Prepared in cooperation with the Indiana Department of Transportation

Flood-Inundation Maps for the Wabash River at Terre Haute, 

Indiana

Pamphlet to accompany

Scientific Investigations Map 3232

U.S. Department of the Interior

U.S. Geological Survey
Cover:

Photo shows south (downstream) side of Eastbound Highway 150 bridge over Wabash River at Terre Haute, Indiana while streamflow 

measurements were being collected (photo was taken by Eric Looper, USGS, April, 2013). Image shows flood inundation at stage of 

30.00 feet and elevation of 475.4 feet.
Flood-Inundation Maps for the Wabash River 

at Terre Haute, Indiana

By Pamela J. Lombard

Prepared in cooperation with the Indiana Department of Transportation

Pamphlet to accompany

Scientific Investigations Map 3232

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: 2013

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as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Lombard, P.J., 2013, Flood-inundation maps for the Wabash River at Terre Haute, Indiana, U.S. Geological Survey 

Scientific Investigations Map 3232, 22 sheets 7-p. pamphlet, http://pubs.usgs.gov/sim/3232/.
iii

Contents

Acknowledgments........................................................................................................................................iv

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

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

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

Study Area Description........................................................................................................................2

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

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

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

Topographic and Bathymetric Data...................................................................................................4

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

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

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

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

Flood-Inundation Maps on the Internet ............................................................................................6

Disclaimer for Flood-Inundation Maps .............................................................................................6

Uncertainties and Limitations for Use of Flood-Inundation Maps ...............................................6

Summary..........................................................................................................................................................7

References Cited............................................................................................................................................7

Sheets

Note: For best resolution and readability, map sheets are designed for printing at a size of 

17 x 22 inches 

[Sheets and additional materials are available online at http://pubs.usgs.gov/sim/3232/.]

1–22. Flood-inundation maps for 6.3-mile reach of the Wabash River at Terre Haute, Indiana, 

corresponding to USGS streamgage Wabash River at Terre Haute (sta. no. 03341500) 

for a stage of:

1. 9 feet above gage datum and an elevation of 454.4

2. 10 feet above gage datum and an elevation of 455.4

3. 11 feet above gage datum and an elevation of 456.4

4. 12 feet above gage datum and an elevation of 457.4

5. 13 feet above gage datum and an elevation of 458.4

6. 14 feet above gage datum and an elevation of 459.4

7. 15 feet above gage datum and an elevation of 460.4

8. 16 feet above gage datum and an elevation of 461.4

9. 17 feet above gage datum and an elevation of 462.4

10. 18 feet above gage datum and an elevation of 463.4

11. 19 feet above gage datum and an elevation of 464.4

12. 20 feet above gage datum and an elevation of 465.4

13. 21 feet above gage datum and an elevation of 466.4

14. 22 feet above gage datum and an elevation of 467.4

15. 23 feet above gage datum and an elevation of 468.4
Sheets–continued

1–22. Estimated Flood-inundation maps for 6.3-mile reach of the Wabash River at Terre 

Haute, Indiana, corresponding to USGS streamgage Wabash River at Terre Haute (sta. 

no. 03341500) for a stage of:

16. 24 feet above gage datum and an elevation of 469.4

17. 25 feet above gage datum and an elevation of 470.4

18. 26 feet above gage datum and an elevation of 471.4

19. 27 feet above gage datum and an elevation of 472.4

20. 28 feet above gage datum and an elevation of 473.4

21. 29 feet above gage datum and an elevation of 474.4

22. 30 feet above gage datum and an elevation of 475.4

Figures

1. Map showing location of study reach for the Wabash River at Terre Haute and 

location of USGS streamgage and National Weather Service forecast site .....................3

Tables

1. USGS streamgage information for study basin, Wabash River at Terre Haute, 

Indiana............................................................................................................................................2

2. Estimates of annual exceedance probability peak-discharges on the Wabash River 

at Terre Haute, Indiana, streamgage number 03341500, (from Federal Emergency 

Management Agency, 2011)........................................................................................................4

3. Stages (elevations referenced to streamgage datum and to NAVD88) with 

corresponding discharge estimates at the Wabash River at Terre Haute 

streamgage for simulated water-surface profiles. .................................................................5
v

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in) 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 distance above the vertical datum.
Acknowledgments

The author wishes to thank the Indiana Department of Transportation and the U.S. Army Corps 

of Engineers, Louisville District for cooperating in the operation and maintenance of the Wabash 

