Prepared in cooperation with the City of Hattiesburg, City of Petal, Forrest County, 

Mississippi Emergency Management Agency, Mississippi Department of Homeland 

Security, and the Emergency Management District

Prepared in collaboration with the National Weather Service

An Expanded Model: Flood-Inundation Maps for the 

Leaf River at Hattiesburg, Mississippi, 2013

Pamphlet to accompany

Scientific Investigations Map 3300

U.S. Department of the Interior

U.S. Geological Survey
Cover. Left, photograph looking at the downstream side of the bridge at Bouie River at Glendale Avenue at Hattiesburg, Mississippi 

(02472980), February 14, 2013. Right, inundation map of Leaf River at Hattiesburg, Mississippi (02473000), at 34.0 feet gage datum (see 

Sheet 13 for details).
An Expanded Model: Flood-Inundation Maps for 

the Leaf River at Hattiesburg, Mississippi, 2013

By John B. Storm

Prepared in cooperation with the City of Hattiesburg, City of Petal, Forrest County, 

Mississippi Emergency Management Agency, Mississippi Department of Homeland 

Security, and the Emergency Management District

Prepared in collaboration with the National Weather Service

Pamphlet to accompany 

Scientific Investigations Map 3300

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Storm, J.B., 2014, An expanded model—Flood-inundation maps for the Leaf River at Hattiesburg, Mississippi, 2013: 

U.S. Geological Survey Scientific Investigations Map 3300, 13 sheets, 8-p. pamphlet, http://dx.doi.org/10.3133/

sim3228.

ISSN 2329-132X (online)
iii

Contents

Acknowledgments........................................................................................................................................vi

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

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

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

Study-Area Description .......................................................................................................................3

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

Modeling Water-Surface Profiles...............................................................................................................4

Hydrologic and Steady-State Flow Data...........................................................................................4

Topographic/Bathymetric Data ..........................................................................................................4

Energy-Loss Factors.............................................................................................................................5

Model Calibration and Performance .................................................................................................5

Development of Water-Surface Profiles...........................................................................................5

Inundation Mapping ......................................................................................................................................7

Leaf River at Hattiesburg, Mississippi, Flood-Inundation Maps on the Internet .......................7

Disclaimer for Flood-Inundation Maps .............................................................................................7

Uncertainties and Limitations Regarding Use of Flood-Inundation Maps ..................................7

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

References Cited............................................................................................................................................8

Figure

1. Map showing location of the study reach for the Leaf River and location of 

USGS streamgages and National Weather Service forecast site .......................................2

Tables

1. USGS streamgage and miscellaneous site information for the study basin, 

Leaf River at Hattiesburg, Mississippi.......................................................................................3

2. 1.0-percent annual exceedance probability peak-discharge estimates, drainage areas, 

and percentage of total discharge for selected locations on the Leaf River.....................4

3. Comparison of hydraulic-model output and water-surface elevations at the 

Leaf River at Hattiesburg, Mississippi, streamgage 02473000 ..............................................5

4. Comparison of hydraulic-model output and surveyed high-water mark elevations 

from the floods of April 15, 1974, and March 11, 2011, at the Leaf River at 

Hattiesburg, Mississippi, streamgage 02473000......................................................................6

5. Stages and water-surface elevations at the Leaf River at Hattiesburg, Mississippi, 

streamgage 02473000, with corresponding discharge estimates for selected 

simulated water-surface profiles...............................................................................................6
iv

Sheets

[Sheets and additional materials are available online at http://pubs.usgs.gov/sim/3300/.]

1–13. Estimated flood-inundation maps for the Leaf River at Hattiesburg, 

Mississippi, referenced to USGS streamgage Leaf River at Hattiesburg, 

Mississippi (sta. no. 02473000) for stream stages of:

1. Gage height of 22.0 feet and an elevation of 140.18 feet

2. Gage height of 23.0 feet and an elevation of 141.18 feet

3. Gage height of 24.0 feet and an elevation of 142.18 feet

4. Gage height of 25.0 feet and an elevation of 143.18 feet 

5. Gage height of 26.0 feet and an elevation of 144.18 feet

6. Gage height of 27.0 feet and an elevation of 145.18 feet

7. Gage height of 28.0 feet and an elevation of 146.18 feet

8. Gage height of 29.0 feet and an elevation of 147.18 feet

9. Gage height of 30.0 feet and an elevation of 148.18 feet

10. Gage height of 31.0 feet and an elevation of 149.18 feet

11. Gage height of 32.0 feet and an elevation of 150.18 feet

12. Gage height of 33.0 feet and an elevation of 151.18 feet

13. Gage height of 34.0 feet and an elevation of 152.18 feet
v

Abbreviations

AHPS Advanced Hydrologic Prediction Service

DEM digital elevation model

DGPS differential global positioning system 

FEMA Federal Emergency Management Agency

FIS Flood Insurance Study 

GIS geographic information system

lidar light detection and ranging

NWS National Weather Service

USGS U.S. Geological Survey

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

inch 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.0929 square meter (m2)

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 North American Vertical Datum of 1988 

(NAVD 88).

