Prepared in cooperation with the Indiana Department of Transportation

Flood-Inundation Maps for the Flatrock River 

at Columbus, Indiana, 2012

Pamphlet to accompany

Scientific Investigations Map 3241

U.S. Department of the Interior

U.S. Geological Survey
Cover. Illustration showing simulated floods corresponding to streamgage stages of 9, 13, and 20 feet for Flatrock River at Columbus, Indiana.
Flood-Inundation Maps for the Flatrock 

River at Columbus, Indiana, 2012

By William F. Coon

Prepared in cooperation with the Indiana Department of Transportation

Pamphlet to accompany

Scientific Investigations Map 3241

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Coon, W.F., 2013, Flood-inundation maps for the Flatrock River at Columbus, Indiana, 2012: U.S. Geological Survey 

Scientific Investigations Map 3241, 12 p., 12 sheets, available at http://pubs.usgs.gov/sim/3241
iii

Contents

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

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

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

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

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

Constructing Water-Surface Profiles.........................................................................................................5

Hydrologic and Steady-State Flow Data...........................................................................................5

Topographic and Bathymetric Data...................................................................................................5

Energy-Loss Factors.............................................................................................................................6

Model Calibration and Performance .................................................................................................6

Development of Water-Surface Profiles...........................................................................................7

Development of Flood-Inundation Maps .................................................................................................10

Flood-Inundation Maps on the Internet ..........................................................................................10

Disclaimer for Flood-Inundation Maps ...........................................................................................10

Uncertainties and Limitations Regarding Use of Flood-Inundation Maps ................................10

Acknowledgments.......................................................................................................................................11

Summary........................................................................................................................................................11

References Cited..........................................................................................................................................11
iv

Figures

1. Location of study reach for the Flatrock River at Columbus, Indiana, and location 

of U.S. Geological Survey streamgage .....................................................................................3

2. Simulated water-surface profile at a streamgage stage of 20.00 feet and high-water 

marks surveyed following the flood of June 7, 2008, at a stage of 19.94 feet, Flatrock 

River at Columbus, Indiana .........................................................................................................8

3. High water-surface profiles of the FEMA 1-percent annual exceedance probability 

flood and simulated floods corresponding to streamgage stages of 18 and 19 feet 

for Flatrock River at Columbus, Indiana. ..................................................................................8

4. Flood extents of the FEMA 1-percent annual exceedance probability flood and 

simulated floods corresponding to streamgage stages of 18 and 19 feet for Flatrock 

River at Columbus, Indiana .........................................................................................................9

Tables

1. U.S. Geological Survey streamgage information for Flatrock River at Columbus, 

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

2. Peak discharges for selected annual exceedance probabilities for Flatrock River 

at Columbus, Indiana (streamgage number 03363900)...........................................................4

3. Calibration of model to target water-surface elevations at U.S. Geological Survey 

streamgage on Flatrock River at Columbus, Indiana (station number 03363900) ..............7
v

Sheets

[Separate documents available online with this report at the U.S. Geological Survey Publications Warehouse 

(http://pubs.usgs.gov/sim/3241/)]

1. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 9.0 feet and an elevation of 618.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

2. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 10.0 feet and an elevation of 619.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

3. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 11.0 feet and an elevation of 620.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

4. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 12.0 feet and an elevation of 621.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

5. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 13.0 feet and an elevation of 622.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

6. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 14.0 feet and an elevation of 623.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

7. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 15.0 feet and an elevation of 624.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

8. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 16.0 feet and an elevation of 625.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

9. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 17.0 feet and an elevation of 626.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

10. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 18.0 feet and an elevation of 627.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

11. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 19.0 feet and an elevation of 628.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River

12. Flood-inundation map for the Flatrock River at Columbus, Indiana, corresponding to a 

stage of 20.0 feet and an elevation of 629.74 feet (NAVD 88) at the U.S. Geological Survey 

streamgage number 03363900 on the Flatrock River
vi

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3

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

Vertical coordinate information is referenced to either (1) stage, the height above an arbitrary 

datum established at a streamgage, or (2) elevation, the height above the North American 

Vertical Datum of 1988 (NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
Flood-Inundation Maps for the Flatrock River at Columbus, 

Indiana, 2012

By William F. Coon 

Abstract

Digital flood-inundation maps for a 5-mile reach of the 

Flatrock River on the western side of Columbus, Indiana, 

from County Road 400N to the river mouth at the confluence 

with Driftwood River, 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/ and the 

Federal Flood Inundation Mapper Web site at http://wim.usgs.

gov/FIMI/FloodInundationMapper.html, depict estimates 

of the areal extent and depth of flooding corresponding to 

selected water levels (stages) at the USGS streamgage on the 

Flatrock River at Columbus (station number 03363900). Nearreal-time stages at this streamgage may be obtained on the 

Internet from the USGS National Water Information System 

at http://waterdata.usgs.gov/ or the National Weather Service 

(NWS) Advanced Hydrologic Prediction Service, which also 

presents the USGS data, at http://water.weather.gov/ahps/.

