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

Flood-Inundation Maps for the Leaf River at 

Hattiesburg, Mississippi

Pamphlet to accompany

Scientific Investigations Map 3228

U.S. Department of the Interior

U.S. Geological Survey
Cover. Left, photograph looking downstream at the Leaf River at State Highway 42 above Hattiesburg, Mississippi, April 25, 2012. 

Right, inundation map of Leaf River at Hattiesburg, Mississippi (02473000), at 34.0 feet gage datum (see Sheet 13 for details).
Flood-Inundation Maps for the Leaf River at 

Hattiesburg, Mississippi

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

Pamphlet to accompany 

Scientific Investigations Map 3228

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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., 2012, Flood-inundation maps for the Leaf River at Hattiesburg, Mississippi: U.S. Geological Survey 

Scientific Investigations Map 3228, 8 p. pamphlet, 13 sheets; available online at http://pubs.usgs.gov/sim/3228/.
iii

Contents

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

Introduction ....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

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

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

Constructing Water-Surface Profiles.........................................................................................................4

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

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

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

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

Development of Water-Surface Profiles...........................................................................................6

Inundation Mapping ......................................................................................................................................6

Leaf River, 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..........................................................................................................................................................7

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

Figure

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

Geological Survey streamgage and National Weather Service forecast site ...................3

Tables

1. Site information for the U.S. Geological Survey streamgage in the 

Leaf River basin at Hattiesburg, Mississippi............................................................................2

2. Estimates of peak discharge for a 1.0-percent annual exceedance probability 

for selected locations on the Leaf River near Hattiesburg, Mississippi..............................4

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

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

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

elevations from the floods of April 1974 and March 2011 at the Leaf River 

at Hattiesburg, Mississippi, streamgage ..................................................................................5

5. Stages (and water-surface elevations) with corresponding discharge 

estimates for selected simulated water-surface profiles at the Leaf River 

at Hattiesburg, Mississippi, streamgage ..................................................................................6
iv

Sheets (Each sheet has individual pdf files available for download. For links, 

see http://pubs.usgs.gov/sim/3228/.)

1–13. Maps showing flood inundation for Hattiesburg, Mississippi, 

corresponding to a gage height and an elevation (NAVD 88) 

as listed below at U.S. Geological Survey streamgage Leaf River 

at Hattiesburg, MS (02473000)—

 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

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

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 Mississippi Department of Environmental Quality, which has 

cooperated in the funding for the operation and maintenance of the streamgage used for 

this study. 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.

Flood-Inundation Maps for the Leaf River at 

Hattiesburg, Mississippi

By John B. Storm 

Abstract

Digital flood-inundation maps for a 1.7-mile reach 

of the Leaf River were developed 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 Leaf River study reach extends from just upstream 

of the U.S. Highway 11 crossing to just downstream of 

East Hardy/South Main Street and separates the cities of 

Hattiesburg and Petal, Mississippi. 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 of 

flooding corresponding to selected water-surface elevations 

(stages) at the USGS streamgage at Leaf River at Hattiesburg, 

Mississippi (02473000). Current conditions at the USGS 

streamgage may be obtained through the National Water 

Information System Web site at http://waterdata.usgs.gov/ms/

nwis/uv/?site_no=02473000&PARAmeter_cd=00065,00060. 

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 collocated at 

USGS streamgages. The forecasted peak-stage information, 

available on the AHPS Web site, 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 using the most current 

stage-discharge relations at the Leaf River at Hattiesburg, 

Mississippi, streamgage 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-surface elevation at the streamgage. The 

simulated water-surface profiles were then combined with 

a geographic information system digital elevation model 

[derived from Light Detection and Ranging (LiDAR) data 

having a 0.6-foot vertical accuracy and 9.84-foot horizontal 

resolution] in order to delineate the area flooded at each 1-foot 

increment of stream stage.

