U.S. Department of the Interior

U.S. Geological Survey

Pamphlet to accompany 

Scientific Investigations Map 3275

Prepared in cooperation with the Will County Stormwater Management Planning Committee

Flood-Inundation Maps for the DuPage River from 

Plainfield to Shorewood, Illinois, 2013
Cover images:

Background: Inundation depths along the DuPage River at a gage height of 14 feet referenced to the U.S. Geological Survey 

streamgage at Shorewood, Illinois.

Upper right: Houses on River Road in Plainfield Township inundated by the DuPage River during the April 2013 flooding. 

(Photograph by Will County staff.)

Lower left: Sign on South Lily Cache Rd just north of West Caton Farm Road during the September 2008 flooding. 

(Photograph by Will County staff.)
Flood-Inundation Maps for the DuPage River 

from Plainfield to Shorewood, Illinois, 2013

By Elizabeth A. Murphy and Jennifer B. Sharpe

Prepared in cooperation with the Will County Stormwater Management 

Planning Committee

Pamphlet to accompany 

Scientific Investigations Map 3275

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

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

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

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

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

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

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

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

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

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

Suggested citation:

Murphy, E.A. and Sharpe, J.B., 2013, Flood-inundation maps for the DuPage River from Plainfield to Shorewood, 

Illinois, 2013: U.S. Geological Survey Scientific Investigations Map 3275, 9 sheets, 8-p. pamphlet, 

http://dx.doi.org/10.3133/sim/3275.

ISSN 2329-132X
iii

Acknowledgments

The authors wish to thank the many local, State, and Federal agencies that provided funding and 

cooperated in the operation and maintenance of the gages used for this study. Special thanks 

are given to Derek O’Sullivan, Thomas Carroll and other staff at the Will County Stormwater 

Management Planning Committee and to the Illinois State Water Survey for providing the crosssection shapefile. Additional thanks are given to Alexander Paul and Terry Ortel for their work on 

the design of the inundation mapping Web site.

v

Contents

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 Verification ...............................................................................................................................5

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

Inundation Mapping ......................................................................................................................................5

Inundation Verification.........................................................................................................................7

DuPage River, Illinois, Flood-Inundation Maps on the Internet ....................................................7

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

Uncertainty and Limitation Associated With Inundation Maps....................................................7

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

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

Glossary...........................................................................................................................................................8

Figures

1. Map showing location of study reach for the DuPage River, Illinois, and location of 

U.S. Geological Survey streamgages and National Weather Service forecast point. .....2

2. A, Aerial photograph taken after the flood peak in September 2008 overlaid with 

simulated flood inundation corresponding to a gage height (elevation) of 10.0 (574.3) 

feet at U.S. Geological Survey streamgage number 05540500, DuPage River at 

Shorewood, Illinois, and B, photos of flooding along the DuPage River on September 

14, 2008, at locations 1 and 2 in photo A. The peak gage height for this flood was 

measured at 9.94 feet at the Shorewood streamgage on September 15, 2008 ..................6

Tables

1. U.S. Geological Survey streamgage information for study area, DuPage River, Illinois. .3

2. 10-, 2-, 1-, and 0.2-percent annual exceedance probability peak discharge estimates 

and drainage areas for selected locations on the DuPage River, Illinois (modified 

from Federal Emergency Management Agency, 2003)...........................................................3

3. Gage heights (elevations) at USGS streamgage 05540500, DuPage River at 

Shorewood, Illinois, with corresponding discharge estimates at selected locations 

along the DuPage River, Illinois, for simulated water-surface profiles ...............................5
vi

Sheets

Sheets and additional materials are available online at http://pubs.usgs.gov/sim/3275.

1–9. Estimated flood-inundation maps for the DuPage River from Plainfield to Shorewood, 

Illinois, referenced to U.S. Geological Survey streamgage DuPage River at Shorewood 

(station no. 05540500) and corresponding to gage heights of:

1. Gage height of 6.0 feet and an elevation of 570.3 feet

2. Gage height of 7.0 feet and an elevation of 571.3 feet

3. Gage height of 8.0 feet and an elevation of 572.3 feet

4. Gage height of 9.0 feet and an elevation of 573.3 feet

5. Gage height of 10.0 feet and an elevation of 574.3 feet

6. Gage height of 11.0 feet and an elevation of 575.3 feet

7. Gage height of 12.0 feet and an elevation of 576.3 feet

8. Gage height of 13.0 feet and an elevation of 577.3 feet

9. Gage height of 14.0 feet and an elevation of 578.3 feet

Conversion Factors, Abbreviations, and Datum

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 the North American Vertical Datum of 1988 

(NAVD 88).

