Hydrology and Flood Profi les of Duck Creek and 

Jordan Creek Downstream from Egan Drive, 

Juneau, Alaska

Scientifi c Investigations Report 2006–5323

Prepared in cooperation with the City and Borough of Juneau

U.S. Department of the Interior

U.S. Geological Survey
Cover: Photographs of channel and structures, Juneau, Alaska, from top to bottom: 

(1) Duck Creek at a private driveway upstream from Berners Avenue (photograph by 

Janet Curran, U.S. Geological Survey, September 24, 2004). (2) Unnamed Tributary 

to Duck Creek at North El Camino Street, and (3) Jordan Creek at a private driveway 

downstream from Jordan Avenue (photographs by Daniel Long, U.S. Geological Survey, 

March 27, 2005).
Hydrology and Flood Profiles of Duck Creek and 

Jordan Creek Downstream from Egan Drive, 

Juneau, Alaska

Janet H. Curran

Prepared in cooperation with the City and Borough of Juneau 

Scientific Investigations Report 2006–5323

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Curran, J.H., 2007, Hydrology and flood profiles of Duck Creek and Jordan Creek downstream from Egan Drive, 

Juneau, Alaska: U.S. Geological Survey Scientific Investigations Report 2006-5323, 35 p.
iii

Contents

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

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

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

Previous Studies ...................................................................................................................................2

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

Hydrology of Duck and Jordan Creeks ......................................................................................................5

Methods of Analysis......................................................................................................................................6

Hydrologic Analysis..............................................................................................................................6

Hydraulic Analysis................................................................................................................................8

Stream Network.........................................................................................................................11

Field Survey of Cross Sections and Hydraulic Structures..................................................11

LIDAR Elevation Data ................................................................................................................20

Channel Roughness (Manning’s n) .........................................................................................20

Starting Water-Surface Elevation...........................................................................................21

Calibration to Known Water-Surface Elevations..................................................................21

Flood Profiles................................................................................................................................................23

Inter-Basin Flow..................................................................................................................................23

Discussion............................................................................................................................................23

Summary........................................................................................................................................................30

References Cited..........................................................................................................................................30

Appendix A. Description of Temporary Benchmarks Placed for Survey, and 

Benchmarks Placed by Others and Used in Survey.................................................................33

Appendix B. Coordinates and Elevations for Surveyed Points, Duck and Jordan

Creeks, Alaska ................................................................................................................................35
iv

Figures

Figure 1. Map showing location of Duck and Jordan Creeks, Juneau, Alaska ............... 3

Figure 2. Map showing location of stream-gaging stations, bridges, and culverts along

Duck and Jordan Creeks, Juneau, Alaska................................................ 4

Figure 3. Photographs showing view of channel and structures along (A) Duck Creek 

at a private driveway upstream from Berners Avenue, (B) Unnamed Tributary 

to Duck Creek at North El Camino Street, and (C) Jordan Creek at a private 

driveway downstream from Jordan Avenue, Juneau, Alaska ........................ 5

Figure 4. Graph showing annual maximum instantaneous peak streamflow for Duck 

and Jordan Creeks, Juneau, Alaska ...................................................... 6

Figure 5. Map showing modeled stream center lines and general elevation data for 

Duck and Jordan Creeks, Juneau, Alaska................................................ 12

Figure 6. Maps showing locations of modeled and surveyed cross sections along (A-D) 

Duck Creek and (E-F) Jordan Creek, Juneau, Alaska ................................. 13

Figure 7. Graph showing profile of simulated water-surface elevations and measured 

water-surface elevations for flow in Duck and Jordan Creeks, Juneau, 

Alaska, November 21, 2005 ............................................................... 22

Figure 8. Grpahs showing flood profiles for Duck and Jordan Creeks, and unnamed 

tributary to Duck Creek, Juneau, Alaska ................................................ 24

Figure 9. Map showing modeled stream center lines, roads, general elevation data, 

and direction ofinter-basin flow for Duck and Jordan Creeks between Egan 

Drive and Glacier Highway in Juneau, Alaska .......................................... 29

Tables

Table 1. Annual maximum instantaneous peak streamflow for Duck and Jordan

Creeks, Juneau, Alaska..................................................................... 5

Table 2. Peak streamflow estimated from streamflow data and regional equations for

selected recurrence intervals, Duck and Jordan Creeks, Juneau, Alaska ......... 7

Table 3. Basin characteristics for Duck and Jordan Creeks, Juneau, Alaska ............... 8

Table 4. Measured streamflows and corresponding simulated streamflows using

drainage-area ratios, Duck Creek, Juneau, Alaska .................................... 9

Table 5. Streamflows used for hydraulic model, Duck and Jordan Creeks, Juneau, 

Alaska ....................................................................................... 10

Table 6. Index to cross section identifiers, Duck and Jordan Creeks, Juneau, Alaska ...... 19

Table 7. Range of Manning’s n for Duck and Jordan Creeks, Alaska ........................... 21

Table 8. Comparison of flood profiles at limits of study area to adjacent published

profiles, Duck and Jordan Creeks, Juneau, Alaska .................................... 30
Conversion Factors, Datums, and Abbreviations and 

Acronyms

Conversion Factors

Multiply By To obtain

cubic foot per second (ft3

/s) 0.02832 cubic meter per second

foot (ft) 0.3048 meter 

inch (in.) 2.54 centimeter

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer 

square mile (mi2

) 259.0 hectare

square mile (mi2

) 2.590 square kilometer

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8.

Datums

Vertical coordinate information is referenced to Mean Lower Low Water (MLLW).