The availability of these maps, when combined with 

real-time stage information from USGS streamgages and 

forecasted stream stage from the NWS, provides emergency 

management personnel and residents with critical information 

during flood-response activities, such as evacuations and road 

closures, as well as for post-flood recovery efforts.
2 Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi

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. Bureau of Census, 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. Damage costs unadjusted for inflation within the cities of Hattiesburg and Petal were reported 

to be $3.25 million for the 1961 flood (Wilson, 1964) and 

$8.3 million for the 1974 flood (U.S. Army Corps of Engineers, 1983). The majority of flood damages have occurred 

along the Leaf River and several tributaries (Bouie River, 

Gordon Creek), all of which flow through the city. Flood 

plains within Hattiesburg are moderately to highly developed 

and contain a mix of residential and commercial structures.

Prior to this study, city officials in Hattiesburg and Petal 

have 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 (Federal Emergency 

Management Agency, 2010). A second source of information 

is the U.S. Geological Survey (USGS) streamgage Leaf River 

at Hattiesburg, Mississippi (MS) (02473000; table 1), from 

which current or historical water-surface elevations (stage) 

can be obtained. A third source is the National Weather 

Service (NWS) forecast of peak stage at the USGS streamgage 

through the Advanced Hydrologic Prediction Service (AHPS) 

Web site at http://water.weather.gov/ahps/. 

Although USGS current stage and NWS forecast stage 

data are particularly useful for residents in the immediate 

vicinity of a streamgage, the data are of limited use to 

residents farther upstream or downstream because the watersurface 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 water depth at locations other than near USGS 

streamgages or NWS flood-forecast points. To help guide the 

general public in taking individual safety precautions and 

provide local officials with a tool to help efficiently manage 

emergency flood operations and flood-mitigation efforts, 

digital flood-inundation maps for a 1.7-mile (mi) reach of 

the Leaf River were developed by the 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. 

Purpose and Scope

The purpose of this report is to describe the development of a series of estimated flood-inundation maps for the 

Leaf River at Hattiesburg, MS. The maps and other useful 

flood information are available on the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/

flood_inundation/ and the previously mentioned NWS AHPS 

Web site. Internet users can select estimated inundation maps 

that correspond to (1) current stages at the USGS Leaf River 

at Hattiesburg streamgage (02437000), or (2) the NWS forecasted peak stage.

The scope of the study was limited to a 1.7-mi reach 

of the Leaf River between U.S. Highway 11 and just downstream of East Hardy/South Main Street (fig. 1). Tasks 

specific to development of the flood-inundation maps were 

(1) collection of topographic data and geometric data for 

bridges throughout the study reach, (2) determination of 

energy loss factors (roughness coefficients) in the stream 

channel and flood plain, (3) collection of steady-flow data 

(discharge rating) at the streamgaging station, (4) computation 

of water-surface profiles using HEC–RAS, a U.S. Army Corps 

of Engineers computer program (U.S. Army Corps of Engineers, Hydrologic Engineering Center, 2010), (5) production 

of estimated flood-inundation maps at various stream stages 

using HEC–GeoRAS, a U.S. Army Corps of Engineers 

computer program (U.S. Army Corps of Engineers, Hydrologic Engineering Center, 2009), and a geographic information 

system (GIS), and (6) development of a Web site interface that 

links to USGS real-time streamgage information and 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 due to local hydrologic 

conditions or available data, they are described in detail in 

Table 1. Site information for the U.S. Geological Survey streamgage in the Leaf River basin at Hattiesburg, Mississippi.

