U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5107

Two-Dimensional Flood-Inundation Model 

of the Flint River at Albany, Georgia

In cooperation with Albany, Georgia, and Dougherty County, Georgia
Cover photograph: Broad Avenue bridge over the Flint River at Albany, Georgia, March 2005

Photograph by Jonathan W. Musser, U.S. Geological Survey
Two-Dimensional Flood-Inundation Model 

of the Flint River at Albany, Georgia

By Jonathan W. Musser and Thomas R. Dyar

In cooperation with Albany, Georgia, and Dougherty County, Georgia

Scientific Investigations Report 2007–5107

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Musser, Jonathan W., and Dyar, Thomas R., 2007, Two-dimensional flood-inundation model of the Flint River 

at Albany, Georgia: Atlanta, Georgia, U.S. Geological Survey Scientific Investigations Report 2007-5107, 49 p., 

Web-only publication at http://pubs.usgs.gov/sir/2007/5107
Contents

Abstract........................................................................................................................................................ 1

Introduction.................................................................................................................................................. 1

Purpose and Scope ........................................................................................................................... 3

Description of Study Area ................................................................................................................ 4

Previous Studies ................................................................................................................................ 4

Method of Study................................................................................................................................. 4

Acknowledgments............................................................................................................................. 4

Two-Dimensional Flood-Inundation Model ............................................................................................ 5

Model Calibration............................................................................................................................... 7

Simulated Flood Inundation ............................................................................................................. 8

Model Limitations............................................................................................................................... 8

Summary....................................................................................................................................................... 8

References Cited......................................................................................................................................... 10

Appendix A. Images showing simulated flood inundation and hazard scale at the Albany 

streamgage compared with Federal Emergency Management Agency’s 

Digital Flood Insurance Rate Maps for the Flint River in Albany, Georgia, 1998.... 11

Appendix B. Flood extent photographs for the Flint River in Albany, Georgia.............................. 41

Figures

1. Map showing location of two-dimensional model study area along the study 

reach of the Flint River at Albany, Georgia ....................................................................... 1

2. Image of flood-inundation study area showing all major Flint River crossings, 

Albany, Georgia ..................................................................................................................... 2

3–5. Maps Showing—

3. U.S. Geological Survey streamgages in the Flint River Basin, Georgia ..................3

4. Finite-element mesh used for two-dimensional model of the Flint River at 

Albany, Georgia. Inflow and outflow boundary conditions are for a 

water-surface altitude of 192.5 feet at the Albany streamgage...............................6

5. Velocity distribution of the Flint River near Oakridge Drive at Albany, Georgia ....9

6. Graph showing simulated flow profiles by streamgage altitude for the Flint River 

at Albany, Georgia................................................................................................................. 9

 iii
Figures—continued

A1–A14. Images showing simulated flood inundation for a water-surface altitude at the 

Albany streamgage compared with Federal Emergency Management Agency’s 

Digital Flood Insurance Rate Maps for the Flint River in Albany, Georgia, 1998—

A1. 179.5 feet .....................................................................................................................12

A2. 180.5 feet .....................................................................................................................13

A3. 181.5 feet .....................................................................................................................14

A4. 182.5 feet .....................................................................................................................15

A5. 183.5 feet .....................................................................................................................16

A6. 184.5 feet ....................................................................................................................17

A7. 185.5 feet .....................................................................................................................18

A8. 186.5 feet .................................................................................................................... 19

A9. 187.5 feet .....................................................................................................................20

A10. 188.5 feet .....................................................................................................................21

A11. 189.5 feet .....................................................................................................................22

A12. 190.5 feet .....................................................................................................................23

A13. 191.5 feet .....................................................................................................................24

A14. 192.5 feet .....................................................................................................................25

A15–A28. Images showing simulated flood-inundation hazard scale for a 

water-surface altitude at the Albany streamgage compared with 

Federal Emergency Management Agency’s Digital Flood Insurance 

Rate Maps for the Flint River in Albany, Georgia, 1998 —

A15. 179.5 feet ....................................................................................................................26

A16. 180.5 feet .....................................................................................................................27

A17. 181.5 feet .....................................................................................................................28

A18. 182.5 feet .................................................................................................................... 29

A19. 183.5 feet .....................................................................................................................30

A20. 184.5 feet .....................................................................................................................31

A21. 185.5 feet .....................................................................................................................32

A22. 186.5 feet .....................................................................................................................33

A23. 187.5 feet .....................................................................................................................34

A24. 188.5 feet .....................................................................................................................35

A25. 189.5 feet .....................................................................................................................36

A26. 190.5 feet .....................................................................................................................37

A27. 191.5 feet .....................................................................................................................38

A28. 192.5 feet .....................................................................................................................39

B1. Simulated flood inundation for a water-surface altitude of 181.5 feet at the 

Albany streamgage with locations of flood extent photographs for the Flint River 

in Albany, Georgia.................................................................................................................42

B2. Flood extent photographs for the Flint River in Albany, Georgia...................................43

iv 
Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

 v

Conversion Factors and Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3) 28.32 cubic decimeter (dm3) 

cubic foot (ft3) 0.02832 cubic meter (m3) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)
vi 
Abstract