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

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

Abbreviations and Acronyms

Abbreviations 

and Acronyms Meaning

AKDOTPF Alaska Department of Transportation and Public Facilities

CORS Continuously Operating Reference Stations

FEMA Federal Emergency Management Agency

FIS Flood Insurance Study

GPS Global Positioning System

HEC-RAS U.S. Army Corps of Engineers’ Hydrologic Engineering Center River Analysis System

LIDAR Light Detection and Ranging

NGS National Geodetic Survey

RTK Real-Time Kinetic

USGS U.S. Geological Survey
vi

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Hydrology and Flood Profiles of Duck Creek and Jordan 

Creek Downstream from Egan Drive, Juneau, Alaska

By Janet H. Curran

Abstract

Hydrologic and hydraulic updates for Duck Creek and 

the lower part of Jordan Creek in Juneau, Alaska, included 

computation of new estimates of peak streamflow magnitudes 

and new water-surface profiles for the 10-, 50-, 100-, and 

500-year floods. Computations for the 2-, 5-, 10-, 25-, 50-, 

100-, 200-, and 500-year recurrence interval flood magnitudes 

for both streams used data from U.S. Geological Survey 

stream-gaging stations weighted with regional regression 

equations for southeast Alaska. The study area for the 

hydraulic model consisted of three channels: Duck Creek from 

Taku Boulevard near the stream’s headwaters to Radcliffe 

Road near the end of the Juneau International Airport runway, 

an unnamed tributary to Duck Creek from Valley Boulevard 

to its confluence with Duck Creek, and Jordan Creek from a 

pedestrian bridge upstream from Egan Drive to Crest Street 

at Juneau International Airport. Field surveys throughout 

the study area provided channel geometry for 206 cross 

sections, and geometric and hydraulic characteristics for 29 

culverts and 15 roadway, driveway, or pedestrian bridges. 

Hydraulic modeling consisted of application of the U.S. Army 

Corps of Engineers’ Hydrologic Engineering Center River 

Analysis System (HEC-RAS) for steady-state flow at the 

selected recurrence intervals using an assumed high tide of 

20 feet and roughness coefficients refined by calibration to 

measured water-surface elevations from a 2- to 5-year flood 

that occurred on November 21, 2005. Model simulation results 

identify inter-basin flow from Jordan Creek to the southeast at 

Egan Drive and from Duck Creek to Jordan Creek downstream 

from Egan Drive at selected recurrence intervals.

Introduction

Duck and Jordan Creeks flow through a low-lying, urban 

to suburban environment in Juneau’s Mendenhall Valley, 

presenting flood hazards to traffic, structures, and properties. 

Flood plain mapping provides a means to mitigate and manage 

such flood hazards, but agencies must revise maps to reflect 

new data and natural or engineered environment changes. 

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

the City and Borough of Juneau, Alaska, began a study in 

2004 to update hydrologic and hydraulic analyses in support 

of flood plain mapping updates. This study took advantage 

of newly available streamflow data and assessed the present 

configuration of culverts and bridges.

The two streams flow several miles through the 

Mendenhall Valley, a broad, recently deglaciated valley, and 

continue another mile over a broad, low-lying plain before 

discharging into salt or brackish water near Fritz Cove. 

Duck Creek and the lower part of Jordan Creek lie within 

an urban to suburban environment, including residential and 

commercial properties and the Juneau International Airport. 

Culverts, road bridges, and pedestrian bridges cross the 

streams an average of every 600 ft in the study area. Flooding 

along both streams periodically overtops roadways and 

encroaches on streamside properties and structures. To manage 

and mitigate these flood hazards, the City and Borough of 

Juneau is participating in a process to revise flood plain maps 

for many local streams, including Duck and Jordan Creeks.

Many cities formalize flood plain mapping by 

participating in the Federal Emergency Management Agency 

National Flood Insurance Program. A Flood Insurance Study 

(FIS) documents an investigation of the extent of flooding 

expected during floods of various magnitudes. The most recent 

FIS for the City and Borough of Juneau, updated in 1990 

(Federal Emergency Management Agency, 1990), maps flood 

plain areas along Duck and Jordan Creeks. The FIS indicates 

the streams’ flood plains may merge in part of their lower 

reaches. New USGS streamflow data, channel changes, and 

engineered structure changes prompted the City and Borough 

of Juneau to seek a hydrologic and hydraulic analysis of Duck 

Creek and the lower reaches of Jordan Creek to help update 

flood plain maps.
Purpose and Scope

The purpose of this study was to provide hydrologic 

and hydraulic analyses to assist the City and Borough of 

Juneau with a re-analysis of the flood plains adjacent to Duck 

Creek and the lower reaches of Jordan Creek. This report 

describes the methods for and results of a flood frequency 

analysis using data from stream-gaging stations and regional 

regression equations. The report also describes the methods 

for and results of development of a flood profile from a onedimensional hydraulic model using the U.S. Army Corps of 

Engineers’ computer program Hydrologic Engineering Center 

River Analysis System (HEC-RAS). The study focuses on 

Duck Creek, including Duck Creek and that part of Jordan 

Creek where its flood plain could merge with Duck Creek’s 

at higher flows. Additional work will be required to update 

Jordan Creek upstream from Egan Drive.

Previous Studies

The existing City and Borough of Juneau FIS (Federal 

Emergency Management Agency, 1990) pre-dated the 

USGS stream-gaging stations on Duck or Jordan Creeks. 