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 relation at the Flatrock River streamgage, high-water marks that 

were surveyed following the flood of June 7, 2008, and watersurface profiles from the current flood-insurance study for 

the City of Columbus. The hydraulic model was then used to 

compute 12 water-surface profiles for flood stages at 1-foot (ft) 

intervals referenced to the streamgage datum and ranging from 

9 ft or near bankfull to 20 ft, which exceeds the stages that 

correspond to both the estimated 0.2-percent annual exceedance probability flood (500-year recurrence interval flood) and 

the maximum recorded peak flow. 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 3.9 ft horizontal resolution) to delineate the area flooded at 

each water level. 

The availability of these maps on the USGS Federal 

Flood Inundation Mapper Web site, along with Internet information regarding current stage from the USGS streamgage, 

will 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 postflood recovery efforts.

Introduction 

The City of Columbus, in Bartholomew County, Indiana (Ind.), is a large urban community with an estimated 

population of 44,061 (U.S. Bureau of the Census, 2010). The 

Flatrock River, which flows southward near the western border 

of the city, has severely flooded numerous times in the past. 

Peak flows have been recorded since October 1967 at a U.S. 

Geological Survey (USGS) streamgage on the Flatrock River 

at Columbus (station number 03363900), about 2.6 miles (mi) 

upstream from its mouth. Prior to this time, Columbus experienced large floods during 1913 and 1963 (Federal Emergency 

Management Agency, 2011). Since October 1967, peak flows 

on the Flatrock River have approximated or exceeded the 

Federal Emergency Management Agency (FEMA) 10-percent annual exceedance probability flood (10-year recurrence 

interval flood) of 19,500 cubic feet per second (ft3/s) during 1968, 1990, 2004, and 2005. The highest of these peak 

flows, 22,400 ft3/s on January 7, 2005, was far exceeded by 

the period-of-record peak of 62,500 ft3/s that occurred on 

June 7, 2008. 

Prior to this study, emergency responders in Columbus and Bartholomew County 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 FEMA flood insurance studies (FISs), which include the FIS for the City of Columbus 

dated January 5, 1996, (Federal Emergency Management 

Agency, 1996) and a preliminary version of a countywide 

FIS for Bartholomew County, which includes data from the 

1996 City of Columbus FIS (Federal Emergency Management Agency, 2011). A second source of information is the 

USGS streamgage, Flatrock River at Columbus, from which 

current (U.S. Geological Survey, 2012a) and historical (that 

is, since 1968; U.S. Geological Survey, 2012b) water levels 
2 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

(stages) and discharges, including annual peak flows, can be 

obtained. A third source of flood-related information is the 

National Weather Service’s (NWS) Advanced Hydrologic 

Prediction Service (AHPS), which also displays the USGS 

stage data from the Columbus streamgage (National Weather 

Service, 2012). The NWS forecasts flood hydrographs at many 

USGS streamgages but does not do so at the Flatrock River 

streamgage at Columbus. 

Although the current stage at a USGS streamgage 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 reach. Knowledge of a water level 

at a streamgage is difficult to translate into water levels—both 

their depth and aerial extent—at different locations along a 

stream. One way to address these informational gaps is to 

produce a library of flood-inundation maps that are referenced 

to the stages recorded at the USGS streamgage. By referring 

to the appropriate map, emergency responders can discern 

the severity of flooding (depth of water and aerial extent), 

identify roads that are or will soon be flooded, and make plans 

for notification or evacuation of residents in harm’s way for 

some distance upstream and downstream from the streamgage. 

In addition, the capability to visualize the potential extent of 

flooding has been shown to motivate residents to take precautions and heed warnings that they previously might have 

disregarded. In 2011–12, the USGS, in cooperation with the 

Indiana Department of Transportation, conducted a project to 

produce a library of flood-inundation maps for the Flatrock 

River at Columbus, Ind.

Purpose and Scope

The purpose of this report is to describe the development 

of a series of estimated flood-inundation maps for the Flatrock River at Columbus, Ind., and to present the maps, which 

are also available on the USGS Flood Inundation Mapping 

Science Web site (U.S. Geological Survey, 2012c). The floodinundation maps cover a reach about 5 mi long, from County 

Road 400N to the river mouth at the confluence with Driftwood River (fig. 1). The maps were produced for flood levels 

referenced to the stage recorded at the USGS streamgage on 

the Flatrock River at Columbus (03363900; table 1), which is 

at U.S. Route 31 about midway through the study reach. The 

maps cover a range in stage from 9 feet (ft), gage datum, or 

approximately bankfull, to 20 ft, gage datum, or greater than 

the water level associated with both the estimated 0.2-percent 

annual exceedance probability flood (500-year recurrence 

interval flood) and the maximum recorded peak flow. 

Tasks specific to development of the flood maps for the 

Flatrock River at Columbus included (1) collection of topographic and bathymetric data for selected cross sections, and 

geometric data for structures and bridges along the study 

reach; (2) estimation of energy-loss factors (roughness coefficients) in the stream channel and flood plain, and steady-flow 

data; (3) computation of water-surface profiles by use of the 

U.S. Army Corps of Engineer’s HEC-RAS computer program (U.S. Army Corps of Engineers, 2010); (4) 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 

Table 1. U.S. Geological Survey streamgage information for Flatrock River at 

Columbus, Indiana.

