Prepared in cooperation with Indiana Office of Community and Rural Affairs

Flood-Inundation Maps for the White River at Spencer, Indiana

Pamphlet to accompany 

Scientific Investigations Map 3251

U.S. Department of the Interior

U.S. Geological Survey
Cover: Flood scenes in Spencer, Indiana, (Photographs by Chad Menke, USGS, June, 2008).
Flood-Inundation Maps for the White River 

at Spencer, Indiana

By Elizabeth A. Nystrom

Prepared in cooperation with Indiana Office of Community and Rural Affairs

Pamphlet to accompany 

Scientific Investigations Map 3251

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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Suggested citation:

Nystrom, E.A, 2013, Flood-inundation maps for the White River at Spencer, Indiana: U.S. Geological Survey Scientific 

Investigations Map 3251, 20 sheets, 8-p. pamphlet. 

http://pubs.usgs/gov/sim/3251/
iii

Acknowledgments

The author wishes to thank the many local, State, and Federal agencies that have cooperated in the funding for the operation and maintenance of the gage used for this study, especially 

the U.S. Army Corps of Engineers, Louisville District. Special thanks are given to the Indiana 

Office of Community and Rural Affairs for their cooperation in this study, the Indiana Department of Natural Resources, and to the National Weather Service for their continued support to 

the USGS flood-inundation mapping initiative.

Photo taken in Spencer, Indiana, by Chad Menke in June 2008.
iv

Photos taken in Spencer, Indiana, by Chad Menke in June 2008.
v

Contents

Acknowledgments........................................................................................................................................iii

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

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

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

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

Previous Studies ...................................................................................................................................3

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

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

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

Energy-Loss Factors.............................................................................................................................4

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

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

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

White River at Spencer, Indiana, Flood-Inundation Maps on the Internet .................................7

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

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

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

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

Sheets

[Sheets and additional materials are available online at http://pubs.usgs.gov/sim/2013/3251/]

1–20. Flood-inundation maps for the White River at Spencer, Indiana, referenced to USGS 

streamgage number 03357000 for stream stage (water-surface elevation) of:

1. 9 feet and an elevation of 534.63 feet

2. 10 feet and an elevation of 535.63 feet

3. 11 feet and an elevation of 536.63 feet

4. 12 feet and an elevation of 537.63 feet

5. 13 feet and an elevation of 538.63 feet

6. 14 feet and an elevation of 539.63 feet

7. 15 feet and an elevation of 540.63 feet

8. 16 feet and an elevation of 541.63 feet

9. 17 feet and an elevation of 542.63 feet

10. 18 feet and an elevation of 543.63 feet

11. 19 feet and an elevation of 544.63 feet

12. 20 feet and an elevation of 545.63 feet

13. 21 feet and an elevation of 546.63 feet

14. 22 feet and an elevation of 547.63 feet

15. 23 feet and an elevation of 548.63 feet

16. 24 feet and an elevation of 549.63 feet

17. 25 feet and an elevation of 550.63 feet
vi

18. 26 feet and an elevation of 551.63 feet

19. 27 feet and an elevation of 552.63 feet

20. 28 feet and an elevation of 553.63 feet

Figures

1. Map showing location of study reach for the White River at Spencer, Indiana, 

and location of U.S. Geological Survey streamgage and National Weather Service 

forecast site...................................................................................................................................2

Tables

1. U.S. Geological Survey streamgage information for the study reach, White River 

at Spencer, Indiana ......................................................................................................................3

2. 1.0-percent annual exceedance probability peak-discharge estimate and 

drainage area for selected locations in Spencer, Indiana ....................................................3

3. Stages (and water-surface elevations), in feet, with corresponding discharge 

estimates at the U.S. Geological Survey streamgage...........................................................5

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

from the flood of June7–9, 2008, White River at Spencer, Indiana.......................................6

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)

Hydraulic gradient

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

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 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 White River at 

Spencer, Indiana 

By Elizabeth A. Nystrom 

Abstract

Digital flood-inundation maps for a 5.3-mile reach of 

the White River at Spencer, Indiana, were created by the U.S. 