[mi2, square mile; ft, foot; current year refers to 2012, year of this publication; NAVD 88, North American Vertical Datum of 1988]

Station name Station 

number

Leaf River

drainage area

 (mi2

)

Latitude Longitude Period of

record

Maximum recorded

stage at gage

(ft above gage datum),

and date

Leaf River at 

Hattiesburg, MS

02473000 1,750 31°20'35"N 89°16'49"W October 1905 to 

current year

34.03 ft

(152.21 ft NAVD 88) 

4/15/1974
Introduction 3

Hattiesburg

Petal

42 11

11

0 0.5 1 MILE

0 0.5 1 KILOMETER

EXPLANATION

Direction of surface-water flow

Study area boundary

89°18' 89°17' 89°16' 89°15'

31°21'

31°20'

31°19'

Forrest

County

MISSISSIPPI

Study

area

Orthography from National Agriculture Imagery Program, 2010

Transverse Mercator projection

North American Datum of 1983 and

North American Vertical Datum of 1988

02473000

02473000

Bouie River

Gordon Creek

Leaf River

W 7TH STREET

CARTERVILLE ROAD

E HARDY STREET

S MAIN STREET

NEW RICHTON ROAD

HARDY STREET

OLD RICHTON ROAD

USGS streamgage and NWS forecast site 

 and identifier

Figure 1. Location of study reach for the Leaf River and location of U.S. Geological Survey streamgage and 

National Weather Service forecast site.
4 Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi

this report. Maps were produced for water levels referenced to 

the water-surface elevation (stage) at the Leaf River at Hattiesburg streamgage (02473000) and range from approximately 

bankfull (22.0 feet) to the maximum observed water-surface 

elevation at the streamgage (34.0 feet). 

Study Area Description

The Leaf River is in southeastern Mississippi in the 

East Gulf Coastal Plain. The drainage area ranges from 

1,750 square miles (mi2) at the Leaf River at Hattiesburg 

streamgage (02473000) to 1,760 mi2 at the downstream extent 

of the study reach. The headwaters of the Leaf River originate 

in Scott County, and the river flows generally southward 

before entering the Hattiesburg city limits. The Bouie River is 

a major tributary to the Leaf River, joining the main stem as it 

flows through Hattiesburg. The Bouie River’s confluence with 

the Leaf River is approximately 0.1 mi upstream of the Leaf 

River at Hattiesburg streamgaging station. The Leaf River 

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

The study reach is approximately 1.7 mi long, has an average 

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

average channel slope of about 2.1 feet per mile (ft/mi). The 

basin is still under development, and population has increased 

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 three major road crossings or other structures 

that lie within the channel or the adjacent floodplain. 

Previous Studies 

The current FIS for Forrest County (Federal Emergency 

Management Agency, 2010) was completed by the State of 

Mississippi in 2008 and revised in 2010. That study provided 

information on the 10.0-, 2.0-, 1.0- and 0.2-percent annual 

exceedance probability water-surface profiles and associated 

flood-plain maps for the Leaf River. Estimates of the peak 

discharges for the 1.0-percent annual exceedance probability 

flood along the Leaf River, as shown in table 2 for the study 

reach, are described in the current FIS.

Constructing Water-Surface Profiles

The water-surface profiles used to produce the 

13 flood-inundation maps in this study were computed using 

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

Hydrologic Engineering Center, 2010). HEC–RAS is a 

one-dimensional step-backwater model for simulation of 

water-surface profiles with steady-state (gradually varied) 

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

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

computation option.

Hydrologic and Steady-Flow Data

The study area hydrologic network consists of one 

streamgage (fig. 1; table 1). Water-surface elevation (stage) 

is measured continuously at the Leaf River at Hattiesburg 

streamgage (02437000), and continuous records of streamflow 

are computed. All water-surface elevations are referenced to 

North American Vertical Datum of 1988 (NAVD 88). The gage 

is equipped with a satellite radio transmitter that allows data 

to be transmitted routinely and made available on the Internet 

within an hour of collection. The site also is equipped with a 

recording tipping-bucket rain gage. Longitudinal water-surface 

profiles from high-water marks along the main channel of the 

Leaf River were documented following the peak of the record 

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

water-surface profiles were used for model calibration. 