Recognizing the potential for inter-basin transfer of flood 

flows between Duck and Jordan Creeks and the potential 

for storage of flood flows, that report includes a customized 

hydrologic analysis to modify discharges initially modeled 

from precipitation. The analysis identified several major 

control areas spanning both streams, in particular Berners 

Avenue/Glacier Highway and Egan Drive. Rating curves 

relating water-surface elevation to discharge were developed 

for each limiting engineered structure—bridge, culvert, or 

roadway where weir flow could occur—within the control 

areas. Combined rating curves determined the outflow from 

each control area. The effects of storage for these control 

areas and for other storage areas were simulated, and a Corps 

of Engineers computer program was applied to route the 

flows and determine the effect on the hydrograph (Federal 

Emergency Management Agency, 1990). This effort resulted 

in reducing the estimated combined 100-year flood for the two 

streams from 1,200 to 699 ft3/s. The tidal elevation used as a 

starting water surface for Duck and Jordan Creeks was 20 ft, 

stated as the high tide that would occur during a month when 

the selected floods would occur.

An updated hydrologic and hydraulic analysis for the 

Mendenhall River (Neal and Host, 1999) indicates that 

channel incision is associated with high regional rates of landsurface uplift. Although uplift equally affects the Mendenhall 

Valley, Duck and Jordan Creeks have a much more limited 

capacity for incision. The gentle gradients, low velocities, and 

locally dense in-stream vegetation along these smaller streams 

may limit channel erosion to local scour.

Description of Study Area

The City and Borough of Juneau, along Gastineau 

Channel in southeast Alaska (fig. 1), is Alaska’s capital and 

the largest population center in the southeastern part of the 

state. Duck and Jordan Creeks flow through the eastern side 

of Juneau’s Mendenhall Valley (fig. 2). Mendenhall Valley 

originates at the Mendenhall Glacier about 10 mi northwest 

of downtown Juneau. East Mendenhall Valley is a developed 

residential and commercial area with a population of 12,122 

in 2001 (City and Borough of Juneau, Alaska, 2001, accessed 

March 2, 2006), or more than one-third of the City and 

Borough of Juneau population.

Duck and Jordan Creeks occupy adjacent drainage basins 

of 1.3 and 2.6 mi2, respectively, east of the Mendenhall River 

and south of the Mendenhall Glacier. The streams’ headwaters 

lie along the forested eastern flanks of the valley, which rise 

abruptly to an elevation of over 2,900 ft at the summit of 

Thunder Mountain. Duck Creek first becomes channelized 

within the developed valley floor, where surrounding land 

elevations are about 60 ft. Jordan Creek originates on the 

east flank of the valley wall and flows through a narrow 

strip of undeveloped muskeg and spruce forest within the 

Tongass National Forest before emerging into developed areas 

upstream from Egan Drive.

The study area consists of channel and flood plain areas 

along Duck Creek and along the reaches of Jordan Creek 

where the two streams’ flood plains could merge. Specifically, 

the study area consists of the main stem of Duck Creek 

(fig. 3A), a short tributary to Duck Creek, termed Unnamed 

Tributary to Duck Creek in this report (fig. 3B), and the main 

stem of Jordan Creek (fig. 3C). The modeled reach of Duck 

Creek is 3.4 mi long, extending from 40 ft upstream from Taku 

Boulevard to 40 ft downstream from Radcliffe Road at the end 

of the Juneau International Airport runway. The modeled reach 

of Unnamed Tributary to Duck Creek is 0.3 mi long, extending 

from 220 ft downstream from Valley Boulevard to a pond 

upstream from McGinnis Drive. The modeled reach of Jordan 

Creek is 1.1 mi long, extending from 370 ft upstream from 

Egan Drive to 50 ft downstream from Crest Street, within the 

perimeter of the Juneau International Airport. An additional, 

unnamed tributary to Duck Creek near Nancy Street was 

included in the previous FIS as East Fork Duck Creek, but 

was omitted from the study area for this report. This tributary 

drains a highly engineered environment dominated by a series 

of ponds formed in former gravel pits.

 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Figure 1. Location of Duck and Jordan Creeks, Juneau, Alaska.

ak20_0003_fig01

Gastineau Channel

Mendenhall

Lake

Nugget Cr Glacier

Lemon Cr Glacier

Salmon Cr 

Sheep Cr 

Montana Cr 

Lake Cr 

Auke Bay 

Fritz Cove 

Mendenhall R

Duck Cr

Jordan Cr

Twin

Lakes

Nugget Cr

STEPHENS

PASSAGE

Gold Cr

Lemon Cr

Mendenhall Glacier

Gastineau Channel

Mendenhall

Lake

Nugget Cr Glacier

Lemon Cr Glacier

Salmon Cr 

Sheep Cr 

Montana Cr 

Lake Cr 

Auke Bay 

Fritz Cove 

Mendenhall R

Duck Cr

Jordan Cr

Twin

Lakes

Nugget Cr

STEPHENS

PASSAGE

Gold Cr

Lemon Cr

JUNEAU

Juneau

International

Airport

DOUGLAS

ISLAND

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, various scales. Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_feet, 

North American Datum 1983. 

Mendenhall

Valley

0 5 MILES

0 5 KILOMETERS

134°50' 134°40' 134°30' 134°20'

58°

20'

58°

15'

58°

30'

58°

25'

Study

Area

ALASKA

Description of Study Area 
ak20_0003_fig02

Juneau International Airport

EXPLANATION

0

0

.3 MILE

.3 KILOMETER

Streamgage and site number

15053200 Duck Creek below Nancy Street

15052475 Jordan Creek below Egan Drive

134°36'30" 134°36' 134°35'30" 134°35' 134°34'30" 134°34' 134°33'30" 134°33' 134°32'30" 134°32'

58°

21'

30"

58°

22'

58°

22'

30"

58°

23'

58°

23'

30"

58°

24'

Base map data modified from U.S. Geological Survey, Census Bureau, University of Alaska, 

Federal Aviation Administration, Juneau International Airport; various scales. Projection: 

NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 1983. 