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

Elevation, as used in this report, refers to distance above the vertical datum.

Selected technical terms defined in the glossary are indicated by bold type where they are first 

used.
Flood-Inundation Maps for the DuPage River from 

Plainfield to Shorewood, Illinois, 2013

By Elizabeth A. Murphy and Jennifer B. Sharpe 

Abstract

Digital flood-inundation maps for a 15.5-mi reach of the 

DuPage River from Plainfield to Shorewood, Illinois, were 

created by the U.S. Geological Survey (USGS) in cooperation 

with the Will County Stormwater Management Planning Committee. The inundation maps, which can be accessed through 

the USGS Flood Inundation Mapping Science Web site at 

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

of the areal extent of flooding corresponding to selected water 

levels (gage heights or stages) at the USGS streamgage at 

DuPage River at Shorewood, Illinois (sta. no. 05540500). 

Current conditions at the USGS streamgage may be obtained 

on the Internet at http://waterdata.usgs.gov/usa/nwis/

uv?05540500. In addition, the information has been provided 

to the National Weather Service (NWS) for incorporation into 

their Advanced Hydrologic Prediction Service (AHPS) flood 

warning system (http://water.weather.gov/ahps/). The NWS 

forecasts flood hydrographs at many places that are often 

colocated with USGS streamgages. The NWS-forecasted 

peak-stage information, also shown on the DuPage River at 

Shorewood inundation Web site, may be used in conjunction 

with the maps developed in this study to show predicted areas 

of flood inundation.

In this study, flood profiles were computed for the stream 

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

The hydraulic model was then used to determine nine watersurface profiles for flood stages at 1-ft intervals referenced to 

the streamgage datum and ranging from NWS Action stage of 

6 ft to the historic crest of 14.0 ft. The simulated water-surface 

profiles were then combined with a Digital Elevation Model 

(DEM) (derived from Light Detection And Ranging (LiDAR) 

data) by using a Geographic Information System (GIS) in 

order to delineate the area flooded at each water level. 

These maps, along with information on the Internet 

regarding current gage height from USGS streamgages and 

forecasted stream stages from the NWS, provide emergency 

management personnel and residents with information that is 

critical for flood response activities such as evacuations and 

road closures, as well as for postflood recovery efforts.

Introduction 

Will County is part of the Chicago, Illinois (Ill.), metropolitan area, with an estimated population of 681,545 in 2011

(U.S. Census Bureau, 2013). Parts of Will County have experienced severe flooding numerous times, most notably in July 

1996, August 2007, and September 2008. President George W. 

Bush signed Major Disaster Declaration FEMA–1800–DR on 

October 3, 2008, for Cook, DeKalb, DuPage, Grundy, Kane, 

LaSalle, and Will counties following severe flooding in September 2008 (Federal Emergency Management Agency, 2008). 

Flood plains within Will County are urbanized and contain a 

mix of residential and commercial structures.

Prior to this study, Will County and municipal officials 

relied on several information sources to make decisions on 

how to best alert the public about impending flooding and to 

mitigate flood damages. One source is the Federal Emergency 

Management Agency (FEMA) Flood Insurance Study (FIS) 

for Will County, Illinois, and Incorporated Areas, dated March 

17, 2003 (Federal Emergency Management Agency, 2003). 

A second source of information has been the U.S. Geological 

Survey (USGS) streamgages, DuPage River at Shorewood, Ill. 

(station no. 05540500) and DuPage River near Plainfield, Ill. 

(station no. 05540290), from which current or historical water 

levels (gage heights) can be obtained. A third source has been 

the National Weather Service (NWS) forecast of peak stage 

(gage height) at the USGS Shorewood streamgage through 

the Advanced Hydrologic Prediction Service (AHPS) site. 

Although USGS current gage height and NWS forecast stage 

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

farther upstream or downstream because the water-surface 

elevation is not constant along the entire stream channel. 