River at Terre Haute, Indiana, streamgage used for this study, and the Indiana Department of 

Transportation for providing bridge plans. In addition, thanks are given to the National Weather 

Service for their continued support of the U.S. Geological Survey flood-inundation mapping 

initiative.
Flood-Inundation Maps for the Wabash River at 

Terre Haute, Indiana

By Pamela J. Lombard

Abstract

Digital flood-inundation maps for a 6.3-mi reach of the 

Wabash River from 0.1 mi downstream of the Interstate 70 

bridge to 1.1 miles upstream of the Route 63 bridge, Terre 

Haute, Indiana, were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Department of 

Transportation. 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 select 

water levels (stages) at the USGS streamgage Wabash River 

at Terre Haute (station number 03341500). Current conditions at the USGS streamgage may be obtained on the Internet 

from the USGS National Water Information System (http://

waterdata.usgs.gov/in/nwis/uv/?site_no=03341500&agency_

cd=USGS& ). In addition, the same data are provided to 

the National Weather Service (NWS) for incorporation into 

their Advanced Hydrologic Prediction Service (AHPS) flood 

warning system (http:/water.weather.gov/ahps/). Within this 

system, the NWS forecasts flood hydrographs for the Wabash 

River at Terre Haute that 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 stagedischarge relation at the Wabash River at the Terre Haute 

streamgage. The hydraulic model was then used to compute 

22 water-surface profiles for flood stages at 1-ft 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 digital 

elevation model (derived from Light Detection and Ranging 

(LiDAR) data having a 0.37-ft vertical accuracy and a 1.02-ft 

horizontal accuracy) to delineate the area flooded at each 

water level.

The availability of these maps along with Internet information regarding the current stage from the USGS streamgage 

and forecasted stream stages from the NWS can 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 Wabash River flows south with the city of Terre 

Haute, Indiana, on its eastern bank and the town of West Terre 

Haute on its western floodplain. The city of Terre Haute is an 

urban community in Vigo County with an estimated population of 60,800 (U.S. Census Bureau, 2010a). It has steep 

banks east of the Wabash River and elevations mostly greater 

than 490 NAVD88 so that it has not been severely affected by 

floodwaters from the Wabash River except at the northwest 

corner of the city around Maple Avenue. The much smaller 

town of West Terre Haute, on the western bank, had a population of 2,240 in 2010 (U.S. Census Bureau, 2010b). West Terre 

Haute is at elevations as low as 461 NAVD88 and traditionally has undergone more severe flooding than Terre Haute 

prior to the construction of the West Terre Haute levee in the 

early 1970s. West Terre Haute is surrounded by the West Terre 

Haute levee on the eastern and southern sides of the town and 

by a railroad bed on the northern side of the town. The West 

Terre Haute levee was in the process of being recertified by 

the Federal Emergency Management Agency (FEMA) at the 

time of this study (2012). There is another levee at the northeastern end of the study that protects the area around Maple 

Avenue in the northwest corner of Terre Haute. Taylorville 

(also known prior to 1960 by the variant name of Dresser) is a 

small, unincorporated town between West Terre Haute and the 

Wabash River which can be severely affected by flooding from 

the Wabash River. Taylorville is partially protected by a levee 

built in the 1930s (known as the old levee or the Sugar Creek 

levee). The old levee is not certified or maintained by the State 

or Federal government.
2 Flood-Inundation Maps for the Wabash River at Terre Haute, Indiana

The Wabash River had instances of severe flooding in 

1913, 1943, 1950, 1958, 1959, and 2005. The maximum 

recorded flow at the Wabash River at Terre Haute streamgage 

was 245,000 ft3/s in 1913, which was associated with a stage 

of 31.2 ft as referenced to gage datum. The streamgage was 

moved and the gage datum was lowered in 1985, so a stage of 

31.2 ft for the 1913 peak flow cannot be directly compared to 

stages presented in this report.

Officials of Terre Haute, West Terre Haute, and Taylorville have relied on three primary information sources (all 

of which are available on the Internet) to make decisions as 

to how best alert the public and mitigate flood damages. The 

first source is the FEMA Flood Insurance Study (FIS) for 

Vigo County dated February 18, 2011 (Federal Emergency 

Management Agency, 2011). A second source of information 

is the USGS streamgage Wabash River at Terre Haute (sta. 

no. 03341500), from which current or historical water levels 

(stage) can be obtained. A third source is the National Weather 

Service’s forecast of peak stage at the USGS streamgage 

through the Advanced Hydrologic Prediction Service (AHPS) 

website (http:/water.weather.gov/ahps/). 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 a USGS streamgage or NWS flood-forecast point. 

