Prepared in cooperation with Green Oak and Hamburg Townships, Michigan and 

the U.S. Army Corps of Engineers

Hydraulic Modeling and Flood-Inundation Mapping for the 

Huron River and Ore Lake Tributary, Livingston County, 

Michigan

Scientific Investigations Report 2018–5048

U.S. Department of the Interior

U.S. Geological Survey
Front cover, Huron River near Hamburg, Michigan U.S. Geological Survey streamgage station number

04172000. Photograph by Julia Prokopec, September 2015.
Hydraulic Modeling and Flood-Inundation 

Mapping for the Huron River and Ore Lake 

Tributary, Livingston County, Michigan

By Julia G. Prokopec

Prepared in cooperation with Green Oak and Hamburg Townships, Michigan and 

the U.S. Army Corps of Engineers

Scientific Investigations Report 2018–5048

U.S. Department of the Interior

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

RYAN K. ZINKE, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018

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

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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:

Prokopec, J.G., 2018, Hydraulic modeling and flood-inundation mapping for the Huron River and Ore Lake Tributary, 

Livingston County, Michigan: U.S. Geological Survey Scientific Investigations Report 2018–5048, 13 p., https://doi.

org/10.3133/sir20185048.

ISSN 2328-0328 (online)
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 streamgages throughout the country. 

We especially thank Hamburg Township for their support of the streamgage referred to in 

this report. Special thanks go to Green Oak Township, Hamburg Township, and the U.S. Army 

Corps of Engineers for the support of this project. Special thanks also are given to the National 

Weather Service for their continued support of the U.S. Geological Society flood-inundation 

mapping program.

v

Contents

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

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

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

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

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

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

Creation of Flood-Inundation-Map Library ...............................................................................................4

Computation of Water-Surface Profiles ...........................................................................................4

Hydrologic Data ...........................................................................................................................4

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

Hydraulic Structures ..................................................................................................................6

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

Hydraulic Model ..........................................................................................................................7

Model Calibration .......................................................................................................................7

Development of Water-Surface Profiles .................................................................................9

Development of Flood-Inundation Maps .........................................................................................9

Flood-Inundation Map Delivery ..............................................................................................10

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

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

Summary .......................................................................................................................................................12

References Cited .........................................................................................................................................12

Figures

 1. Graphs showing 
vi

Tables

 1. Information for U.S. Geological Survey Huron River near Hamburg, Michigan 
vii

Abbreviations and Acronyms

Abbreviation or acronym Definition

AHPS Advance Hydrologic Prediction Service

DEM Digital elevation model

FIS Flood insurance study

HEC–RAS Hydrologic Engineering Center River Analysis System

lidar Light detection and ranging 

NAD 83 North American Datum of 1983

NAVD 88 North American Vertical Datum of 1988

NWS National Weather Service

RTK Realtime kinematic

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

Conversion Factors

U.S. customary units to International System of Units

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)

Datum

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

established at a streamgage, and (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).

Hydraulic Modeling and Flood-Inundation Mapping for the 

Huron River and Ore Lake Tributary, Livingston County, 

Michigan

By Julia G. Prokopec

Abstract

Digital flood-inundation maps for an 8-mile (mi) reach 

of the Huron River near Hamburg, Michigan (station number 

04172000), from downstream of Rickett Road to Strawberry 

Lake, were created by the U.S. Geological Survey (USGS), 

in cooperation with Green Oak and Hamburg Townships, 

Michigan, and the U.S. Army Corps of Engineers. The floodinundation maps also include a 1.16-mi reach of the Ore Lake 

Tributary until it joins the Huron River, approximately 2.22 mi 

downstream of Rickett Road. The flood-inundation maps, 

which can be accessed through the USGS Flood Inundation 

Mapping Science website 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 on the Huron River near Hamburg, 

Michigan (station number 04172000). Near real-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 at http:/water.weather.gov/

ahps/. The NWS Advanced Hydrologic Prediction Service also 

provides forecasted flood hydrographs at this website. 

Flood profiles were computed for the stream reach by 

means of a one-dimensional step-backwater model. The 

hydraulic model was calibrated by using the current stagedischarge relation at the Huron River near Hamburg, Mich., 

streamgage and was calibrated to water levels determined with 

stage sensors (pressure transducers) temporarily deployed 

along the stream reach. The hydraulic model was used to 

compute a set of water-surface profiles for flood stages ranging 

from 7.0 to 10.5 feet (ft). This range represents stages just 

above 6.0 (bankfull) to 2.04 ft above the maximum recorded 

stage at the USGS streamgage on the Huron River near 

Hamburg, Mich. (station number 04172000). The computed 

water-surface profiles were then combined with a Geographic 

Information System digital elevation model (derived from 

light detection and ranging [lidar] data having a 0.49-ft 

vertical accuracy and 3.8-ft horizontal resolution) to delineate 

the area flooded at each water level. 

The availability of these maps, along with Internet 

information regarding current stage and forecasted high-flow 

stages from the NWS, will provide emergency management 

personnel and residents with information critical for floodresponse activities such as evacuations, road closures, and 

postflood recovery efforts.