[Station location is shown in figure 1. ft3/s, cubic feet per second; NAVD 88, North American Vertical Datum of 1988]

Station name Flatrock River at Columbus, Indiana

Station number 03363900

Drainage area (square miles) 534

Latitude 39°14′06′′

Longitude 85°55′36′′

Period of peak–flow record (water years1

) 1968–2011

Maximum recorded stage, in feet, gage datum 

(and elevation, in feet above NAVD 88) and date 19.94 (629.68) on June 7, 2008

Maximum discharge, in ft3

/s, and date 62,500 on June 7, 2008

1

Water year is the 12-month period from October 1 of one year through September 30 of the 

following year and is designated by the calendar year in which it ends. 
Introduction 3

85°58' 85°57' 85°56' 85°55'

39°15'

39°14'

39°13'

0

0

1 MILE

1 KILOMETER

EXPLANATION

Limit of study area

Low-head dam

Flow arrow—Indicates direction 

of water flow

U.S. Geological Survey 

streamgage and number

State route marker

Interstate route marker

U.S. route marker

03363900

46

31

65

Projection: Indiana State Plane Eastern Zone

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

Orthophotography from Esri ArcGIS World Imagery, 

2011, available at http://goto.arcgisonline.com/maps/World_Imagery

03363900

Columbus NORTH NATIONAL ROAD 

N O R T H I N D I A N A P O L I S R O A D

LOUISVILLE AND INDIANA RAILROAD

COUNTY ROAD 400N 31

31

65

46

11

11

East Fork White River

D r i f t w o o d

R i v e r

D r i f t w o o d

R i v e r

Fl

a

t

r

o

c

k

Riv

e

r

Fl

a

t

r

o

c

k

Riv

e

r

INDIANA

Study

area

Figure 1. Location of study reach for the Flatrock River at Columbus, Indiana, and location of U.S. Geological Survey 

streamgage.
4 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

a Geographic Information System (GIS); and (5) preparation 

of the maps, both as shapefile polygons that depict the areal 

extent of flood inundation and as depth grids that provide the 

depth of flood waters, for display on the USGS Federal Flood 

Inundation Mapper Web site (U.S. Geological Survey, 2012d). 

Techniques that varied substantially from previously documented methods because of local hydrologic conditions or 

available data are described in detail in this report.

Study Area Description

The Flatrock River, in the southeastern quarter of Indiana, rises in Henry County and flows southwesterly through 

Rush, Decatur, and Shelby Counties until in Bartholomew 

County it flows along the western side of the City of Columbus. At Columbus, the Flatrock River joins Driftwood River 

to form the East Fork White River. The drainage area of 

the Flatrock River Basin is 534 square miles at the USGS 

streamgage at Columbus, which is 2.6 mi upstream from 

the river mouth. There are no major tributaries to the Flatrock River that join the main stem as it flows through the 

study reach. 

The study reach is approximately 5 mi long and has 

an average top-of-bank channel width of 200–250 ft. The 

average channel slope is 0.0009, whereas the high-watersurface slope is about 0.0006. The main channel within the 

study reach is traversed by two major 4-lane highways, a 

2-lane county road, a railroad, and a low-head dam. The basin 

terrain is generally flat, and the flood plain is dominated by 

agricultural uses; however, a large sand-and-gravel operation 

dominates the land on the upstream western part of the flood 

plain along the study reach. Large swaths of forested land 

cover the banks and flood plains adjacent to the river. Most 

of the densely developed areas of the City of Columbus, both 

residential and commercial uses, are on high ground to the east 

of the Flatrock River. Although most of these areas are safe 

from flooding, those residential areas closest to the river along 

the eastern edge of the flood plain are subject to inundation 

during major floods. Commercial and industrial establishments 

along the main roads that either cross the Flatrock River (U.S. 

Route 31 and State Route 11) or run parallel to the river along 

the western side of the flood plain (State Route 11) also are 

prone to flooding during moderate and major floods.

Previous Studies

The current FIS for the City of Columbus (Federal Emergency Management Agency, 1996) is a revision and update of 

the 1982 FIS (Federal Emergency Management Agency, 1982) 

and includes previously unincorporated areas of Bartholomew 

County that, by 1996, had been annexed to the city. Presently 

(March 2012), a preliminary version of a countywide FIS 

(Federal Emergency Management Agency, 2011) that will 

supersede the 1996 City of Columbus FIS is in the process of 

review and approval. The hydrologic and hydraulic analyses 

on which these studies were based were performed by the 

U.S. Army Corps of Engineers, Louisville District. The peak 

discharges and their frequencies of recurrence are the same in 

all three FISs, and, except for the change in datum from the 

National Geodetic Vertical Datum of 1929, which was used for 

the 1982 and 1996 FISs, to the North American Vertical Datum 

of 1988 (NAVD 88) that is used for the 2011 (preliminary) 

FIS, the water-surface elevations and resultant flood profiles 

are identical. The FISs present estimates of the peak discharges 

with 10, 2, 1, and 0.2 percent annual exceedance probabilities 

and their associated water-surface elevations for the Flatrock 

River at Columbus streamgage at the U.S. Route 31 bridge. 

These flood frequencies are presented in table 2.

Table 2. Peak discharges for selected annual exceedance probabilities for Flatrock 

River at Columbus, Indiana (streamgage number 03363900).