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

Elevation, as used in this report, refers to the distance above NAVD 88.

Stage, as used in this report, is the height of the water surface above an arbitrary datum 

established at the gage (gage datum).
Acknowledgments

The author wishes to thank the many local, State, and Federal agencies that have cooperated 

in the funding for the operation and maintenance of the gages used for this study, especially 

the Mississippi Department of Environmental Quality. Special thanks are given to the City 

of Hattiesburg, City of Petal, Forrest County, Mississippi Emergency Management Agency, 

Mississippi Department of Homeland Security, and the Emergency Management District for 

their cooperation in this study and to the National Weather Service for their continued support 

to the USGS flood-inundation mapping initiative. 

vi
An Expanded Model: Flood-Inundation Maps for 

the Leaf River at Hattiesburg, Mississippi, 2013

By John B. Storm

Abstract

Digital flood-inundation maps for a 6.8-mile reach of the 

Leaf River at Hattiesburg, Mississippi (Miss.), were created by 

the U.S. Geological Survey (USGS) in cooperation with the 

City of Hattiesburg, City of Petal, Forrest County, Mississippi 

Emergency Management Agency, Mississippi Department 

of Homeland Security, and the Emergency Management 

District. The inundation maps, which can be accessed through 

the USGS Flood Inundation Mapping Science Web site at 

http://water.usgs.gov/osw/flood_inundation/, depict estimates 

of the areal extent and depth of flooding corresponding to 

selected water levels (stages) at the USGS streamgage at 

Leaf River at Hattiesburg, Miss. (station no. 02473000). 

Current conditions for estimating near-real-time areas of 

inundation by use of USGS streamgage information may 

be obtained on the Internet at http://waterdata.usgs.gov/. In 

addition, the information has been provided to the National 

Weather Service (NWS) for incorporation into their Advanced 

Hydrologic Prediction Service (AHPS) flood warning system 

(http:/water.weather.gov/ahps/). The NWS forecasts flood 

hydrographs at many places that are often colocated with 

USGS streamgages. NWS-forecasted peak-stage information 

may be used in conjunction with the maps developed in this 

study to show predicted areas of flood inundation. 

In this study, flood profiles were computed for the 

stream reach by means of a one-dimensional step-backwater 

model. The model was calibrated by using the most current 

stage-discharge relations at the Leaf River at Hattiesburg, 

Miss. streamgage (02473000) and documented high-water 

marks from recent and historical floods. The hydraulic model 

was then used to determine 13 water-surface profiles for 

flood stages at 1.0-foot intervals referenced to the streamgage 

datum and ranging from bankfull to approximately the 

highest recorded water level at the streamgage. The simulated 

water-surface profiles were then combined with a geographic 

information system (GIS) digital elevation model (DEM, 

derived from light detection and ranging (lidar) data having a 

0.6-foot vertical and 9.84-foot horizontal resolution) in order 

to delineate the area flooded at each water level.

Development of the estimated flood inundation maps 

as described in this report update previously published 

inundation estimates by including reaches of the Bouie and 

Leaf Rivers above their confluence. The availability of these 

maps along with Internet information regarding current stage 

from USGS streamgages and forecasted stream stages from 

the NWS provide emergency management personnel and 

residents with information that is critical for flood response 

activities such as evacuations and road closures as well as for 

post flood recovery efforts.

Introduction 

The City of Hattiesburg is a medium-sized urban 

community (4th largest city in Mississippi) with an estimated population of 45,989 (U.S. Census Bureau, 2010). 

Hattiesburg, which is in Forrest County, has experienced 

severe flooding numerous times, most notably the four 

largest floods occurring during the past 100 years in 1920, 

1921, 1961, and 1974. These floods also affected the City of 

Petal, which is located directly across the Leaf River from 

Hattiesburg (fig. 1). Damage costs not adjusted for inflation 

within the cities of Hattiesburg and Petal were reported to be 

$3.25 million (Wilson, 1964) and $8.3 million (U.S. Army 

Corps of Engineers, 1983) for the 1961 and 1974 floods, 

respectively. The majority of flood damages have occurred 

along the Leaf River and a couple of tributaries (Bouie River 

and Gordon Creek), both of which flow through Hattiesburg. 

Flood plains within Hattiesburg are moderately developed and 

contain a mix of residential and commercial structures.