Also, FEMA and State emergency management mitigation 

teams or property owners typically lack information related 

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

streamgage or NWS flood-forecast points. 
30

55

52

30

126

126

59

59

-88°14' -88°13' -88°12' -88°11' -88°10' -88°9'

41°42'

41°41'

41°40'

41°39'

41°38'

41°37'

41°36'

41°35'

41°34'

41°33'

41°32'

41°31'

0 1 MILE

0 1 KILOMETER

05540290

05540500

Naperville

Bolingbrook

Plainfield

Plainfield

Romeoville

Joliet Joliet

Joliet Shorewood

EXPLANATION

Stream

Current U.S. Geological

 Survey streamgage 

 and identifier

National Weather 

 Service forecast point

Interstate marker

U.S. route marker

Illinois State route

 marker

05540290

Figure 1. Location of mapped reach for the DuPage River, Illinois, and location of U.S. Geological Survey streamgages 

and National Weather Service forecast point at Shorewood. 

Orthography from the U.S. Department of Agriculture Farm Service 

Agency, Aerial Photography Field Office 2012 National Agriculture 

Imagery Program (NAIP) Natural Color Imagery for Illinois, accessed 

in 2013 at http://gis.apfo.usda.gov/arcgis/services

59

30

55

Lily Cache

Creek

DuPage

River

Location

of fig. 2A

Will County

DuPage County

Cook County

Grundy

County

Kendall

County

Kane

County

DuPage River near

DuPage River at

Des Plaines

River

DuPage

River

West

Branch

Branch

East

Mapped

reach

Shorewood 05540500

Plainfield Plainfield 05540290

ILLINOIS

DuPage River

Watershed

2 Flood-Inundation Maps for the DuPage River from Plainfield to Shorewood, Illinois, 2013

Purpose and Scope

The purpose of this report is to (1) describe the development of a series of estimated flood-inundation maps for a 

15.5-mile reach of the DuPage River between Plainfield and 

Shorewood, Ill., (fig.1) and (2) provide users with a library of 

flood-inundation maps that correspond to water levels referenced to the water-surface elevation and gage heights at the 

USGS streamgage on the DuPage River at Shorewood, Ill. The 

reference gage heights range from 6 ft to 14 ft, corresponding 

to the NWS Action Stage and the historic crest, respectively. 

This report is a description of the DuPage River inundation 

maps and other flood information available on the USGS 

Flood Inundation Mapping Science Web site at http://water.

usgs.gov/osw/flood_inundation/.

Figure 1. Location of study reach for the DuPage River, Illinois, and location of U.S. Geological Survey streamgages and National 

Weather Service forecast point.
Introduction 3

Study Area Description

The DuPage River is in northeast Illinois in the Central 

Lowland physiographic province (Illinois State Geological 

Survey, 2013). The drainage area is 324 mi2 at the Shorewood 

streamgage and 220 mi2 at the Plainfield streamgage (table 1; 

U.S. Geological Survey, 2013a and 2013b). 

The DuPage River is formed by the East Branch DuPage 

River joining the West Branch of the DuPage River approximately 1.6 miles upstream of Plainfield-Naperville Road, and 

the stream flows generally southwestward before entering 

the study area (fig. 1). The basin terrain is generally flat. The 

study reach is approximately 15.5 mi long, has an average 

top-of-bank channel width of about 180 ft and an average 

channel slope of 4.4 ft/mi (U.S. Geological Survey, 2013c). 

Will County is still under development, as evidenced by a 

population increase of 35 percent (from 502,266 to 677,560) 

between 2000 and 2010 (U.S. Census Bureau, 2013). The land 

use along the study reach is a mix of commercial, residential, 

agricultural, and forest preserve land. The main channel within 

the modeled reach has fifteen major road crossings. 

Table 1. U.S. Geological Survey streamgage information for study area, DuPage River, Illinois.

[mi2, square miles; ft, feet; NAVD 88, North American Vertical Datum of 1988]

Station name Station 

number

Drainage 

area 

(mi2

)

Latitude

(degrees, 

minutes, 

seconds)

Longitude

(degrees, 

minutes, 

seconds)

Period of record

Maximum recorded 

elevation at gage 

(ft above NAVD 88) 

and date

DuPage River near 

Plainfield, Ill.

05540290 220 41° 41′ 24′′ N. 88° 09′ 59′′ W. 1962-1970;

December 29, 

2010, to current 

year (2013)

622.37 ft

May 12, 1966.

DuPage River at 

Shorewood, Ill.

05540500 324 41° 31′ 20′′ N. 88° 11′ 33′′ W. October 1940, to 

current year 

(2013)

578.35 ft

July 18, 1996.