[ft3/s, cubic feet per second; ft, feet, FEMA, Federal Emergency Management Agency; NAVD 88, 

North American Vertical Datum of 1988; USGS, U.S. Geological Survey]

Annual 

exceedance

 probability

(percent)

Discharge1

(ft3

/s)

FEMA 

water-surface 

elevation1

(ft, NAVD 88)

USGS 

water-surface 

elevation2

(ft, NAVD 88)

Difference 

in elevation

(ft)

10 19,500 625.3 625.7 0.4

2 29,000 627.1 627.6 .5

1 32,500 627.7 628.0 .3

0.2 43,000 629.0 628.9 -.1

1

Data from Federal Emergency Management Agency, 1982 and 1996.

2

Values from most recent (January 2012) stage-discharge relation for Flatrock River at Columbus, 

Indiana.
Constructing Water-Surface Profiles 5

Constructing Water-Surface Profiles

The water-surface profiles used to produce the 12 floodinundation maps in this study were computed by using HECRAS, 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. 

Hydrologic and Steady-State Flow Data

The study reach includes one streamgage (03363900; 

fig. 1; table 1) that has been in operation since October 1967. 

Stage is measured every 15 minutes, transmitted hourly by a 

satellite radio in the gage, and made available on the Internet through the USGS National Water Information System 

(NWIS; U.S. Geological Survey, 2012a). Stage data from this 

gage are referenced to a local datum but can be converted to 

water-surface elevations referenced to the NAVD 88 by adding 

609.74 ft. Continuous records of streamflow are computed 

from a stage-discharge relation that has been developed for the 

site and also are available through the USGS NWIS Web site. 

Longitudinal water-surface profiles from high-water marks 

along the main channel were documented following the flood 

of June 7, 2008 (Morlock and others, 2008), and were used for 

model calibration. 

The HEC-RAS analysis for this study was done using the 

steady-state flow computation option. Steady-state flow data 

consisted of flow regime, boundary conditions (either known 

stage associated with a discharge measurement, critical depth, 

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

flows that produced water-surface elevations at the streamgage 

cross section that matched target water-surface elevations. 

These target elevations coincided with even 1-ft increments 

of stage, referenced to the local gage datum. Subcritical flow 

regime was assumed for the simulations. Initially, normal 

depth, based on an estimated average water-surface slope of 

0.0008 from data contained in the FEMA FISs (Federal Emergency Management Agency, 1996; 2011), was used as the 

reach’s downstream boundary condition. However, backwater 

at the confluence with Driftwood River at the downstream 

end of the study reach required that the boundary condition 

for high-stage flows (14- to 20-ft flood profiles) be changed 

to a specific water-surface elevation for each profile to enable 

correct computation of water-surface elevations at the most 

downstream cross sections in the model. The peak flows used 

in the model simulations were taken from the current stagedischarge relation and corresponded with the target stages. 

No major tributaries join the Flatrock River within the 5-mi 

study reach; therefore, the gage-derived discharges were not 

adjusted for tributary inflows but were held constant throughout the study reach for a given profile. 

Topographic and Bathymetric Data

All topographic data used in this study are referenced 

vertically to NAVD 88 and horizontally to the North American 

Datum of 1983. 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 AeroMetric, 

Inc., Sheboygan, Wisconsin. Postprocessing of these data was 

completed by AeroMetric, 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 was resampled to a grid-cell size of 10 ft by 10 ft to 

decrease the GIS processing time. By using HEC-GeoRAS, a 

set of procedures, tools, and utilities for processing geospatial 

data in ArcGIS, elevation data were extracted from the DEM 

for 53 cross sections and subsequently were input to the HECRAS model. Because LiDAR data cannot provide ground 

elevations below a stream’s water surface, channel cross 

sections were surveyed by USGS field crews during 2011. 

Cross-sectional depths were measured by using hydroacoustic instrumentation, whereas a differential global positioning 

system (DGPS) with real-time kinematic (RTK) technology 

was used to derive horizontal locations and the elevation of 

the water surface at each surveyed cross section. Elevations 

determined by RTK DGPS at three benchmark locations were 

within 0.08–0.21 ft of the known elevations, an error range 

that falls within the accuracy of the LiDAR data. Where possible, DEM-generated cross sections were made to coincide 

with the locations of the within-channel field-surveyed cross 

sections. In these cases, within-channel data were directly 

merged with the DEM data. For all other cross sections, the 

within-channel data were estimated by interpolation from the 

closest field-surveyed cross section. This interpolation was 

accomplished by (1) assuming that the channel geometry at an 

unsurveyed cross section was comparable to that of the nearest 

surveyed cross section; (2) estimating the thalweg elevation 

at each unsurveyed cross section based on the channel slope, 

which was assumed to be constant between adjacent surveyed 

cross sections; and (3) adjusting the within-channel elevations 

of the surveyed cross section by the difference between the 

thalweg elevations at the surveyed and unsurveyed cross sections and applying these adjusted elevations to the unsurveyed 

cross section. 

Five structures, consisting of three road crossings 

(County Road 400N, U.S. Route 31, and State Route 11), a 

railroad bridge, and a low-head dam, have the potential to 

affect water-surface elevations during floods along the stream. 

Bridge geometry data for the County Road 400N bridge at 
6 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

the upstream end of the study reach were obtained from 1998 

bridge plans provided by the Bartholomew County Highway 

Department (D. Hollander, County Engineer, Bartholomew 

County Highway Department, written commun., 2012). Data 

for the Route 31 (National Road) bridge at the USGS gage 

were obtained from a 2008 indirect measurement of discharge 

made by the USGS. Data for the Route 11 (Indianapolis Road) 

bridge and the low-head dam were obtained from USGS field 

surveys. The Louisville & Indiana Railroad Company owns 

two bridges that carry the railroad over an overflow channel on 

the left (eastern) flood plain and the main channel. Geometric 

data for the overflow bridge were obtained partly by a USGS 

field survey; additional data for the overflow bridge and that 

for the main bridge were obtained from a HEC-2 model (U.S. 