Prior to this study, Hattiesburg and Petal officials relied 

on several information sources, all of which are available 

on the Internet, to make decisions on how to best alert the 

public and mitigate flood damages. One source is the Federal 

Emergency Management Agency (FEMA) Flood Insurance 

Study (FIS) for Forrest County dated March 2, 2010 (Federal 

Emergency Management Agency, 2010). A second source 

of information is the U.S. Geological Survey (USGS) Leaf 

River at Hattiesburg Miss. streamgage (station no. 02473000), 
2 An Expanded Model: Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi, 2013

Hattiesburg

Petal

42

11

11

11

11

49

02473000

02472980

SOUTHERN RAILROAD

E HARDY STREET CARTERVILLE ROAD

OLD RICHTON ROAD

GLENDALE AVENUE

HARDY STREET

W 7TH STREET

W PINE STREET

EVELYN GANDY PARKWAY

NEW RICHTON ROAD

89°19' 89°18' 89°17' 89°16' 89°15' 89°14'

31°22'

31°21'

31°20'

31°19'

31°18'

EXPLANATION

Figure 1.

USGS streamgage and National Weather

 Service forecast site and identifier

USGS streamgage and identifier

Study area boundary

Direction of surface-water flow

02473000

Leaf River

Bouie River

Gordon Creek

02472980

0 0.5 1 MILE

0 0.5 1 KILOMETER

Forrest

County

Scott

County

MISSISSIPPI

Study

area

Orthography from National Agriculture Imagery Program, 2010

Projection: Transverse Mercator

North American Datum of 1983 (NAD 83)

North American Vertical Datum 1988 (NAVD 88)

City of Hattiesburg 

Wastewater Treatment

Lagoons

Leaf R

Figure 1. Location of the study reach for the Leaf River and location of USGS streamgages and National Weather Service 

forecast site. 
Introduction 3

from which current or historical water levels (stage) can be 

obtained. A third source is the National Weather Service’s 

(NWS) forecast of peak stage at the USGS gage through 

the Advanced Hydrologic Prediction Service (AHPS) site. 

Although USGS current stage and NWS forecast stage 

information is particularly useful for residents in the immediate vicinity of a streamgage, it is of limited use to residents 

farther upstream or downstream because the water-surface 

elevation is not constant along the entire stream channel. 

Also, FEMA and State emergency management mitigation 

teams or property owners typically lack information related 

to how deep the water is at locations other than near USGS 

streamgage or NWS flood-forecast points. 

Beginning in October 2010, the USGS in cooperation with 

the City of Hattiesburg initiated a study to develop flood inundation maps for the City of Hattiesburg. This study included 

reaches on both the Bouie and Leaf Rivers in Hattiesburg and 

was designed to reference an existing USGS streamgage on 

the Leaf River and an added gage on the Bouie River. 

Purpose and Scope

This report describes the development of a series 

of estimated flood-inundation maps for the Leaf River at 

Hattiesburg, Miss. These maps supersede previously published 

flood-inundation estimates (Storm, 2012) and expand the 

spatial scope of earlier work to include reaches above the 

confluence of the Bouie and Leaf Rivers. These updated maps 

and other useful flood information are available on the USGS 

Flood Inundation Mapping Science Web site and the NWS 

Advanced Hydrologic Prediction Service Web site. Internet 

users can select estimated inundation maps that correspond to 

(1) current stages at the USGS streamgage, or (2) the NWS 

forecasted peak stage.

The scope of analysis described in this report is spatially 

limited to a 6.8-mile (mi) reach of the Leaf River between the 

Evelyn Gandy Parkway (State Road 42) and the Hattiesburg 

wastewater treatment lagoons downstream as well as a 

2.2-mi reach of the Bouie River between Glendale Avenue 

and its confluence with the Leaf River (fig. 1). Six procedural 

and analytical steps in the production of inundation maps are 

also described. These include: (1) examination of current and 

historical data at streamgages in the study reach (table 1), 

(2) collection of topographic data and geometric data (for 

structures/bridges) throughout the study reach, (3) determination of energy-loss factors (roughness coefficients) in the 

stream channel and flood plain and compilation of steady-flow 

data, (4) computation of water-surface profiles by use of the 

U.S. Army Corps of Engineers HEC–RAS computer program 

(U.S. Army Corps of Engineers, 2010), (5) production of 

estimated flood-inundation maps at various stream stages 

by use of the U.S. Army Corps of Engineer’s HEC–GeoRas 

computer program (U.S. Army Corps of Engineers, 2009) and a 

geographic information system (GIS), and (6) development of 

a Web interface that links to USGS real-time streamgage information and (or) NWS forecasted peak stage to facilitate the 

display of user-selected flood-inundation maps on the Internet.