Purpose and Scope

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

Wabash River near Terre Haute, Indiana. The scope of the 

study was limited to a 6.3-mi reach of the Wabash River from 

0.1 mi downstream of the I‒70 bridge to 1.1 mi upstream of 

the Route 63 bridge in Terre Haute (fig. 1). Twenty-two flood 

maps were created at 1-ft intervals between and including 9 ft 

and 30 ft as referenced to the Wabash River at Terre Haute 

streamgage (sta. no. 03341500) (table 1). Maps were produced for water levels referenced to the water-surface elevation (stage) at Wabash River at Terre Haute and ranging from 

approximately bankfull to the maximum observed water level 

at the streamgage.

Study Area Description

The Wabash River is 503 mi long and flows southwest 

from northwest Ohio across northern Indiana to southern 

Illinois, where it forms the Illinois-Indiana border before 

draining into the Ohio River. The city of Terre Haute is located 

in central Vigo County and is the county seat of government. 

The Wabash River forms the western boundary of the corporate limits of Terre Haute. The drainage area is 12, 263 mi2

 at 

the Terre Haute streamgage. The basin terrain is generally flat. 

The study reach is approximately 6.3 mi long, and has an average top-of-bank channel width of approximately 600 ft. The 

land contiguous to the study reach on the eastern side of the 

river is urban or developed, on the western side of the study 

reach it is primarily cropland with some forested areas. The 

main channel within the study reach has four road crossings 

and two railroad crossings. Route 40 is treated as two road 

crossings because its west and east bound lanes are 500 feet 

apart on the eastern bank. Although I‒70 and Route 63 both 

have east and west bound lanes that are on separate bridges, 

they are treated as single structures because the bridges are 

only 40 feet apart.

Table 1. USGS streamgage information for study basin, Wabash River at Terre Haute, Indiana.

[mi2, square miles; ft, feet; ° ′ ′′, degrees minutes seconds; gage datum is 445.43 NAVD88]

Station name Station number Drainage area 

(mi2

) Latitude Longitude Period of record

Wabash River at 

Terre Haute

03341500 12,263 39°28′33′′ 87°25′08′′ November 1927 to 

September, 2011.
Introduction 3

87°28' 87°26' 87°24'

39°30'

39°28'

39°26'

Study

area

INDIANA

EXPLANATION

USGS streamgage and number

Limit of study area

Flow arrow—Indicates 

direction of water flow

Levee

63

41

Interstate route marker

U.S. route marker

State route marker

70

03341500

Wabash

River

03341500

41

PRAIRIETONE RD

Terre Haute

WEST NATIONAL AVE

West Terre Haute

41

41

150

40

63

70

70

63

63

OHIO ST

MAPLE AVE

SOUTH 3RD ST

OHIO ST

Taylorville

CSX RAILROAD

CSX RAILROAD

41

0 0.5 1.0 2.0 MILES

0 0.5 1.0 2.0 KILOMETERS

Projection: Transverse Mercator

Horizontal coordinate information is referenced to the North American Datum of 1983

Orthophotography from Indiana Spatial Data Portal, 

National Agriculture Imagery Program 2010, available at http://gis.iu.edu/

Figure 1. Location of study reach for the Wabash River at Terre Haute and location of USGS streamgage and 

National Weather Service forecast site. 
4 Flood-Inundation Maps for the Wabash River at Terre Haute, Indiana

Previous Studies 

The current FIS for Vigo County (Federal Emergency 

Management Agency, 2011) was completed by United Consulting Engineers and Architects on behalf of the Indiana 

Department of Natural Resources in 2011. The study provided 

information on the 10-, 2-, 1- and 0.2-percent annual exceedance probability water-surface profiles and discharges for 

rivers and tributaries throughout Vigo County. Estimates of the 

peak discharges along the Wabash River at Terre Haute were 

completed by the USGS in 1981 and were incorporated into 

the county wide publication by FEMA (2011) (table 2).

Table 2. Estimates of annual exceedance probability peakdischarges on the Wabash River at Terre Haute, Indiana, 

streamgage number 03341500, (from Federal Emergency 

Management Agency, 2011).

