U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008–5171

Prepared in cooperation with the City of Montgomery, Alabama

Simulation of Flood Profiles for Catoma Creek 

near Montgomery, Alabama, 2008
Cover. Catoma Creek near Hayneville Road, Montgomery, Alabama.
Simulation of Flood Profiles for Catoma Creek 

near Montgomery, Alabama, 2008

By K.G. Lee and T.S. Hedgecock

Prepared in cooperation with the City of Montgomery, Alabama

Scientific Investigations Report 2008–5171

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: 2008

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Lee, K.G., and Hedgecock, T.S., 2008, Simulation of flood profiles for Catoma Creek near Montgomery, Alabama, 2008: 

U.S. Geological Survey Scientific Investigations Report 2008–5171, 32 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................1

Description of the Study Reach..........................................................................................................1

Flood History..........................................................................................................................................3

Flood of 1961 .................................................................................................................................3

Flood of 1990 .................................................................................................................................4

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

Approach.........................................................................................................................................................6

Data Collection......................................................................................................................................6

Hydrologic Analyses ..........................................................................................................................10

Alabama River.....................................................................................................................................10

Hydraulic Modeling ............................................................................................................................12

Model Calibration ......................................................................................................................12

Simulation of Flood Flows.........................................................................................................13

Summary .......................................................................................................................................................17

References Cited .........................................................................................................................................17

Appendix. Photographs showing locations of cross sections for 

Catoma Creek near Montgomery, Alabama, 2008.....................................................................19

Figures

1–8. Maps showing—

 1. The Catoma Creek basin, Montgomery, Alabama ...........................................................2

 2. Isohyetal map of the Southeastern States showing storm rainfall, 

February 23–26, 1961.............................................................................................................4

 3. Areas of Alabama, Georgia, and Florida affected by heavy rainfall 

in February and March 1990 ................................................................................................5

 4. Locations of lines of equal recurrence intervals for March 1990 

peak discharges for unregulated and unurbanized streams

in Alabama, Georgia, and Florida........................................................................................6

 5. Approximate locations of cross sections A–F in the Catoma Creek study reach......7

 6. Approximate locations of cross sections D–I in the Catoma Creek study reach.......8

 7. Catoma Creek study reach, Montgomery County, Alabama..........................................9

 8. Land-cover data for the Catoma Creek basin.................................................................11

9–11. Graphs showing—

 9. Computed and observed flood profiles for the March 1990 

flood for Catoma Creek near Montgomery, Alabama....................................................13

 10. Computed flood profiles for current conditions for 

Catoma Creek near Montgomery, Alabama....................................................................15

 11. U.S. Geological Survey and Federal Emergency Management Agency 

computed 100-year flood profiles for Catoma Creek 

near Montgomery, Alabama..............................................................................................16
iv

Conversion Factors

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

) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29).

Within the study reach, the National Geodetic Vertical Datum of 1929 was an average of 

0.03 foot lower than the North American Vertical Datum of 1988.

Abbreviations and Acronyms

FEMA Federal Emergency Management Agency

FIS Flood Insurance Study

HEC-RAS Hydrologic Engineering Center’s River Analysis System

NGVD29 National Geodetic Vertical Datum of 1929

NLCD National Land Cover Dataset

USGS U.S. Geological Survey

Tables

1. Historical flood flows at the Catoma Creek streamgage 

(USGS 02421000) near Montgomery, Alabama ........................................................................3

2. Computed peak flows for the March 17, 1990, flood for 

Catoma Creek near Montgomery, Alabama...........................................................................10

3. Computed peak flows for current (2008) conditions for 

Catoma Creek near Montgomery, Alabama...........................................................................10

4. Difference between observed and computed water-surface profiles for 

the March 1990 flooding of Catoma Creek near Montgomery, Alabama ..........................12

5. Computed flood profiles for current (2008) conditions for 

Catoma Creek near Montgomery, Alabama...........................................................................14

6. U.S. Geological Survey and Federal Emergency Management Agency computed 

100-year flood elevations for Catoma Creek near Montgomery, Alabama.......................15

7. 100-year water-surface elevations with local roadway crossings 

for Catoma Creek near Montgomery, Alabama.....................................................................16
Abstract

A one-dimensional step-backwater model was used to 

simulate flooding conditions for Catoma Creek near Montgomery, Alabama. A peak flow of 50,000 cubic feet per 

second was computed by the U.S. Geological Survey for the 

March 1990 flood at the Norman Bridge Road gaging station. Using this estimated peak flow, flood-plain surveys with 

associated roughness coefficients, and surveyed high-water 

marks for the March 1990 flood, a flow model was calibrated 

to closely match the known event. The calibrated model then 

was used to simulate flooding for the 10-, 50-, 100-, and 

500-year recurrence-interval floods. The 100-year flood stage 

for the Alabama River also was computed in the vicinity of the 

Catoma Creek confluence using observed high-water profiles 

from the 1979 and 1990 floods and gaging-station data. 

The results indicate that the 100-year flood profile for 

Catoma Creek within the 15-mile study reach is about 2.5 feet 

higher, on average, than the profile published by the Federal 

Emergency Management Agency. The maximum and minimum differences are 6.0 feet and 0.8 foot, respectively. All 

water-surface elevations computed for the 100-year flood are 

higher than those published by the Federal Emergency Management Agency. The 100-year flood stage computed for the 

Alabama River in the vicinity of the Catoma Creek confluence 

was about 4.5 feet lower than the elevation published by the 

Federal Emergency Management Agency. The results of this 

study provide the community with flood-profile information 

that can be used for flood-plain mitigation, future development, and safety plans for the city.

Introduction

The future flooding potential of Catoma Creek is of 

great interest to the City of Montgomery and local residents. 

Effective flood-plain management and planning depend on 

the accurate determination of flood profiles. In most cases, 

the application of both a hydrologic and a hydraulic model is 

necessary in the computation of flood profiles. 