Yandukin Dr

Radcliffe Rd

Crest St

Industrial Blvd

Muir St

Old Dairy Rd

Berners Ave

Airport Blvd

Mall Access Rd Atlin Dr

Del Rae

Rd

Jordan

Ave

James Blvd

Sasha

Ave

JORDAN

CREEK

Glacier Hwy North

Simmons Dr

MENDENHALL RIVER

D

UCK

CREEK

MONTANA

CREEK

Egan Drive

15053200

15052475

Nancy Riverwood Dr

Taku Blvd

Julep St

Mendenhall Glacier Rd

Kanat'a Deyi St

Glacier Hwy Nugget

Stephen Richards Dr

Cinema Dr

Haloff

Way

Division St

Shell

Aspen Ave

Glacier Hwy Nugget

Garnet St

Grant St

Threadneedle St Dredge Lake Dr

North Loop Way

Cloverdale St

Mendenhall Blvd Tongass Blvd

Rivercourt Way

Hayes

Way

Glacierwood Dr

Alex Holden

Way

Riverside Dr

Glacier/Douglas Hwy

Longrun Dr River Rd

Dudley St

Portage Blvd

Jennifer Dr

Nugget Dr

Valley Blvd

Northland Dr

McGinnis Dr

Duran

Kiowa St

Trout

St

Parkwood

Dr

El Camino

South

Aspen Ave

Duck

Creek

Loop

Jordan

Creek

Bentwood Pl

Mendenhall Loop Rd

Columbia Blvd

St

St

Glacier Hwy/Lemon Rd

7

7

Unnamed tributary to Duck Creek

El Camino

North

Thunder Mountain

T O N G A S S N A T I O N A L F O R E S T

Cessna St

Bridge

Culvert

Driveway Bridge

Pedestrian Bridge

Crossing type

Figure 2. Location of stream-gaging stations, bridges, and culverts along Duck and Jordan Creeks, Juneau, Alaska.

 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Figure 3. View of channel and structures along (A) Duck 

Creek at a private driveway upstream from Berners Avenue, (B) 

Unnamed Tributary to Duck Creek at North El Camino Street, 

and (C) Jordan Creek at a private driveway downstream from 

Jordan Avenue, Juneau, Alaska.

ak20_0003_fig03

A

B

C

Hydrology of Duck and Jordan Creeks

Duck and Jordan Creeks receive water primarily from 

rainfall, and secondarily from snowmelt and ground water, 

depending on the season. Tides influence both streams near 

their mouths. The USGS systematically collected peakstreamflow data at continuously-operating stream-gaging 

stations on Duck Creek below Nancy Street (15053200) 

from 1994–2004 and on Jordan Creek below Egan Drive 

(15052475) from 1998–2005. The Jordan Creek streamflow

record also includes a 1996 peak, considered a historic 

peak because it falls outside the systematic record. Daily 

mean discharge and annual maximum instantaneous peak 

streamflow data are available at http://waterdata.usgs.gov/

ak/nwis, or through the Alaska Science Center at the address 

listed at the back of this report. Annual peak streamflows are 

listed in table 1.

Table 1. Annual maximum instantaneous peak streamflow for 

Duck and Jordan Creeks, Juneau, Alaska.

[Abbreviations: USGS, U.S. Geological Survey; ft3/s, cubic foot per second]

USGS stream-gaging 

station and number Water year

Annual maximum 

instantaneous peak

streamflow (ft3

/s)

Duck Creek below Nancy Street 

near Auke Bay (15053200)

1994 38

1995 41

1996 49

1997 26

1998 25

1999 48

2000 1

80

2001 34

2002 27

2003 35

2004 27

Jordan Creek below Egan Drive 

near Auke Bay (15052475)

1996 2

140

1998 83

1999 147

2000 149

2001 58

2002 73

2003 114

2004 46

2005 64

1

 High outlier, but no adjustment possible because no historic period is 

available (Ed Neal, U.S. Geological Survey, oral commun., 2004).

2

 Historic peak, but no adjustment made because historic peak is less than 

systematic peaks.

Hydrology of Duck and Jordan Creeks 
Duck Creek’s streamflow correlates to ground water 

conditions (Neal, 2006) and rises and declines relatively 

slowly. Both of these conditions reflect its valley floor origin. 

In contrast, Jordan Creek has a steep, mountainous headwater 

and flashy—quickly rising and declining—peak streamflows. 

Despite the urban nature of the watersheds, annual peakstreamflow data for Duck and Jordan Creeks show no readily 

discernible trends during their respective periods of record 

(fig. 4). The short systematic record of Jordan Creek peak 

streamflows appears to show a roughly declining trend, but 

a USGS miscellaneous measurement made in November 

2005 (Ed Neal, USGS, written commun., 2006), shortly 

after the gaging station was discontinued, eliminates this 

appearance. The short period of record for both streams 

precludes the likelihood of identifying an urbanizing trend 

and the likelihood of comparing data from less- to moreurbanized areas. No known streamflow regulation affects peak 

streamflows in the study area.

For the period of record at the respective USGS streamgaging stations, peak streamflows for Duck Creek occurred 

from September to February, and peak streamflows for Jordan 

Creek occurred from late July to December. Average annual 

mean flow for Duck Creek is 4 ft3

/s and for Jordan Creek is 

8 ft3/s. Records show zero-discharge days on both streams 

during dry periods, and observers reported seeing the channel 

bed dry.

In-channel ponding is common along both streams. In the 

study area, Duck Creek flows through small ponds at various 

locations upstream from Egan Drive, and Jordan Creek flows 

through several ponds downstream from Glacier Highway. 