Geological Survey (USGS) in cooperation with the Indiana 

Office of Community and Rural Affairs. The inundation maps, 

which can be accessed through the USGS Flood Inundation 

Mapping Science Web site at http://water.usgs.gov/osw/flood_

inundation/, depict estimates of the areal extent and depth of 

flooding corresponding to selected water levels (stages) at 

the USGS streamgage White River at Spencer, Indiana (sta. 

no. 03357000). Current conditions for estimating near-realtime areas of inundation using USGS streamgage information 

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

National Weather Service (NWS)-forecasted peak-stage information may be used in conjunction with the maps developed 

in this study to show predicted areas of flood inundation.

In this study, flood profiles were computed for the stream 

reach by means of a one-dimensional step-backwater model. 

The model was calibrated by using the most current stagedischarge relation at the White River at Spencer, Indiana, 

streamgage and documented high-water marks from the 

flood of June 8, 2008. The hydraulic model was then used to 

compute 20 water-surface profiles for flood stages at 1-foot 

intervals referenced to the streamgage datum and ranging from 

the NWS action stage (9 feet) to the highest rated stage (28 

feet) 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) in order to delineate the area flooded 

at each water level.

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

streamgage and forecasted stream stages from the NWS 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 post-flood 

recovery efforts.

Introduction 

The Town of Spencer is a small community with an estimated population of 2,217 (U.S. Bureau of the Census, 2010). 

The Town of Spencer has experienced severe flooding numerous times, most notably in 1913, 2005, and 2008. The greatest 

historical flood occurred on March 26, 1913, with an estimated 

stage of 28.5 ft and flow of 100,000 ft3/s. Recent highs flows 

include the floods of January 7, 2005, and June 8, 2008, with 

stages of and 25.06 ft and 26.84, respectively. The majority of 

flood damages have occurred along the White River and several tributaries (including Meadowbrook Creek), which flow 

through the town. Flood plains within the town contain a mix 

of agricultural and residential areas.

Prior to this study, Town of Spencer officials relied on 

several information sources (all of which are available on the 

Internet) to make decisions on how to best alert the public 

and mitigate flood damages. One source of information is the 

Indiana Department of Natural Resources (IDNR) Floodway 

Boundary Study for the Town of Spencer dated March 2002 

(Indiana Department of Natural Resources, 2002). A second 

source is the USGS streamgage White River at Spencer, Indiana (Ind.) (sta. no. 03357000), from which current or historical water levels (stage) can be obtained. A third source is the 

NWS forecast of peak stage at the USGS streamgage through 

the Advanced Hydrologic Prediction Service (AHPS) site. 

The NWS does not routinely forecast stages at the Spencer 

streamgage; rather, forecasts are issued as needed during 

times of high flows. 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 watersurface elevation is not constant along the entire stream channel. Also, Federal Emergency Management Agency (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 the USGS streamgage or 

NWS flood-forecast points.
2 Flood-Inundation Maps for the White River at Spencer, Indiana

Purpose and Scope

The purpose of this report is to describe the development 

of a series of estimated flood-inundation maps for the White 

River near Spencer, Ind. The maps and other useful flood 

information are available on the USGS Flood Inundation Mapping Science Web site and the NWS AHPS Web site. Internet 

users can select estimated inundation maps that correspond 

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

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

The scope of the study was limited to a 5.3 mi reach of 

the White River at Spencer (fig. 1), from 3.1 mi upstream 

to 2.2 mi downstream of the Main Street Bridge in Spencer. 

Maps were produced for water levels referenced to the stage 

at the streamgage White River at Spencer, Ind., ranging from 

the NWS action stage (9 ft) to the maximum rated stage 

(28 ft) at the streamgage. Tasks specific to development of 

the maps were (1) examination of current and historical stage 

and discharge data from the streamgage on the White River 

(table 1); (2) collection of topographic data and geometric 

data for two bridges in the study reach; (3) determination 

of energy-loss factors (roughness coefficients) in the stream 

channel and flood plain, and steady-flow data; (4) computation 

of water-surface profiles by use of the U.S. Army Corps of 

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

Engineers, 2010); (5) production of estimated flood-inundation 

maps at various stream stages by use of the the U.S. Army 

Corps of Engineer’s HEC–GeoRas computer program (U.S. 

