Creeks greatly EXPLANATION exceeded the estimated 0.2-percent (500-year) floods for these . Streamflow at one or more USGS • In Douglas County, the at Ga. Highway 5 near Fairplay had streamgages exceeded the given annual exceedance probability a peak stage nearly 20 feet higher than the estimated peak stage of the 1 percent (100 year) 0.2-percent (500-year) flood. 0.5 percent (200 year) • On the , the U.S. Geological Survey (USGS) gage at 0.2 percent (500 year) Vinings reached the highest level recorded in the past 81 years. Gwinnett, USGS office De Kalb, Fulton, and Rockdale Counties also had record flooding. GEORGIA South Georgia March and April 2009 Floods • The March and April 2009 floods in South Georgia were smaller in magnitude than the September floods but still caused significant damage. • No lives were lost in this flood. Approximately $60 million in public infra­s­tructure damage occurred to roads, culverts, bridges and a water treatment facility (Joseph T. McKinney, Federal Emergency Management Agency, written commun., July 2009). • Flow at the near Waycross, exceeded the 0.5-percent (200-year) flood. Flows at seven other stations in South Georgia exceeded the 1-percent (100-year) flood. USGS Role During the Floods • One of the primary missions of the USGS is the measurement and documentation of the magnitude and extent of hydrologic hazards, such as floods, droughts, and hurricane storm surge. • In Georgia, the USGS maintains a network of more than 300 - gages that provide data in real time via the Internet. Data from these stream­gages are used by local, State, and Federal officials for numerous purposes, including public safety, National Weather Service (NWS) flood forecasting, and to aid emergency management officials in making informed decisions before, during, and after flood events. • During these two flood events, USGS personnel made more than 100 discrete flood measurements, performed extensive ongoing analysis of ratings and flood frequency, collected water-quality Altamaha Regional Park, Glynn County, Georgia, April 14, 2009. The samples in flooded areas, and provided routing briefings to USGS water is 3 feet deep. Photo by Alan M. Cressler, USGS. Headquarters, NWS, local government officials, and the press.

U.S. Department of the Interior Fact Sheet 2010–3107 U.S. Geological Survey October 2010 02392975 at Shallowford Road, 02207120 at Ga. 124, near Woodstock, Georgia near Lithonia, Georgia 100,000 September 2009 100,000 September 2009 flood magnitude flood magnitude is

1 percent AEP /s 3 /s 10,000

3 exceeded the about equal to the 10,000 0.2-percent Dashed where 0.5-percent (200- estimated 1,000 (500-year) year) AEP flood. annual exceedance 1,000 100 probability Discharge, in ft Discharge, in ft (AEP) flood. 10 100 19 20 21 22 23 24 25 19 20 21 22 23 24 25 September September September 2009 flood about equal to the September 2009 flood is greater than the 0.2 percent (500 years) annual exceedance 02336000 Chattahoochee River at Atlanta, Georgia 0.2 percent (500 years) annual exceedance probability flood. Streamgage was inundated EXPLANATION 100,000 84° probability flood. Dade*# Catoosa whichTowns resulted in loss of continuous data. The River basin *# Fannin *# *# Rabun *# peak*# streamflow*# was determined from high /s *# Altamaha Ogeechee