This study did not investigate the extent of storage provided by 

these ponds during floods.

Methods of Analysis

This study updated the hydrologic analysis for Duck 

and Jordan Creeks by using streamflow data, a resource 

not available for the previous FIS. A log-Pearson type III 

analysis of the streamflow data, weighted with estimates from 

regional regression equations for southeast Alaska, provided 

peak streamflow estimates for various recurrence intervals. 

For the Duck Creek study reach, which is longer than the 

Jordan Creek study reach, streamflow estimates for locations 

upstream and downstream from the gaging station reflect 

changes in drainage area along the study reach.

Hydraulic analysis consisted of construction of a onedimensional, steady-state hydraulic model using results from 

the hydrologic analysis, channel geometry and engineered 

structures field surveys, LIDAR data interpretations, high-tide 

elevation, and the HEC-RAS modeling software. Modeling 

produced estimated water-surface profiles for floods with 10-, 

50-, 100-, and 500-year recurrence intervals.

Hydrologic Analysis

Frequency analysis of a series of annual peak-streamflow 

data produces estimates of peak-streamflow frequency and 

magnitude, reported as T-year discharges. T is a recurrence 

interval, or the number of years during which the discharge 

is expected to be exceeded once, and is the reciprocal of the 

annual exceedance probability. For example, every year the 

50-year peak streamflow, or 50-year flood, has a 1 in 50, or 

2 percent, chance of being exceeded. For Duck and Jordan 

Creeks, analysis of data from the USGS gaging station on 

each stream provided initial estimates of the peak-streamflow 

magnitude for the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-

year recurrence intervals (50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 

0.2-percent exceedance probabilities, respectively). Weighting 

these station-data-based estimates with regional equations 

developed for Alaska (Curran and others, 2003) provided final 

peak-streamflow estimates.

The USGS computer program PEAKFQ, available at 

http://water.usgs.gov/software/surface_water.html, automates 

the log-Pearson Type III frequency distribution analysis 

recommended in the Interagency Advisory Committee on 

Water Data’s Bulletin 17B (Interagency Advisory Committee 

Figure 4. Annual maximum instantaneous peak streamflow for 

Duck and Jordan Creeks, Juneau, Alaska.

WATER YEAR

EXPLANATION

1992 1994 1996 1998 2000 2002 2004 2006 2008

0

20

40

60

80

100

120

140

160

Jordan Creek below Egan Drive (15052475)

Jordan Creek below Egan Drive (15052475)

Duck Creek below Nancy Street (15053200)

STREAMFLOW, IN CUBIC FEET PER SECOND

Maximum instantaneous peak streamflow

Miscellaneous stramflow measurement

 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
on Water Data, 1982). PEAKFQ facilitated computation of 

station-data-based peak-streamflow magnitudes for Duck 

and Jordan Creeks. Systematic peak-streamflow records are 

available for the USGS gaging station on Duck Creek from 

1994-2004 (11 years of record) and on Jordan Creek from 

1998-2005 (8 years of record) (table 1). PEAKFQ identified 

the water year 2000 peak streamflow for Duck Creek as 

a high outlier, but no historic period could be determined 

so the frequency distribution was not adjusted. The 1996 

historic peak for Jordan Creek was omitted from analysis 

because it was less than several systematic peaks (table 1). 

The generalized skew coefficient and standard error of the 

generalized skew for Streamflow Analysis Region 1 (Curran 

and others, 2003) were used for the PEAKFQ analysis. Peakstreamflow estimates computed from PEAKFQ are shown 

with 5- and 95-percent confidence limits in table 2.

Weighting the gaging-station-based peak-streamflow 

estimate with a regional-equation-based estimate can temper 

the uncertainties in streamflow estimates from gaging stations 

with short periods of record (Interagency Advisory Committee 

on Water Data, 1982). The Duck and Jordan Creek gaging 

stations have short periods of record that should statistically 

benefit from incorporating regional hydrology. The regional 

equations for southeast Alaska correlate peak streamflows to 

the basin characteristics drainage area, area of lakes and ponds 

(storage), mean annual precipitation, and mean minimum 

January temperature (Curran and others, 2003). Drainage 

area boundaries drawn on paper USGS topographic maps 

and digitized provided a digital determination of drainage 

area. Summing the areas of lake and pond polygons on digital 

hydrography coverages available at http://agdc.usgs.gov/data/

usgs/to_geo.html and dividing by drainage area produced the 

percentage of lakes and ponds. Mean annual precipitation 

was computed from an Arc/Info AML application applied to 

the Arc/Info coverage of plate 2 of Jones and Fahl (1994) and 

mean minimum January temperature was visually estimated 

from plate 1 of Jones and Fahl (1994). Basin characteristics 

for Duck and Jordan Creeks (table 3) are similar, except Duck 

Creek’s drainage area is about one-half as large as Jordan 

Creek’s drainage area.

Table 2. Peak streamflow estimated from streamflow data and regional equations for selected recurrence intervals, Duck and Jordan 

Creeks, Juneau, Alaska.