Previous Studies 

The current FIS for Will County, Ill., and incorporated 

areas (Federal Emergency Management Agency, 2003), was 

published in 2003. The FIS includes information on the 1.0- 

and 0.2-percent annual exceedance probability water-surface 

profiles and associated flood-plain maps for the DuPage River. 

In addition to the information in the 2003 FIS, two Letter 

of Map Revision (LOMR) studies were incorporated. These 

LOMR studies were obtained from the FEMA map library 

(John Adams, FEMA Engineering Library, written commun., 

2012). The first LOMR study (case 02–05–3236P) is from 

2002 and covers the area from 5,800 ft upstream of Black 

Road to 1,950 ft upstream of Black Road. The second LOMR 

study (case 01–05-3978P) is also from 2002 and covers the 

area from 100 ft downstream of Naperville Road to approximately 1,700 ft downstream of Naperville Road. Estimates of 

the peak discharges for the 10-, 2-, 1-, and 0.2-percent annual 

exceedance probability flood along the DuPage River, as 

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

(2003). 

Table 2. 10-, 2-, 1-, and 0.2-percent annual exceedance probability peak discharge estimates and drainage areas for selected 

locations on the DuPage River, Illinois (modified from Federal Emergency Management Agency, 2003).

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

Annual exceedance probability peak-discharge estimate

Location on DuPage River Drainage area 

(mi2

)

10-percent 

discharge 

estimate

(ft3

/s)

2-percent 

discharge 

estimate

(ft3

/s)

1-percent 

discharge 

estimate 

(ft3

/s)

0.2-percent 

discharge 

estimate 

(ft3

/s)

At Shorewood streamgage 

(05540500)

324 8,470 11,950 13,690 17,300

Approximately 415 feet 

upstream of Renwick Road

258 7,054 10,100 11,527 14,900

At Lockport Street 252 6,950 10,000 11,372 14,800

At State Route 59 

(Division Street)

251 6,890 9,950 11,280 14,700
4 Flood-Inundation Maps for the DuPage River from Plainfield to Shorewood, Illinois, 2013

Constructing Water-Surface Profiles

The water-surface profiles used to produce the nine 

flood-inundation maps for this study were computed by using 

HEC-2, version 4.6 (U.S. Army Corps of Engineers, Hydrologic Engineering Center 1991). HEC-2 is a one-dimensional 

step-backwater model for simulation of water-surface profiles 

with steady-state computation. 

Hydrologic and Steady-Flow Data

Hydrologic data in the study area were from two 

streamgages (fig. 1; table 1): DuPage River at Shorewood, Ill. 

(05540500) and DuPage River near Plainfield, Ill. (05540290). 

The Shorewood gage was installed in April 1941 and has been 

used to measure gage heights and discharge continuously 

since installation. The records were published as “DuPage 

River at Troy” from 1940 through 1965. The Plainfield site 

was originally established as a crest-stage partial record station on October 1, 1961, and was discontinued on September 

30, 1970. Crest-stage gages record information on peak gage 

heights. The site was then reestablished in 1978 as part of 

the Illinois Environmental Protection Agency (IEPA) Ambient Water-Quality Network with a wire-weight gage, and 

water-quality samples were taken at this location until 1988. 

As an IEPA wire-weight gage station, it would have typically 

been used to measure the gage height at the time of a waterquality sample and is unlikely to have been used for peak 

gage heights. The current record begins when the station was 

reestablished in December 2010. 

Discrete discharge measurements have been made at 

these two sites since their respective installations. These discharge measurements are the basis for rating (stage-discharge) 

curves at the two streamgages from which streamflow records 

are computed. The current rating curve for the Plainfield 

streamgage was developed in 2013. All water-surface elevations are referenced to North American Vertical Datum of 

1988 (NAVD 88); however, the datum for the Shorewood 

streamgage is listed as NGVD29 on the USGS National Water 

Information System: Web Interface (U.S. Geological Survey, 

2013a). At the Shorewood streamgage, the NGVD29 elevation 

can be converted to a NAVD88 elevation by subtracting 0.3 ft 

(National Geodetic Survey, 2013).