Army Corps of Engineers, 2009) and a Geographic Information System (GIS), and (6) preparation of the maps as shapefile polygons that depict the areal extent of flood inundation 

and as depth grids that provide the depth of flood water for 

display on the USGS Flood Inundation Mapper web site that 

links to USGS real-time streamgage information and(or) NWS 

forecasted peak stage to facilitate the display of user-selected 

flood-inundation maps on the Internet.

River

White 

McBride Branch 

Meadowbrook Creek 

McCormicks Creek 

Elliston Creek 

46

231

03357000

67

46

231 67

46 231 67 S. MAIN STREET

Study

area

INDIANA INDIANA

0.5 1 KILOMETER

0.5

0

0 1 MILE

EXPLANATION

46

231

USGS streamgage

and number

Limits of study area

U.S. route marker

State road marker

Flow arrow—Indicates

direction of water flow

03357000

39°16’

39°17’

39°18’

86°47’ 86°46’ 86°45’ 86°44’

Projection: Transverse Mercator, NAD 83, 

State Plane Coordinate System, Indiana West, FIPS 1302

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 White River at Spencer, 

Indiana, and location of U.S. 

Geological Survey streamgage 

and National Weather Service 

forecast site.
Introduction 3

Table 1. U.S. Geological Survey streamgage information for the study reach, White River at Spencer, Indiana.

Station name Station 

number

Drainage 

area 

(mi2

)

Latitude Longitude Period of record

Maximum recorded 

stage at gage (ft) 

and date

White River at 

Spencer, Ind.

03357000 2,988 39°16′52′′ 86°45′44′′ July 1925 to September 1971 

(discharge)

October 1987 to current year 

(stage only)

26.84, June 8, 20081.

1

 A historic peak of 28.5 ft occurred in 1913 prior to installation of the gage. During 1925 to 1971, the period of record for discharge, the peak recorded flow 

was 59,400 ft3/s at a stage of 23.2 ft; floods in 2005 and 2008 exceeded this stage but are outside of the period of record for discharge.

Methods used are generally cited from previously published reports. If techniques varied significantly from previously documented methods due to local hydrologic conditions 

or available data, they are described in detail in this report. 

Study Area Description

The White River is in southwest Indiana in Owen County, 

in the Mitchell Plateau section of the Southern Hills and 

Lowlands Region (Gray, 2000). The drainage area at the White 

River at Spencer, Ind., streamgage is 2,988 mi2; the drainage 

area at the downstream extent of the study reach is less than 

1 percent larger than at the upstream extent of the study reach. 

The headwaters originate in Randolf County, and the stream 

flows generally southwestward through the city of Indianapolis before approaching the town of Spencer. Several minor 

tributaries to the White River join the main stem as it flows 

through Spencer, including Meadowbrook Creek, McCormicks Creek, and Elliston Creek. The basin terrain is generally flat to rolling. The study reach is approximately 5.3 mi 

long and extends from 3.1 river miles upstream of streamgage 

03357000, located at the Main Street Bridge, to 2.2 river 

miles downstream of the bridge; it has an average top-of-bank 

channel width of about 320 ft and an average channel slope of 

1.3 ft/mi. The land contiguous to the study reach is predominantly classified as agricultural and forested; a developed area 

encroaches on the northern flood plain near the gage. The main 

channel within the study reach has two road crossings—the 

State Road 46 and Main Street bridges.

Previous Studies

A preliminary flood insurance study (FIS) for Owen 

County (Federal Emergency Management Agency, 2012) was 

issued in April 2012. Hydrologic and hydraulic analyses for 

the FIS were completed by the IDNR and Morley and Associates on behalf of the IDNR. That study provided information 

on the 1.0- and 0.2-percent annual exceedance probability 

water-surface profiles and associated peak flows for the 

West Fork White River, herein referred to as “White River,” 

and Meadowbrook Creek, which were studied by detailed 

methods, as well as other areas within Owen County, which 

were studied by approximate methods. Estimates of the peak 

discharges for the 1.0-percent annual exceedance probability 

flood along the White River from this FIS are shown in table 2 

below.