Potential flow characteristics of future flooding along 

a 4.8-mile reach of the Flint River in Albany, Georgia, were 

simulated using recent digital-elevation-model data and the 

U.S. Geological Survey finite-element surface-water modeling system for two-dimensional flow in the horizontal plane 

(FESWMS-2DH). Simulated inundated areas, in 1-foot (ft) 

increments, were created for water-surface altitudes at the 

Flint River at Albany streamgage (02352500) from 192.5-ft 

altitude with a flow of 123,000 cubic feet per second (ft3/s) 

to 179.5-ft altitude with a flow of 52,500 ft3/s. The model 

was calibrated to match actual floods during July 1994 and 

March 2005 and Federal Emergency Management Administration floodplain maps. Continuity checks of selected stream 

profiles indicate the area near the Oakridge Drive bridge had 

lower velocities than other areas of the Flint River, which 

contributed to a rise in the flood-surface profile. The modeled 

inundated areas were mapped onto monochrome orthophoto 

imagery for use in planning for future floods. As part of a 

cooperative effort, the U.S. Geological Survey, the City of 

Albany, and Dougherty County, Georgia, conducted this study.

Two-Dimensional Flood-Inundation Model of the 

Flint River at Albany, Georgia

By Jonathan W. Musser and Thomas R. Dyar

Introduction

The U.S. Geological Survey (USGS), the City of Albany, 

and Dougherty County, Georgia, are cooperating on floodplain 

studies along the Flint River at Albany, Georgia (fig. 1). Since 

1994, the City of Albany has experienced two major floods. 

During July 1994, Tropical Storm Alberto caused recordbreaking flooding in most of the Flint River Basin. The maximum flood flow in Albany was about 123,000 cubic feet per 

second (ft3/s) at an altitude of about 192.5 feet (ft) at the USGS 

Albany streamgage (02352500) at the Norfolk Southern Railroad 

bridge (fig. 2). The probable recurrence interval (RI) of the flood 

was estimated to be about 200–300 years (Stamey, 1996). The 

flood inundated a large part of Albany, caused widespread community infrastructure and property damage, affected public safety 

and health, and required the evacuation of about 75,000 people. 

Floodwaters at Albany remained above the 100-year flood stage, 

about 187.5-ft altitude, for 7 days. The second major flood, 

during March 1998, resulted from a regional winter storm, 

which also caused substantial flooding at Albany and required 

the evacuation of about 14,000 people. This flood was estimated 

to have about a 70-year RI, about 86,100 ft3/s flow, with a flood 

altitude of about 186.5-ft altitude (Stamey and Hess, 1993).

Figure 1. Location of two-dimensional model study area 

along the study reach of the Flint River at Albany, Georgia.

N

Base from U.S. Geological Survey

1:100,000-scale data

Albany

Study

area

GEORGIA

DOUGHERTY COUNTY

5 MILES

5 KILOMETERS

0

0

Fl ni t River
Figure 2. Flood-inundation study area showing all major Flint River crossings, Albany, Georgia. [RR, Railroad]

Human-made 

 peninsula

Study area

Liberty Expressway

Norfolk Southern RR

Oglethorpe Blvd

Broad Ave

Flint River at Albany, Georgia

(02352500)

Oakridge Dr

Oxbow

Chehaw 

Lake

Lake Chehaw Dam

Riverwalk Park

Muckafoonee Diversion Dam

Georgia Southern RR

N

Image from Albany-Dougherty Planning Commission, 1996 0 0.5 1 MILE

0 0.5 1 KILOMETER

Muckafoonee Diversion Dam

Human-made

 peninsula

84°11’ 84°10’ 84°09’ 84°08’

31°33’

31°34’

31°35’

31°36’

19 82

2 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Albany is growing rapidly and has a number of active 

community improvement projects. Some of the projects, 

such as the planned 8.5-mile (mi) extension to the new 

Riverwalk along the west bank of the Flint River, may improve 

floodwater conveyance in the study reach. In the 1998 Governor’s Task Force on Reducing the Impacts of Flooding in 

the Flint River Basin, Preliminary Report (Georgia Emergency Management Agency and the Georgia Department of 

Natural Resources, 1998), reexamination of the river basin 

development plans and flood mitigation infrastructure was 

cited as a principal need. The report concluded flood improvements—including the repair and replacement of the 250 failed 

dams, numerous roadways and bridges, as a result of Tropical 

Storm Alberto—needed to be factored into reexamination of 

the Flint River Basin. Development of a metropolitan area 

can result in changing flood frequency and higher flood peaks 

for areas downstream (Konrad, 2003). The rapid development of the Atlanta area could have this kind of impact on 

the Flint River at Albany. In response to past flooding and the 

possibility of future flooding, the City of Albany and Dougherty County are cooperating with the USGS in the development of a model to map the extent of flooding in Albany from 

the Flint River. The USGS monitors streamflow conditions 

throughout the Flint River Basin (fig. 3). The cooperative 

effort between the City of Albany, Dougherty County, and the 

USGS will assist the community in planning for future floods 

as well as emergency response during future floods. With a 

National Weather Service forecast, the city and county emergency response groups will be able to assess what areas will 

require their assistance during a flood.