Steady-flow data consisted of flow regime, boundary 

conditions (either a known water-surface elevation associated with a discharge measurement, critical depth, normal 

depth, or streamgage rating curve value), and peak discharge 

information. The steady-flow data for the study reach were 

obtained from field measurements of streamflow at the Leaf 

River at Hattiesburg streamgage. At the streamgage site 

(02473000), all computations using discharge values with 

known stages from actual streamflow measurements or stagedischarge relations were used. For ungaged sites, normal-depth 

boundary conditions were assumed (using a friction slope 

estimated from the average streambed slope through the reach) 

unless miscellaneous discharge measurements referenced to a 

known stage 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 mechanical means 

to measure depth, velocity, and horizontal distance at the 

U.S. Highway 11 and East Hardy Street/South Main Street 

bridges. The channel cross section at the Southern Railroad 

bridge was defined by tapedowns to the channel bed from 

Table 2. Estimates of peak discharge for a 1.0-percent annual 

exceedance probability for selected locations on the Leaf River 

near Hattiesburg, Mississippi (Federal Emergency Management 

Agency, 2010).

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

Location on

Leaf River

Drainage

area

(mi2

)

Peak

discharge 

estimate

(ft3

/s)

Percentage

of total

discharge

At U.S. Highway 11 1,760 110,000 100

Upstream from Bouie

River confluence

1,100 82,000 75
Constructing Water-Surface Profiles 5

the downstream side of the bridge. Control at the railroad 

bridge was established by real-time kinematic global positioning system survey procedures and then elevations were 

determined using closed level-loop surveying techniques 

with a total station. Light Detection and Ranging (LiDAR) 

data with horizontal resolution of 9.84 ft and vertical accuracy of 0.6 ft 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. The LiDAR data were 

collected in March and April 2006 by EarthData International, 

Inc.; postprocessing of these data was completed by EarthData 

International, Inc., in 2007. 

Various manmade drainage structures (bridges, culverts, 

roadway embankments, levees, and dams) in and along the 

stream affect or have the potential to affect water-surface 

elevations during flooding. To properly account for these 

features in the model, structural dimensions for three bridges 

were measured and surveyed in the field concurrently with 

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 (pre-calibration) Manning’s 

roughness coefficients (“n” values) for energy (friction) 

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

0.026 to 0.042 for the main channel and from 0.040 to 0.28 

for the overbank areas modeled in this analysis. 

Model Calibration and Performance

The hydraulic model was calibrated to the most current 

(2012) stage-discharge relation at the Leaf River at Hattiesburg streamgage (02473000) and to high-water marks from 

the floods of April 1974 and March 2011. The measured peak 

discharges (and stages) for the 1974 and 2011 floods were 

121,000 cubic feet per second (ft3

/s) (34.03 ft) and 33,400 ft3/s 

(21.34 ft), respectively. Model calibration was accomplished 

by adjusting Manning’s n values and, in some cases, changing 

the channel cross section or slope until the results of the 

hydraulic computations closely agreed with the known flood 

discharge and stage values. Differences between measured 

and simulated water-surface elevations at the streamgaging 

station for specified flows were equal to or less than 0.17 ft 

and were within 5 percent of the current stage-discharge relation (table 3). Differences between measured and simulated 

water-surface elevations for models calibrated to high-water 

marks were equal to or less than 0.15 ft (table 4). The results 

demonstrate that the model is capable of simulating accurate 

water-surface elevations 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).

Table 3. Comparison of hydraulic-model output and watersurface elevations at the Leaf River at Hattiesburg, Mississippi, 

streamgage (02473000).