3 Union *# *# Gilmer water marks. *# Whitfield *# *# *# Murray *#*# Chattahoochee Satilla–St. Marys Walker *# *#*# White *# *# *#*# *# Lumpkin *# Coosa–Tallapoosa Savannah Chattooga *# *# Dawson *# *# *# Stephens 10,000 *# *#Gordon Habersham Pickens *# *# Flint Suwannee *# # *# Franklin * *# Banks *# Bartow *# *# Hart Ochlockonee Tennessee Floyd*#*#*# *# *# *#*# Forsyth *# *# *# Hall Discharge, in ft *#*# Cherokee *# *# *# *# *# *# *# Active streamgage *# *# Jackson Madison Elbert *# *# *# *# *# *# *#*# *#*# *# *# *# 1,000 34° Polk *# *#*#*#*# *# Barrow *# *# *# *# *# Clarke*# 19 20 21 22 23 24 25 Paulding Cobb *# *# *# Oglethorpe *#*#*# *#*#*# Gwinnett *# *#*#*#*#*# *#*# Oconee September Haralson *# *# *#*# Walton *# Wilkes *# *# *# # Lincoln Douglas *# DeKalb **# *# *# *# *#*#*# *# *# September 2009 2009 flood flood is betweenmagnitude the is 1 andbetween *# *# *# *# Fulton Rockdale Greene *# *# *# 82° Carroll *# Taliaferro McDuffie Columbia 0.5the percent 1- and 0.5-percent(100 and 200 (100-years) and annual 200-year) *# *# Newton Morgan *# Clayton *# Fayette *#*# exceedance probability flood. *#*# *# Henry Augusta AEP flood. Heard *# Warren *# *# *# Coweta Putnam *# *# *#Jasper *# Richmond *# *#Spalding*# *# Butts *# *# Hancock *# Glascock *# *# *# *# *# *# Jefferson Burke *# Pike Lamar Monroe *# Baldwin Washington Troup Jones *# *# *# *# *# *# *# Meriwether *# Upson *# Bibb*# *# *# *# Screven Harris *# Jenkins Talbot *# Johnson Twiggs Wilkinson *# Emanuel *# Crawford *# *# *# Taylor Peach *# *#*#MuscogeeColumbus*# Houston *# Effingham *#*# Macon Bleckley *# Treutlen Bulloch *# *#*# 02337000 Sweetwater Creek near Austell, Georgia Chattahoochee Laurens Candler Marion *# *# *# 35,000 *# *# Schley *# *# *# *# *# *#*# *# *# Dooly Pulaski Dodge Wheeler *# 30,000 *# Toombs *# Evans *# /s Stewart *# *#

3 32° *# Bryan Chatham Sumter Montgomery Wilcox *# *# 25,000 Webster Crisp *# *# Tattnall Terrell Lee Telfair Liberty# Quitman*# * 20,000 *# *# Jeff Estimated RandolphRandolph *# Turner Ben Hill Davis Appling *#Long 15,000 *# *# *# Coffee Clay *# Irwin *# Worth Bacon Wayne 10,000 *# Dougherty Tift Mcintosh Calhoun *# *# *# Discharge, in ft *# *# *# *# 5,000 Early *# *# *# *# Pierce *# Berrien Atkinson Glynn *# Baker *# *# 0 *# Mitchell Colquitt Cook 19 20 21 22 23 24 25 Miller *# *# *# *# Brantley *# Lanier Ware September *# Grady *# Clinch *# *# Camden *#Thomas Charlton September 2009 flood magnitude greatly Seminole September 2009 flood exceeded the 0.2 percent Decatur *# *# *# *# Lowndes exceeded(500 years) the annual 0.2-percent exceedance (500-year) probability AEP flood. flood. *# Brooks *# Echols *#*# Streamgage was inundated which resulted in loss of continuous data. USGS personnel were 0 20 40 MILES at the site and measured02327500 the Ochlockonee peak streamflow. River *# 0 20 40 KILOMETERS near Thomasville, Georgia April 2009 flood 100,000 magnitude is /s

between the 3 1- and 0.5-percent 10,000 02226500 Satilla River near Waycross, Georgia (100- and 200-year) 100,000 April 2009 flood AEP flood. magnitude is

1,000 /s 3 about equal to 10,000 Discharge, in ft the 0.5-percent (200-year) 100 25 30 4 9 14 19 24 29 AEP flood. 1,000 March April Discharge, in ft

By Anthony J. Gotvald and Brian E. McCallum For more information contact: 100 25 30 4 9 14 19 24 29 Design and layout by Caryl J. Wipperfurth USGS Georgia Water Science Center 3039 Amwiler Road, Suite 130 March April http://ga.water.usgs.gov Atlanta, Georgia 30360 http://www.usgs.gov telephone: 770–903–9100