Purpose and Scope

The purpose of this report is to describe the procedure 

and results of a study to create 1-ft-interval flood-inundation 

maps of the Flint River in Albany, Georgia. The scope of the 

work included field examination of the study area (fig. 1); 

mapping of eight river cross sections; delineating land-use 

areas for about 13.7 square miles (mi2); and applying a twodimensional finite-element model (FESWMS-2DH) covering the Flint River near Albany from about 0.2 mi south of 

Lake Chehaw to about 1.1 mi south of Oakridge Drive. When 

the model was completed, field checks were completed for the 

flood-inundation extent at nine locations, as well as presentation of maps of the model results.

Figure 3. U.S. Geological Survey streamgages 

in the Flint River Basin, Georgia.

Flint River

Kinchafoonee Cr

Flint River

Muckalee Cr LEE

SUMTER

BAKER

MACON

PIKE

TAYLOR

UPSON

DECATUR

EARLY

MITCHELL

DOOLY

MILLER

TERRELL

WORTH

TALBOT

MARION

CRISP

CALHOUN DOUGHERTY

MERIWETHER

RANDOLPH

COWETA

FAYETTE

WEBSTER

SCHLEY

SEMINOLE

CRAWFORD

SPAULDING

CLAYTON

LAMAR

FULTON

GEORGIA

Flint

 River

 Basin

EXPLANATION

Streamgage

Study area

Albany

20 MILES

20 KILOMETERS

02352500

N

Base modified from U.S. Geological Survey

1:100,000-scale digital data

10

0

0

10

Introduction 3
Description of Study Area

In the Albany area, the natural state of the Flint River 

has been changed by the construction of dams, a human-made 

peninsula, and numerous bridges (fig. 2). The northern part 

of the area includes the Muckafoonee Diversion Dam, which 

impounds Muckalee and Kinchafoonee Creeks at low and 

medium flows. The area also includes Lake Chehaw Dam 

(a Georgia Power Company facility), which regulates the 

combined flows of the Flint River (drainage area 4,190 mi2), 

Kinchafoonee Creek (drainage area 658 mi2), and Muckalee 

Creek (drainage area 443 mi2). The recreation area around 

Lake Chehaw is being connected to downtown Albany via the 

development of Riverwalk Park. From Lake Chehaw Dam, the 

Flint River passes under five highway and two railroad bridges 

as shown in figure 2. (The Liberty Expressway crossing is 

composed of two bridges.) In addition to the river community 

infrastructure, there are two natural features that substantially 

affect flood flows in the study reach. The natural river constriction in Albany is most evident near the downtown Broad 

Avenue and Oglethorpe Boulevard bridges. The river flow 

through this area is also limited by a human-made peninsula 

about 500 ft downstream from the Oglethorpe Boulevard 

bridge. This peninsula is an area of the channel filled in from 

the east bank of the river, and is visible at low flows. During 

high flows, the peninsula creates a large amount of turbulence. 

The second natural feature is the river oxbow near Oakridge 

Drive (fig. 2). Both features constrain flood flow through 

Albany. The community infrastructure—including dams, 

roadway embankments, and bridges—tends to further hinder 

flood flows through Albany. Of these features, the most influential on extreme high flows is the river constriction at Broad 

Avenue and Oglethorpe Boulevard. The Riverwalk Park, 

which is being constructed on the west bank of the river, may 

reduce roughness and improve conveyance, thereby improving 

flood flows.

Previous Studies

Previous studies include a flood insurance study for 

Dougherty County and incorporated areas (Federal Emergency Management Agency, 2001), and a Section 205 detailed 

project report and environmental assessment for Kinchafoonee 

Creek and Hogpen Ditch at Albany (U.S. Army Corps of Engineers, 1997). The U.S. Army Corps of Engineers (USACE) 

completed a Section 205 detailed project report for the Flint 

River at Albany (U.S. Army Corps of Engineers, 2002), which 

included simulation of the Flint River at Albany. The USACE 

study involved usage of the one-dimensional step-backwater 

model HEC-2, developed by the Hydrologic Engineering Center in Davis, California (U.S. Army Corps of Engineers, 1990). 

The HEC-2 model was calibrated to high watermarks from the 

July 1994 Tropical Storm Alberto flood. 

Method of Study

The current study included field investigations, review 

of previous studies, data acquisition, and model development. Numerous field visits were required to obtain sufficient site information, flood and flood-damage history, 

bridge-structure characteristics, stream cross sections, and 

land-cover characteristics. 

The study was performed in several stages:

1. Data necessary for the model were obtained 

including ground-surface altitude, orthophoto 

imagery, river cross sections, bridge geometry, 

floodplain boundaries, and land use.

2. A finite-element surface-water inundation 

model was constructed using Surface Water 

Modeling System (SMS) (Environmental 

Monitoring Systems, Incorporated, 2006) and 

FESWMS-2DH (U.S. Geological Survey, 2006).