Army Corps of Engineers, 1972) that was developed and used 

for the 1982 FIS (Federal Emergency Management Agency, 

1982).

Energy-Loss Factors

Initial (precalibration) Manning’s roughness coefficients 

(n values) for energy-loss (friction-loss) calculations were estimated by comparison of field photographs with photographs 

of channels for which n values have been computed and published in references, such as Barnes (1967), Coon (1998), and 

Hicks and Mason (1991). An n value of 0.045 was selected for 

the wide, low-gradient main channel with sandy bed and treelined banks. The flood plains have mixed land uses but are 

dominated by agriculture and a large sand-and-gravel operation, which covers the right (west) flood plain in the upper half 

of the study reach. Forested areas cover wide swaths of land 

on both banks and flood plains adjacent to the river. Densely 

populated residential areas of Columbus are east of the 

Flatrock River, but these areas are mostly on elevated ground 

above the left flood plain. A composite n value (0.070) that 

was presumed to represent the diverse energy-loss factors of 

these land types was deemed appropriate to use for the initial 

estimate of the flood plain n value.

The initial n values were adjusted as part of the calibration process. The HEC-RAS model was calibrated to (1) the 

stage-discharge relation at the USGS gage, (2) water-surface 

profiles included in the most recent FIS (Federal Emergency 

Management Agency, 1996), and (3) high-water marks 

that were surveyed following the June 7, 2008, flood in the 

downstream half of the study reach. These marks, which corresponded to a stage of 19.94 ft at the USGS gage, were applicable to the greatest (20-foot stage) flow that was simulated as 

part of this project. Calibration of the model followed a threestep process. (1) Roughness-coefficient adjustment factors 

that were varied by flow and applied to the initially selected n

values were adjusted until the water-surface elevations for the 

simulated within-bank flows matched those for the observed 

flows at the USGS gage. The actual n values were computed 

by multiplying the initial n value by each of the roughnesscoefficient adjustment factors. These computed values were 

then input to the “vertical variation in n value” table for each 

cross section in the study reach. (2) While keeping the mainchannel n values constant, the roughness-coefficient factors 

were adjusted once again until the water-surface elevations for 

simulated overbank flows matched those for observed flows at 

the USGS gage. The actual n values were again computed, this 

time for the overbank areas, and these values were input to 

the “vertical variation in n value” table for each cross section. 

(3) Minor adjustments to the overbank n values were made 

to improve the final match between observed and simulated 

water-surface elevations at the USGS gage. Final mainchannel n values ranged from 0.044 to 0.058, and those for the 

overbank areas ranged from 0.100 to 0.153. 

The simulated water-surface elevations at the upstream 

end of the study reach, near County Road 400N, were lower 

than those published in the current FIS (Federal Emergency 

Management Agency, 1996). A noticeable decrease in the 

simulated water-surface slope in the upper quarter of the 

study reach was evident. The HEC-2 model that was used to 

compute water-surface profiles for the 1982 FIS and on which 

the current effective flood-insurance maps are based did not 

include any cross sections in this subreach of the study reach. 

Nevertheless, to improve agreement between the simulated 

and FIS water-surface elevations near County Road 400N, 

roughness-coefficient adjustment factors were increased to 

raise the water-surface slope. The increases in the roughness 

coefficient were attributed to the presence of sharp meander bends in the main channel, the heavy vegetation across 

meander bends that would impede out-of-bank flows, and the 

diversion of flows across a low bank into and through excavation ponds of a sand-and-gravel operation on the right (west) 

flood plain in this part of the study reach. The resultant n

values in the upstream quarter of the study reach ranged from 

0.064 to 0.116 for the main channel and from 0.130 to 0.276 in 

the overbank areas.

Model Calibration and Performance

As described in the previous section, the HEC-RAS 

model was calibrated to (1) the most current stage-discharge 

relation at the Flatrock River streamgage, (2) high-water 

marks that were surveyed following the June 7, 2008 flood, 

and (3) FEMA FIS water-surface elevations. Collectively, the 

calibration results demonstrated that the HEC-RAS model 

is capable of simulating accurate water levels over a wide 

range of flows in the study reach. Roughness coefficients and 

coefficients to account for energy losses due to expansion 

and contraction of flow at bridge constrictions were adjusted 

to minimize the differences between simulated and observed 

(target) water-surface elevations. The maximum difference 

between observed and simulated water-surface elevations at 
Constructing Water-Surface Profiles 7

the USGS gaging station 03363900 (at the downstream side 

of the U.S. Route 31 bridge) for the 12 simulated flows was 

0.03 ft (table 3). 

High-water marks that were surveyed following the flood 

of June 7, 2008, were used as approximate target elevations 

for the water-surface profile from the mouth of Flatrock River 

to the U.S. Route 31 bridge (fig. 2). The marks represent water 

levels for a flow of 62,500 ft3/s (computed by indirect methods 

by Morlock and others, 2008) at a streamgage stage of 19.94 ft 

and were compared with the water-surface profile generated 

by a flow of 61,200 ft3/s, which was taken from the stagedischarge relation for a stage of 20.00 ft. Large discrepancies 

between surveyed and simulated elevations (greater than 

0.5 ft) were found for high-water marks that were rated “poor” 

by USGS personnel at the time that the marks were surveyed. 