Methods used are generally cited from previously 

published reports. If techniques varied substantially from 

previously documented methods because of local hydrologic 

conditions or availability of data, they are described in detail 

in this report. Maps were produced for water levels referenced 

to the stage at Leaf River at Hattiesburg, Miss. (02473000) 

and range from approximately bankfull to the maximum 

observed water level at the streamgage.

Study-Area Description

The Leaf River is in southeast Mississippi in the East 

Gulf Coastal Plain. The drainage area ranges from approximately 1,074 square miles (mi2

) at the upstream extent of 

the study reach to 1,748 mi2 at the Leaf River at Hattiesburg 

Miss. streamgage to 1,773 mi2 at the downstream extent of the 

study reach. The headwaters originate in Scott County, and 

the stream flows generally southward before entering the city 

limits. The Bouie River is a major tributary to the Leaf River 

and joins the main stem as it flows through Hattiesburg. The 

Bouie River confluence with the Leaf River is approximately 

Table 1. USGS streamgage and miscellaneous site information for the study basin, Leaf River at Hattiesburg, Mississippi.

[mi2, square mile; ft, foot; °, degree; ', minute; ", second; NAVD 88, North American Vertical Datum of 1988]

Station name Station 

number

Drainage 

area

(mi2)

Latitude Longitude Period of record

Maximum recorded

stage at gage

(ft above gage datum)

and date

Bouie River at Glendale Avenue 

at Hattiesburg, MS

02472980 671 N 31°20'57" W 89°18'21" October 2010 to 

September 2013

24.10

(142.28 ft NAVD 88)

Feb. 13, 2013

Leaf River at Hattiesburg, MS 02473000 1,748 N 31°20'35" W 89°16'49" October 1905 to 

September 2013

34.03

(152.21 ft NAVD 88)

April 15, 1974
4 An Expanded Model: Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi, 2013

0.1 mi upstream of the Leaf River at Hattiesburg Miss. 

streamgage and has a drainage area of 674 mi2. The basin 

terrain is generally flat, and most of the basin is rural. The 

study reach is approximately 6.8 mi long and has an average 

top-of-bank channel width of about 350 feet (ft) and an 

average channel slope of 1.8 feet per mile (ft/mi). About 

47 percent of the land contiguous to the study reach is classified as urban or developed, 25 percent as forest, and 6 percent 

as cropland. The basin is still under development, as evidenced 

by a population increase of 2.7 percent from 44,779 to 45,989 

between 2000 and 2010 (U.S. Bureau of Census, 2010). The 

main channel within the study reach has four major road 

crossings and one railroad crossing that lie within the channel 

or the adjacent flood plain.

Previous Studies 

The current FIS for Forrest County (Federal Emergency 

Management Agency, 2010) was completed by Neel-Schaffer, 

Inc., in 1990 and revised by the State of Mississippi in 2010. 

That study provided information on the 1.0- and 0.2-percent 

annual exceedance probability water-surface profiles and 

associated flood-plain maps for the Leaf River and Bouie 

River. Estimates of the peak discharges for the 1.0-percent 

annual exceedance probability flood along the Leaf River, as 

listed in table 2 below for the study reach, are described by the 

Federal Emergency Management Agency (2010). 

In the report by Storm (2012), flood inundation maps 

were estimated only for reaches of the Leaf River below 

the confluence with the Bouie River due to budget and time 

constraints. These initial flood estimates provided an intermediate product for cooperating agencies until analyses for 

the upper portion of the study area could be completed for the 

project as described in this report.

Modeling Water-Surface Profiles

HEC–RAS, version 4.1.0 (U.S. Army Corps of Engineers, 

2010) was used to produce longitudinal water-surface profiles 

at 1.0-ft increments between 22.0 ft and 34.0 ft of stage on 

the Leaf River at Hattiesburg, Miss. (02473000). HEC–RAS 

is a one-dimensional step-backwater model for simulation of 

water-surface profiles with gradually varied, steady-state (or 

unsteady-state) flow computation options. The HEC–RAS 

analysis for this study was done by using the steady-state flow 

computation option. The information required to drive and calibrate HEC-RAS for the Leaf River included hydrologic data 

and steady-state flow conditions, channel geometry at multiple 

cross sections, and estimates of channel roughness. This model 

was calibrated to the most current (2012) stage-discharge 

relation at the Leaf River streamgage and to high-water marks 

from the floods on April 15, 1974, and March 11, 2011.