Annual exceedance probability 

(percent)

Discharge estimate 

(ft3

/s)

10 98,500

2 136,500

1 151,000

0.2 188,500

Constructing Water-Surface Profiles

The water-surface profiles used to produce the 22 

flood-inundation maps in this study were computed using 

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

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.

Tasks specific to development of the maps were (1) 

analyses of streamgaging data at the Wabash River at Terre 

Haute streamgage, (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 steadyflow data, (4) computation of water-surface profiles using 

the U.S. Army Corps of Engineer’s HEC–RAS computer 

program (U.S. Army Corps of Engineers, 2010), (5) production of estimated flood-inundation maps at various stream 

stages using the U.S. Army Corps of Engineer’s HEC–GeoRas 

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

available on the Internet at http://wim.usgs.gov/FIMIdev/

FloodInundationMapper.html

Hydrologic and Steady Flow Data

The study area hydrologic network consists of one 

streamgage, Wabash River at Terre Haute (sta. no. 03341500) 

that has been operated by the USGS continuously since 1927, 

although the actual streamgage location was moved in 1985 

(fig. 1; table 1). Water level (stage) is measured continuously 

and continuous records of streamflow are computed at this 

streamgage. Although datum of the streamgage is referenced 

to 445.78 feet above NGVD29, all water-surface elevations in 

this report have been converted so that they reference NAVD 

88. The streamgage is equipped with a satellite radio transmitter that allows data to be transmitted routinely on the Internet 

within four hours of collection at url: http://waterdata.usgs.

gov/in/nwis/uv/?site_no=03341500&agency_cd=USGS&. 

Steady-flow data consisted of flow regime, boundary 

conditions (normal depth slope was set to 0.0002, the energy 

gradient slope in the model), and peak discharge information. 

The peak discharge data for the study reach were obtained 

from field measurements and the stage-discharge relation that 

was developed by the USGS at the Wabash River at Terre 

Haute streamgage. 

Topographic and Bathymetric Data

Channel cross sections were developed from USGS field 

surveys that were carried out in September, 2011. Detailed 

channel depths below the water surface were collected using 

hydroacoustic instrumentation while differential Global Positioning System (DGPS) instrumentation determined horizontal 

position. Cross-section elevation data were obtained from a 

digital elevation model (DEM) that was derived from Light 

Detection and Ranging (LiDAR) data that were collected as 

part of this project during April, 2010, by Aero-Metric, Inc., 

Sheboygan, Wisconsin. Post-processing of these data was 

completed by Aero-Metric, Inc., on July 14, 2010. The original 

LiDAR data have horizontal accuracy of 1.02 ft (31 centimeters) with horizontal resolution of 3.9 ft (1.2 meters) and vertical accuracy of 0.37 ft at a 95-percent confidence level for the 

“open terrain” land cover category (root mean squared error 

of 0.19 ft (5.8 centimeters)). Although a finer resolution of the 

DEM was possible given the accuracy of the LiDAR data, the 

final DEM had a grid-cell size of 10-ft2

 in order to decrease 

the GIS processing time. A detailed description of the methods 

used to acquire and process the topographic and bathymetric 

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

Six bridges and two levees in Terre Haute and West 

Terre Haute have the potential to affect water-surface elevations during high water along the Wabash River. To properly 

account for these features in the model, bridge geometry was 

obtained from a previous USGS E431 step-backwater model 
Constructing Water-Surface Profiles 5

(Federal Emergency Management Agency, 2011); from bridge 

plans received from the Indiana Department of Transportation 

(IN DOT) (Teresa Hammons, written commun., 2012); and 

from railroad bridge plans from CSX Transportation Inc. (Rick 

Garro, written commun., 2012). All six bridges were verified 

as current structures with pictures and elevation checks from a 

digital-elevation model and field observations. The geometry 

data for the levee were acquired from the U.S. Army Corps of 

Engineers (ACE), Louisville District (Matthew Whelan, written commun., 2012) and the elevation data of the levee were 

included in the model to properly account for these structures. 