Steady-flow data consisted of flow regime, boundary conditions (normal depth downstream boundary condition), and 

peak discharge information. The steady-flow data for the study 

reach were obtained from field measurements of streamflow at 

the DuPage River streamgages at Shorewood and Plainfield, 

Ill. The stage-discharge relation (rating curve) was used to 

determine the flows at the Shorewood gage. The streamflow 

records at the Shorewood and Plainfield streamgages were 

used to derive a relation between peak flows at the two gages, 

and the Drainage-Area Ratio method (Hirsch, 1979) was used 

to estimate flows away from the Shorewood streamgage. This 

approach was used to account for the variability in individual 

storm events. The Drainage-Area Ratio method states that the 

ratio of two drainage areas (DA1

/DA2) raised to an exponent is 

equal to the ratio of the corresponding flows (Q1/Q2). The ratio 

between the Plainfield and Shorewood streamgage drainage 

areas is 0.68. After data from storm events that have occurred 

since the installation of the Plainfield streamgage in December 

2010 were examined, the relation between the Shorewood and 

Plainfield streamgages was characterized by a peak flow ratio 

of approximately 0.71. Using the drainage area ratio and flow 

ratio from the streamgages, the exponent was determined to 

be 0.88. Therefore the Drainage-Area Ratio with an exponent 

of 0.88 was used to estimate the flows at the Plainfield gage, 

and upstream and downstream of the confluence with Lily 

Cache Creek with drainage areas of 220, 267.6, and 313.6 mi2, 

respectively. The USGS Streamstats program (U.S. Geological Survey, 2013c) was used to calculate drainage areas for the 

discharge estimates. 

Topographic/Bathymetric Data

The study model was an updated version of the effective FIS HEC-2 hydraulic model (FEMA, 2003). The USGS 

did not do any surveying in the field to change channel cross 

sections in the model. A Digital Elevation Model (DEM) with 

a grid size of 5 ft was used to represent the ground surface. 

The DEM was created from spot elevations and contour 

lines derived from a processed Light Detection And Ranging 

(LiDAR) dataset collected in 2007 with accuracy sufficient to 

produce 2-ft contours. The elevation and contour data were 

obtained from the Will County GIS Department (Nate Rock, 

Will County GIS Department, written commun., 2012). 

The study reach includes various structures (bridges, 

culverts, roadway embankments, levees, and dams) that have 

the potential to affect water-surface elevations during floods. 

To properly account for these features in the model, the 

structures in the study reach were checked for needed updates. 

Structural plans for bridges were provided by Will County 

(Derek O’Sullivan, Will County Land Use Department, written commun., 2012). As part of this study, the USGS made 

updates to the HEC-2 model bridge geometry based on plans 

of Naperville-Plainfield Road, 111th Street (Hassert Boulevard), 119th Street (Rodeo Drive), 135th Street (Pilchers Road), 

Division Street (State Route 59), Lockport Street, new bridge 

on Renwick Road, a second crossing of State Route 59, Caton 

Farm Road, Black Road, Jefferson Street (U.S. Route 52), and 

Cottage Street (State Route 59). 

Energy Loss Factors

Manning’s roughness coefficients (“n” values) are used 

in hydraulic modeling for energy (friction) loss calculations. 

The Manning’s n values used ranged from 0.02 to 0.094, and 

the majority of values ranged from 0.03 to 0.05 for the main 

channel and from 0.05 to 0.14 for the overbank areas modeled in this analysis. The main channel bed is mostly sand 
Inundation Mapping 5

and gravel near the Shorewood streamgage and mostly sand, 

gravel, and silt near the Plainfield streamgage; the overbank 

areas are vegetated, with some areas having shrub and tree 

cover.

In addition to Manning’s roughness coefficients, contraction and expansion coefficients of 0.3 and 0.5, respectively, 

were added to the cross sections upstream and downstream of 

bridges.

Model Verification 

Water-surface elevations calculated by the model were 

compared to the rating curve for the Plainfield streamgage. 

The Shorewood streamgage rating curve was used to determine the flows input to the model, so the Plainfield streamgage 

rating curve was used to verify the model performance. The 

difference between the model-simulated water-surface elevation and the water-surface elevation estimated from the rating 

curve for the nine simulated discharges (table 3) ranged from 

0.71 to -0.50 ft with an average error of -0.06 ft. 

Development of Water-Surface Profiles

Water-surface profiles were developed for a total of 

nine gage heights at 1-ft intervals between 6 ft and 14 ft as 

referenced to the DuPage River at Shorewood streamgage 

(05540500). Discharges corresponding to the various gage 

heights were obtained from the stage-discharge relation 

interpolated for the DuPage River at Shorewood streamgage. 