Introduction

Green Oak and Hamburg Townships in Livingston County, 

Michigan, are small communities with estimated populations 

of 17,476 and 21,165, respectively (U.S. Bureau of Census, 

2010a and b). An upward trend in discharge and water levels 

has resulted in more frequent flooding from the Huron River 

in Green Oak and Hamburg Townships, as indicated by the 

time series of annual peak water levels at U.S. Geological 

Survey’s (USGS) streamgage 04172000 Huron River near 

Hamburg, Mich. (fig. 1). Flood-mitigation efforts after the 

2004 flood event have included removal of aquatic vegetation 

starting at USGS streamgage on Hamburg Road and continuing 

downstream towards Strawberry Lake. Growth of aquatic 

vegetation, mainly eelgrass, can cause backwater conditions on 

the Huron River. With backwater conditions, heavy rains during 

the growing season can lead to increased flooding (Hamburg 

Township, 2014). 

Prior to this study, emergency responders in Hamburg 

Township relied on several information sources (all of 

which are available on the Internet) to make decisions on 

how to best alert the public regarding flood conditions 

and mitigate flood damages. One source is the Federal 

Emergency Management Agency’s flood insurance study 

(FIS) for Hamburg Township, dated 2008 (Federal Emergency 

Management Agency, 2008). A second source is the USGS 

streamgage, Huron River near Hamburg, Mich. (04172000), 

from which current (U.S. Geological Survey, 2016a) and 

historical (since October 1951; U.S. Geological Survey, 2016b) 

water levels and discharges, including annual peak flows, can 

be obtained. A third source is the National Weather Service 

(NWS) Advanced Hydrologic Prediction Service (AHPS), 

which displays stage data and forecasts possible stages at 

the USGS Huron River near Hamburg, Mich., streamgage 

(04172000) (National Weather Service, 2016a). Throughout 

this report, the USGS streamgage Huron River near Hamburg, 

Mich., (04172000) will be referred to as the Huron River 

streamgage.
2 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

1950 1960 1970 1980 1990 2000 2010

400

600

800

1,000

1,200

1,400

1,600

1950 1960 1970 1980 1990 2000 2010

5

6

7

8

Water Year

Discharge,

in cubic feet per second

Stage,

in feet above gage datum

A

B

Figure 1. A, Time series of peak annual flows (discharge, in 

cubic feet per second) and B, associated water levels (feet), 

including National Weather Service major flood stage (red dashed 

line), showing increasing trend in median annual peak discharges 

and peak water levels at the U.S. Geological Survey Huron River 

near Hamburg, Michigan streamgage (04172000). 

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 further upstream or 

downstream given 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 depth and areal extent 

of flooding at points distant from the streamgage. One way 

to address these informational gaps is to produce a library of 

flood-inundation maps referenced to the various stages recorded 

at a specific USGS streamgage. By referring to the appropriate 

map, emergency responders can discern the severity of flooding 

(depth of water and areal 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 of a specified 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 

2015, the USGS, in cooperation with Green Oak and Hamburg 

Townships and the U.S. Army Corps of Engineers (USACE), 

conducted a project to produce a library of flood-inundation 

maps for a segment of the Huron River near Hamburg, Mich., 

and one of its tributaries, Ore Lake.

Purpose and Scope

The purpose of this report is to provide a library of 

estimated flood-inundation maps for portions of Green Oak 

and Hamburg Townships, in Livingston County, Mich., 

adjacent to an 8-mile (mi) reach of the Huron River and its 

tributary, Ore Lake (fig. 2). The maps were produced for 

flood levels referenced to the stage recorded at the USGS 

streamgage on the Huron River near Hamburg (table 1); 

the gage is located on Hamburg Road Bridge in the middle 

of the study reach, approximately 0.5 mi downstream from 

the Ore Lake Tributary confluence to the Huron River. The 

maps cover a range of stages at 0.5 ft increments from 7.0 ft 

to 10.5 ft. The 6.0-ft stage is approximately bankfull for the 

Huron River near Hamburg, Michigan, and is defined by the 

NWS (2016b) as the “action stage” or that stage which, when 

reached by a rising stream, requires the NWS or a partner to 

take some type of mitigation action in preparation for possible 

significant hydrologic activity. The 7.5-ft stage is defined 

by the NWS (2016b) as the “major flooding” or that stage 

which is characterized by extensive inundation and usually 

the evacuation of people and closure of both primary and 

secondary roads. The 10.5-ft stage exceeds the maximum 

recorded peak stage by 2.04 ft (table 1). 

The map library identifies areas likely to be flooded 

throughout a broad range of hydrologic conditions. Real-time 

streamflow data for the Huron River streamgage supports 

forecasts by the NWS that are used to guide the selection 

of flood-inundation maps. These flood-inundation maps, 

corresponding to stage or forecasted stage, are made freely 

available to the public through the Internet. 

Study Area Description

Green Oak and Hamburg Townships are in the lower 

peninsula of Michigan about 25 mi northwest of Ann Arbor, 

Mich. (fig. 2). Green Oak and Hamburg Townships are in the 

southeastern corner of Livingston County. The Huron River is 

the largest river in Livingston County.