The Federal Emergency Management Agency’s (FEMA) 

flood profiles are being used for flood insurance zoning and 

planning and design for current and future development. 

The Flood Insurance Study (FIS) was completed in January 1991 and released in January 1992. Select portions of the 

study were updated and released in 2003 (Federal Emergency 

Management Agency, 2003). Approximately 43.5 miles (mi) 

of Catoma Creek are included in the original FIS. The portion 

updated in the 2003 study only includes about 1.25 mi of the 

stream reach. Since the completion of the 1992 study, local 

residents have questioned the validity of the profiles being 

used for flood-plain zoning. 

The U.S. Geological Survey (USGS), in cooperation 

with the City of Montgomery, revised the hydrology and flood 

profiles for an approximately 15-mi reach of Catoma Creek to 

accurately depict the current flooding potential. These flood 

profiles are designed to aid Montgomery’s engineers and planners in making decisions concerning flood-plain mitigation, 

future development, current zoning, and evacuation routes. 

Purpose and Scope

The purpose of this report is to document the results of 

an investigation to determine the flood profiles for a reach of 

Catoma Creek that is about 15 mi long. This reach extends 

from Norman Bridge Road downstream to the confluence 

with the Alabama River. Flood profiles were developed for the 

10-, 50-, 100-, and 500-year floods by using hydrologic and 

hydraulic models. Prior to the development of these profiles, 

the hydraulic model was calibrated to match the March 17, 

1990, flood in order to apply the model to other flooding scenarios. The flood-profile information in this report can be used 

by the community for future planning and design purposes.

Description of the Study Reach

The City of Montgomery is in south-central Alabama in 

Montgomery County. The county is bound on the northeast 

by the Tallapoosa River. The Tallapoosa River joins the Coosa 

River to form the Alabama River, the northwest county boundary. The stream network in the county is made up of several 

large streams feeding the Tallapoosa and Alabama Rivers. 

Approximately 70 percent of the surface area of the county 

drains into the Alabama River, and 18 percent drains into the 

Tallapoosa River. The large streams contributing flow directly 

to the Alabama River are Pintlalla Creek and Catoma Creek 

(fig. 1). 

Simulation of Flood Profiles for Catoma Creek 

near Montgomery, Alabama, 2008

By K.G. Lee and T.S. Hedgecock
2 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure 1. The Catoma Creek basin, Montgomery County, Alabama. 

Catoma

Pintlalla

Catoma Cr.

Little

Creek

Creek

Alabama

Coosa

River

River

River

Caney

Branch

AUTAUGA

COUNTY

LOWNDES

COUNTY

CRENSHAW

COUNTY PIKE

COUNTY

BULLOCK

COUNTY

ELMORE COUNTY

MONTGOMERY MACON COUNTY

COUNTY

Tallapoosa

Line

Creek

Catoma

Creek

Ramer

Creek

0 5 10 KILOMETERS

0 5 10 MILES

Catoma Creek basin boundary

Catoma Creek gage (USGS 02421000)

Alabama River gage (USGS 02420000)

EXPLANATION

Base from U.S. Geological Survey digital data, 1:100,000

Hydrography from U.S. Environmental Protection Agency

Reach File 1, 1:500,000

LOCATION OF CATOMA CREEK

BASIN IN MONTGOMERY COUNTY,

ALABAMA

Madison

Snowdoun

Montgomery

Pike Road

Cecil

Hunter

Grady

Ramer

Sprague

Pine

Level

8624’ 86

3224’

32
Introduction 3

The drainage area of Catoma Creek at the confluence 

with the Alabama River is 360 square miles (mi2). This is 

approximately 45 percent of Montgomery County’s total 

surface area (fig. 1). The major tributaries to Catoma Creek are 

Ramer Creek (82 mi2) and Little Catoma Creek (53 mi2). The 

study reach is a 15-mi portion of Catoma Creek that extends 

from the USGS streamgage (USGS 02421000) at Norman 

Bridge Road to the confluence with the Alabama River. The 

study reach contains 7 roadway crossings (including railroads) 

consisting of 13 hydraulic structures. The mean slope of the 

channel in the study reach is 2 feet per mile (ft/mi). The stream 

flows in a northwesterly direction and has a mean bankfull 

width of 190 feet (ft) with minimum and maximum widths 

of 90 and 570 ft, respectively. Bankfull width is the width 

between the top left and right channel banks for a stream channel. The average flood-plain width (headwater flooding only) 

is 5,600 ft and ranges from about 880 to 10,300 ft. 

Flood History

Two types of storms are associated with floods in 

Alabama—frontal systems and tropical storms. The intense 

precipitation associated with tropical storms and hurricanes, 

thunderstorms, and slow-moving frontal systems usually result 

in flooding. The flooding potential is increased when rivers 

and creeks are already swollen from spring runoff. The mean 

annual precipitation varies seasonally and geographically. The 

statewide mean rainfall is about 55 inches and varies from 

about 50 inches in central and west-central Alabama to about 

65 inches near the Gulf of Mexico (Paulson and others, 1991).

Past flooding on Catoma Creek has affected many 

residents of Montgomery County. The USGS has operated 

a streamflow gaging station (USGS 02421000) at the Norman Bridge Road crossing of Catoma Creek since June 1952. 

Streamflow records indicate significant flooding along the 

creek in 1961, 1975, and 1990. Minor flooding also occurred 

in 1949, 1958, 2001, and 2005 (table 1).

A portion of the study reach is directly affected by river 

flooding as a result of backwater. The downstream boundary 

of the study reach is at the confluence of Catoma Creek with 

the Alabama River. To determine the effect of the Alabama 

River on Catoma Creek, data from the Alabama River streamgage (USGS 02420000) upstream from the confluence was 

examined along with measured flood profiles for the 1979 and 

1990 floods. The Alabama River streamgage is approximately 

5.5 mi upstream from the confluence. Inspection of streamgage data indicates that significant flooding occurred on the 

Alabama River in 1886, 1888, 1929, 1948, 1961, 1979, and 

1990. Record-high concurrent flooding on the Alabama River 

and Catoma Creek occurred in 1961 and 1990. Both floods 

are calculated to be greater than a 50-year recurrence interval 

flood for the Alabama River and Catoma Creek streamgages 

(Hedgecock and Feaster, 2007). 