[Abbreviaton: ft3/s, cubic foot per second]

Recurrence 

interval 

(years)

Estimated from streamflow data Estimated from regional equations Weighted 

estimate

Peak 

streamflow 

(ft3

/s)

Confidence limits Peak 

streamflow

(ft3/s)

Confidence limits Equivalent 

years of

record

Peak 

streamflow

(ft3/s) 5 percent 95 percent 5 percent 95 percent

Duck Creek below Nancy Street near Auke Bay (15053200)

2 35.7 29.4 42.9 142 77 261 0.8 39.2

5 48.8 40.8 63.9 202 111 368 1.3 56.7

10 58.6 47.9 82.8 243 133 445 1.7 70.9

25 72.0 56.8 113 296 159 551 2.4 92.7

50 82.9 63.5 140 336 177 637 2.8 110

100 94.6 70.4 171 376 194 728 3.1 128

200 107 77.4 207 418 210 832 3.4 148

500 125 87.3 265 474 229 978 3.7 175

Jordan Creek below Egan Drive near Auke Bay (15052475)

2 83.4 62.7 110 375 205 686 1.0 98.6

5 121 93.8 187 537 297 973 1.6 155

10 149 112 259 649 357 1,180 2.1 202

25 186 134 375 789 428 1,460 2.9 273

50 215 150 481 896 477 1,680 3.4 329

100 246 166 605 999 520 1,920 3.9 389

200 278 182 750 1,110 564 2,190 4.2 448

500 324 204 979 1,250 614 2,560 4.6 530

Methods of Analysis 
Table 3. Basin characteristics for Duck and Jordan Creeks, 

Juneau, Alaska.

[Abbreviations: mi2, square miles; in., inches]

Stream

Drainage 

area 

(mi2

)

Area of lakes 

and ponds 

(storage) 

(percent)

Mean annual 

precipitation 

(in.)

Mean 

minimum 

January 

temperature 

(degrees F)

Duck 

Creek 1.30 2 90 22

Jordan 

Creek

2.60 0 90 22

The basin characteristics provided input variables for 

a USGS computer program developed for application of the 

regional regression equations (available at http://pubs.water.

usgs.gov/wri034188). The program computed equation-based 

estimates of peak-streamflow magnitude and 5- and 95-percent 

confidence limits (table 2), as well as the equation’s sitespecific equivalent years of record. Following procedures 

outlined in Curran and others (2003), the gaging-stationbased and equation-based estimates were weighted by the 

station’s years of record and the equation’s equivalent years 

of record, respectively. The final peak streamflow estimate 

for the selected recurrence intervals is this weighted estimate 

(table 2).

The weighted estimates of peak-streamflow magnitude 

for the 10-, 50-, 100-, and 500-year recurrence intervals at 

the gaging station provided inputs for the hydraulic analysis 

for all of Jordan Creek. Duck Creek is longer and includes 

two tributaries, and adjustments to the estimates to account 

for location within the watershed improved the simulated 

water-surface profile, particularly in the upper study reaches. 

Although procedures for estimating peak streamflow at 

ungaged locations on gaged streams are available (Curran 

and others, 2003), these require the use of the regional 

regression equation. The regional regression equation is not 

valid for drainage areas less than 0.72 mi2 in this region. The 

upper reaches of Duck Creek are too small for the regression 

equations to be valid, so the estimates for the gaging station 

were adjusted by applying a ratio of the drainage areas of 

the desired location and the gaging station. Streamflow is 

not necessarily directly proportional to drainage area, but 

comparison to concurrent USGS miscellaneous measurements 

of streamflow at various locations along Duck Creek (table 4) 

shows drainage-area-weighted streamflows are reasonable. 

Measured values were available only for streamflows on the 

order of the 2-year recurrence interval flood, requiring the 

assumption that the flow distribution throughout the watershed 

would be similar for larger floods. An arbitrary minimum of 

10 percent of the streamflow in the adjacent main stem was 

assigned to the flow from the ponds upstream from Nancy 

Street, and to the unnamed tributary of the stream upstream 

from McGinnis Drive, because of the uncertainty inherent 

in the delineation of the drainage area boundaries. Final 

distribution of discharges to locations in the hydraulic model is 

shown in table 5.

Estimates provided for the 500-year peak streamflow 

should be interpreted cautiously. Record lengths for the 

Duck and Jordan Creek gaging stations, and for the gaging 

stations used to develop the regional equations, might not be 

long enough to support extrapolation to such long recurrence 

intervals (Curran and others, 2003). For critical applications, 

site-specific data such as paleoflood indicators might be 

advisable, although the recent post-glacial history of the 

Mendenhall Valley limits available flood records.

The discharges applied to the limits of the study area 

are consistently less than those in the previous FIS (table 5, 

assuming the upstream-most discharge published for the 

previous FIS is applied to the upstream study area limit). 

For example, the present estimate of the 100-year flood for 

Jordan Creek is 36 percent less than the previous value. These 

differences reflect changes in analysis methods and source 

data, particularly the introduction of streamflow data, rather 

than changes in hydrology.

Hydraulic Analysis

Water-surface profiles were computed for the study 

reaches using HEC-RAS version 3.1.3 (U.S. Army Corps 

of Engineers, 2002a, b, c). HEC-RAS is a one-dimensional 

modeling system that computes water-surface profiles for 

gradually varied flow by solving the one-dimensional energy 

equation and for rapidly varied flow (such as flow at hydraulic 

structures) by solving the momentum equation (U.S. Army 

Corps of Engineers, 2002a). The HEC-RAS modeling system 

can simulate unsteady flow; however, this study used only 

the steady flow capabilities. For this investigation, ponds 

along Duck and Jordan Creeks were arbitrarily assumed to 

have minimal storage capacity. Input parameters for steadyflow analysis in HEC-RAS include geometric and elevation 

data for the channel, culverts, bridges, and roads; roughness 

coefficients for the channel, overbank areas, and culverts; and 

flood discharge.

 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Table 4. Measured streamflows and corresponding simulated streamflows using drainage-area ratios, Duck Creek, Juneau, Alaska.