Marks that were rated “good” to “fair” were within 0.4 ft of 

the simulated water-surface profile. 

Water-surface profiles for 10-, 2-, 1-, and 0.2-percent 

annual peak-flow exceedance probabilities were computed 

and presented in the 1996 FIS (Federal Emergency Management Agency, 1996). The profile for the 1-percent probability 

flood (100-year recurrence interval flood) of 32,500 ft3/s at a 

streamgage stage of 18.27 ft was compared with the simulated 

water-surface profiles that were generated by the hydraulic 

model for the streamgage flows of 30,000 and 40,000 ft3/s at 

stages of 18 and 19 ft, respectively (fig. 3). The expectation 

was that the FIS profile would fall near or between the two 

simulated profiles. This expectation was realized for most 

of the reach; however, one anomalously high FIS elevation, 

625.5 ft, at river station 5,634 ft, was noted. This elevation is 

actually higher than the surveyed high-water mark (625.0 ft) 

for the June 2008 flow of 62,500 ft3/s, as shown in figure 2. 

Therefore, this discrepancy in the compared profiles was 

disregarded. Similarly, the flood extent of the FEMA 1-percent 

probability flood was compared with the simulated inundated 

areas for flows that bracket this flood, that is, the flows corresponding to the streamgage stages of 18 and 19 ft (fig. 4). 

The FEMA delineation is an interim version of a digital 

Flood Insurance Rate Map (Indiana Department of Natural 

Resources, 2004) and is presented herein for comparison 

purposes only.

Development of Water-Surface Profiles

Profiles were developed for a total of 12 stages at 1-ft 

intervals between 9 ft and 20 ft as referenced to the local 

datum of the Flatrock River at Columbus streamgage. These 

stages correspond to elevations of 618.74 ft and 629.74 ft, 

NAVD 88, respectively. Discharges corresponding to the 

various stages were obtained from the most current stagedischarge relation (rating 23, effective February 5, 2010) at 

the Flatrock River gage. No major tributaries join the Flatrock 

River within the 5-mi study reach; therefore, the discharges (as 

listed in table 3) were held constant throughout the study reach 

for a given profile. 

Table 3. Calibration of model to target water-surface elevations at U.S. Geological Survey 

streamgage on Flatrock River at Columbus, Indiana (station number 03363900).

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

Water-surface

 profile1

Discharge, 

corresponding to target 

water-surface elevation 

(ft3

/s)

Target 

water-surface 

elevation 

(feet, NAVD 88)

Modeled 

water-surface 

elevation 

(feet, NAVD 88)

Difference 

in elevation 

(feet)

9 3,400 618.74 618.73 -0.01

10 4,440 619.74 619.73 -0.01

11 5,700 620.74 620.71 -0.03

12 7,310 621.74 621.72 -0.02

13 9,320 622.74 622.72 -0.02

14 12,200 623.74 623.74 0.00

15 15,700 624.74 624.74 0.00

16 19,800 625.74 625.74 0.00

17 24,500 626.74 626.73 -0.01

18 30,000 627.74 627.74 0.00

19 40,000 628.74 628.76 0.02

20 61,200 629.74 629.76 0.02

1

Water-surface profiles are one-foot increments of stage, referenced to the gage datum of the U.S. 

Geological Survey streamgage.
8 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

622

623

624

625

626

627

628

629

630

631

632

633

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000

Elevation above North American Vertical Datum of 1988, in feet

Distance upstream from mouth, in feet

Simulated high-water profile (stage 20 feet)

Surveyed high-water marks from 2008 flood Railroad bridge Low-head dam

State Route 11

U.S. Geological Survey streamgage 03363900and U.S. Route 31 

VERTICAL SCALE GREATLY EXAGGERATED

EXPLANATION

Figure 2. Simulated 

water-surface profile 

at a streamgage stage 

of 20.00 feet and highwater marks surveyed 

following the flood of 

June 7, 2008, at a stage of 

19.94 feet, Flatrock River 

at Columbus, Indiana.

620

622

624

626

628

630

632

634

636

638

640

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

Elevation above North American Vertical Datum of 1988, in feet

Distance upstream from mouth, in feet

VERTICAL SCALE GREATLY EXAGGERATED

FEMA 1-percent annual exceedance probability flood profile

Simulated profile (stage 18 feet)

Simulated profile (stage 19 feet)

U.S. Geological Surveystreamgage 03363900 and U.S. Route 31

County Road 400N

State Route 11

Railroad bridge

Low-head dam

EXPLANATION

Figure 3. High watersurface profiles of the 

FEMA 1-percent annual 

exceedance probability 

flood and simulated 

floods corresponding 

to streamgage stages 

of 18 and 19 feet for 

Flatrock River at 

Columbus, Indiana. 
Constructing Water-Surface Profiles 9

85°58' 85°57' 85°56' 85°55'

39°15'

39°14'

39°13'