3. Different model scenarios were run, and results 

were obtained for each 1-ft interval.

4. Model results were mapped onto the imagery 

with floodplain boundaries and other pertinent 

information (R.W. Weathersby, GIS Specialist, 

Monochrome Imagery of Albany and Dougherty County, Albany and Dougherty County 

Planning and Development Services, written 

commun., 2003).

5. Problem areas were identified where the model 

could be used to study the effects of changes 

along the river. 

Acknowledgments

The technical assistance of Randy Weathersby, 

Elizabeth Dean, and Tracy Hester from the Albany and 

Dougherty County Planning and Development Services is 

greatly appreciated.

4 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Two-Dimensional FloodInundation Model

The two-dimensional flood surfaces for the Flint River 

floodplain at Albany were used to develop the USGS twodimensional, steady-state flow model based on finite-element 

principles (FESWMS-2DH) (U.S. Geological Survey, 2006), 

along with SMS (Environmental Modeling Systems, Incorporated, 2006). Flood surfaces, in 1-ft increments, were developed that correspond to streamflow values from gage heights 

at the USGS Albany streamgage (fig. 2; 02352500) from about 

30 ft (or 179.5 ft NAVD 88, just below the 10-year recurrence 

interval flood) to about 43 ft (or 192.5 ft, the peak altitude 

for Tropical Storm Alberto during July 1994). These surfaces 

were printed over 1-ft resolution gray-scale digital orthophotos 

(R.W. Weathersby, GIS Specialist, Monochrome Imagery of 

Albany and Dougherty County, Albany and Dougherty County 

Planning and Development Services, written commun., 2003). 

The USGS streamgage (02352500) at Albany is a National 

Weather Service flood-forecast location, and flood-forecast 

predictions are indexed to gage heights at the streamgage 

(the difference between streamgage stage and water-surface 

altitude is 149.5 ft). In addition to the flood-extent information 

provided by this effort, depth, velocities, sectional-flow and 

flow-direction vectors were calculated. These hydraulic data 

can be displayed and used to develop warnings and hazard 

scales for a flood. 

The mesh for the model was initially designed as a 

120-ft square grid to ensure equal resolution across the study 

area. During model development, it was determined that the 

area along the Flint River required a more detailed mesh with 

cells of about 20 ft by 40 ft, because of high flow volumes 

and velocities, steep bank slopes, and the presence of bridge 

structures (fig. 4). The cells on the outside of the river channel 

were transitioned into the square grid cells across the rest of 

the study area. Altitude was obtained from the City of Albany 

as point data, and an altitude grid with 10-ft horizontal cells 

was produced for input to the model. Cross sections of the 

stream channel were determined for the study reach and were 

georeferenced to the model. Additional altitude points were 

added to the altitude grid at a point just downstream from the 

Oglethorpe Boulevard bridge where a human-made peninsula 

was built into the river channel. A number of the square and 

rectangular cells in the mesh had an indefinite flow direction 

because they included two diagonal corners that are higher 

than the other two corners, which could result in two different 

flow directions. These cells were split into two triangular cells 

to alleviate this problem (Environmental Monitoring Systems, 

Incorporated, 2006).

All areas in the study reach were classified into five 

land-cover categories: clear (paved areas, fields, and grass 

areas), forest, low-density urban, high-density urban, and 

channel. Roughness coefficients (Manning’s n), derived from 

Barnes (1967), were assigned to each land-cover category: 

clear—0.03, forest—0.13, low-density urban—0.15, highdensity urban—0.20, and the channel varied from 0.027 to 

0.0415. The calibrated model incorporates the effects of the 

partially completed (as of 2005) Riverwalk Park at Albany. 

The Riverwalk is a new park adjacent to the Flint River, and 

consists of green space and pedestrian walkways. 

The boundary conditions used for the model are inflow 

volume and outflow altitude. The inflow boundary is located 

at the edge of the model mesh downstream from the Lake 

Chehaw Dam and the Muckafoonee Diversion Dam. The outflow boundary is located on the south edge of the model mesh 

where the outflow boundary altitude is higher than groundsurface altitude. As the outflow boundary altitude changes, the 

location of outflow boundary is adjusted. To obtain a stable 

solution, initial model boundaries must be set to a no-flow 

condition with a constant water level across the entire mesh. 

Boundary conditions are then slowly adjusted to their final 

values. Initial boundary conditions used to start the model were 

an inflow of 0 ft3/s and an outflow altitude of 231 ft. Through 

an iterative process, the inflow was increased gradually to 

123,000 ft3/s, followed by a reduction of the outflow boundary 

condition altitude of 184.5 ft. This altitude was obtained from 

the USACE (2002) Flint River report. Following adjustment of 

boundary conditions, bridge piers and deck altitudes for the five 

highway bridges (two at Liberty Expressway) and two railroad 

bridges were input to the model. Cells in the study area that 

were dry at this point were removed from the model, and the 

model was reconfigured to its final mesh configuration.