[Measured streamflows: U.S. Geological Survey, written commun., 2005). Abbreviations: USGS, U.S. Geological Survey; ft3/s, cubic foot per second; –, not 

available]

Location

Measured and simulated streamflows (ft3

/s)

Measured 

09-11-95 Simulated Measured 09-25-96 Simulated Measured 02-24-97 Simulated

Duck Creek at Taku Boulevard 1.0 7.9 10.0 12.1 0.5 6.0

Duck Creek at Mendenhall Boulevard 2.7 10.2 – 15.6 1.8 7.8

Duck Creek at Stephan Richards Drive 14.6 14.3 – 21.8 4.5 10.9

Nancy Street Ponds at Nancy Street – 2.1 – 3.2 – 1.6

Duck Creek upstream from confluence of tributary 

near Nancy Street

– 18.9 – 28.8 – 14.4

Duck Creek downstream from confluence of 

tributary near Nancy Steet (15053200)

– 21.0 – 32.0 – 16.0

Duck Creek at Mall Access Road – 22.6 – 34.5 – 17.3

Duck Creek at Egan Drive – 23.4 – 35.6 – 17.8

Duck Creek at Del Rae Road 22.5 24.1 – 36.7 21.4 18.3

Duck Creek at Berners Avenue 25.2 24.6 39.5 37.5 19.0 18.7

Location

Measured and simulated streamflows (ft3/s)

Measured 

09-01-98 Simulated Measured 01-14-04 Simulated Measured 11-21-05 Simulated

Duck Creek at Taku Boulevard – 4.5 – 7.9 – 15.4

Duck Creek at Mendenhall Boulevard – 5.8 – 10.2 6.3 19.9

Duck Creek at Stephan Richards Drive – 8.2 – 14.3 – 27.9

Nancy Street Ponds at Nancy Street 4.8 1.2 – 2.1 – 4.1

Duck Creek upstream from confluence of tributary 

near Nancy Street

10.7 10.8 – 18.9 – 36.8

Duck Creek downstream from confluence of 

tributary near Nancy Steet (15053200)

– 12.0 – 21.0 40.9 40.9

Duck Creek at Mall Access Road – 12.9 22.0 22.6 – 44.1

Duck Creek at Egan Drive – 13.4 23.9 23.4 41.6 45.5

Duck Creek at Del Rae Road – 13.7 – 24.1 – 46.9

Duck Creek at Berners Avenue – 14.1 24.4 24.6 45.6 47.9

Methods of Analysis   
Table 5. Streamflows used for hydraulic model, Duck and Jordan Creeks, Juneau, Alaska.

[Streams and locations are shown in figure 6. Previous flood insurance study: from Federal Emergency Management Agency (1990); equivalent locations 

assigned. Abbreviations: USGS, U.S. Geological Survey; ft, foot; ft3/s, cubic foot per second; –, not appropriate]

Stream and location

River 

station 

(ft)

Current study Previous flood insurance study

Peak streamflow, for given 

recurrence interval or date

(ft3

/s)

Peak streamflow, for given 

recurrence interval

(ft3/s)

10-year 50-year 100-year 500-year 11-21-05 10-year 50-year 100-year 500-year

Duck Creek

Duck Creek upstream from Taku 

Boulevard

18,193 26.8 41.6 48.4 66.1 15.4 – – – –

Duck Creek upstream from Mendenhall 

Boulevard

16,755 34.5 53.5 62.3 85.2 19.9 – – – –

Duck Creek upstream from Duran 

Street

14,998 40.3 62.6 72.8 99.6 23.2 – – – –

Duck Creek upstream from McGinnis 

Drive

13,575 45.2 70.3 81.8 111 26.1 – – – –

Duck Creek upstream from Stephan 

Richards Drive 

12,542 48.4 75.2 87.5 120 27.9 – – – –

Duck Creek upstream from Kodzoff 

Acres

10,398 61.4 95.3 111 152 35.4 51 62 67 78

Duck Creek downstream from Nancy 

Street at USGS gaging station 

(15053200)

8,858 70.9 110 128 175 40.9 – – – –

Duck Creek upstream from Mall 

Access Road

6,905 76.4 119 138 189 44.1 74 116 180 212

Inter-basin transfer from Duck Creek to 

Jordan Creek

1

5,606

2

6,737 – 6.0 21.7 62.3 – – – – –

Duck Creek upstream from Cessna 

Street

2,892 90.8 141 164 225 52.4 140 209 254 293

Tributaries

Unnamed Tributary to Duck Creek 

downstream from Valley Boulevard 1,589 5.0 7.7 9.0 12.3 2.9 – – – –

Unnamed Tributary to Duck Creek 

downstream from Nancy Street – – – – – 65 90 113 135

Jordan Creek

Jordan Creek upstream of pedestrian 

bridge upstream from Egan Drive

8,037 202 329 389 530 138 – – – –

Inter-basin transfer from Jordan 

Creek upstream from Egan Drive to 

southeast

7,888 – 61.9 106 218 – – – – –

Jordan Creek upstream from Egan 

Drive

7,815 202 267 282 315 138 355 395 444 474

1

On Duck Creek.

2

On Jordan Creek.

10 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Stream Network

The initial basis for defining the stream network was 

a GIS-based hydrology coverage provided by the City and 

Borough of Juneau. The network for this study consists of 

the main stems of Duck and Jordan Creeks, plus a small 

unnamed tributary to Duck Creek upstream from McGinnis 

Drive. A final stream center line coverage for the study area 

was generated from this hydrology coverage, survey data for 

this study, and LIDAR data provided by the City and Borough 

of Juneau (fig. 5). The primary purpose of these stream 

center lines was to compute data such as reach lengths for the 

model, necessitating straight paths through the centers of the 

numerous ponds along both streams. Thus, the stream center 

lines are not a precise representation of the streams’ location 

and morphology.