Table 2. 1.0-percent annual exceedance probability peakdischarge estimates and drainage areas for selected locations in 

Spencer, Indiana (from Federal Emergency Management Agency, 

2012)

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

Location

Drainage 

area 

(mi2

)

Discharge 

estimate 

(ft3/s)

White River at Main Street 2,988 80,000

Meadowbrook Creek at confluence 

with White River (approx. 0.7 mile 

downstream of Main Street)

3.44 1,350
4 Flood-Inundation Maps for the White River at Spencer, Indiana

Constructing Water-Surface Profiles

The water-surface profiles used to produce the 20 

flood-inundation maps in this study were computed by 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 gradually varied, 

steady-state or unsteady-state flow computation options. The 

HEC–RAS analysis for this study was done by using the 

steady-state flow computation option.

Hydrologic and Steady Flow Data

The study area hydrologic network consists of one 

streamgage (fig. 1; table 1), which was installed in 1925. Historical discharge records are available for this site from July 

1925 to September 1971. Water level (stage) has been measured at the site since October 1987; however, discharges are 

no longer computed. All water-surface elevations in this study 

are referenced to the North American Vertical Datum of 1988 

(NAVD 88); the datum of the gage at White River at Spencer, 

Indiana is 525.63 ft NAVD 88 (526.04 ft as referenced to the 

National Geodetic Vertical Datum of 1929 (NGVD 29)). The 

gage is equipped with a satellite radio transmitter that allows 

data to be transmitted routinely, and on the Internet within an 

hour of collection. Longitudinal water-surface profiles from 

high-water marks along the main channel from the State Road 

46 bridge to the downstream limit of the study reach were 

documented after the flood of June 8, 2008 (Morlock and others, 2008). 

Steady-state flow data consisted of flow regime, boundary condition, and peak-discharge information. Normal depth 

with a slope of 0.00035, which was estimated from LiDAR 

water-surface elevations through the downstream portion of 

the reach, was used as the downstream starting boundary condition. The steady-flow data for the study reach were obtained 

from the most current stage-discharge relation that has been 

developed for the USGS streamgage, White River at Spencer, 

Ind. The most recent stage-discharge rating, number 41.0, was 

created in June 2008; it is based on previous ratings, which 

were developed from measurements collected during and prior 

to 1971, when continuous discharge records were computed 

for the station. Since the station was inactivated in 1971, only 

five verification measurements have been made. The modeled flows coincide with target water-surface elevations at 1-ft 

increments of stage as referenced to the local datum at the 

White River streamgage. 

Topographic/Bathymetric Data

Nineteen channel cross sections were surveyed within the 

study reach by USGS personnel during November 2011; these 

cross sections provided detailed channel elevation data below 

the water surface and were collected by using hydroacoustic 

instrumentation (to measure depth) and Differential Global 

Positioning System (DGPS) instrumentation (to determine 

horizontal position). Control for the USGS survey was established by tying the elevations of two reference marks into 

known elevations. The surveyed elevations were within 0.04 ft 

of their known elevations.

LiDAR data with horizontal accuracy of 1.02 ft and 3.9 

ft cell size (resampled to 10.0 by 10.0 ft cell size), 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) were used to provide digital elevation data for the portions of the cross sections that were above the water surface 

at the time of the surveys. The LiDAR data were collected 

during April 2010 by Aero-Metric, Inc., Sheboygan, Wisconsin (Aero-Metric, Inc., 2010); postprocessing of these data 

was completed by Aero-Metric, Inc., during July 2010. Using 

a GIS, elevation data for 62 cross sections, spaced approximately 500 ft apart, were extracted from a LiDAR digital 

elevation model. In-channel bathymetry for cross sections that 

did not coincide with the surveyed channel cross sections was 

estimated by interpolation.