The study reach covers approximately 8 miles of the 

Huron River from downstream of Rickett Road to Strawberry 

Lake. The area also includes Ore Lake and Little Ore Lake 

tributary (herein referred to as Ore Lake Tributary) which 

is confluent with the Huron River approximately 0.5 mi 

upstream the Huron River streamgage. The study reach is 

traversed by five bridges: Riverside Drive, Hamburg Road, 

West Michigan 36, Lakelands Trail State Park pedestrian 

bridge, and a railroad bridge. The drainage area of the Huron 

River and Ore Lake Tributary at the downstream extent of the 

study reach is 355 square miles. Within the study limits of this 

project, the drainage area is mostly residential, public lands, 

conserved open space, and undeveloped lands (Hamburg 

Township, 2011).
Introduction 3

Ore Lake

Strawberry Lake

Zukey Lake

Winans Lake

Gut Lake

Hamburg Lake

Oneida Lake

Buck Lake

Maltby Lake

Gallagher Lake

Whitmore Lake

-83°50' -83°48' -83°46'

42°29'

42°28'

42°27'

42°26'

HAMBURG TOWNSHIP

GREEN OAK TOWNSHIP

WASHTENAW COUNTY

LIVINGSTON COUNTY

Huron River

MICHIGAN

LIVINGSTON

COUNTY

04172000

EXPLANATION

River

Flow

Study reach

Water body

County

Township

Stage sensors

Measurement and stage sensors

U.S. Geological Survey streamgage 04172000

Huron River near Hamburg, MI

#

#

#

0 0.75 1.5 MILES

0 0.75 1.5 KILOMETERS

Map image is the intellectual property of Esri and

isused herein under license. Copyright © 2014 Esri and 

its licensors. All rights reserved.

Universal Transverse Mercator, projection, zone 17

North American Datum 1983

Figure 2. The location of Huron River and Ore Lake tributary study reaches, stage sensor and discrete measurement of discharge 

locations, and the location of the U.S. Geological Survey Huron River near Hamburg, Michigan streamgage (04172000).
4 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

Table 1. Information for U.S. Geological Survey Huron River near 

Hamburg, Michigan streamgage (04172000).

[Station location is shown in figure 1. mi2, square miles; ft3/s, cubic feet per 

second; NAVD 88, North American Vertical Datum of 1988]

Station name

Huron River 

near Hamburg, 

Mich.

Station number 04172000

Drainage area (mi2) 308

Latitude 42° 27'55"

Longitude 83°47'59"

Period of peak-flow record (water years1) 1952–2016

Maximum recorded stage, in feet, gage datum 

(and elevation, in feet above NAVD 88) 

and date

8.46

(858.13) 

June 30, 1968

Maximum discharge, in ft3/s, 

and date

1,560

May 15, 1956

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.

Previous Studies

The most recent FIS for Livingston County, Michigan 

was published in 2008 (Federal Emergency Management 

Agency, 2008). The 2008 report updated the 1984 FIS for 

Green Oak Township (Federal Emergency Management 

Agency, 1984) and the 1986 FIS for Hamburg Township 

(Federal Emergency Management Agency, 1986). The 

previous flood elevations were based upon hydraulic data and 

hydrologic analyses completed in July 1983 for Green Oak 

Township and May 1985 for Hamburg Township. The 2008 

FIS update redelineated flood-plain boundaries based on more 

detailed topographic information made available after the 

1983 and 1985 studies. The 2008 FIS did not include updated 

hydrology or hydraulics in the study area, only a redelineation 

of the flood-plain boundaries on the updated topography.

Creation of Flood-Inundation-Map 

Library

The USGS has standardized the procedures for creating 

flood-inundation maps for flood-prone communities (U.S. 

Geological Survey, 2016c) so that the process followed 

and products produced are similar regardless of which 

USGS office is responsible for the work. Tasks specific to 

development of the flood maps for Green Oak and Hamburg 

Townships, Mich., were the (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 and flow 

expansion and contraction loss coefficients) in the stream 

channel and flood plain and determination of steady-floodflow rates used in hydraulic computations, (3) computation 

of water-surface profiles using the USACE Hydrologic 

Engineering Center-River Analysis System (HEC–RAS) 

computer program (U.S. Army Corps of Engineers, 2010), 

(4) production of estimated flood-inundation maps at various 

stream stages using the USACE HEC–GeoRAS computer 

program (U.S. Army Corps of Engineers, 2009) and 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 floodwaters, for display on a USGS floodinundation 

mapping application.

Computation of Water-Surface Profiles

The water-surface profiles used to produce the eight 

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 steady-state 

(gradually varied) or unsteady-state flow computation options. 

Hydrologic Data

The study reach includes one streamgage (Huron 

River streamgage; fig. 2; table 1) that has been in operation 

since October 1951. Stage is measured every 15 minutes, 

transmitted hourly by a satellite radio in the streamgage, and 

made available on the Internet through the USGS National 

Water Information System (NWIS; U.S. Geological Survey, 

2016b). Stage data from this streamgage are referenced 

to North American Vertical Datum of 1988 (NAVD 88). 

Continuous records of streamflow are computed from a 

stage-discharge relation specific to the gaging station and are 

available through the USGS NWIS website. The study reach 

included six temporary stage sensors (pressure transducers) 

that collected stage data in 15-minute intervals. 