In the Albany area during Tropical Storm Alberto, a 

number of areas near the Flint River were inundated because 

of underground hydraulic connections, such as storm sewers 

and subsurface natural flow pathways. To show these lowlying areas, simulated river-surface altitudes were extended 

beyond the river banks. A number of these low areas with 

altitudes below the river-surface altitude also were mapped 

in figures A1–A14 (Appendix A). During the flood on 

March 30, 2005, a number of these low-lying areas were 

checked for flooding. No area more than 0.5 mi from the river 

was found to be flooded, so the mapped low-lying areas are 

limited to an area within 0.5 mi of the modeled flood area.

Two-Dimensional Flood-Inundation Model 5
boundary

Inflow

Outflow boundary

Liberty Expressway

Slappy Blvd

Oglethorpe Blvd

Jefferson St

Broad Ave

Oakridge Dr

oxbow

Newton Road

Radium Springs Rd

Study area

N

0 0.5 1 MILE

0 0.5 1 KILOMETER

Image from Albany-Dougherty Planning Commission, 1996

Roads from Georgia Department of Transportation, 1998

Flint River at 

Albany, Georgia

(02352500)

Square mesh cell

Mesh cell split due 

 to indefinite 

 flow direction

EXPLANATION

84°11’ 84°10’ 84°09’ 84°08’

31°33’

31°34’

31°35’

31°36’

19 82

Georgia Southern Railroad

Figure 4. Finite-element mesh used for two-dimensional model of the Flint River at Albany, Georgia. Inflow and 

outflow boundary conditions are for a water-surface altitude of 192.5 feet at the Albany streamgage.

6 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Model Calibration

The model was calibrated to observed flooding from 

Tropical Storm Alberto during July 1994, and a smaller flood 

during March 2005. Initial model calibration involved running the model for the peak streamflow observed during the 

1994 Tropical Storm Alberto flood, about 123,000 ft3/s, which 

was estimated to have a recurrence interval of between 200 

and 300 years. An adjustment of the channel roughness for 

the model was done until the water-surface altitude at the 

USGS Albany streamgage was 192.5 ft. The model essentially reproduced the measured Tropical Storm Alberto flood 

inundation, as indicated in the comparison of the model results 

with the Federal Emergency Management Agency (FEMA) 

floodplain at Albany shown in figure A14. The actual flood 

altitudes and simulated values are in close agreement as indicated by the position of the inundated area boundary between 

the 100- and the 500-year floodplain boundaries (fig. A14). 

Once the model was calibrated for the 192.5-ft water-surface 

altitude at Albany, the inflow was gradually lowered to the 

value corresponding to an altitude of 191.5 ft. The outflow 

altitude was then gradually lowered to 183.5 ft to represent 

the 1-ft incremental decrease in the water-surface altitude. 

Based on an earlier modeling study by the USACE (2002), an 

assumption was made that a 1-ft drop at the gage corresponded 

to a 1-ft drop at the outflow. Following adjustment of stage at 

the outflow boundary, the channel roughness value was adjusted 

until the model was at 191.5-ft altitude at the streamgage. 

This procedure was repeated for the rest of the water-surface 

altitudes down to the 179.5-ft altitude. The channel roughness 

ranged from 0.027 to 0.0415. At the 192.5-ft gage altitude, the 

model became unstable when the eddy viscosity was lowered 

below 6.5. As a result of this, channel roughness was used for 

model calibration and eddy viscosity was set at 6.5.

A continuity check of the model was done for the 192.5-ft 

altitude by dividing a cross section of the model into sections 

of about 20 ft. The width multiplied by the depth multiplied 

by the velocity gave the flow rate for that section. The section 

flows were then added together to form a total flow across 

the section. The resulting flow was 124,904 ft3/s, which is 

within 1.5 percent of 123,000 ft3/s, the model flow input for 

the 193-ft altitude. In addition, a continuity check was done 

at a cross section that included the Oakridge Drive bridge; the 

continuity check helped determine the percentage of water 

flowing under the Oakridge Drive bridge and the percentage 

flowing around it. The model indicated that 45,808 ft3/s was 

flowing around the bridge and 74,466 ft3/s was flowing under 

the bridge. The sum of these two flows is 2.2 percent different 

than the expected 123,000 ft3/s, which can probably be attributed to the unstable nature of the model in the vicinity of the 

bridge. In terms of percentages, only 62 percent of the flow at 

this water-surface altitude is directed under the Oakridge Drive 

bridge, with 38 percent of the flow directed around the bridge.

On March 30, 2005, a field check of simulated and 

measured flood extents was done using a flood at about 182-ft 

altitude. The actual flood extent at multiple sites along the 

model reach was checked against simulated values. In all locations, the measured extent confirmed the boundary that was 

simulated by the model. Selected photographs of the sites that 

were checked and their locations are shown in Appendix B.

Two-Dimensional Flood-Inundation Model 7
Simulated Flood Inundation

A series of simulated flood inundation maps was prepared to assist planners and emergency personnel in dealing 

with flood depth hazards from future floods. The extent of

 the inundated areas is shown in Appendix A (figs. A1–A14). 

The depth of water—which is categorized into three flood 

depth hazard: less than 1 ft; between 1 and 3 ft; and greater 

than 3 ft—also is shown in Appendix A (figs. A15–A28). 