Flood of 1961

During February 17–26, 1961, Alabama, Florida, Georgia, Louisiana, and Mississippi had widespread, prolonged 

flooding. A succession of three large storms produced accumulated rainfall totals as high as 18 inches in central and southern 

Alabama (fig. 2). This series of storms produced the annual 

maximum peak at the Catoma Creek streamgage for the 1961 

water year. The peak flow value of 48,600 cubic feet per second (ft3

/s) is slightly larger than the 50-year recurrence interval 

flood (Hedgecock and Feaster, 2007). Many small streams 

had flooding that became superimposed in the large rivers to 

produce record peak flows (Barnes and Somers, 1961). The 

1961 flood was also an extreme event for the Alabama River 

near the Montgomery streamgage, where the recorded peak 

discharge also was calculated to be greater than a 50-year 

recurrence interval flood. Flood stages of this magnitude had 

not been experienced since 1886. The extreme variations in 

intensity produced prolonged inundation. The Alabama River 

remained above flood stage for 19 days (Barnes and Somers, 1961). 

Table 1. Historical flood flows at the Catoma Creek streamgage 

(USGS 02421000) near Montgomery, Alabama.

[ft3/s, cubic feet per second; ft, feet; +, plus]

Water 

year1 Date Discharge(ft3/s)

Gage 

height

(ft)

Approximate 

recurrence 

interval

(years)

1949 Nov. 28 238,300 27.50 25+

1958 Mar. 8 25,600 25.70 10+

1961 Feb. 25 48,600 328.60 50+

1975 Feb. 17 43,900 28.13 25+

1990 Mar. 17 50,000 29.78 50+

2001 Mar. 4 28,600 27.20 10+

2005 Mar. 28 28,300 27.14 10+

1

 Water year is the period October 1 to September 30 and is designated by 

the year in which the period ends.

2

 Discharge is a historic peak. Historic peaks are annual maximum observations that occurred outside any period(s) of systematic data collection.

3

 Gage height is an estimate.
4 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Flood of 1990

Alabama, Georgia, and Florida sustained substantial 

flooding during 1990 as a result of three separate events during February, March, and December. Throughout the threeState region, 74 gaging stations exceeded previously recorded 

maximum streamflows, and 46 exceeded the 100-year flood 

flow (Pearman and others, 1991). 

The calendar year began with above-average rainfall 

during January. The first flood occurred as a result of heavy 

rainfall during February 15–16 (fig. 3). The west-central and 

northeastern counties of Alabama incurred most of the rainfall, 

with totals ranging from 4 to 8 inches (Jordan and Combs, 

1996). The March flood affected a greater portion of the State 

(fig. 3). The rainfall began on March 15 in southwestern 

Alabama and proceeded northeastward on March 16. Rainfall ranged from 8 to 13 inches across most of southwestern 

and south-central Alabama with local highs in other areas. 

About 35 percent of the State had 2-day rainfall totals exceeding 8 inches (Pearman and others, 1991). The lines of equal 

recurrence intervals shown in figure 4 are based on streamgage 

data for unregulated and unurbanized streams with drainage 

areas between 10 and 1,000 mi2. The Catoma Creek streamgage recorded a record-breaking peak discharge of 50,000 ft3

/s 

on March 17. This flood was calculated to be greater than a 

50-year recurrence interval. Based on historical high-water 

marks, approximately 5.7 mi of Catoma Creek (measured 

from the mouth) was affected by river flooding in 1990. Stage 

values recorded at the Alabama River streamgage indicate that 

the 1990 flood stage was 4 ft lower than the 1961 flood. The 

1990 flood, however, had a higher peak discharge, which is 

thought to be a result of the effects of regulation and channel 

modifications that occurred after 1961.

Acknowledgments

Special thanks are given to Chris Conway, City Engineer, 

and John Trevor, Engineering Services, of the City of Montgomery for their assistance with this study.

Figure 2. Isohyetal map of the Southeastern States showing storm rainfall, 

February 23–26, 1961 (modified from Rostvedt, 1961, p. 8).

EXPLANATION

8 Rainfall, in inches

92° 90° 88° 86° 84° 82°

35°

33°

31°

29°

NORTH

CAROLINA

SOUTH

CAROLINA

GEORGIA ALABAMA

LOUISIANA

ARKANSAS

TENNESSEE

MISSISSIPPI

FLORIDA

0 50 100 MILES

0 50 100 KILOMETERS
Introduction 5

88° 86° 84° 82°

34°

32°

30°

ALABAMA

FLORIDA

GEORGIA

Gulf

of

Mexico

cit nalt A

O

cea

n

0 50 100 MILES

0 50 100 KILOMETERS

Area affected by heavy rainfall in February 1990

EXPLANATION

Area affected by heavy rainfall in March 1990

NORTH

CAROLINA

SOUTH

CAROLINA

GEORGIA ALABAMA

LOUISIANA

ARKANSAS

TENNESSEE

MISSISSIPPI

FLORIDA

Figure 3. Areas of Alabama, Georgia, and Florida affected by heavy rainfall in February 

and March 1990 (modified from Pearman and others, 1991, p. 4).
6 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Approach

New flood profiles were developed through (1) field data 

collection, (2) hydrologic analyses, and (3) hydraulic modeling for the 10-, 50-, 100-, and 500-year floods by using hydrologic and hydraulic models. Prior to the development of these 

profiles, the hydraulic model was calibrated to closely match 

the surveyed high-water marks from the March 17, 1990, flood 

to increase the accuracy of the results provided by this study. 