Various manmade drainage structures (bridges, culverts, roadway embankments, levees and dams) in and along 

a stream affect or have the potential to affect water-surface 

elevations during floods along the stream. To properly account 

for these features in the model, structural dimensions for two 

bridges—the Main Street and State Road 46 bridges—were 

measured and surveyed in the field concurrently with the 

stream-channel surveys. A detailed description of the methods 

used to acquire and process the topographic and bathymetric 

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

Energy-Loss Factors

Field observations and high-resolution aerial photographs were used to select initial (pre-calibration) Manning’s 

roughness coefficients (“n” values) for energy-loss (frictionloss) calculations. The main channel of the White River near 

Spencer is generally meandering, but contains several sharp 

bends near town boundaries. The banks immediately along the 

channel are typically vegetated with trees and shrubs; overbank areas are forested or agricultural. It was determined that 

roughness coefficients varied with stage for this reach of the 

White River, and n values were adjusted for channel type/land 

cover categories by using groups of flood profiles representing ranges of stage. The final Manning’s n values used ranged 

from 0.027 to 0.048 for the main channel and 0.050 to 0.155 

for the overbank areas modeled in this analysis. 
Constructing Water-Surface Profiles 5

Model Calibration and Performance

The hydraulic model was calibrated to the most current 

stage-discharge relation at the White River at Spencer, Ind. 

streamgage and to high-water marks from the flood of June 8, 

2008. Model calibration was accomplished by adjusting Manning’s n values within each group of profiles representing a 

range of stages 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 measured or rated flows at USGS streamgage 03357000 

were equal to or less than 0.3 ft (table 3). 

Table 3. Stages (and water-surface elevations), with corresponding discharge estimates at the 

U.S. Geological Survey streamgage, White River at Spencer, Indiana, for selected simulated 

water-surface profiles.

[NAVD 88, North American Vertical Datum of 1988]

Stage, in feet 

above gage 

datum

Elevation, in 

feet above 

NAVD 88

Associated discharge 

value, in cubic feet 

per second

Sheet 

number

Simulated 

elevation, in feet 

above NAVD 88

Elevation 

difference, 

in feet

9 534.63 5,790 1 534.93 0.30

10 535.63 6,800 2 535.77 0.14

11 536.63 7,850 3 536.62 -0.01

12 537.63 8,960 4 537.40 -0.23

13 538.63 10,200 5 538.70 0.07

14 539.63 11,600 6 539.59 -0.04

15 540.63 13,100 7 540.49 -0.14

16 541.63 15,000 8 541.51 -0.12

17 542.63 17,400 9 542.61 -0.02

18 543.63 20,400 10 543.71 0.08

19 544.63 23,800 11 544.76 0.13

20 545.63 27,500 12 545.93 0.30

21 546.63 31,700 13 546.84 0.21

22 547.63 36,100 14 547.68 0.05

23 548.63 41,000 15 548.56 -0.07

24 549.63 46,300 16 549.45 -0.18

25 550.63 51,900 17 550.73 0.01

26 551.63 58,000 18 551.64 0.01

27 552.63 64,600 19 552.68 0.05

28 553.63 71,600 20 553.72 0.09
6 Flood-Inundation Maps for the White River at Spencer, Indiana

The estimated peak discharge for the June 8, 2008, flood 

was 63,500 ft3/s at a stage of 26.84 ft (elevation 552.47 ft, 

NAVD 88) at the gage. High-water marks were surveyed 

mainly between the State Road 46 and Main Street bridges. 

Differences between measured and simulated elevations of 

high-water marks were less than 0.8 ft (table 4). These 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).

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

flood of June 7–9, 2008, White River at Spencer, Indiana.