About 4.8 mi of the Flint River at Albany were included 

within the model. At a flood altitude of 179.5 ft, about 1.5 mi2

were simulated as being inundated and at a flood altitude of 

192.5 ft, about 5.9 mi2 were inundated.

The simulated velocity magnitude of the area around 

the Oakridge Drive bridge is shown in figure 5. A substantial 

drop in velocity is evident upstream from the bridge. The 

drop in velocity occurs because of the effects of the highway 

embankment, the bridge, and the nearby Flint River channel 

oxbow. Selected simulated flow profiles along the river for 

the area of the model are shown in figure 6. The flow profile 

upstream from the Oakridge Drive bridge has leveled, or in 

some cases increased. This corresponds with the area of lower 

velocities shown in figure 5. These model results support the 

findings described in the USACE (2002) Flint River report, 

concerning modifications of the channel floodway upstream 

and downstream from the bridge. Likewise, the model could 

be configured to simulate the effects of changes in the floodplain, such as modifications to the channel or expansion of 

the Riverwalk Park.

Model Limitations

The results of this study could differ from actual flood 

results for several reasons. The model is based on a steadystate constant flow and does not account for rising or falling 

flow values or for any inflow into the system from sources 

other than the Flint River. The boundary condition at the 

outflow is assumed to be a constant value across the entire 

southern edge of the mesh, and these values are not known 

precisely. Finally, the discretization of the altitude and the 

mesh causes the model to be an approximation of the actual 

conditions in the area.

Summary

Potential flow characteristics of future flooding along 

a 4.8-mile reach of the Flint River in Albany, Georgia, were 

simulated using recent digital-elevation-model data and the 

U.S. Geological Survey (USGS) finite-element surface-water 

modeling system for two-dimensional flow in the horizontal 

plane (FESMWS-2DH). Results of the study—conducted 

by the USGS in cooperation with the City of Albany and 

Dougherty County, Georgia—are being used by the local 

community to plan for future floods.

Information on land-surface altitude, orthophoto imagery, 

river cross sections, bridge geometry, floodplain boundaries, 

and land use were compiled into a Geographic Information 

System to facilitate model development. A finite-element 

mesh for the model was created using the land-surface altitude 

and river cross-section data. Land-use data were used for categorizing areas for roughness coefficients, and bridge geometry 

was entered into the model. The model was calibrated to a peak 

flow of 123,000 cubic feet per second (ft3/s) at a water-surface 

altitude of 192.5 feet (ft) at the Flint River at Albany, Georgia, 

streamgage (02352500), and was gradually reduced at 1-ft 

increments to a flow of 52,500 ft3/s and a water-surface altitude 

of 179.5 ft. Floodplains were mapped over orthophoto imagery 

to show the floodplain extent as well as the water depth. Simulated flow velocities upstream from the Oakridge Drive bridge 

indicated an area of decreased velocity, and water-surface altitude profiles in this area indicated a leveling or slight increase 

in the water surface upstream from the bridge. 

8 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Summary 9

192.5 feet gage altitude

187.5 feet gage altitude

185.5 feet gage altitude

180.5 feet gage altitude

DISTANCE DOWN RIVER, IN FEET

ALTITUDE OF WATER SURFACE, IN FEET ABOVE NAVD 88

170

175

180

185

190

195

0 5,000 10,000 15,000 20,000 25,000 30,000

Flint River, Albany, Georgia (02352500)

Liberty Expressway

Georgia Southern Railroad

Broad Avenue

Oglethorpe Boulevard

Oakridge Drive

Figure 6. Simulated flow profiles by streamgage altitude in model area for the Flint River at Albany, Georgia 

(see figure 4 for location).

Image from Albany-DoughertyPlanning Commission, 1996

Study

area

EXPLANATION

Simulated water velocity,

 in feet per second

Greater than 0 to 1

0

Greater than 1 to 2

Greater than 2 to 3

Greater than 3 to 4

Greater than 4 to 5

Greater than 5 to 6

6 to 7 

Not in model area

Map

area

N

Figure 5. Velocity distribution of the Flint River near Oakridge Drive at Albany, Georgia.
References Cited

Barnes, H.H., 1967, Roughness characteristics of natural 

channels: U.S. Geological Survey Water-Supply 

Paper 1849, 213 p., available online at http://pubs.usgs.

gov/wsp/wsp_1849/.

Environmental Monitoring Systems, Incorporated, 2006, 

Surface-water Modeling System (SMS): South Jordan, 

Utah, accessed September 2006, at http://www.ems-i.com.

Federal Emergency Management Agency, 2001, Flood 

insurance study for Dougherty County, Georgia, and 

incorporated areas, 29 p.

Georgia Emergency Management Agency and the Georgia 

Department of Natural Resources, 1998, The Governor’s 

Task Force on Reducing the Impacts of Flooding in the 

Flint River Basin, Preliminary Report, 22 p.

Konrad, C.P., 2003, Effects of urban development on floods: 

U.S. Geological Survey Fact Sheet 076-03, 4 p., available 

online at http://pubs.usgs.gov/fs/fs07603/.