Hydrologic and Steady-State Flow Data

The study-area hydrologic network consists of two 

streamgages (fig. 1; table 1). The Leaf River gage is a longterm continuously operating gage. The Bouie River gage 

was constructed and equipped with a continuous recorder at 

the beginning of this study in 2010. Water levels (stage) are 

measured continuously and continuous records of streamflow 

are computed for both sites. All water-surface elevations are 

referenced to the North American Vertical Datum of 1988 

(NAVD 88). The gages are equipped with satellite radio 

transmitters that allow data to be transmitted routinely on the 

Internet within an hour of collection. The Leaf River gage 

is also equipped with a recording tipping-bucket rain gage. 

Longitudinal water-surface profiles from high-water marks 

along the main channel were documented following the peak 

of record flood in 1974 and during a bankfull event in 2011. 

These water-surface profiles were used for model calibration. 

Steady-state flow data consisted of selected flow-regime 

characteristics, boundary conditions (including either observed 

stage associated with a discharge measurement, critical 

depth, normal depth, or streamgage rating-curve value), and 

peak-discharge information. The steady-state flow data for 

the study reach were obtained from previous studies and field 

measurements of streamflow at the Leaf River at Hattiesburg 

Miss. streamgage or at miscellaneous sites. At gaged sites, all 

computations based on discharge values with known stages 

from actual streamflow measurements or stage-discharge 

relations were used. For ungaged sites, normal-depth boundary 

conditions were assumed by using a friction slope estimated 

from the average streambed slope through the reach unless 

miscellaneous discharge measurements referenced to a known 

datum were available. 

Topographic/Bathymetric Data

Channel cross sections were developed from USGS 

field surveys that were conducted from 1990 to 2011; these 

cross sections provide detailed channel-elevation data below 

the water surface and were collected using hydroacoustic 

instrumentation and mechanical means to measure depth and 

horizontal distance at all five hydraulic structures within the 

Table 2. 1.0-percent annual exceedance probability peakdischarge estimates, drainage areas, and percentage of total 

discharge for selected locations on the Leaf River (from Federal 

Emergency Management Agency, 2010).

[mi2, square mile; ft3/s, cubic foot per second]

Location on

Leaf River

Drainage area

(mi2)

Discharge estimate

(ft3/s)

At U.S. Highway 11 1,760 110,000

Upstream from Bouie 

River confluence

1,100 82,000
Modeling Water-Surface Profiles 5

study area. Differential Global Positioning System (DGPS) 

instrumentation was used to determine vertical control at the 

hydraulic structures. Lidar data were collected in the area 

in March and April 2006 by EarthData International, Inc. 

(written commun., 2007) and postprocessed in 2007. These 

data provided horizontal resolution of 9.84 ft and vertical 

accuracy of 0.6 ft and were used to provide digital elevation 

data for the portions of the cross sections that were above the 

water surface at the time of the surveys. 

Various manmade drainage structures such as bridges, 

culverts, roadway embankments, levees, and dams can affect 

water-surface elevations during floods. To properly account 

for these features in the Leaf River model, structural dimensions for five bridges were measured and surveyed in the 

field concurrently with the stream-channel surveys. A detailed 

description of the methods used to acquire and process the 

topographic and bathymetric data can be found in Bales and 

others (2007). 

Energy-Loss Factors

Field observations and high-resolution aerial photographs 

were used to select initial (precalibration) Manning’s roughness coefficients (“n” values) for energy-loss (friction-loss) 

calculations. The final Manning’s n values used ranged from 

0.024 to 0.048 for the main channel and 0.050 to 0.28 for the 

overbank areas modeled in this analysis. 

Model Calibration and Performance

The model was calibrated by adjusting roughness values 

(Manning’s n) and channel geometry (cross-sectional area and 

slope) to bring hydraulic computations into agreement with 

the observed flood-discharge and stage values. The estimated 

peak discharge for the 1974 flood was 121,000 cubic feet 

per second (ft3/s) at an estimated stage of 34.03 ft at the 

gage and the measured peak discharge for the 2011 flood 

was 33,400 ft3/s at a stage of 21.34 ft. Differences between 

measured and simulated water levels for measured or rated 

flows at USGS streamgage 02473000 were equal to or less 

than 0.17 ft (table 3). Differences between measured and 

simulated water levels for models calibrated to high-water 

marks in the study reach were equal to or less than 0.14 ft 

(table 4). The results demonstrate that the model is capable of 

simulating accurate water levels over a wide range of flows in 

the basin. Details on techniques used in model development 

and calibration can be found in Bales and others (2007).

Development of Water-Surface Profiles

Discharges corresponding to the various stages were 

obtained from the most current stage-discharge relation 

(rating no. 29.0) at the Leaf River gage. Discharges for all 

profiles (table 5) at locations downstream of the Leaf River 

streamgage (02473000) were held constant because of the 

relatively small amount of contributing drainage that enters 

the Leaf River within this part of the study reach. Tributaries 

entering the reach below the streamgage will most likely be 

ineffective during a flood event because of backwater storage 

for floodwaters from the Leaf River. There is a possibility of 

localized heavy rainfall contributing to the backwater inundation areas, but estimating the probability and quantity of 

such contributions is beyond the scope of this report.