For the Huron River streamgage, the stage-discharge 

relation (rating) was used to determine the flow for the study 

reach corresponding to the target stage value (base rating 

number 5.0, effective 1999) (table 2). Summer months, 

from approximately May to September, have higher watersurface elevations compared to the winter months for the 

same discharge value. Aquatic vegetation contributes to the 

higher water-surface elevations during the warmer months, 

because the vegetation can cause backwater conditions along 

the Huron River thus raising water stages and causing a shift 

in the rating (fig. 3). Peak flows from the May 25, 2004, 

flood were used in the final model simulations, to which a 

-2.0 ft shift was applied due to dense aquatic vegetation in the 

channel. The base rating number 5.0, which covers water level 

ranges from 2.81 ft to 9.21 ft, was extended to include higher 

stages by use of a straight-line extension of log-log plot. 
Creation of Flood-Inundation-Map Library 5

50 100 200 500 1000 2000

4

6

8

10

12

Discharge, in cubic feet per second

Jan.

Feb.

Mar.

Dec.

Apr.

Nov.

May

Oct.

June

Sept.

July

Aug.

Regression curves shown as lines, data points as symbols.

Base Rating 5

Water level, in feet above gage datum

EXPLANATION

Figure 3. Seasonal relation between stage and discharge measurements, without ice-affected measurements, at the Huron River near 

Hamburg, Michigan (04172000), from base rating 5, after January 1999.

An average percent contribution of streamflow from discrete 

discharge measurements at USGS 04171800 Little Ore Lake 

Outlet near Hamburg, Mich., to the Huron River was used 

to determine the streamflow of Ore Lake Tributary and the 

upstream portion of the Huron River’s (table 3). 

Topographic and Bathymetric Data

All overbank topographic and channel bathymetry data 

used in this study are referenced vertically to NAVD 88 and 

horizontally to the North American Datum of 1983 (NAD 

83). Cross-section elevation data were obtained from a digital 

elevation model (DEM) that was derived from light detection 

and ranging (lidar) data collected March 2010 by Woolpert, 

Inc., Dayton, Ohio (Woolpert, 2010). Postprocessing of these 

data was completed by Woolpert, Inc. on April 2010, and 

the final DEM was provided to the USGS by the Livingston 

County GIS Department. The lidar data have horizontal 

resolution of 3.8 ft (1.16 meters) and vertical accuracy of 

0.49 ft (0.15 meters) at a 95 percent confidence interval for the 

open terrain landcover category. 

Through the use of HEC–GeoRAS, which utilizes a set 

of procedures, tools, and utilities for processing geospatial 

data in ArcGIS, elevation data were extracted from the DEM 

for 112 cross sections and subsequently were input to the 

HEC–RAS model. Because lidar data cannot provide ground 

elevations below a stream’s water surface, select channel 

cross sections were surveyed by USGS personnel during 

September 2014. Crosssectional depths were measured by 

wading at 23 locations, including upstream and downstream 

from all hydraulic structures. A differential global positioning 

system 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 at two benchmark locations were within 0.03–0.11 ft 

of the known elevations, an error range that is less than the 

uncertainty of the lidar data. 

DEM-generated cross sections coincide with all locations 

where channel cross sections were obtained during the field 

surveys. 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. The average distance 

between field-surveyed cross sections along the Huron River 

channel and Ore Lake Tributary were 1,660 ft and 743 ft, 

respectively, for a total average distance of 1,400 ft. 
6 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

Table 2. Estimated discharges corresponding to stage and water-surface elevations at select locations. 

[Locations shown in figure 1. ft, feet; NAVD 88, North American Vertical Datum of 1988]

Stage of watersurface profile

(ft)1

Water-surface

elevation 

(ft, NAVD 88)

Estimated discharge at indicated location, 

in cubic feet per second

Upstream from confluence 

with Ore Lake Tributary Ore Lake Tributary Downstream end of study reach

7.0 856.67 384 64 448

7.5 857.17 486 81 567

8.0 857.67 603 101 704

8.5 858.17 755 126 881

9.0 858.67 926 154 1,080

9.5 859.17 1,116 186 1,302

10.0 859.67 1,325 221 1,546

10.5 860.17 1,553 259 1,812

Stage of watersurface profile

(ft)1

Water-surface

elevation 

(ft, NAVD 88)

Estimated discharge at indicated location,

in cubic feet per second

Huron River from Rickett 

Road to Ore Lake 

Tributary confluence 

Little Ore Lake Outlet 

near Hamburg, Mich. 

(USGS 04171800)

Huron River near 

Hamburg, Mich. 

(USGS 04172000)

7.0 856.67 384 64 448

7.5 857.17 486 81 567

8.0 857.67 603 101 704

8.5 858.17 755 126 881

9.0 858.67 926 154 1,080

9.5 859.17 1,116 186 1,302

10.0 859.67 1,325 221 1,546

10.5 860.17 1,553 259 1,812

1

Water-surface profiles are 0.50-foot increments of stage, referenced to the gage datum of the U.S. Geological Survey streamgage, Huron River near Hamburg, 

Michigan (station number 04172000).

Hydraulic Structures

Along the study reach, five structures—consisting 

of three road crossings (Riverside Drive, Hamburg Road, 

County Road West Michigan 36), the Lakelands Trail State 

Park pedestrian bridge, and a railroad bridge—have the 

potential to affect water-surface elevations during high-flow 

conditions. Structure-geometry data were obtained from 

field surveys by USGS personnel who used RTK surveying 

techniques. Structure geometry and loss coefficients were 

input to the hydraulic model and water-surface profiles were 

computed seamlessly with the channel cross-section data in 

HEC–RAS.