Energy Loss Factors

Field observations were used to select initial (pre-calibration) Manning’s roughness coefficients (“n” values) for energy 

(friction) loss calculations. Manning’s roughness coefficients 

were determined to be 0.03 to 0.032 for the main channel, and 

0.066 to 0.068 for the overbank areas. It was determined that 

roughness coefficients varied with stage for this reach of the 

Wabash River. Final values were increased up to 123 percent 

or decreased down 87 percent depending on the stage profile, 

and generally decreased with increasing stage as expected for 

large rivers. For the lower flows, final values increased with 

increased stage likely due to increased vegetation as the water 

started to come over the banks. 

Model Calibration and Performance

The hydraulic model was calibrated to the most current 

stage-discharge relation at the Wabash River at Terre Haute 

streamgage. The estimated peak discharge for the March, 1913 

flood was 245,000 ft3/s at an estimated stage of about 31.2 ft at 

the streamgage. The measured peak discharges (and stages) for 

the 1943, 1958, 2005, and the 1950 floods were 189,000 ft3/s 

(30.5 ft), 125,000 ft3/s (29.53 ft), 123,000 ft3/s (27.38 ft) and 

122,000 ft3/s (27.65 ft), respectively. Note that the streamgage 

location was changed and the streamgage datum was lowered 

2.9 feet in 1985; so stages prior to 1985 cannot be compared 

directly to stages after 1985. In addition, starting in 1968, discharges are affected to an unknown degree by regulation from 

upstream reservoirs. Model calibration was accomplished by 

adjusting Manning’s n values until the results of the hydraulic 

computations closely agreed with the known flood discharge 

and stage values. Differences between measured and simulated water levels for specified flows were equal to or less than 

0.1 ft. 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

Profiles were developed for a total of 22 stages at 1-ft 

intervals between and including 9 ft (action stage) and 30 ft 

(flood of record) as referenced to the Wabash River at Terre 

Haute streamgage (sta. no. 03341500). Discharges corresponding to the various stages were obtained from the most current 

stage-discharge relation (rating no. 55.1) at the streamgage. 

The streamgage is near the midpoint of the 6-mi reach. There 

are no major tributaries; thus discharges for each profile were 

held constant throughout the reach (table 3).

Table 3. Stages (elevations referenced to streamgage datum 

and to NAVD88) with corresponding discharge estimates at the 

Wabash River at Terre Haute streamgage for simulated watersurface profiles.

Stage

(feet above gage datum)

Elevation

(feet, NAVD 88)

Discharge 

(ft3

/s)

9 454.4 15100

10 455.4 16900

11 456.4 18800

12 457.4 20900

13 458.4 23000

14 459.4 25200

15 460.4 28000

16 461.4 31000

17 462.4 34500

18 463.4 39000

19 464.4 44000

20 465.4 49000

21 466.4 55000

22 467.4 61400

23 468.4 70700

24 469.4 81000

25 470.4 92200

26 471.4 104000

27 472.4 118000

28 473.4 132000

29 474.4 148000

30 475.4 165000
6 Flood-Inundation Maps for the Wabash River at Terre Haute, Indiana

Inundation Mapping

Flood-inundation maps were created for the 6.3-mi reach 

of the Wabash River centered on the USGS streamgage at 

Terre Haute, which is currently (as of 2012) a NWS floodforecast point. The maps were created in a GIS by combining the water-surface profiles and DEM data. The DEM data 

were derived from LiDAR data that had a horizontal accuracy of 1.02 ft and a vertical accuracy of 0.37 ft. 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. 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). The HEC–GeoRAS results, shapefile polygons and depth grids of the inundated areas, were 

modified to ensure a hydraulically reasonable transition of the 

flood boundaries between modeled cross sections relative to 

the digital-elevation model of the land surface. 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.

Flood-Inundation Maps on the Internet

A USGS Flood Inundation Mapping Science World Wide 

Web portal has been established by the USGS to provide estimated flood-inundation information to the public (http://water.

usgs.gov/osw/flood_inundation/). The maps and data from this 

study showing the extent of inundated areas can be downloaded in two electronic file formats from that portal: (1) GIS 

shapefile format, and (2) Portable Document Format (PDF). 

Users can print out formatted maps quickly or create a customized map using available GIS data layers. In addition, downloadable GIS raster files showing the depth of flooded areas 

are available at the web portal. All PDF maps show aerial photography beneath the flood layers. Each stream reach displayed 

on the Web site contains links to NWISWeb graphs of the current stage and stream-flow at USGS streamgage Wabash River 

at Terre Haute, Indiana (station number 03341500), to which 

the inundation maps are referenced (http://waterdata.usgs.gov/

in/nwis/uv/?site_no=03341500&agency_cd=USGS& ). A 

link also is provided to the NWS Advanced Hydrologic Prediction Service (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. 