The Bouie River is a major tributary to the Leaf River 

and its confluence is approximately 0.1 mi above the Leaf 

River streamgage (02473000). A streamgage on the Bouie 

River at Glendale Avenue (02472980) has been in operation 

since October 1, 2010. There have been no flood events 

greater than the flood stage (22.0 ft) as defined by the NWS at 

the Leaf River gage during the period of record at the Bouie 

River gage. A conservative flow distribution of approximately 

70/30 in the Leaf and Bouie Rivers respectively, above the 

confluence, was assumed based on the discharge rating at the 

Bouie River streamgage. 

Table 3. Comparison of hydraulic-model output and water-surface elevations at the Leaf 

River at Hattiesburg, Mississippi, streamgage 02473000.

[ft3/s, cubic foot per second; ft, foot; NAVD 88, North American Vertical Datum of 1988]

Discharge

(ft3/s)

Stage

(ft above

gage datum)

Water-surface 

elevation

(ft above NAVD 88)

Simulated watersurface elevation

(ft above NAVD 88)

Elevation

 difference 

(ft)

33,400 21.34 139.52 139.64 0.12

35,350 22.00 140.18 140.21 0.03

38,530 23.00 141.18 141.16 –0.02

42,070 24.00 142.18 142.21 0.03

45,970 25.00 143.18 143.13 –0.05

50,450 26.00 144.18 144.05 –0.13

55,200 27.00 145.18 145.08 –0.10

60,200 28.00 146.18 146.01 –0.17
6 An Expanded Model: Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi, 2013

Table 4. Comparison of hydraulic-model output and surveyed high-water mark elevations from 

the floods of April 15, 1974, and March 11, 2011, at the Leaf River at Hattiesburg, Mississippi, 

streamgage 02473000.

[ft, foot; mi, mile; NAVD 88, North American Vertical Datum of 1988]

Flood date

High-water mark

elevation

(ft above NAVD 88)

Model water-surface

elevation

(ft above NAVD 88)

Elevation

difference

(ft)

East Hardy/South Main Street Bridge (river station 70.4 mi)

April 15, 1974 146.8 146.72 – 0.08

March 11, 2011 136.1 136.14 0.04

Southern Railroad Bridge (river station 71.2 mi)

April 15, 1974 149.7 149.62 – 0.08

March 11, 2011 137.8 137.85 0.05

USGS Streamgage 02473000 (river station 71.8 mi)

April 15, 1974 152.2 152.25 0.05

March 11, 2011 139.5 139.64 0.14

*Evelyn Gandy Parkway Bridge (State Highway 42) (river station 73.0 mi)

March 11, 2011 140.8 140.66 – 0.14

*The Evelyn Gandy Parkway was constructed in 1997.

Table 5. Stages and water-surface elevations at the Leaf River at Hattiesburg, Mississippi, streamgage 02473000, with corresponding 

discharge estimates for selected simulated water-surface profiles.

[NAVD 88, North American Vertical Datum of 1988. Sheet numbers correspond to the separate flood-inundation maps available online at http://pubs.usgs.gov/

sim/3300/]

Location Water-surface elevations and discharge estimates

Stage, in feet above gage datum (elevation, in feet above NAVD 88)

Leaf River at Hattiesburg, MS 

(02473000)

22

(140.18)

23

(141.18)

24

(142.18)

25

(143.18)

26

(144.18)

27

(145.18)

28

(146.18)

Discharge, in cubic feet per second

Leaf River at Evelyn Gandy Parkway 25,000 27,600 30,000 33,000 36,400 39,500 43,400

Bouie Creek at Glendale Avenue 10,300 11,000 12,000 13,200 14,800 16,100 17,700

Leaf River at Hattiesburg, MS 

(02473000)

35,300 38,600 42,000 46,200 51,200 55,600 61,100

Sheet number 1 2 3 4 5 6 7

Location Water-surface elevations and discharge estimates

Stage, in feet above gage datum (elevation, in feet above NAVD 88)

Leaf River at Hattiesburg, MS 

(02473000)

29

(147.18)

30

(148.18)

31

(149.18)

32

(150.18)

33

(151.18)

34

(152.18)

Discharge, in cubic feet per second

Leaf River at Evelyn Gandy Parkway 48,900 57,200 63,400 70,200 78,000 85,500

Bouie Creek at Glendale Avenue 20,000 23,300 25,900 28,700 31,800 34,900

Leaf River at Hattiesburg, MS 

(02473000)