Data Collection

In order to accurately represent the stream-channel and 

flood-plain geometry of the reach, field surveys were conducted. Six flood-plain cross sections were surveyed by USGS 

personnel using an electronic total station in December 2007 

(fig. 5). Cross-section data also were obtained from the Alabama Department of Transportation (fig. 6). The geometry of 

all drainage structures and adjacent roadways was measured. 

The study reach includes 4 roadway crossings and 3 railroad 

crossings consisting of 13 hydraulic structures (fig. 7). Four 

high-water marks from the March 17, 1990, flood also were 

surveyed by USGS personnel for model-calibration purposes. 

Three of these high-water marks were provided by local residents who experienced the 1990 flood. The fourth high-water 

mark was recorded at the USGS gaging station on Catoma 

Creek. The high-water marks define a 70,938-ft reach of the 

flood profile extending from river station 1,709 to 72,647 and 

were all considered to be reliable. A river station was defined 

for each cross section, hydraulic structure, and high-water 

mark. River stationing for the study reach is arbitrary and 

0 50 100 MILES

0 50 100 KILOMETERS

88 87 86 85 84 83 82 81

35

34

33

32

31

30 Gulf

of

Mexico

cit nalt A

O

cean

NORTH

CAROLINA

SOUTH

CAROLINA

GEORGIA ALABAMA

LOUISIANA

ARKANSAS

TENNESSEE

MISSISSIPPI

FLORIDA

LINE OF EQUAL RECURRENCE INTERVAL—

 Interval variable, in years

EXPLANATION

5

Figure 4. Locations of lines of equal recurrence intervals for March 1990 peak 

discharges for unregulated and unurbanized streams in Alabama, Georgia, 

and Florida (modified from Pearman and others, 1991, p. 10).
Approach 

7

32°22’

86°27’ 86°24’

32°20’

Text

0 1 2 KILOMETERS

0 1 2 MILES EXPLANATION

Study reachUSGS cross-section locationsCross-section identifier A

Base from U.S. Geological Survey digital data, 1:24,000 DRG,Cantelous, 1981; Montgomery North, 1958, revised 1981;Montgomery South, 1958, revised 1981; Prattville, 1981

A

B

C

D

E

F

Figure 5. Approximate locations of cross sections A–F in the Catoma Creek study reach.
8 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure 6. Approximate locations of cross sections D–I in the Catoma Creek study reach.

Text

EXPLANATION

Study reachUSGS cross-section locationsDOT cross-section locationsCross-section identifierCatoma Creek gage (USGS 02421000)

D

Base from U.S. Geological Survey digital data, 1:24,000 DRG,Cantelous, 1981; Montgomery North, 1958, revised 1981;Montgomery South, 1958, revised 1981; Prattville, 1981

E

F

D

G H

 I

0 1 2 KILOMETERS

0 1 2 MILES

32°20’

86°24’ 86°18’

32°18’
Approach 9

Figure 7. Catoma Creek study reach, Montgomery County, Alabama.

Hunter

Snowdoun

Montgomery

Catoma

Creek

Alabama River

Base from U.S. Geological Survey digital data, 1:100,000

Hydrography from U.S. Environmental Protection Agency

Reach File 1, 1:500,000

0 2.5 5 KILOMETERS

0 2.5 5 MILES

3215’

32

25’

86

30’ 8620’

Western Railway of Alabama

Louisville and Nashville Railroad 

Seaboard Coast Line Railroad 

Old Selma

Rd.

Caney

Branch

AUTAUGA

COUNTY

LOWNDES COUNTY

ELMORE COUNTY

MONTGOMERY COUNTY

31

65

331

Catoma Creek basin boundary

Study reach extent

Catoma Creek gage (USGS 02421000)

Alabama River gage (USGS 02420000)

EXPLANATION
10 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

is referenced from the downstream-most cross section (section A), which is river station zero. Cross section A is approximately 5,800 ft above the mouth of Catoma Creek.

Inspection of the 2001 National Land Cover Dataset 

(NLCD; Multi-Resolution Land Characteristics Consortium, 

2006), showed that the land cover of the drainage basin is 

characterized by grassy fields (30 percent) and wooded areas 

(57 percent) with moderate vegetative undergrowth. Approximately 12 percent of the drainage basin is covered by residential development, which typically has minimal or maintained 

vegetative growth and areas of ineffective flow. The remaining 

1 percent of the basin is described as open water (fig. 8). 

Roughness characteristics for the reach were assessed 

from field investigations and aerial photography (2002). Manning’s roughness coefficients were selected to reflect current 

conditions and the conditions during the 1990 flood. Manning’s roughness coefficients and geometric conditions were 

calibrated to provide the best match to the surveyed 1990 flood 

profile. The hydraulic parameters were then adjusted slightly 

to reflect current conditions. Manning’s roughness coefficients 

ranged from 0.04 to 0.06 for the channel and from 0.04 to 0.16 

for the overbank areas. Photographs of the cross sections and 

the surrounding area are included as appendix figures A1–A24. 

Hydrologic Analyses 

The Catoma Creek drainage basin at the confluence with 

the Alabama River drains 360 mi2. The upstream extent of 

the study reach, Norman Bridge Road, has a drainage area of 

290 mi2. To accurately represent the change in contributing 

area, two subreaches were defined. The first subreach extends 

from Norman Bridge Road to the confluence with Caney 

Branch (fig. 7). The second subreach extends from Caney 

Branch to the confluence of Catoma Creek and the Alabama 

River (figs. 5 and 6). Peak flows were computed for the 1990 

flood, and for the 10-, 50-, 100-, and 500-year floods for 

Catoma Creek at the Norman Bridge Road (gaged site) crossing and at Caney Branch (ungaged site, tables 2, 3).

Hydrologic analyses were conducted using streamflow 

gaging-station data and the USGS rural regression equations 

and procedures outlined in Hedgecock and Feaster (2007). 