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 for Use of FloodInundation 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 (water-surface 

elevations) and streamflows at the Wabash at Terre Haute 

(03341500) streamgage. 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. 

The hydraulic model reflects the land-cover characteristics and 

any bridge, dam, levee, or other hydraulic structures existing 

as of September, 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. Furthermore, a steady 

state model is not able to take timing into account. Flood inundation maps show areas that would be flooded at a given stage, 

but do not indicate how long it might take for the inundation to 

occur. If a given stage only occurs for a brief amount of time, 

the extent of the flooding may not be as extreme as the map 

indicates. 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 or ice jams. 

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. 

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 (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). For more information on AHPS forecasts, 

please see: http://water.weather.gov/ahps/pcpn_and_river_

forecasting.pdf. 
References Cited 7

Summary

A series of 22 estimated flood-inundation maps were 

developed in cooperation with the Indiana Department of 

Transportation for a 6.3-mi reach of the Wabash River from 

0.1 mi downstream of the I‒70 bridge to 1.1 mi upstream 

of the Route 63 bridge, at Terre Haute, Indiana. These 

maps, available at a publications url: http://pubs.usgs.gov/

sim/3232/ in conjunction with the real-time stage data from 

the USGS streamgage, Wabash River at Terre Haute (sta. 

no 03341500, http://waterdata.usgs.gov/in/nwis/uv/?site_

no=03341500&agency_cd=USGS&), and the flood-stage 

forecasts by the National Weather Service, can help to guide 

the general public in taking individual safety precautions and 

can provide municipal officials with a tool to efficiently manage emergency flood operations and flood mitigation efforts. 

The maps and other useful flood information are available on 

the USGS Flood Inundation Mapping Science Web site 

(http://water.usgs.gov/osw/flood_inundation/ ) and the NWS 

AHPS website (http:/water.weather.gov/ahps/ ). Internet users 

can select estimated inundation maps that correspond to (1) 

current stages at the USGS streamgage, (2) NWS forecasted 

peak stage, or (3) other desired stream stages.

Flood profiles were computed along the stream reach for 

selected stream stages by means of a one-dimensional stepbackwater model using the U.S. Army Corps of Engineers’ 

HEC–RAS program. The model was calibrated using the most 

current stage-discharge relation at the Wabash River at Terre 

Haute gage. Estimated flood-inundation areas were delineated 

using the U.S. Army Corps of Engineers’ HEC–GeoRAS 

program. The maps show estimated flood-inundation areas 

overlaid on high-resolution, georeferenced, aerial photographs 

of the study area for stream stages between and including 9 ft 

and 30 ft at the Wabash River streamgage. 

References Cited

Aero-Metric, Inc., 2010, Indiana Flood LiDAR (ARRA) 

Task Order, Remote-sensing Image: Sheboygan, Wis., 

Aero-Metric, Inc.

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, 2011, Flood 

Insurance Study Vigo County, Indiana and Incorporated 

Areas, Flood Insurance Study Number 18167CV000A, 

February 18, 2011, 36 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: 

U.S. Army Corps of Engineers, Hydrologic Engineering 

Center [variously paged]. Available at http://www.hec.usace.

army.mil/software/hec-ras/documents/HEC-GeoRAS42_

UsersManual.pdf. 

U.S. Army Corps of Engineers, Hydrologic Engineering 

Center, 2010, HEC–RAS River Analysis System, Hydraulic 

Reference Manual, version 4.1: U.S. Army Corps of Engineers, Hydrologic Engineering Center [variously paged]. 

Available at http://www.hec.usace.army.mil/software/hecras/documents/HEC-RAS_4.1_Reference_Manual.pdf.

U.S. Census Bureau, 2010a, Terre Haute, Indiana quickfacts: 

U.S. Census Bureau. Accessed on May, 2012 at http://

quickfacts.census.gov/qfd/states/18/1875428.html.

U.S. Census Bureau, 2010b, U.S. Census Bureau American 

Fact Finder accessed on June, 2012 at http://factfinder2.

census.gov/faces/tableservices/jsf/pages/productview.

xhtml?pid=DEC_10_DP_DPDP1.

Lombard—Flood-Inundation Maps for the Wabash River at Terre Haute, Indiana—Scientific Investigations Map 3232