68,900 80,500 89,300 98,900 109,800 120,400

Sheet number 8 9 10 11 12 13
Inundation Mapping 7

Inundation Mapping

Flood-inundation maps were created for 13 profiles at the 

USGS Leaf River at Hattiesburg Miss. streamgage (02473000), 

which has been designated as a NWS flood-forecast point (as of 

1957). The maps were created in a GIS by combining the watersurface profiles and digital elevation model (DEM) data. The 

DEM data were derived from 9.84-ft horizontal resolution lidar 

data with a vertical accuracy of 0.6 ft obtained from EarthData 

International, Inc. (written commun., 2007). Estimated 

flood-inundation boundaries for each simulated profile were 

developed with HEC–GeoRAS software (U.S. Army Corps 

of Engineers, 2009). HEC–GeoRAS is a set of procedures, 

tools, and utilities for processing geospatial data in ArcGIS by 

using a graphical user interface (Whitehead and Ostheimer, 

2009). The interface allows the preparation of geometric data 

for import into HEC–RAS and processes simulation results 

exported from HEC–RAS (U.S. Army Corps of Engineers, 

2010). USGS personnel then modified the HEC–GeoRAS 

results to ensure a hydraulically reasonable transition of the 

boundary between modeled cross sections relative to the 

contour data for the land surface (Whitehead and Ostheimer, 

2009). The resulting inundation maps have a vertical accuracy 

of about 1.0 ft. The maps show estimated flood-inundated 

areas overlaid on high-resolution, georeferenced aerial 

photographs of the study area for each of the water-surface 

profiles that were generated by the hydraulic model.

Leaf River at Hattiesburg, Mississippi, 

Flood-Inundation Maps on the Internet

The flood-inundation maps described in this report and 

other study documentation are available online at the USGS 

Publications Warehouse (http://pubs.usgs.gov/sim/3300/). 

Also, a Flood Inundation Mapping Science Web site has been 

established at http://water.usgs.gov/osw/flood_inundation/ to 

provide a portal for USGS flood-inundation study information 

to the public. That Web portal has a link (http://wim.usgs.gov/

FIMI/FloodInundationMapper.html) to interactive online map 

libraries that can be downloaded in several commonly used 

electronic file formats. At the map library site, each stream reach 

displayed contains further links to NWISWeb graphs of the 

current stage and streamflow at USGS streamgage Leaf River 

at Hattiesburg Miss. (02473000) to which the inundation maps 

are referenced. A link also is provided to the NWS AHPS site 

(http:/water.weather.gov/ahps/) so that the user can obtain 

applicable information on forecasted peak stage. The 

estimated flood-inundation maps are displayed in sufficient 

detail to note the extent of flooding with respect to individual 

structures so that preparations for flooding and decisions for 

emergency response can be performed efficiently. Roadways 

and bridges were closely reviewed and are shown as shaded 

(inundated and likely impassable) or not shaded (dry and 

passable) to facilitate emergency planning and use. However, 

buildings that are shaded do not reflect inundation but denote 

that bare-earth surfaces in the vicinity of the buildings are 

inundated. When the water depth (as indicated in the Web 

Mapping Application by holding the cursor over an inundated 

area) adjacent to the building of interest exceeds that building’s height, the structure can be considered fully submerged.

Disclaimer for Flood-Inundation Maps

Inundated areas shown should not be used for navigation, 

regulatory, permitting, or other legal purposes. The USGS 

provides these maps “as-is” for a quick reference, emergency 

planning tool but assumes no legal liability or responsibility 

resulting from the use of this information.

Uncertainties and Limitations Regarding 

Use of Flood-Inundation Maps

Although the flood-inundation maps represent the 

boundaries of inundated areas with a distinct line, some 

uncertainty is associated with these maps. The flood 

boundaries shown were estimated based on water stages and 

streamflows at selected USGS streamgages. Water-surface 

elevations along the stream reaches were estimated by 

steady-state hydraulic modeling, assuming unobstructed flow, 

and using streamflows and hydrologic conditions anticipated 

at the USGS streamgage(s). The hydraulic model reflects the 

land-cover characteristics and any bridge, dam, levee, or other 

hydraulic structures existing as of September 2013. Unique 

meteorological factors (timing and distribution of precipitation) may cause actual streamflows along the modeled reach 

to vary from those assumed during a flood, which may lead 

to deviations in the water-surface elevations and inundation 

boundaries shown. Additional areas may be flooded due to 

unanticipated conditions such as: changes in the streambed 

elevation or roughness, backwater into major tributaries along 

a main stem river, or backwater from localized debris. The 

accuracy of the floodwater extent portrayed on these maps will 

vary with the accuracy of the DEM used to simulate the land 

surface. Additional uncertainties and limitations pertinent to 

this study may be described elsewhere in this report.