Flows corresponding to each of the gage heights to be mapped 

were entered into the hydraulic model at the downstream end. 

Two other sets of discharges were derived using the drainage area relation as described in the “Hydrologic and Steady 

Flow” section above. Discharges for all profiles mapped in this 

study reach on the DuPage River are listed in table 3. 

Inundation Mapping

Flood-inundation maps were developed for the nine 

water-surface profiles generated for the gage heights observed 

at the DuPage River at Shorewood gage. Before mapping, 

the water-surface elevations output from the HEC-2 model 

were referenced to the NAVD88 vertical datum instead of 

the NGVD29 vertical datum by subtracting 0.3 ft. The maps 

were created in the ArcMap GIS (Ormsby and others, 2010) 

by combining the water-surface profiles and DEM data. 

Estimated flood-inundation boundaries for each simulated 

profile were created by using a DEM with a 5-ft cell size, 

modeled cross sections, and water-surface elevations for 

specific predefined stages for the cross sections derived from 

the HEC-2 hydraulic model. Water-surface elevation values 

were joined to the corresponding cross section, and a waterlevel surface for each predefined gage height was generated 

by using an Arc Macro Language (AML; ESRI, 1999) script. 

The inundation surface and the depth grids were then created by subtracting the ground-surface DEM elevations from 

the water-level-surface elevations. Cells with a value greater 

than 0.1 were retained, and the result was two grids—a flatsurface grid representing the extent of inundation and a depth 

grid retaining the differences between the ground-surface and 

water-surface elevations. The inundation maps show depth 

shading for estimated flooded areas overlaid on high-resolution, georeferenced aerial photographs of the study area for 

each of the water-surface profiles that were generated by the 

hydraulic model for approximately every 1-ft change in gage 

height ranging from 6.0 to 14 ft. For mapping purposes, the 

depth grids were displayed by using a 1-ft interval up to 2 ft, 

grouping depths from 2.1 ft to 5 ft and then one shade of color 

for values greater than 5 ft. 

Many bridges span the DuPage River in the study reach 

(fig. 1). The LiDAR data used for mapping deletes the bridge 

decks, and the deleted area is assigned the elevation of the 

Table 3. Gage heights (elevations) at USGS streamgage 05540500, DuPage River at Shorewood, Illinois, with corresponding discharge 

estimates at selected locations along the DuPage River, Illinois, for simulated water-surface profiles. 

[NAVD 88, North American Vertical Datum of 1988; ft3/s, cubic feet per second. Sheet numbers correspond to separate flood-inundation maps available online 

at http://pubs.usgs.gov/sim/ 3275/]

Gage height, in feet above gage datum at the DuPage River

(elevation, in feet, NAVD 88) 

Location 6.0

(570.3)

7.0

(571.3)

8.0

(572.3)

9.0

(573.3)

10.0

(574.3)

11.0

(575.3)

12.0

(576.3)

13.0

(577.3)

14.0

(578.3)

Discharge (ft3

/s)

Shorewood 

gage

3,840 5,110 6,500 7,970 9,540 11,200 12,900 14,700 16,600

Upstream of 

Lily Cache 

Creek

3,245 4,318 5,493 6,735 8,062 9,465 10,902 12,423 14,029

Plainfield gage 2,731 3,635 4,623 5,669 6,786 7,967 9,176 10,456 11,808

Sheet no. 1 2 3 4 5 6 7 8 9
1. View looking northeast from bridge

2. View looking south from parking lot

1

2

EXPLANATION

Extent of flood inundation corresponding

 to a gage height (elevation) of 10.0 (574.3)

 feet at U.S. Geological Survey streamgage

 number 05540290, DuPage River at

 Shorewood

Location and direction of photo showing 

 flooding on the DuPage River on 

 September 14, 2008

Illinois State route marker

1

Figure 2. A) Comparison between aerial photo taken after the flood peak in September 2008 and simulated flood inundation 

corresponding to a gage height (elevation) of 10.0 (574.3) feet at U.S. Geological Survey streamgage number 05540290, DuPage 

River at Shorewood, and B) pictures of flooding from specific locations on September 14, 2008. The peak gage height for this

storm was measured at 9.94 ft on September 15, 2008. 

A. B.

Photos from dupageriverflooding.com

Photo provided by Will County, Illinois Land Use Department.