The rural regression equations are based on peak-flow data 

collected through September 2003 at 216 rural gaging stations having 10 or more years of record. The logarithms of the 

annual peaks were fitted to a Pearson Type III distribution to 

determine the frequency of peak discharge. Multiple regression equations were developed for estimating peak discharges 

having recurrence intervals of 1.5-, 2-, 5-, 10-, 25-, 50-, 100-, 

200-, and 500-years. The explanatory variable affecting peak 

discharge is drainage area. Average standard errors of prediction for the relations in this hydrologic area range from +23 to 

+30 percent for the 10- to 500-year recurrence interval flows. 

The USGS has operated a streamflow gaging station on 

Catoma Creek (USGS 02421000) at Norman Bridge Road 

since June 1952. The peak flow for the March 17, 1990, flood 

was determined to be 50,000 ft3/s (table 2). Recurrence intervals for flood estimates at this site were determined by weighting the regional and station flood estimates for the specified 

recurrence interval using the number of years of station record 

and the accuracy of the regional flood-frequency relations 

expressed as equivalent years of record. The 1990 flood 

peak and computed recurrence-interval peaks for the Catoma 

Creek gage were transferred downstream to the confluence 

with Caney Branch by using the transfer equation outlined in 

Hedgecock and Feaster (2007). The transfer equation is based 

on the drainage area ratio with a regional slope exponent.

Alabama River

The 100-year flood stage for the Alabama River was 

computed in the vicinity of the Catoma Creek confluence using 

observed high-water profiles from the 1979 and 1990 floods, 

gaging station data from the Alabama River gage near Montgomery (USGS 02420000), and the published 100-year flow 

(308,000 ft3/s) for the gage (Hedgecock and Feaster, 2007). 

Table 2. Computed peak flows for the March 17, 1990, 

flood for Catoma Creek near Montgomery, Alabama.

[ft, feet; mi2,square miles; ft3/s, cubic feet per second]

River 

station

(ft)

Location

Drainage 

area

(mi2)

Peak 

flow

(ft3/s)

38,633 Mouth of Caney 

Branch

330 53,900

72,513 Norman Bridge Road

(USGS 02421000)

290 50,000

Table 3. Computed peak flows for current (2008) conditions for 

Catoma Creek near Montgomery, Alabama. 

[ft, feet; mi2, square miles;ft3/s, cubic feet per second]

River 

station

(ft)

Location

Drainage 

area

(mi2)

10-year 

peak 

flow

(ft3/s)

50-year 

peak 

flow

(ft3/s)

100-year 

peak 

flow

(ft3/s)

500-year 

peak 

flow

(ft3/s)

38,633 Mouth of Caney 

Branch

330 27,200 49,600 61,800 98,400

72,513 Norman Bridge Road

(USGS 02421000)

290 25,200 46,000 57,300 91,100
Approach 11 Figure 8. Land-cover data for the Catoma Creek basin.

3220’

3210’

8630’ 8550’

0 3 6 MILES0 3 6 KILOMETERS

Open waterDeveloped, open spaceDeveloped, low intensityDeveloped, medium intensityDeveloped, high intensityBarren land (rock/sand/clay)Deciduous forestEvergreen forest

Mixed forestShrub/scrubGrassland/herbaceousPasture/hayCultivated cropsWoody wetlandsEmergent herbaceous wetlandRoads

Base from U.S. Geological Survey National Land Cover Data, fromLandsat-7 Thematic Mapper images 30-meter resolution, 2001

EXPLANATION

LOCATION OF CATOMA CREEK

BASIN IN MONTGOMERY COUNTY,

ALABAMA
12 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

The 1979 and 1990 floods had almost identical water-surface 

slopes for approximately 41 river miles below the gage. Both 

floods represent events occurring in modern time (post 1961) 

in which the dam locations and channel configuration represent current conditions. The rating (stage-discharge relation) 

for the gage was transferred downstream about 3 river miles 

using the average slope (fall relation) of the 1979 and 1990 

floods to yield a 100-year flood stage of 155.0 ft. At this 

location the Catoma Creek and Alabama River share a common flood plain. The 100-year flood stage computed for the 

Alabama River in the vicinity of the Catoma Creek confluence 

was about 4.5 ft lower than the elevation published by FEMA. 

The differences in computed water-surface elevations are 

likely because of the use of a stepback-water model by FEMA 

(Federal Emergency Management Agency, 2003) as opposed 

to application of a fall relation used by USGS. This fall relation is based on detailed high-water profiles (1979 and 1990 

floods) and stage-discharge information from the Alabama 

River gage near Montgomery (USGS 02420000). 

Hydraulic Modeling

The Hydrologic Engineering Center’s River Analysis System (HEC-RAS; U.S. Army Corps of Engineers, 2002) was 

selected as the model to simulate flood flow in the Catoma 

Creek basin. The HEC-RAS model was used to calculate the 

water-surface profiles for both gradually and rapidly varied 

steady flow. The gradually varied flow results of the model are 

based on the solution of the one-dimensional energy equation. The energy losses considered are those of friction and 

contraction and expansion. The frictional losses are computed 

by using Manning’s equation. The contraction and expansion 

losses are computed as a function of the velocity head. In the 

areas of rapidly varied flow, the momentum equation is used in 

the model.

Model Calibration

Input data were entered and checked, and the computational component of the HEC-RAS model was used to 

simulate the March 17, 1990, flood profile. The initial output 

showed that the simulated water-surface elevation was higher 

in some areas (primarily between sections D and F) than the 

flood profile interpolated between measured high-water marks. 

Roughness values were adjusted slightly to improve agreement with the 1990 flood profile. The roughness values used 

were taken from topographic maps and aerial photography 

reflective of the land cover of that time period. The computed 

water-surface profile (table 4) was calibrated within 0.1 ft of 

the observed high-water marks from the 1990 flood. A plot 

showing the comparison of the computed flood profile to measured high-water marks is shown in figure 9. Two of the seven 

roadway crossings were overtopped by the 1990 flood—Old 

Selma Road, and the Seaboard Coast Line Railroad (fig. 7). 