If this series of flood-inundation maps will be used in 

conjunction with NWS river forecasts, the user should be 

aware of additional uncertainties that may be inherent to 

NWS forecast procedures. The NWS uses forecast models 

to estimate the quantity and timing of water flowing through 

selected stream reaches in the United States. These forecast 

models (1) estimate the amount of runoff generated by 

precipitation and snowmelt, (2) simulate the movement of 

floodwater as it proceeds downstream, and (3) predict the flow 

and stage (and water-surface elevation) for the stream at a 

given location (AHPS forecast point) throughout the forecast 

period (every 6 hours and 3 to 5 days out in many locations). 

Each of these steps involves some degree of approximation 

so results should be applied with allowances for possible 

error. For more information on AHPS forecasts, please see: 

http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. 
8 An Expanded Model: Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi, 2013

Summary

Estimated flood-inundation maps were developed in 

cooperation with the City of Hattiesburg, City of Petal, 

Mississippi Emergency Management Agency, Mississippi 

Department of Homeland Security, and the Emergency 

Management District for the Leaf River at Hattiesburg, Miss. 

These maps, in conjunction with the real-time stage data 

from the USGS streamgage at Leaf River at Hattiesburg, 

Miss. (station no. 02473000) and flood-stage forecasts by the 

National Weather Service, can be used to guide the general 

public in taking individual safety precautions and will provide 

city officials with a tool to efficiently manage emergency flood 

operations and flood mitigation efforts. These maps supersede 

previously published flood-inundation estimates to include 

reaches above the confluence of the Bouie and Leaf Rivers.

The maps were developed by using the U.S. Army 

Corps of Engineers’ HEC–RAS and HEC–GeoRAS 

programs to compute water-surface profiles and to delineate 

estimated flood-inundation areas for selected stream stages. 

The maps show estimated (shaded) flood-inundation 

areas overlaid on high-resolution, georeferenced aerial 

photographs of the study area for stream stages between 

22.0 feet and 34.0 feet at the Leaf River at Hattiesburg Miss. 

streamgage. The maps are available at a USGS Web portal at 

http://pubs.usgs.gov/sim/3300/. Interactive use of the maps by 

using the mouse cursor to click within the shaded areas can 

give users a general indication of depth of water at any point. 

References Cited

Bales, J.D., Wagner, C.R., Tighe, K.C., and Terziotti, Silvia, 

2007, LiDAR-derived flood-inundation maps for realtime flood-mapping applications, Tar River Basin, North 

Carolina: U.S. Geological Survey Scientific Investigations 

Report 2007–5032, 42 p.

Federal Emergency Management Agency, 2010, Flood 

insurance study, Forrest County, Mississippi and 

incorporated areas: 79 p.

Storm, J.B., 2012, Flood-inundation maps for the Leaf River at 

Hattiesburg, Mississippi: U.S. Geological Survey Scientific 

Investigations Map 3228, 8 p. pamphlet, 13 sheets (Also 

available at http://pubs.usgs.gov/sim/3228/.)

U.S. Army Corps of Engineers Hydrologic Engineering 

Center, 2009, HEC–GeoRAS, GIS tools for support of 

HEC–RAS using ArcGIS—User’s manual, version 4.2 

[variously paged]. 

U.S. Army Corps of Engineers Hydrologic Engineering 

Center, 2010, HEC–RAS River Analysis System—

Hydraulic reference manual, version 4.1 [variously paged].

U.S. Army Corps of Engineers, 1983, Leaf and Bouie Rivers 

Hattiesburg and Petal, Mississippi: Detailed Project Report 

and Environmental Impact Statement, 267 p.

U.S. Census Bureau, 2010, State population datasets—

Population, population change and estimated components

of population change: 2000 to 2010 (http://quickfacts.

census.gov/qfd/states/28000.html).

Whitehead, M.T., and Ostheimer, C.J., 2009, Development 

of a flood-warning system and flood-inundation mapping 

for the Blanchard River in Findlay, Ohio: U.S. Geological 

Survey Scientific Investigations Report 2008–5234, 9 p.

Wilson, K.V., 1964, Floods of 1961 in Mississippi: U.S. 

Geological Survey Bulletin 64–4, 93 p. 
Manuscript approved on May 9, 2014

Edited by Michael Deacon

Layout by Caryl J. Wipperfurth

Science Publishing Network

 Raleigh Publishing Service Center

For more information about this publication, contact:

Director, Mississippi Water Science Center

U.S. Geological Survey

308 Airport Road South

Jackson, MS 39208-6649

(601) 933-2900

http://ms.water.usgs.gov/
Storm—An Expanded Model: Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi, 2013—Scientific Investigations Map 3300

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3300