Energy-Loss Factors

Hydraulic analyses require the estimation of energy 

losses that result from frictional resistance exerted by a 

channel on flow or losses associated with flow expansion 

and contraction. These frictional energy losses are quantified 

by the Manning’s roughness coefficient (“n” value). Initial 

(precalibration) n values were selected by comparing field 

observations with information from the May 25, 2004, 

Declaration of Disaster (Hamburg Township, 2014) (which 

details flooded areas related to stage at the Huron River 

streamgage). An initial n value of 0.030 was selected for the 

area of the Huron River with a wider, low-gradient, main 

channel, a silty bed and tree-lined banks. This section is 

between Rickett Road to the Huron River streamgage. An 

initial n value of 0.095 was selected for a section of the Huron 

River that contains dense invasive aquatic vegetation. Forested 

and residential areas cover wide swaths of land on both banks 

and flood plains adjacent to the Ore Lake Tributary and the 

Huron River. A composite n value (0.06) that is thought to 

represent the diverse energy-loss factors of these land types 

was used for the initial estimate of the flood plain n value.
Creation of Flood-Inundation-Map Library 7

Table 3. Measured discharges for specific dates at U.S. Geological Survey streamgages 04171800, Little Ore Lake Outlet near 

Hamburg, Michigan, and 04172000, Huron River near Hamburg, Michigan, and estimated discharge for specific dates at the Huron River 

upstream of the Ore Lake Tributary. 

[Locations are shown in figure 1. Date in month/day/year; USGS, U.S. Geological Survey; EST, eastern standard time; ft3/s, cubic feet per second]

Date and time

Streamflow (ft3/s) Little Ore Lake 

Outlet near Hamburg, Mich. 

(USGS 04171800)

Streamflow (ft3/s) Huron River 

near Hamburg, Mich. 

(USGS 04172000)

Estimated streamflow (ft3/s) 

from Rickett Road to 

Ore Lake Tributary

7/9/2015 09:30 EST 27.0 184 157

7/24/2015 10:30 EST 19.0 137 118

8/12/2015 12:15 EST 28.2 172 144

8/26/2015 10:00 EST 13.5 93 79.5

9/16/2015 10:00 EST 12.0 80 92

Date and time

Estimated streamflow (ft3/s) of 

the Huron River from Rickett 

Road to Ore Lake Tributary 

confluence

Streamflow (ft3/s) Little Ore Lake 

Outlet near Hamburg, Mich. 

(USGS 04171800)

Streamflow (ft3/s) Huron River 

near Hamburg, Mich. 

(USGS 04172000)

7/9/2015 09:30 EST 157 27.0 184

7/24/2015 10:30 EST 118 19.0 137

8/12/2015 12:15 EST 144 28.2 172

8/26/2015 10:00 EST 79.5 13.5 93

9/16/2015 10:00 EST 92 12.0 80

As part of the calibration process, the initial n values 

were varied by flow and aquatic vegetation growing season 

and adjusted until the differences between simulated and 

observed water-surface elevations at the streamgage and 

stream sensors were minimized. Final n values ranged from 

0.035 to 0.095 for the main channel of the Huron River 

to represent the aquatic growing season, and 0.06 for the 

overbank areas (fig. 4).

Hydraulic Model

The HEC–RAS analysis for this study included two 

stream reaches, the Huron River and Ore Lake Tributary, 

and was based on a one-dimensional, steady-state flow 

computation that included a junction where the two stream 

reaches meet. Steady-state flow data consisted of flow regime, 

boundary conditions, and peak flows that produced watersurface elevations at the streamgage cross section that matched 

target water-surface elevations within 0.75 ft. Target elevations 

coincided with 0.5-ft increments of stage, referenced to the 

Huron River streamgage datum. Subcritical (tranquil) flow 

regime was assumed for the simulations. Normal depth, based 

on an estimated average water-surface slope of 0.000052, 

was used as the Huron River reach’s downstream boundary 

condition to accommodate possible backwater flow at the 

end of the study reach from the inlet of Strawberry Lake. 

The calculated water-surface slope between the last two 

downstream stage sensors on the Huron River was 0.00027 ft, 

which caused an abrupt decrease in water-surface elevations 

at the downstream boundary of the model. A water-surface 

slope of 0.000052 ft minimized differences between modeled 

and observed values over the Huron River study reach, which 

provided internal consistency in the model. Peak flows used in 

the model are discussed in the section “Hydrologic Data.”

Ore Lake Tributary is subject to backwater conditions 

from the Huron River. To account for concurrent flooding 

from the tributary, the hydraulic model joined the two streams 

together by means of a junction. As a result, the model used 

water-surface elevations from the Huron River as downstream 

boundary conditions for the Ore Lake Tributary. 

Model Calibration

The HEC–RAS model was calibrated by varying n

values to improve the match between measured and simulated 

flows and water levels. Measured flows and water levels used 

the current (base rating 5.0, effective 1999) stage-discharge 

relation at the Huron River streamgage. Six stage sensors 

(pressure transducers) were installed at separate locations 

along the modeled reaches of the stream and tributary in May 

2015, providing additional water-level data for calibration 

(fig. 2). RTK surveys were conducted to establish the vertical 

datum of each stage sensor relative to NAVD 88. The stage 

sensors were checked, data were downloaded, and sensors 

were cleaned three times during their 6-month deployment. 