High-water mark 

field identification 

number1

High-water-mark 

elevation, 

in feet

Model water-surface 

elevation, 

in feet

Elevation 

difference, 

in feet

Gaged maximum stage 552.47 552.51 0.03

22 555.40 555.62 0.22

23 556.09 555.56 -0.53

24 555.90 555.55 -0.35

26 554.87 554.54 -0.33

27 554.56 554.35 -0.21

28 554.59 554.23 -0.36

29 553.96 553.94 -0.02

30 554.33 553.70 -0.63

31 553.60 553.30 -0.30

32 553.29 553.02 -0.27

33 552.55 552.14 -0.41

34 552.36 552.08 -0.28

35 552.30 552.07 -0.23

36 552.11 552.19 0.08

37 552.44 552.15 -0.29

39 553.69 552.92 -0.77

41 553.30 552.70 -0.60

43 551.71 551.83 0.12

44 551.50 551.76 0.26

45 551.67 551.76 0.09

46 551.80 551.73 -0.07

47 551.73 551.76 0.03

48 551.66 551.76 0.10

49 551.76 551.75 -0.01

50 551.26 551.75 0.49

51 551.23 551.75 0.52

52 548.62 548.62 0.00

53 548.38 548.49 0.11

1

Indiana Department of Natural Resources high-water marks for the flood of June 2008, collected June 17, 2008.
Inundation Mapping 7

Development of Water-Surface Profiles

Profiles were developed for a total of 20 stages at 1-ft 

intervals between 9 ft and 28 ft as referenced to the White 

River at Spencer, Ind. (sta. no. 03357000). Discharges corresponding to the various stages were obtained from the most 

current stage-discharge relation (rating no. 41.0) at the Spencer gage. Discharges for all profiles (table 3) were selected 

with the assumption that within the 5.3-mi study reach there 

were no significant inflows; therefore, the discharges (as listed 

in table 3) were held constant throughout the study reach for a 

given profile. 

Inundation Mapping

Flood-inundation maps were created for the White River 

at Spencer, Ind., USGS site, which has been designated as an 

NWS flood-forecast point (as of 2012). The maps were created 

in a GIS by combining the water-surface profiles and digital 

elevation model (DEM) data. The DEM data were derived 

from 3.9-ft horizontal resolution LiDAR data with a vertical 

accuracy of 0.37 ft, obtained from Aero-Metric, Inc. (AeroMetric, Inc., 2010). The original LiDAR data were resampled 

to a 10- by 10-ft cell size to reduce GIS processing time. 

Estimated flood-inundation boundaries for each simulated 

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

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

procedures, tools, and utilities for processing geospatial data 

in ArcGIS by using a graphical user interface (Whitehead 

and Ostheimer, 2009). The interface allows the preparation of 

geometric data for import into HEC–RAS and processes simulation results exported from HEC–RAS (U.S. Army Corps of 

Engineers, 2010). USGS personnel then modified the HEC–

GeoRAS results to ensure a hydraulically reasonable transition 

of the boundary between modeled cross sections relative to the 

contour data for the land surface (Whitehead and Ostheimer, 

2009). The resulting inundation maps have a vertical accuracy 

of about 1 ft. The maps show estimated flood-inundated areas 

overlaid on high-resolution, geo-referenced aerial photographs 

of the study area for each of the water-surface profiles that 

were generated by the hydraulic model.

White River at Spencer, Indiana, FloodInundation 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/2013/3251). 

Also, a Flood Inundation Mapping Science website has been 

established to provide a portal for USGS flood-inundation 

study information to the public at http://water.usgs.gov/osw/

flood_inundation/. That web portal has a link (http://wim.usgs.

gov/FIMI/FloodInundationMapper.html) to interactive online 

map libraries that can be downloaded in several commonlyused electronic file formats. In the latter link, each stream 

reach displayed contains further links to NWISWeb graphs 

of the current stage and streamflow at USGS streamgage 

03357000, to which the inundation maps are referenced. A link 

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

gov/ahps/) so that the user can obtain applicable information 

on forecasted peak stage. The estimated flood-inundation 

maps are displayed in sufficient detail to note the extent of 

flooding with respect to individual structures so that preparations for flooding and decisions for emergency response can 

be performed efficiently. Roadways and bridges were closely 

reviewed and are shown as shaded (inundated and likely 

impassable) or not shaded (dry and passable) to facilitate 

emergency planning and use. However, buildings that are 

shaded do not reflect inundation but denote that bare earth 

surfaces in the vicinity of the buildings are inundated. When 

the water depth (as indicated in the Web Mapping Application 

by holding the cursor over an inundated area) 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 should not be used for navigation, 

regulatory, permitting, or other legal purposes. The USGS 

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

planning tool but assumes no legal liability or responsibility 

resulting from the use of this information.