Table 4. Difference between observed and computed 

water-surface profiles for the March 1990 flooding of 

Catoma Creek near Montgomery, Alabama.

[ft, feet; HEC-RAS, Hydrologic Engineering Center’s River Analysis System; 

—, no data; see figures 5 and 6 for cross-section locations]

River 

station

(ft)

Crosssection

identifier

Observed 

watersurface 

elevation

(ft)

HEC-RAS 

computed 

water-surface 

elevation

(ft)

Difference 

between observed 

and computed 

water-surface 

elevations

(ft)

25,236 — 152.0 151.9 0.1

26,288 — 153.0 153.1 0.1

52,518 Section G 171.6 171.6 0.0

72,647 — 180.8 180.8 0.0
Approach 13

Simulation of Flood Flows

After the model was successfully calibrated to the 1990 

flood, the 10-, 50-, 100-, and 500-year flood flows were simulated. Manning’s roughness coefficient was slightly altered 

from the 1990 values to reflect current conditions. The resulting water-surface profiles represent the flooding potential for 

current flood-plain conditions (fig. 10). Water-surface elevations corresponding to these profiles are listed in table 5. Some 

water-surface elevations at the downstream face of a bridge 

can be lower than those at the next section downstream. This is 

because of the simulated drawdown effect.

The results of the simulation indicate that for the 

100-year recurrence interval, the flood profile for Catoma 

Creek was about 2.5 ft higher, on average, than the profile 

published in the FEMA study (table 6). The maximum and 

minimum differences were 6.0 ft and 0.8 ft, respectively. All 

water-surface elevations (headwater flooding only) computed 

for the 100-year flood were higher than those published by 

FEMA (table 6; fig. 11). The differences in computed watersurface elevations may be attributed to: hydraulic structure 

changes, different hydraulic models, different modeling 

techniques, differences in the quality of flood-plain surveys 

used in the model, and differences in land cover (Manning’s 

roughness coefficient). Flood discharges, however, were similar for both studies.

The mean flood-plain depth for the 100-year flood (headwater flooding only) was computed for each cross section by 

dividing the effective flow area by the total top width of flow. 

These depths ranged from about 3 ft just downstream from 

section D (fig. 5) to about 14 ft about 600 ft downstream from 

the Western Railway (fig. 7). It should be noted that these are 

mean values based on the flood-plain conditions on either 

side of the channel (overbank region). The actual depth varies 

throughout the flood plain based on the local ground-surface 

elevation. The elevations of the 100-year flood were compared 

to the elevations of local roadways and railroads in Montgomery to determine the depth of overtopping (table 7). 

The mean top width of flow (headwater flooding only) 

for the study reach for the 100-year flood was about 5,600 ft. 

This value varied from section to section based on the geometry of the flood plain. For instance, the flow at section B had 

a top width of about 880 ft. The maximum top width of flow 

of 10,305 ft occurred about 800 ft upstream from U.S. Highway 331. This information is provided to show that the mean 

value of top width of flow is for the entire reach and is not 

indicative of every cross section.

100

120

140

160

180

200

RIVER STATION, IN FEET

ELEV

ATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

Western Railway of Alabama

Old Selma Road

Louisville and Nashville Railroad

U.S. Highway 31

Interstate 65

Seaboard Coast Line Railroad

U.S. Highway 331

USGS-surveyed streambed

March 1990 computed flood profile

Flooding controlled by Alabama River

March 1990 measured high-water mark Section A Section B Section C

Section D

Section E

Section FSection GSection H

Section IUSGS Gage 02421000

Elevation 152.0 feet

-10,000 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Figure 9. Computed and observed flood profiles for the March 1990 flood for Catoma Creek near Montgomery, Alabama. 

(See figures 5 and 6 for locations of cross sections.)
14 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Table 5. Computed flood profiles for current (2008) conditions for Catoma Creek near Montgomery, Alabama.

[ft, feet; —, no data; see figures 5 and 6 for cross-section locations]

River 

station

(ft)

Cross-section identifier/

roadway crossing

10-year

water-surface 

elevation

(ft)

50-year

water-surface 

elevation

(ft)

100-year

water-surface 

elevation

(ft)

500-year

water-surface 

elevation

(ft)