The stage sensors were removed in November 2015.
8 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

#

83°50'W 83°49'W 83°48'W 83°47'W 83°46'W

42°29'N

42°28'N

42°27'N

0 0.5 1 2 MILES

0 0.5 1 2 KILOMETERS

EXPLANATION

Manning's n of 0.035

Manning's n of 0.040

Manning's n of 0.047

Manning's n of 0.095

Study reach boundaries

# U.S. Geological Survey 04172000 Huron River

near Hamburg, MI

Map image is the intellectual property of Esri and

isused herein under license. Copyright © 2014 Esri and 

its licensors. All rights reserved.

Universal Transverse Mercator, projection, zone 17

North American Datum 1983

Figure 4. Locations of varying Manning’s n values for the Huron River near Hamburg, Michigan (04172000) within the modeled study 

reach. 

Stages measured during this period were low to 

moderate, ranging from 3.54 to 6.21 ft at the Huron River 

streamgage. The streamflow value used to calibrate the HEC–

RAS model for aquatic growing season months was 137 cubic 

feet per second for the Huron River Streamgage on July 24, 

2015, and was obtained from base rating 5 from the Huron 

River streamgage, with a -2.0 ft shift to account for aquatic 

vegetation at the streamgage. Flows from July 24, 2015, 

were used because of ideal/worst case scenario backwater 

conditions that were best fit for model calibration due to 

high water surface elevations during peak aquatic vegetation 

growth. After calibration, the modeled elevations from sensors 

and the measured elevation from the streamgage on July 24, 

2015, had a root mean square error of 0.68 ft, with a maximum 

difference of -0.89 ft (table 4). 

Discrete discharge measurements were made monthly 

from July 2015 to September 2015 at three locations along 

Ore Lake Tributary (fig. 2) during periods when flow varied 

from 81 to 184 cubic feet per second at the Huron River 

streamgage. The flow measurements were used to modeled 

streamflow on the Huron River upstream from Ore Lake 

Tributary and for Ore Lake Tributary. 

The model was calibrated by adjusting Manning’s n

values until the results of the hydraulic computations closely 

agreed with the measured water-surface elevations for given 

flows. Differences between observed and simulated watersurface elevations for eight simulated flows at the Huron River 

streamgage were equal to or less than 0.16 ft (table 5). The 

results demonstrate that the model is capable of simulating 

accurate water levels over a wide range of flows in the basin. 
Creation of Flood-Inundation-Map Library 9

Table 4. Comparison of modeled and measured water-surface elevations on July 24, 2015, at selected locations along the Huron River 

and Ore Lake Tributary during a high-water period due to aquatic growth.

[USGS, U.S. Geological Survey; ft, feet; NAVD 88, North American Vertical Datum of 1988]

USGS station name 

and number Description

River 

station1

(ft)

Target watersurface 

elevation 

(ft, NAVD 88)

Modeled

water-surface

elevation 

(ft, NAVD 88)

Difference

in elevation

(ft)

Ore Lake Tributary

Dibrova Lake outlet at Mohican Dr near 

Hamburg, Mich.

(04171022)

Stage sensor 6,659 855.26 854.70 -0.56

Little Ore Lake outlet near Hamburg, Mich.

(04171800)

Stage sensor 339 855.06 854.54 -0.52

Huron River

Huron R 1,200 feet downstream from 

Rickett Rd. near Hamburg, Mich.

(04171022)

Stage sensor 30,268 856.24 855.56 -0.68

Huron River downstream of Little Ore 

Lake outlet near Hamburg, Mich.

(04171900)

Stage sensor 18,085 855.14 854.54 -0.60

Huron River near Hamburg, Mich.

(04172000)

Streamgage 16,307 855.20 854.31 -0.89

Huron River 2,300 feet Highway M-36 

near Hamburg, Mich. 

(04172004)

Stage sensor 9,562 854.06 853.34 -0.72

Huron River immediately upstream of 

Strawberry Lake near Hamburg, Mich.

(04171703)

Stage sensor 30 851.48 850.47 -0.75

1

River stations are referenced to the longitudinal baseline used in the hydraulic model, referenced to the mouth.

Table 5. Comparison of modeled and measured water-surface 

elevations at the U.S. Geological Survey streamgage on Huron 

River near Hamburg, Michigan (station number 04172000).

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

Stage of 

water-surface 

profile 

(ft)

Observed

water-surface

elevation 

(ft, NAVD 88)

Modeled

water-surface

elevation 

(ft, NAVD 88)

Difference

in elevation

(ft)

7.0 856.67 856.51 -0.16

7.5 857.17 857.02 -0.15

 8.0 857.67 857.53 -0.14

8.5 858.17 858.09 -0.08

9.0 858.67 858.64 -0.03

9.5 859.17 859.19 0.02

10.0 859.67 859.73 0.06

10.5 860.17 860.27 0.10

Development of Water-Surface Profiles

The calibrated hydraulic model was used to generate 

water-surface profiles for eight target stages at 0.50-ft intervals 

between 7.0 ft and 10.5 ft as referenced to the gage datum 

of the Huron River streamgage. These stages correspond to 

water-surface elevations of 856.67 ft and 860.17 ft, NAVD 88, 

respectively. Discharges corresponding to the various stages 

were obtained from the current stage-discharge relation (rating 

number 5) for the Huron River streamgage by using a -2.0 ft 

shift due to aquatic vegetation. Discharges through the study 

reach were adjusted, as necessary, for tributary inflow as 

shown in table 3.