Lincoln Highway

DuPage

River

126

126

6 Flood-Inundation Maps for the DuPage River from Plainfield to Shorewood, Illinois, 2013

stream instead of the elevation of the bridge crossing the 

stream. Because of this feature of the LiDAR data, it was 

necessary to manually process the bridge deck elevations. A 

rectangular area representing each bridge deck was digitized 

and assigned the minimum elevation of the bridge deck from 

bridge data in the HEC-2 hydraulic model. These rectangular 

areas were then merged into the land-elevation DEM, so when 

the inundated area was subtracted from the land-surface elevation, the bridge decks remained above the inundated surface 

when the road was not inundated. In the published maps, 

however, the bridge decks are shown as inundated when the 

roads approaching the bridge decks are inundated in order to 

discourage people from crossing the bridge.

Figure 2. A, Aerial photograph taken after the flood peak in September 2008 overlaid with simulated flood inundation corresponding 

to a gage height (elevation) of 10.0 (574.3) feet at U.S. Geological Survey streamgage number 05540500, DuPage River at Shorewood, 

Illinois, and B, photos of flooding along the DuPage River on September 14, 2008, at locations 1 and 2 in photo A. The peak gage height 

for this flood was measured at 9.94 feet at the Shorewood streamgage on September 15, 2008. (Refer to figure 1 for the location where 

photo A was taken.)
Inundation Mapping 7

Inundation Verification

 Aerial photographs taken during the September 2008 

flooding along the DuPage River in Will County by The 

Sidwell Company were provided by Will County (Derek 

O’Sullivan, Will County Land Use Department, written 

commun., 2013). The peak gage height during this event was 

9.94 ft on September 15, 2008, as measured at the Shorewood 

streamgage (U.S. Geological Survey, 2013a). The extent of 

flooding shown in the aerial photography is comparable with 

the boundaries of the inundation surface generated for the 

gage height of 10 ft at the Shorewood streamgage.

DuPage River, Illinois, Flood-Inundation Maps 

on the Internet

The flood-inundation maps and current study documentation are available online at the USGS Publications Warehouse 

(http://pubs.usgs.gov/sim/3275). Also, a USGS Flood Inundation Mapping Science World Wide Web portal has been established at http://water.usgs.gov/osw/flood_inundation/ to provide a portal for USGS estimated flood-inundation information 

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

FIMI/FloodInundationMapper.html) to interactive online map 

libraries that can be downloaded in several commonly used 

electronic file formats. The maps from this study showing the 

extent of inundated areas can be downloaded in three electronic file formats from that portal; (1) GIS shapefile format, 

(2) Keyhole Markup Language zipped file format (KMZ), 

and (3) Portable Document Format (PDF). Users can print out 

formatted maps or create customized maps using available 

GIS data layers. Each stream reach displayed on the Web site 

contains links to NWISWeb graphs of the current gage height 

at USGS streamgage DuPage River at Shorewood, 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 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 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.

Uncertainty and Limitation Associated With 

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 gage heights (water-surface 

elevations) and streamflows (discharges) at a selected USGS 

streamgage. Water-surface elevations along the stream reaches 

were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and hydrologic 

conditions anticipated at the USGS streamgage. The hydraulic 

model reflects the land-cover characteristics and any bridge, 

dam, levee, or other hydraulic structures existing in November 

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 NWS river forecasts, the user should be 

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

models to estimate the quantity and timing of water flowing 

through selected stream reaches in the United States. These 

forecast models (1) estimate the amount of runoff generated 

by precipitation and snowmelt, (2) simulate the movement of 

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

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

location (AHPS forecast point) throughout the forecast period 

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

more information on AHPS forecasts, please see http://water.

weather.gov/ahps/pcpn_and_river_forecasting.pdf.
8 Flood-Inundation Maps for the DuPage River from Plainfield to Shorewood, Illinois, 2013

Summary

A series of estimated flood-inundation maps for the 

DuPage River between Plainfield and Shorewood, Illinois, 

were developed in cooperation with the Will County Stormwater Management Planning Committee. These maps (available 

at http://water.usgs.gov/osw/flood_inundation/), in conjunction with the real-time gage-height data from the USGS 

streamgage at the DuPage River at Shorewood, Ill. (station no. 

05540500), and National Weather Service flood-stage forecasts, can help to guide the general public in taking individual 

safety precautions and can provide city officials with a tool 

to efficiently manage emergency flood operations and flood 

mitigation efforts. 