0 Section A 130.7 136.5 138.7 143.6

5,590 Section B 134.0 139.4 141.6 146.4

16,787 Section C 141.7 146.8 149.2 154.4

21,012 — 143.8 148.8 151.3 156.3

25,236 — 146.5 151.1 153.8 158.2

25,738 — 147.0 151.8 154.4 158.5

25,838 Section D 147.3 152.1 154.6 158.2

25,839 Western Railway of Alabama — — — —

25,858 — 147.0 151.8 154.2 158.3

26,288 — 147.4 152.3 154.9 160.4

27,325 — 148.0 153.1 155.6 160.8

27,425 — 148.1 153.0 155.4 160.8

27,426 Old Selma Road — — — —

27,455 — 148.2 153.2 155.5 160.9

27,805 — 148.6 154.0 156.5 161.2

31,151 — 151.3 156.5 158.6 162.5

34,496 Section E 154.7 159.4 160.8 163.8

34,746 — 155.2 159.8 161.0 164.0

38,633 — 158.2 162.6 163.6 166.0

48,042 Section F 165.8 169.0 170.1 172.3

51,308 — 167.5 170.5 171.7 174.3

51,408 — 167.5 170.5 171.7 174.2

51,409 Louisville and Nashville Railroad — — — —

51,428 — 167.6 170.7 171.9 174.6

52,388 — 167.9 171.1 172.4 175.3

52,518 Section G 167.9 171.1 172.4 175.2

52,583 — 167.9 171.0 172.3 175.1

52,584 U.S. Highway 31 — — — —

52,668 — 167.9 171.0 172.3 175.8

53,478 — 168.4 171.9 173.3 176.7

56,773 Section H 170.2 173.5 175.0 178.3

56,873 — 170.2 173.4 174.8 178.0

56,874 Interstate 65 — — — —

56,983 — 170.4 173.7 175.0 179.4

57,883 — 171.2 174.7 176.2 180.7

69,043 — 176.0 179.2 180.5 183.9

69,143 — 176.0 179.1 180.4 184.0

69,144 Seaboard Coast Line Railroad — — — —

69,163 — 176.0 179.4 180.7 184.0

69,773 — 176.3 179.9 181.1 184.2

69,943 Section I 176.3 179.9 181.1 184.2

70,043 — 176.4 179.9 181.1 184.2

70,044 U.S. Highway 331 — — — —

70,247 — 176.4 180.0 181.2 184.6

71,047 — 176.7 180.3 181.6 184.9

72,547 — 177.1 180.7 182.0 185.2

72,647 — 177.2 180.7 182.0 185.2
Approach 15

Western Railway ofAlabama

Old Selma Road

Louisville and NashvilleRailroad

U.S. Highway 31

Interstate 65

Seaboard Coast LineRailroad

U.S. Highway 331

Section A

Section B

Section C

Section D

Section E

Section FSection GSection H

Section IUSGS Gage 02421000

USGS-surveyed streambed

100-year flood controlled

 by Alabama River

10-year flood

50-year flood

100-year flood

500-year flood

March 1990 measured 

 high-water mark

Elevation 155.0 feet

RIVER STATION, IN FEET

-10,000 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

100

120

140

160

180

200

ELEV

ATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

Figure 10. Computed flood profiles for current conditions for Catoma Creek near Montgomery, Alabama. 

(See figures 5 and 6 for locations of cross sections.)

Table 6. U.S. Geological Survey and Federal Emergency Management Agency computed 100-year flood elevations 

for Catoma Creek near Montgomery, Alabama.

[ft, feet; see figure 7 for roadway crossing locations; USGS, U.S. Geological Survey; FEMA, Federal Emergency Management Agency]

River 

station

(ft)

Roadway crossing

USGS 100-year 

water-surface 

elevation 

(ft)

FEMA 100-year 

water-surface 

elevation 

(ft)1

Difference 

(ft)

25,839 Western Railway of Alabama 154.6 148.6 6.0

27,426 Old Selma Road 155.6 150.6 5.0

51,409 Louisville and Nashville Railroad 171.7 170.0 1.7

52,584 U.S. Highway 31 172.4 171.6 0.8

56,874 Interstate 65 175.0 174.2 0.8

69,144 Seaboard Coast Line Railroad 180.5 177.9 2.6

70,044 U.S. Highway 331 181.1 179.3 1.8

72,647 Norman Bridge Road 182.0 180.4 1.6

1

 Federal Emergency Management Agency, 2003.
16 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

USGS-surveyed streambed

USGS 100-year flood

USGS 100-year flood controlled 

 by Alabama River

FEMA 100-year flood controlled

 by Alabama River

FEMA 100-year flood

Western Railway of Alabama

Old Selma Road

Louisville and NashvilleRailroad

U.S. Highway 31

Interstate 65

Seaboard Coast Line Railroad

U.S. Highway 331

Section A

Section B

Section C

Section D

Section E

Section FSection GSection H

Section IUSGS Gage 02421000

Elevation 155.0 feet

100

120

140

160

180

200

ELEV

ATION, IN FEET ABOVE NATIONAL GEODETIC VERTICAL DATUM OF 1929

RIVER STATION, IN FEET

-10,000 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000

Figure 11. U.S. Geological Survey and Federal Emergency Management Agency computed 100-year flood profiles for 

Catoma Creek near Montgomery, Alabama. (See figures 5 and 6 for locations of cross sections.)

Table 7. 100-year water-surface elevations with local roadway crossings for Catoma Creek near 

Montgomery, Alabama. 

[ft, feet]

River 

station

(ft)

Roadway crossing

100-year 

upstream 

water-surface 

elevation

(ft)

Minimum 

roadway 

elevation in 

vicinity of the 

bridge

Maximum 

depth of 

overtopping

(ft)

25,839 Western Railway of Alabama 154.4 157.0 0

27,426 Old Selma Road 155.6 154.0 1.6

51,409 Louisville and Nashville Railroad 171.9 173.4 0

52,584 U.S. Highway 31 172.4 172.5 0

56,874 Interstate 65 175.0 177.9 0

69,144 Seaboard Coast Line Railroad 180.7 178.2 2.5

70,044 U.S. Highway 331 181.2 182.0 0
References Cited 17

Summary 

A one-dimensional step-backwater model was used to 

simulate flooding conditions for Catoma Creek near Montgomery, Alabama. The results of this study provide the community with flood-profile information that can be used for 

flood-plain mitigation, future development, and safety plans 

for the city. 

Using data collected by the USGS from the March 17, 

1990, flood, a flow model was calibrated to match (within 

0.1 ft) the measured high-water marks. The calibrated model 

then was used to simulate flooding for the 10-, 50-, 100-, and 

500-year recurrence-interval floods. The results indicate that 

the 100-year recurrence-interval flood profile for Catoma 

Creek was about 2.5 ft higher, on average, than the profile 

published by FEMA in 2003. The absolute maximum and 

minimum differences were 6.0 ft and 0.8 ft, respectively. All 

water-surface elevations (headwater flooding only) computed 

for the 100-year flood were higher than those published 

by FEMA. 

 The mean flood-plain depth was computed for each cross 

section for the 100-year flood and ranged from about 3 ft to 

about 14 ft. The results indicate that for the 100-year recurrence interval, overtopping would occur at Old Selma Road 

and at the Seaboard Coast Line Railroad. The top-width of 

flow (for headwater flooding only) at a given section in the 

study reach for the 100-year flood ranged from about 880 ft to 

about 10,300 ft (mean of 5,600 ft).