Development of Flood-Inundation Maps

Flood-inundation maps were created for the flood 

plain formed along Ore Lake Tributary and the 8-mi reach 

of the Huron River streamgage, which has been designated 
10 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

as a NWS flood-forecast point. Flood-inundation maps 

were created using GIS for the eight water-surface profiles 

by combining the profiles created through HEC–RAS and 

HEC–GeoRAS and DEM data. The DEM data were derived 

from the same lidar data described previously in the section 

“Topographic and Bathymetric Data.” Estimated floodinundation boundaries for each simulated profile were 

developed with HEC–GeoRAS software (U.S. Army Corps of 

Engineers, 2009), which 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). Shapefile polygons and depth grids of the 

inundated areas for each profile were modified, as required, 

in the ArcMap application of ArcGIS (Esri, 2014) to ensure 

a hydraulically reasonable transition of the flood boundaries 

between modeled cross sections. The datasets used in this 

study are available through a data release at https://doi.

org/10.5066/F79G5M11 (Prokopec, 2018). 

Any inundated areas that were detached from the main 

channel were examined to identify subsurface connections 

with the main river, such as through culverts under roadways. 

Where such connections existed, the mapped inundated areas 

were retained in their respective flood maps; otherwise, the 

erroneously delineated parts of the flood extent were deleted. 

The flood-inundation areas are overlaid on high-resolution, 

georeferenced, aerial photographs of the study area. Bridge 

surfaces are shown as noninundated 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 flood maps on an interactive USGS mapping application 

described in the following section “Flood-Inundation 

Map Delivery.” Indicated depths are limited by the spatial 

resolution of the DEM and may vary rapidly with time. Thus, 

actual depths could be significantly greater than indicated 

on the maps, and, in particular, should not be relied upon to 

assess the safety of travel. The flood map corresponding to the 

highest simulated water-surface profile, a stage of 10.5 ft, is 

presented in figure 5.

Flood-Inundation Map Delivery

A Flood Inundation Mapping Science website (U.S. 

Geological Survey, 2016c) was established to make USGS 

flood-inundation study information available to the public. The 

site links to a mapping application that presents map libraries 

and provides detailed information on flood extents and depths 

for modeled sites. The mapping application enables the 

production of customized flood-inundation maps from the map 

library for Huron River near Hamburg, Mich. A link on this 

website connects to the USGS NWIS (U.S. Geological Survey, 

2016a), which presents the current stage and streamflow for 

the USGS streamgage 04172000, the streamgage that the 

inundation maps are referenced to in this report. A second 

link connects to the NWS Advanced Hydrologic Prediction 

Service (AHPS) site (National Weather Service, 2016a) so 

that the user can obtain applicable information on forecasted 

peak stage. The estimated flood-inundation maps are displayed 

in sufficient detail so that preparations for flooding and 

decisions for emergency response can be performed efficiently. 

Depending on the flood magnitude, roadways are shown as 

shaded (inundated and likely impassable) or not shaded (dry 

and passable) to facilitate emergency planning and use. A 

shaded building should not be interpreted to mean that the 

structure is completely submerged; rather that bare earth 

surfaces near the building are inundated. In these instances, 

the water depth (as indicated in the mapping application by 

holding the cursor over an inundated area) near the building 

would be an estimate of the water level inside the structure, 

unless flood-proofing measures had been implemented.

Disclaimer for Flood-Inundation Maps 

The flood-inundation 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 

and streamflows at selected USGS stream gages. Watersurface 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 December 

2015. 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. 
Creation of Flood-Inundation-Map Library 11

#

83°50'W 83°49'W 83°48'W 83°47'W 83°46'W

42°29'N

42°28'N

42°27'N

EXPLANATION

Stage of 10.5 feet

Study Reach Boundaries

# U.S. Geological Survey 04172000

Huron River near

Hamburg, MI

0 0.5 1 2 MILES

0 0.5 1 2 KILOMETERS

Map image is the intellectual property of Esri and

isused herein under license. Copyright © 2014 Esri and 

its licensors. All rights reserved.

Universal Transverse Mercator, projection, zone 17

North American Datum 1983

Figure 5. Flood-inundation map for the Huron River near Hamburg, Michigan, corresponding to a stage of 10.5 feet at the U.S. 

Geological Survey streamgage (station number 04172000).

If this library 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, see: http://water.weather.gov/ahps/pcpn_and_river_

forecasting.pdf. 