0

0

1 MILE

1 KILOMETER

EXPLANATION

Simulated inundated area—

Streamgage stage 18 feet

Simulated inundated area—

Streamgage stage 19 feet

Federal Emergency Management 

Agency 1-percemt annual 

exceedance probability flood

Limit of study area

Low-head dam

Flow arrow—Indicates direction 

of water flow

U.S. Geological Survey 

streamgage and number

State route marker

Interstate route marker

U.S. route marker

03363900

46

31

65

Projection: Indiana State Plane Eastern Zone

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

Orthophotography from Esri ArcGIS World Imagery, 

2011, available at http://goto.arcgisonline.com/maps/World_Imagery

03363900

Columbus NORTH NATIONAL ROAD 

N O R T H I N D I A N A P O L I S R O A D

LOUISVILLE AND INDIANA RAILROAD

COUNTY ROAD 400N 31

31

65

46

11

11

East Fork White River

D r i f t w o o d

R i v e r

D r i f t w o o d

R i v e r

Fl

a

t

r

o

c

k

Riv

e

r

Fl

a

t

r

o

c

k

Riv

e

r

INDIANA

Study

area

Figure 4. Flood extents of the FEMA 1-percent annual exceedance probability flood and simulated floods corresponding 

to streamgage stages of 18 and 19 feet for Flatrock River at Columbus, Indiana.
10 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

Development of Flood-Inundation Maps

Flood-inundation maps were created in a Geographic 

Information System (GIS) for the 12 water-surface profiles 

by combining the profiles and digital elevation model (DEM) 

data. The DEM data were derived from the same LiDAR data 

described previously in the section “Topographic and Bathymetric Data.” Estimated flood-inundation boundaries for each 

simulated profile were developed with HEC-GeoRAS software 

(U.S. Army Corps of Engineers, 2009). As with the resampled 

LiDAR data (10 ft by 10 ft grid-cell size), from which the 

flood maps were derived, the resulting flood maps have an 

estimated vertical accuracy of 2 ft (that is, plus or minus 1 ft). 

Shapefile polygons and depth grids of the inundated areas 

for each profile were modified, as required, in the ArcMap 

application of ArcGIS (Esri, 2012) to ensure a hydraulically 

reasonable transition of the flood boundaries between modeled cross sections. Any inundated areas that were detached 

from the main channel and, therefore, erroneously delineated 

as parts of the flood extent were removed from the mapped 

inundated areas. Bridge surfaces are shown as non-inundated 

up to the lowest flood stage that either intersects the lowest 

structural chord of the bridge or completely inundates one or 

both approaches to the bridge. In these latter circumstances, 

the bridge surface is depicted as being inundated. Estimates of 

water depth can be obtained from the depth-grid data that are 

included with the presentation of the flood maps on the interactive online map-library Web site described in the following 

section, “Flood-Inundation Maps on the Internet.” The mapped 

areas of inundation are overlaid on high-resolution, georeferenced aerial photographs of the study area. The most up-todate orthoimagery available was downloaded from an ArcGIS 

online world imagery base map (Esri, 2011) for this purpose.

Flood-Inundation Maps on the Internet

The flood-inundation maps and current study documentation are available online at the U.S. Geological Survey Publications Warehouse (http://pubs.usgs.gov/sim/2012/3241). Also, 

a Flood Inundation Mapping Science Web site (U.S. Geological Survey, 2012c) has been established to provide a portal at 

http://water.usgs.gov/osw/flood_inundation/ to make USGS 

flood-inundation study information available to the public. 

That Web portal has a link to an interactive flood mapper Web 

site (U.S. Geological Survey, 2012d) at http://wim.usgs.gov/

FIMI/FloodInundationMapper.html that presents map libraries 

that provide detailed information on flood extents and depths 

for selected sites, including Flatrock River at Columbus. 

Included on this latter Web site is a link to the USGS National 

Water Information System (http://waterdata.usgs.gov/in/nwis/

uv?site_no= 03363900), which presents graphs of the current stage and streamflow at the USGS streamgage 03363900 

to which the inundation maps are referenced. A link also is 

provided to the NWS Advanced Hydrologic Prediction Service 

(AHPS) site (http:/water.weather.gov/ahps/); however, because 

the NWS does not forecast stage at this site, the data presented 

on the USGS and NWS Web sites are identical. 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 

which 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) in 

the vicinity of the building of interest exceeds that building’s 

height, the structure can be considered fully submerged.

Disclaimer for Flood-Inundation Maps

Inundated areas shown on the flood maps 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 on the basis of water stages at 

the USGS streamgage on the Flatrock River at Columbus 

(03363900). 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 March 

2012. 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 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. 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 
References Cited 11

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.

Acknowledgments

The author wishes to thank the Indiana Department of 

Transportation, which has cooperated in the funding for the 

operation and maintenance of the gage used for this study, and 

personnel from the City of Columbus–Bartholomew County 

Planning Department, who reviewed the flood-inundation 

maps. Special thanks are given to the National Weather Service for their continued support of the U.S. Geological Survey 

flood-inundation mapping initiative. 