Stamey, T.C., 1996, Summary of data-collection activities and 

effects of flooding from Tropical Storm Alberto in parts of 

Georgia, Alabama, and Florida, July 1994: U.S. Geological 

Survey Open-File Report 96-228, 23 p., available online at 

http://pubs.usgs.gov/of/1996/ofr96-228/.

10 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia

Stamey, T.C., and Hess, G.W., 1993, Techniques for 

estimating magnitude and frequency of floods in rural 

basins of Georgia: U.S. Geological Survey Water-Resources 

Investigations Report 93-4016, 75 p., available online at 

http://pubs.er.usgs.gov/usgspubs/wri/wri934016

U.S. Army Corps of Engineers, 1990, HEC-2 water surface 

profiles, User’s manual: Davis, California, Hydrologic 

Engineering Center, variable pagination

U.S. Army Corps of Engineers, Mobile District, 1997, 

Section 205 detailed project report and environmental 

assessment, Kinchafoonee Creek and Hogpen Ditch, 

Albany, Georgia: Mobile, Alabama, various pagination.

U.S. Army Corps of Engineers, Mobile District, 2002, 

Section 205 detailed project report, Flint River Albany, 

Georgia: Mobile, Alabama, various pagination.

U.S. Geological Survey, Finite-element surface-water modeling system for two-dimensional flow in the horizontal 

plane (FESWMS-2DH), accessed September 2006, at 

http://water.usgs.gov/software/feswms.html.
Appendix A 11

Appendix A. Images showing simulated flood inundation 

and hazard scale at the Albany streamgage compared 

with Federal Emergency Management Agency’s 

Digital Flood Insurance Rate Maps for the Flint River 

in Albany, Georgia, 1998
EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

Flood altitude at gage: 179.5 feet NAVD 88

Gage stage: 30 feet

Inflow: 52,500 cubic feet per second

0

0

Image from Albany-Dougherty Planning Commission, 1996

Figure A1. Simulated flood inundation for a water-surface altitude of 179.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

12 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

0 0.25 0.5 1 MILE

0 0.25 0.5 1 KILOMETER

Flood altitude at gage: 180.5 feet NAVD 88

Gage stage: 31 feet

Inflow: 56,700 cubic feet per second

Image from Albany-Dougherty Planning Commission, 1996

Figure A2. Simulated flood inundation for a water-surface altitude of 180.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

Appendix A 13
EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

USGS streamgage

Flood altitude at gage: 181.5 feet NAVD 88

Gage stage: 32 feet

Inflow: 61,100 cubic feet per second

Study area

Figure A3. Simulated flood inundation for a water-surface altitude of 181.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

14 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A4. Simulated flood inundation for a water-surface altitude of 182.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE 

0.25 0.5 1 KILOMETER

0

0

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 182.5 feet NAVD 88

Gage stage: 33 feet

Inflow: 65,600 cubic feet per second

Image from Albany-Dougherty Planning Commission, 1996

Appendix A 15
Figure A5. Simulated flood inundation for a water-surface altitude of 183.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 183.5 feet NAVD 88

Gage stage: 34 feet

Inflow: 70,400 cubic feet per second

16 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A6. Simulated flood inundation for a water-surface altitude of 184.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 184.5 feet NAVD 88

Gage stage: 35 feet

Inflow: 75,400 cubic feet per second

Appendix A 17
Figure A7. Simulated flood inundation for a water-surface altitude of 185.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 185.5 feet NAVD 88

Gage stage: 36 feet

Inflow: 80,600 cubic feet per second

18 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A8. Simulated flood inundation for a water-surface altitude of 186.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 186.5 feet NAVD 88

Gage stage: 37 feet

Inflow: 86,100 cubic feet per second

Appendix A 19
Figure A9. Simulated flood inundation for a water-surface altitude of 187.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 187.5 feet NAVD 88

Gage stage: 38 feet

Inflow: 91,700 cubic feet per second

20 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A10. Simulated flood inundation for a water-surface altitude of 188.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 188.5 feet NAVD 88

Gage stage: 39 feet

Inflow: 97,500 cubic feet per second

Appendix A 21
Figure A11. Simulated flood inundation for a water-surface altitude of 189.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 189.5 feet NAVD 88

Gage stage: 40 feet

Inflow: 104,000 cubic feet per second

22 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A12. Simulated flood inundation for a water-surface altitude of 190.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 190.5 feet NAVD 88

Gage stage: 41 feet

Inflow: 110,000 cubic feet per second

Appendix A 23
Figure A13. Simulated flood inundation for a water-surface altitude of 191.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

N

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 191.5 feet NAVD 88

Gage stage: 42 feet

Inflow: 116,000 cubic feet per second

Flint River at 

Albany, Georgia

(02352500)

Image from Albany-Dougherty Planning Commission, 1996

EXPLANATION

24 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A14. Simulated flood inundation for a water-surface altitude of 192.5 feet at the Albany streamgage 

compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) for the 

Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Modeled inundated areas

Modeled low areas of possible inundation

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Flood altitude at gage: 192.5 feet NAVD 88