References Cited 

Barnes, H.H., Jr., and Somers, W.P., 1961, Floods of 

February–March 1961 in the southeastern States: 

U.S. Geological Survey Circular 452, 21 p.

Federal Emergency Management Agency, 2003, Flood insurance study—Montgomery County, Alabama and incorporated areas: Federal Emergency Management Agency, 155 p.

Hedgecock, T.S., and Feaster, T.D., 2007, Magnitude and frequency of floods in Alabama, 2003: U.S. Geological Survey 

Scientific Investigations Report 2007–5204, 28 p.

Jordan, P.R., and Combs, L.J., eds., 1996, Summary of floods 

in the United States during 1990 and 1991: U.S. Geological 

Survey Water-Supply Paper 2474, 254 p. 

Multi-Resolution Land Characteristics Consortium, 2006, 

National Land Cover Database 2001; accessed July 19, 

2007, at http://www.mrlc.gov/mrlc2k_nlcd.asp

Paulson, R.W., Chase, E.B., Roberts, R.S., and Moody, D.W., 

comps., 1991, National water summary, 1988–89—Hydrologic events and floods and droughts: U.S. Geological 

Survey Water-Supply Paper 2375, 591 p.

Pearman, J.L., Stamey, T.C., Hess, G.W., and Nelson, G.H., 

Jr., 1991, Floods of February and March 1990 in Alabama, 

Georgia, and Florida: U.S. Geological Survey WaterResources Investigations Report 91–4089, 44 p.

Rostvedt, J.O., 1961, Summary of floods in the United 

States during 1961: U.S. Geological Survey Water-Supply 

Paper 1810, 123 p.

U.S. Army Corps of Engineers, 2002, HEC-RAS river analysis 

system users’ manual, version 3.1: U.S. Army Corps of 

Engineers, 420 p. 

Appendix. Photographs showing locations 

of cross sections for Catoma Creek near 

Montgomery, Alabama, 2008

Appendix 21

Figure A1. Channel and right 

overbank at cross section A, 

Montgomery, Alabama. (See 

figure 5 for location.)

Figure A2. Left overbank at cross 

section A, Montgomery, Alabama. 

(See figure 5 for location.)
22 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A3. Looking north at cross 

section B, Montgomery, Alabama. 

(See figure 5 for location.)

Figure A4. Right overbank at 

cross section C, Montgomery, 

Alabama. (See figure 5 

for location.)
Appendix 23

Figure A5. Western Railway 

of Alabama crossing of Catoma 

Creek, Montgomery, Alabama. 

(See figure 7 for location.)

Figure A6. Downstream face of 

Old Selma Road relief bridge #1, 

in the vicinity of cross section D, 

Montgomery, Alabama. (See 

figures 5 and 7 for location.)
24 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A7. Downstream face of 

Old Selma Road relief bridge #2, 

in the vicinity of cross section D, 

Montgomery, Alabama. (See 

figures 5 and 7 for location.)

Figure A8. Downstream 

face of Old Selma Road 

main-channel bridge, in the 

vicinity of cross section D, 

Montgomery, Alabama. (See 

figures 5 and 7 for location.)
Appendix 25

Figure A9. Cross section D, 

Montgomery, Alabama. (See 

figure 5 for location.)

Figure A10. Right overbank of 

cross section E, Montgomery, 

Alabama. (See figure 5 

for location.)
26 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A11. Downstream view 

of cross section E, Montgomery, 

Alabama. (See figure 5 

for location.)

Figure A12. Catoma Creek 

streambed drop at cross 

section E, Montgomery, Alabama. 

(See figure 5 for location.)
Appendix 27

Figure A13. Right overbank of 

cross section F, Montgomery, 

Alabama. (See figure 5 

for location.)

Figure A14. Downstream face of 

Louisville and Nashville Railroad 

Bridge, Montgomery, Alabama. 

(See figure 6 for location.)
28 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A15. Downstream 

face of U.S. Highway 31 Bridge, 

Montgomery, Alabama. (See 

figure 7 for location.)

Figure A16. Downstream 

face of Interstate 65 bridge, 

Montgomery, Alabama. (See 

figure 7 for location.)
Appendix 29

Figure A17. Downstream view 

of cross section H, Montgomery, 

Alabama. (See figure 6 

for location.)

Figure A18. Downstream face 

of Seaboard Coast Line Railroad 

bridge, Montgomery, Alabama. 

(See figure 7 for location.)
30 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A19. Seaboard 

Coast Line Railroad bridge, 

Montgomery, Alabama. (See 

figure 7 for location.)

Figure A20. Downstream of 

Seaboard Coast Line Railroad 

bridge, Montgomery, Alabama. 

(See figure 7 for location.)
Appendix 31

Figure A21. Upstream face 

of U.S. Highway 331 bridge, 

Montgomery, Alabama. (See 

figure 7 for location.)

Figure A22. Downstream view 

of cross section I, Montgomery, 

Alabama. (See figure 6 

for location.)
32 Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008

Figure A23. Upstream face of 

Norman Bridge Road crossing, 

Montgomery, Alabama. (See 

figure 7 for location.)

Figure A24. Norman Bridge 

Road crossing, Montgomery, 

Alabama. (See figure 7 

for location.)
Prepared by:

USGS Publishing Network

Raleigh Publishing Service Center

3916 Sunset Ridge Road

Raleigh, NC 27607

For additional information regarding this publication, contact:

Kathryn Lee, Civil Engineer

USGS Alabama Water Science Center

75 TechnaCenter Drive

Montgomery, AL 36117

email: kmlee@usgs.gov

Or visit the USGS Alabama Water Science Center website at:

http://al.water.usgs.gov/
Lee and Hedgecock—Simulation of Flood Profiles for Catoma Creek near Montgomery, Alabama, 2008—Scientific Investigations Report 2008–5171

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