Summary

A series of 12 digital flood-inundation maps were 

developed in cooperation with the Indiana Department of 

Transportation for the Flatrock River at Columbus. The maps 

cover a reach about 5 mi long from the river mouth at its 

confluence with Driftwood River upstream to County Road 

400N. 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 and depths of flooding. The HEC-RAS 

hydraulic model was calibrated by using the most current 

stage-discharge relation at the Flatrock River streamgage, 

high-water marks that were surveyed following the flood 

of June 7, 2008, and water-surface profiles from the current 

flood-insurance study for the City of Columbus. The model 

was used to compute 12 water-surface profiles for flood stages 

at 1-ft intervals referenced to the streamgage datum and 

ranging from 9 ft or near bankfull to 20 ft, which exceeds the 

stages that correspond to both the estimated 0.2-percent annual 

exceedance probability flood (500-year recurrence interval 

flood) and the maximum recorded peak flow. The simulated 

water-surface profiles were then combined with a Geographic 

Information System (GIS) digital elevation model (derived 

from Light Detection and Ranging (LiDAR) data) to delineate 

estimated flood-inundation areas as shapefile polygons and 

depth grids for each profile. These flood-inundation polygons 

were overlaid on high-resolution, georeferenced aerial photographs of the study area. 

Interactive use of the maps on a USGS flood-inundation 

mapping Web portal can give users a general indication of 

depth of water at any point by using the mouse cursor to click 

within the shaded areas. These maps, in conjunction with the 

real-time stage data from the USGS streamgage Flatrock River 

at Columbus (station number 03363900), will help to guide 

the general public in taking individual safety precautions and 

will provide emergency management personnel with a tool to 

efficiently manage emergency flood operations and post-flood 

recovery efforts.

References Cited

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

natural channels: U.S. Geological Survey Water-Supply 

Paper 1849, 213 p.

Coon, W.F., 1998, Estimation of roughness coefficients for 

natural stream channels with vegetated banks: U.S. Geological Survey Water-Supply Paper 2441, 133 p. (Also available at http://pubs.usgs.gov/wsp/2441/report.pdf.)

Esri, 2011, ArcGIS World Imagery, accessed September, 2011, 

at http://www.arcgis.com/home/item.html?id=10df2279f968

4e4a9f6a7f08febac2a9.

Esri, 2012, ArcGIS, accessed August 7, 2012, at http://www.

esri.com/software/arcgis/.

Federal Emergency Management Agency, 1982, Flood Insurance Study, City of Columbus, Indiana, Bartholomew 

County: Washington D.C., 23 p., 8 pl.

Federal Emergency Management Agency, 1996, Flood Insurance Study, City of Columbus, Bartholomew County, 

Indiana: Washington D.C., 23 p., 19 pl.

Federal Emergency Management Agency, 2011, Preliminary 

Flood Insurance Study, Bartholomew County, Indiana, and 

incorporated areas: Washington D.C., 32 p., 34 pl., and 

interim digital flood-insurance rate maps (DFIRMS, dated 

2004), accessed April 2, 2012, at http://www.in.gov/dnr/

water/7246.htm.

Hicks, D.M., and Mason, P.D., 1991, Roughness characteristics of New Zealand rivers: Wellington, New Zealand, 

Water Resources Survey, DSIR Marine and Freshwater, 

329 p.

Indiana Department of Natural Resources, 2004, Digital flood 

insurance rate map database, Bartholomew County, Indiana, 

USA, accessed April 2, 2012, at http://www.in.gov/dnr/

water/7246.htm.
12 Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012

Morlock, S.E., Menke, C.D., Arvin, D.V., and Kim, M.H., 

2008, Flood of June 7–9, 2008, in central and southern Indiana: U.S. Geological Survey Open-File Report 2008–1322, 

15 p., 3 app. 

National Weather Service, 2012, Advanced Hydrologic Prediction Service, accessed May 9, 2012, at http://water.weather.

gov/ahps2/hydrograph.php?wfo=ind&gage=flci3.

U.S. Army Corps of Engineers, 1972, Computer program, 

HEC2, water-surface profiles: U.S. Army Corps of Engineers, Hydrologic Engineering Center, 132 p. 

U.S. Army Corps of Engineers, 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]. 

U.S. Army Corps of Engineers, 2010, HEC-RAS River Analysis System, Hydraulic Reference Manual, version 4.1: U.S. 

Army Corps of Engineers, Hydrologic Engineering Center 

[variously paged].

U.S. Bureau of the Census, 2010, American FactFinder, 

accessed May 8, 2012, at http://factfinder2.census.gov.

U.S. Geological Survey, 2012a, USGS 03363900 Flatrock 

River at Columbus, IN: U.S. Geological Survey, accessed 

May 9, 2012, at http://waterdata.usgs.gov/in/nwis/uv?site_

no=03363900.

U.S. Geological Survey, 2012b, USGS Surface-water data for 

the Nation: U.S. Geological Survey, accessed May 9, 2012, 

at http://waterdata.usgs.gov/nwis/sw.

U.S. Geological Survey, 2012c, USGS Flood Inundation 

Mapping Science: U.S. Geological Survey, accessed May 

9, 2012, at http://water.usgs.gov/osw/flood_inundation/

toolbox/.

U.S. Geological Survey, 2012d, Federal flood inundation 

mapper: U.S. Geological Survey, accessed May 9, 2012, at 

http://wim.usgs.gov/FIMI/FloodInundationMapper.html.
For additional information contact:

Director, Indiana Water Science Center

5957 Lakeside Blvd.

Indianapolis, IN 46278

http://in.water.usgs.gov/

Publishing support provided by: West Trenton Publishing Service Center
Coon—Flood-Inundation Maps for the Flatrock River at Columbus, Indiana, 2012—Scientific Investigations Map 3241