Uncertainties and Limitations Regarding Use of 

Flood-Inundation Maps

Although the flood-inundation maps represent the 

boundaries of inundated areas with a distinct line, some 

uncertainty is associated with these maps. The flood boundaries shown were estimated based on water stages and streamflows at the USGS streamgage on the White River at Spencer 

(03357000). 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 

November 2011. Unique meteorological factors (timing and 

distribution of precipitation) may cause actual streamflows 

along the modeled reach to vary from those assumed during a 

flood, which may lead to deviations in the water-surface elevations and inundation boundaries shown. Additional areas may 

be flooded due to unanticipated conditions such as: changes 

in the streambed elevation or roughness, backwater into major 

tributaries along a main stem river, or backwater from localized debris or ice jams. The accuracy of the floodwater extent 

portrayed on these maps will vary with the accuracy of the 
8 Flood-Inundation Maps for the White River at Spencer, Indiana

DEM used to simulate the land surface. Additional uncertainties and limitations pertinent to this study may be described 

elsewhere in this report.

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

conjunction with NWS river forecasts, the user should be 

aware of additional uncertainties that may be inherent or factored into NWS forecast procedures. The NWS uses forecast 

models to estimate the quantity and timing of water flowing 

through selected stream reaches in the United States. These 

forecast models (1) estimate the amount of runoff generated 

by precipitation and snowmelt, (2) simulate the movement 

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

flow and stage (and 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. 

Summary

A series of estimated flood-inundation maps for a 5.3-mi 

reach of the White River at Spencer, Ind., were developed in 

cooperation with the Indiana Office of Community and Rural 

Affairs for the White River at Spencer. These maps, available 

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

data from the USGS streamgage at White River at Spencer, 

Ind. (sta. no. 03357000), and NWS flood-stage forecasts, will 

help to guide the general public in taking individual safety 

precautions and will provide city officials with a tool to efficiently manage emergency flood operations and flood mitigation efforts. 

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

of Engineers HEC–RAS and HEC–GeoRAS programs to 

compute water-surface profiles and to delineate estimated 

flood-inundation areas for selected stream stages at 1-ft intervals referenced to the streamgage datum and ranging from the 

NWS action stage (9 ft) to the highest rated stage (28 ft). A 

HEC-RAS hydraulic model was calibrated by using the most 

current stage-discharge relation at the White River at Spencer 

streamgage and documented high-water marks from the flood 

of June 8, 2008. The simulated water-surface profiles were 

then combined with a geographic information system digital 

elevation model (derived from LiDAR data) to delineate the 

area flooded at each water level. The maps show estimated 

(shaded) flood-inundation areas overlaid on high-resolution, 

georeferenced aerial photographs of the study area. Interactive use of the maps using the mouse cursor to click within the 

shaded areas can give users a general indication of depth of 

water at any point.

References Cited

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, 2012, Flood Insurance Study, Owen County, Indiana and Incorporated Areas, 

Preliminary Flood Insurance Study Number 18119CV000A.

Gray, H.H., 2000, Physiographic divisions of Indiana: Bloomington, Ind., Indiana Geological Survey Special Report 61, 

15 p., 1 pl.

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.

Indiana Department of Natural Resources, 2002, Floodway/

flood boundary study, Town of Spencer, Owen County, 

West Fork White River.

U.S. Army Corps of Engineers, Hydrologic Engineering Center, 2009, HEC–GeoRAS, GIS Tools for support of HEC–

RAS using ArcGIS, user’s manual, version 4.2 [variously 

paged]. 

U.S. Army Corps of Engineers, Hydrologic Engineering 

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

reference manual, version 4.1 [variously paged].

U.S. Bureau of the Census, 2010, 2010 Census interactive population search IN-Town of Spencer: Washington, 

D.C., accessed November 5, 2012, at http://2010.census.

gov/2010census/popmap/ipmtext.php?fl=18:1871972

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

of a flood-warning system and flood-inundation mapping 

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

Survey Scientific Investigations Report 2008–5234, 

9 p., 11 pl. 

Nystrom—Flood-Inundation Maps for the White River at Spencer, Indiana—Scientific Investigations Map 3251