Gage stage: 43 feet

Inflow: 123,000 cubic feet per second

Appendix A 25
EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 179.5 feet NAVD 88

Gage stage: 30 feet

Inflow: 52,500 cubic feet per second

Figure A15. Simulated flood-inundation hazard scale for a water-surface altitude of 179.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

26 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A16. Simulated flood-inundation hazard scale for a water-surface altitude of 180.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 180.5 feet NAVD 88

Gage stage: 31 feet

Inflow: 56,700 cubic feet per second

Appendix A 27
Figure A17. Simulated flood-inundation hazard scale for a water-surface altitude of 181.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 181.5 feet NAVD 88

Gage stage: 32 feet

Inflow: 61,100 cubic feet per second

28 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A18. Simulated flood-inundation hazard scale for a water-surface altitude of 182.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 182.5 feet NAVD 88

Gage stage: 33 feet

Inflow: 65,600 cubic feet per second

Appendix A 29
Figure A19. Simulated flood-inundation hazard scale for a water-surface altitude of 183.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 183.5 feet NAVD 88

Gage stage: 34 feet

Inflow: 70,400 cubic feet per second

30 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A20. Simulated flood-inundation hazard scale for a water-surface altitude of 184.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 184.5 feet NAVD 88

Gage stage: 35 feet

Inflow: 75,400 cubic feet per second

Appendix A 31
Figure A21. Simulated flood-inundation hazard scale for a water-surface altitude of 185.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 185.5 feet NAVD 88

Gage stage: 36 feet

Inflow: 80,600 cubic feet per second

32 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A22. Simulated flood-inundation hazard scale for a water-surface altitude of 186.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 186.5 feet NAVD 88

Gage stage: 37 feet

Inflow: 86,100 cubic feet per second

Appendix A 33
Figure A23. Simulated flood-inundation hazard scale for a water-surface altitude of 187.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 187.5 feet NAVD 88

Gage stage: 38 feet

Inflow: 91,700 cubic feet per second

Image from Albany-Dougherty Planning Commission, 1996

34 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A24. Simulated flood-inundation hazard scale for a water-surface altitude of 188.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 188.5 feet NAVD 88

Gage stage: 39 feet

Inflow: 97,500 cubic feet per second

Appendix A 35
Figure A25. Simulated flood-inundation hazard scale for a water-surface altitude of 189.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 189.5 feet NAVD 88

Gage stage: 40 feet

Inflow: 104,000 cubic feet per second

36 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A26. Simulated flood-inundation hazard scale for a water-surface altitude of 190.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 190.5 feet NAVD 88

Gage stage: 41 feet

Inflow: 110,000 cubic feet per second

Appendix A 37
Figure A27. Simulated flood-inundation hazard scale for a water-surface altitude of 191.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Flood altitude at gage: 191.5 feet NAVD 88

Gage stage: 42 feet

Inflow: 116,000 cubic feet per second

38 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure A28. Simulated flood-inundation hazard scale for a water-surface altitude of 192.5 feet at the Albany 

streamgage compared with Federal Emergency Management Agency’s Digital Flood Insurance Rate Maps (DFIRM) 

for the Flint River in Albany, Georgia, 1998.

EXPLANATION

N

Flint River at 

Albany, Georgia

(02352500)

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Flood altitude at gage: 192.5 feet NAVD 88

Gage stage: 43 feet

Inflow: 123,000 cubic feet per second

WATER DEPTH ABOVE LAND SURFACE

DFIRM 500-year floodplain

DFIRM 100-year floodplain

Study area

USGS streamgage

Less than 1 foot

1 foot to 3 feet

Greater than 3 feet

Appendix A 39
40 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Appendix B. Flood extent photographs 

for the Flint River in Albany, Georgia

Appendix B 41
Figure B1. Simulated flood inundation for a water-surface altitude of 181.5 feet at the Albany streamgage with 

locations of flood extent photographs (shown in Figure B2) for the Flint River in Albany, Georgia. 

2

3

4

5

6

1

1

Flint River at 

Albany, Georgia

(02352500)

EXPLANATION

N

0.25 0.5 1 MILE

0.25 0.5 1 KILOMETER

0

0

Image from Albany-Dougherty Planning Commission, 1996

Location of photograph

USGS streamgage

Modeled inundated areas

Modeled low areas of possible inundation

Flood altitude at gage: 181.5 feet NAVD 88

Gage stage: 32 feet

Inflow: 61,100 cubic feet per second

Study area

42 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia
Figure B2. Flood extent photographs for the Flint River in Albany, Georgia. (Photographs by Jonathan W. Musser, 

USGS, March 3, 2005. See figure B1 for location.)

2

3 4

5 6

1

Appendix B 43
44 Two-Dimensional Flood-Inundation Model of the Flint River at Albany, Georgia

Manuscript approved for publication, May 30, 2007

Prepared by USGS Georgia Water Science Center

Editing and layout by Patricia L. Nobles

Graphics by Bonnie J. Turcott

For more information concerning the research 

in this report, contact

USGS Georgia Water Science Center, Atlanta

telephone: 770-903-9100