The maps were developed by using the HEC-2 and 

ArcMap programs to compute water-surface profiles and 

to delineate estimated flood-inundation areas for selected 

gage heights. The maps show depth shading for estimated 

flood-inundation areas overlaid on high-resolution, georeferenced aerial photographs of the study area for gage heights 

between 6 ft and 14 ft at the DuPage River at Shorewood, Ill. 

streamgage. 

References Cited

ESRI, 1999, ARC Macro Language, self-study workbook—

Developing ARC/INFO menus and macros with AML: 

Redlands, California, ESRI Press, 828 p.

Federal Emergency Management Agency, 2003, Flood insurance study, Will County, Illinois, and incorporated areas: 

Flood Insurance Study Number 17197CV001A 

[variously paginated].

Federal Emergency Management Agency, 2008, Illinois severe 

storms and flooding—FEMA–1800–DR, Illinois: accessed 

January 28, 2013, at http://www.fema.gov/pdf/news/

pda/1800.pdf.

Hirsch, R.M., 1979, An evaluation of some record reconstruction techniques: Water Resources Research, v. 18, no. 4, 

p. 1081–1088.

Illinois State Geological Survey, 2013, Physiographic divisions of Illinois: accessed February 12, 2013, at http://www.

isgs.illinois.edu/maps-data-pub/publications/physio.shtml.

National Geodetic Survey, 2013, VERTCON-North American Vertical Datum Conversion: accessed July 31, 2013, at 

http://www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html.

Ormsby, Tim; Napoleon, E.J.; Burke, Robert; Groessl, Carolyn; and Bowden, Laura, 2010, Getting to know ArcGIS 

Desktop: Redlands, California, ESRI Press, 604 p. 

U.S. Census Bureau, 2013, Will County QuickFacts: accessed 

January 28, 2013, at http://quickfacts.census.gov/qfd/

states/17/17197.html.

U.S. Army Corps of Engineers, Hydrologic Engineering Center, 1991, HEC-2 Water surface profiles—User’s manual: 

334 p.

U.S. Geological Survey, 2013a, National Water Information System—Web Interface, USGS 05540500 DuPage 

River at Shorewood, IL: accessed January 28, 2013, 

at http://waterdata.usgs.gov/nwis/nwismap/?site_

no=05540500&agency_cd=USGS.

U.S. Geological Survey, 2013b, National Water Information System—Web Interface, USGS 05540290 DuPage 

River near Plainfield, IL: accessed January 28, 2013, 

at http://waterdata.usgs.gov/nwis/nwismap/?site_

no=05540290&agency_cd=USGS.

U.S. Geological Survey, 2013c, Illinois Streamstats: 

accessed January 31, 2013, at http://streamstats.usgs.gov/

illinois.html.

Glossary

Annual exceedance probability The annual exceedance probability is the probability, or chance, of a flood of a given streamflow 

magnitude being equaled or exceeded in any given year. As an 

example, a 1-percent annual exceedance probability flood has a 

1-percent chance of being equaled or exceeded in any single year. A 

1-percent annual exceedance probability flood is also referred to as 

a 100-year flood.

DEM A Digital Elevation Model (DEM) is a digital file consisting of 

terrain elevations for ground positions at regularly spaced horizontal intervals.

Depth grid A digital file consisting of the mathematical difference 

between the water-elevation surface and ground-elevation surface 

for ground positions at regularly spaced horizontal intervals.

Gage height Gage height is the term used by the USGS National 

Water Information System display to describe the height of water 

above the datum at a streamgage. It is synonymous with stage.

Inundation surface The mathematical difference between the waterand ground-elevation surface results in the inundation surface, 

which represents the area covered by water.

Rating curve A rating curve is the relation between stage and discharge at a cross section in a river. 

Stage Stage is the term used by the National Weather Service to

describe the height of water above the datum at a streamgage. It is 

synonymous with gage height. 

Water-surface elevation Water-surface elevation at a streamgage is 

determined by adding the gage height of the water to the datum for 

the streamgage. 

Water-surface profile A water-surface profile shows how the elevation of a river changes along its centerline.

Murphy and Sharpe—Flood-Inundation Maps for the DuPage River from Plainfield to Shorewood, Illinois, 2013 —Scientific Investigations Map 3275

ISSN 2329-132X

http://dx.doi.org/10.3133/sim3275