[ft3/s, cubic feet per second; NAVD 88, North American Vertical Datum 

of 1988; ft, foot]

Discharge 

(ft3

/s)

Stage,

in feet

above

gage

datum

Watersurface

elevation,

in feet,

NAVD 88

Simulated 

watersurface

elevation,

in feet,

NAVD 88

Elevation 

difference 

(ft)

33,400 21.34 139.52 139.65 0.13

35,350 22.00 140.18 140.26 0.08

35,680 22.11 140.29 140.36 0.07

38,530 23.00 141.18 141.24 0.06

40,120 23.48 141.66 141.73 0.07

41,200 23.77 141.95 142.10 0.15

42,070 24.00 142.18 142.28 0.10

45,970 25.00 143.18 143.11 – 0.07

46,170 25.05 143.23 143.15 – 0.08

50,450 26.00 144.18 144.05 – 0.13

54,700 26.90 145.08 144.95 – 0.13

55,200 27.00 145.18 145.05 – 0.13

60,200 28.00 146.18 146.01 – 0.17

Table 4. Comparison of hydraulic-model output and surveyed 

high-water mark elevations from the floods of April 1974 and 

March 2011 at the Leaf River at Hattiesburg, Mississippi, 

streamgage (02473000).

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

Flood

date

Measured

high-water mark

elevation,

in feet,

NAVD 88

Simulated 

water-surface 

elevation,

in feet,

NAVD 88

Elevation

difference

(ft)

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

April 15, 1974 146.8 146.73 –0.07

March 11, 2011 136.1 136.04 –0.06

Southern Railroad Bridge (71.2 mi river station)

April 15, 1974 149.7 149.6 –0.10

March 11, 2011 137.8 137.75 –0.05

USGS streamgage 02473000 (71.8 mi river station)

April 15, 1974 152.2 152.22 0.02

March 11, 2011 139.5 139.65 0.15
6 Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi

Development of Water-Surface Profiles

Profiles were developed for 13 stages at 1.0-ft intervals 

between 22.0 ft and 34.0 ft (140.18 ft and 152.18 ft NAVD 88, 

respectively) as referenced to the local datum at the Leaf River 

at Hattiesburg streamgage (02473000). Discharges corresponding to the various stages were obtained from the most 

current stage-discharge relation at the streamgage. 

Discharges for all profiles (table 5) at locations downstream of streamgage 02473000 on the Leaf River were held 

constant due to the relatively small amount of contributing 

drainage that enters the Leaf River within the study reach. 

Gordon Creek most likely will be ineffective during a flood 

event because of backwater storage of floodwaters from the 

Leaf River. There is a possibility of localized heavy rainfall 

contributing to the backwater inundation areas, but this is 

beyond the scope of this report.

Inundation Mapping

Flood-inundation maps were created for 13 profiles at 

the USGS Leaf River at Hattiesburg streamgage (02473000), 

which has been designated as an NWS flood-forecast point 

since 1957 (fig. 1). The maps were created in a GIS by 

combining the water-surface profiles and digital elevation 

model data. The digital elevation model data were collected 

and processed to yield an average spacing of points no 

greater than 9.84 ft (3 meters) apart and achieve a vertical 

accuracy of 0.6 ft (18.5 centimeters) root mean square error. 

Estimated flood-inundation boundaries for each simulated 

profile were developed with HEC–GeoRAS software (U.S. 

Army Corps of Engineers, Hydrologic Engineering Center, 

2009). HEC–GeoRAS is a set of procedures, tools, and utilities for processing geospatial data in ArcGIS (Esri, 2010) 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, 

Hydrologic Engineering Center, 2010). USGS personnel 

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 maps show 

estimated flood-inundated areas overlain on high-resolution, 

georeferenced, aerial photographs of the study area for each 

of the water-surface profiles that were generated by the 

hydraulic model.

Table 5. Stages (and water-surface elevations) with corresponding discharge estimates for selected simulated water-surface 

profiles at the Leaf River at Hattiesburg, Mississippi, streamgage (02473000).