An additional source of uncertainty is the modeled watersurface elevations and depth for overbank areas due to limited 

calibration data during study period. Additional uncertainties 

and limitations pertinent to this study may be described 

elsewhere in this report.
12 Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

Summary

The U.S. Geological Survey (USGS), in cooperation 

with Green Oak and Hamburg Townships, Michigan, and 

the U.S. Army Corps of Engineers, developed a library of 

digital flood-inundation maps for an 8-mile reach of the Huron 

River near Hamburg, Mich. (station number 04172000), from 

downstream of Rickett Road to Strawberry Lake, and Ore 

Lake Tributary, from Ore Lake and Little Ore Lake, until its 

confluence with the Huron River study reach. The maps were 

developed by using the U.S. Army Corps of Engineer’s HEC–

RAS and HEC–GeoRAS programs and Esri’s ArcGIS program 

to compute water-surface profiles and to delineate estimated 

flood-inundation areas and depths of flooding for selected 

stream stages. The HEC–RAS hydraulic model was calibrated 

to the current stage-discharge relation at the Huron River 

streamgage, and to water-level data measured with pressure 

transducers. The model was used to compute water-surface 

profiles at 0.5-foot (ft) increments for flood stages from 7.0 ft 

to 10.5 ft corresponding to above bankfull to 2.04 ft above the 

maximum recorded water level. 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. The flood maps are available through a 

mapping application that can be accessed on the USGS Flood 

Inundation Mapping Science website (http://wimcloud.usgs.

gov/apps/FIM/FloodInundationMapper.html).

Interactive use of the maps on this mapping application 

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 04172000 and forecasted 

flood stage data from the NWS Advanced Hydrologic 

Prediction Service 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 postflood recovery 

efforts.

References Cited

Esri, 2014, ArcGIS, accessed February 16, 2016, at http://

www.esri.com/software/arcgis/.

Federal Emergency Management Agency, 1984, Flood 

insurance study for the Township of Green Oak, Livingston 

County, Michigan; Washington, D.C., Flood Insurance 

Study Number 260440V000, Community Number 260440, 

22 p. 

Federal Emergency Management Agency, 1986, Flood 

insurance study for the Township of Hamburg, Livingston 

County, Michigan; Washington, D.C., Flood Insurance 

Study Number 260118V000, Community Number 260118, 

21 p.

Federal Emergency Management Agency, 2008, Flood 

insurance study, Livingston County, Michigan 

(All Jurisdictions), Flood Insurance Study Number 

26093CV000A, 90 p.

Hamburg Township, 2011, Master Plan, p. 27, accessed 

November 3, 2016, at http://www.hamburg.mi.us/

government/lawroom_(ordinances)_general_ordinances/

master_plan.php.

Hamburg Township, 2014, Flood Response Action Plan— 

NFIP Community #26011–Hamburg Township, Livingston 

County, Michigan: Hamburg Township report, 123 p., 

accessed December 15, 2015, at http://www.hamburg.mi.us/

government/lawroom_(ordinances)_general_ordinances/

flooding_response_action_plan.php. 

National Weather Service, 2016a, Advanced Hydrologic 

Prediction Service, Huron River at Hamburg, accessed 

October 3, 2016, at http://water.weather.gov/ahps2/

hydrograph.php?wfo=dtx&gage=hmgm4.

National Weather Service, 2016b, National Weather Service 

Glossary, accessed October 3, 2016, at http://w1.weather.

gov/glossary/index.php?word=action+stage.

Prokopec, J.G., 2018, Huron River near Hamburg, Michigan, 

flood-inundation model and field data: U.S. Geological 

Survey data release, accessed February 2018, at https://doi.

org/10.5066/F79G5M11.

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 Census, 2010a, QuickFactsPopulation, Census, 

April 1, 2010, Hamburg Township, Livingston County, 

Michigan. Accessed June 21, 2017, at https://www.census.

gov/quickfacts/table/PST045216/2609336100.

U.S. Bureau of Census, 2010b, QuickFacts Population, 

Census, April 1, 2010, Green Oak Township, 

Livingston County, Michigan. Accessed June 21, 

2017, at https://www.census.gov/quickfacts/fact/table/

greenoaktownshiplivingstoncountymichigan/PST045216.

U.S. Geological Survey, 2016a, USGS <04172000> Huron 

River near Hamburg, MI: U.S. Geological Survey, accessed 

October 3, 2016, at http://waterdata.usgs.gov/mi/nwis/

uv/?site_no=04172000.
References Cited 13

U.S. Geological Survey, 2016b, USGS surface-water data for 

the Nation: U.S. Geological Survey, accessed October 3, 

2016, at http://waterdata.usgs.gov/nwis/sw.

U.S. Geological Survey, 2016c, USGS Flood Inundation 

Mapping Science: U.S. Geological Survey, accessed 

October 4, 2016, at http://water.usgs.gov/osw/flood_

inundation.

Woolpert, Inc., 2010, 2010 ARRA Lidar: 4 Southeast Counties 

(MI)[metadata]: National Oceanic and Atmospheric 

Administration, Woolpert Order No. 70398, prepared 

by Woolpert, Inc., Geospatial Services [Dayton, Ohio], 

accessed January 31, 2018, at https://coast.noaa.gov/htdata/

lidar1_z/geoid12b/data/5019/mi2010_arra_4_county_se_

m5019_metadata.html.

For more information about this publication, contact

Director, Upper Midwest Water Science Center

U.S. Geological Survey

6520 Mercantile Way

Suite 5

Lansing, MI 48911 

For additional information visit https://mi.water.usgs.gov/.

Publishing support provided by the

Lafayette, Madison, and Pembroke Publishing Service Centers
Prokopec—Hydraulic Modeling and Flood-Inundation Mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan—SIR 2018–5048

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20185048