[Values 22.0–34.0 represent stage, in feet above gage datum. Values in parentheses (140.18–152.18) represent water-surface elevations, in feet above 

North American Vertical Datum of 1988]

Leaf River at Hattiesburg, Mississippi

Stage (water-surface

elevation)

22.0

(140.18)

23.0

(141.18)

24.0

(142.18)

25.0

(143.18)

26.0

(144.18)

27.0

(145.18)

28.0

(146.18)

Discharge, in cubic 

feet per second

35,200 38,100 41,400 46,300 50,900 56,000 61,300

Sheet number 1 2 3 4 5 6 7

Stage (water-surface

elevation)

29.0

(147.18)

30.0

(148.18)

31.0

(149.18)

32.0

(150.18)

33.0

(151.18)

34.0

(152.18)

Discharge, in cubic 

feet per second

67,500 74,100 83,000 94,900 107,800 121,000

Sheet number 8 9 10 11 12 13
Summary 7

Leaf River, Hattiesburg, Mississippi, FloodInundation Maps on the Internet

A USGS Flood Inundation Mapping Science World Wide 

Web portal (http://water.usgs.gov/osw/flood_inundation/) 

has been established by the USGS to provide estimated 

flood-inundation information to the public. The maps from 

this study are available in several commonly used electronic 

file formats that can be downloaded from that portal. Each 

stream reach displayed on the Web site contains links to 

USGS National Water Information System graphs of the 

current stage and streamflow at USGS Leaf River at Hattiesburg streamgage (02473000), to which the inundation maps 

are referenced (http://waterdata.usgs.gov/ms/nwis/uv/?site_

no=02473000&PARAmeter_cd=00065,00060). A link also is 

provided to the NWS AHPS Web site (http://water.weather.

gov/ahps/) so that users 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. 

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 the 

Leaf River at Hattiesburg streamgage (02473000). Watersurface elevations along the stream reaches were estimated by 

steady-state hydraulic modeling, assuming unobstructed flow, 

and by using streamflows and hydrologic conditions anticipated at the USGS streamgage. The hydraulic model reflects 

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

other hydraulic structures existing as of the date of the model 

calibration (December 2011). 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 digital elevation model 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 National Weather Service (NWS) river 

forecasts, the user should be aware of additional uncertainties 

that may be inherent or factored into 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 watersurface 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). For more information 

on AHPS forecasts, please see: http://water.weather.gov/ahps/

pcpn_and_river_forecasting.pdf.

Summary

A series of estimated flood-inundation maps for a 

1.7-mile reach of the Leaf River at Hattiesburg, Mississippi, was developed 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. These maps, available at a 

USGS Web portal, in conjunction with the real-time stage data 

from the USGS streamgage at Leaf River at Hattiesburg, MS 

(02473000), and National Weather Service flood-stage forecasts, can help to guide the general public in taking individual 

safety precautions and can provide local officials with a tool 

to efficiently manage emergency flood operations and floodmitigation efforts. 

The maps were developed using the U.S. Army Corps of 

Engineers HEC–RAS and HEC–GeoRAS computer programs 

to compute water-surface profiles and to delineate estimated 

flood-inundation areas for selected stream stages. The maps 

show estimated flood-inundation areas overlain on highresolution, georeferenced, aerial photographs of the study area 

for stream stages between 22.0 ft and 34.0 ft (gage datum) at 

the Leaf River at Hattiesburg streamgage (02473000). 
8 Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi

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.

Esri [2010], ArcGis Desktop: Version 9.3.1: Accessed 

August 2010 at http://www.esri.com.

Federal Emergency Management Agency, 2010, Flood Insurance Study, Forrest County, Mississippi and Incorporated 

Areas, 79 p.

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. Bureau of Census, 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 August 8, 2012

Edited by Kimberly A. Waltenbaugh

Layout by Caryl J. Wipperfurth

Science Publishing Network, Raleigh PSC

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—Flood-Inundation Maps for the Leaf River at Hattiesburg, Mississippi—Scientific Investigations Map 3228