Further simplification of the stream network was useful 

to simulate flow leaving the main stem of Duck and Jordan 

Creeks. Inter-basin flow from Jordan Creek to the southeast at 

Egan Drive and from Duck Creek to Jordan Creek downstream 

from Egan Drive was simulated as lateral weirs.

Field Survey of Cross Sections and Hydraulic 

Structures

The surveying method for cross sections and hydraulic 

structures included a combination of Global Positioning 

System (GPS) and conventional survey techniques. Baselines 

were created from static GPS data collected at local 

benchmarks and data from National Geodetic Survey (NGS) 

Continuously Operating Reference Stations (CORS) sites, then 

processed and used in a network adjustment to obtain latitude, 

longitude, and ellipsoid heights. Selected benchmarks with 

published elevations provided constraints on the GEOID99 

geoid model, which then was used to obtain elevations relative 

to Mean Lower Low Water, a commonly used local vertical 

datum. Using this local geoid model and the constrained 

coordinates for the benchmarks, temporary benchmarks 

(appendix A) were established throughout the study area using 

GPS Real-Time Kinetic (RTK) techniques. These reference 

marks became hubs and backsights for a conventional survey 

of most cross sections and miscellaneous points.

Static and RTK GPS data were collected using Trimble 

4700 receivers with a microcentered L1/L2 antenna with a 

ground plane antenna. Selected NGS, Alaska Department 

of Transportation and Public Facilities (AKDOTPF), and 

USGS benchmarks provided pre-surveyed locations for 

base stations. Published horizontal coordinates for four base 

stations (lev1, ais1, JUN.TIDAL.GPS, and gus2) provided 

constraints for network adjustment. Horizontal coordinates 

for this project are referenced to the NAD83 (CORS96) epoch 

2003 datum. A 2002 AKDOTPF leveling survey (Tim Reed, 

Alaska Department of Transportation and Public Facilities, 

written commun., 2004) and NGS (http://www.ngs.noaa.

gov) provided elevations (orthometric heights) for four base 

stations (JUN.TIDAL.GPS, EDDIE, 95J16, and UW8043) 

used to constrain the GEOID99 model. Wild T1600 and Wild 

T1610 total stations and a Trimble datalogger were used for 

conventional surveying tasks.

Between August 2004 and June 2005, the USGS 

surveyed 146 cross sections at 25 culverts and 5 bridges on 

Duck Creek, and 60 cross sections at 4 culverts and 10 bridges 

on Jordan Creek (fig. 6A-F). Two cross sections were added 

at the study margins, one a duplicate of survey data and one 

from LIDAR data. Map identification numbers are crossreferenced to survey identifiers (used as node descriptions in 

the hydraulic model) in table 6 and to letter identifiers given to 

selected cross sections. Typically, surveys included two cross 

sections upstream and two downstream from each hydraulic 

structure to help model the hydraulic effect of the structure, 

and one or two cross sections between hydraulic structures 

to characterize the typical channel geometry. Data for culvert 

dimensions, materials, and other physical characteristics were 

collected with measuring tapes and visual observations. This 

study does not include culverts replaced since 2004.

The absolute error in surveyed points, or difference from 

actual elevation, depends on the absolute error in the GPS 

network and RTK GPS survey and the relative error in the 

conventional survey. The absolute error in the GPS network 

is less than 0.03 ft for the study area. The absolute error in 

the RTK survey was not determined directly for this study, 

but is estimated to be less than 0.1 ft based on the equipment 

and procedures used (Trimble, 1999). The relative error for 

the conventionally surveyed points, or difference from the 

elevation relative to the hubs, is less than 0.1 ft. The absolute 

error for the survey is the sum of these errors rounded to one 

significant figure, or less than 0.2 ft.

GPS and conventional survey data were processed 

using Trimble Geomatics Office software (Trimble, 1999). 

Final horizontal and vertical coordinates and elevations 

(appendix B) were transformed to station and elevation data 

for cross sections using a customized macro in a Microsoft 

Excel® spreadsheet. This macro allows selection of two 

survey points for alignment of the cross section, and then 

projects all other points onto this alignment to provide a true 

channel distance along the alignment.

Methods of Analysis 11
ak20_0003_fig05

t

r

Egan Drive

Juneau International Airport

Thunder

Mountain

(elevations

greater than

100 ft

truncated)

Nancy

James Blvd

St

Shell Simmons Dr

McGinnis

Dr.

Unnamed tributary to Duck Creek

JORDAN

DUCK

CREEK

MENDENHALL RIVER

Base map data modified from U.S. Geological Survey, Census Bureau, University of Alaska; 

various scales. LIDAR data (2002) from City and Borough of Juneau, AK. Projection: 

NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 1983.

CREEK

58°

21'

58°

22'

EXPLANATION

0

0

.5 MILE

.5 KILOMETER

Elevation, in feet

13

77

70

60

50

40

30

20

58°

23'

58°

24'

134°36' 134°35' 134°34' 134°33'

Figure 5. Modeled stream center lines and general elevation data for Duck and Jordan Creeks, 

Juneau, Alaska.

12  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
ak20_0003_fig06_A

7

7

Radcliffe Rd

Muir St

Stikine St

Miner Dr

Berners Ave

O'Day Dr

Eagle St

Lee Smith Dr

Hurlock Ave

Egan Drive

Del Rae Rd

La Perouse St

Airport Boundary

Runway

Safety Area

Sunset Dr

Alex Holden Way

Meadow Lane

Glacier Hwy North

Glacier Hwy North

MENDENHALL

RIVER

DUCK CREEK

Juneau International Airport

Egan Drive

Float Plane Access Road

Shell Simmons Drive

Cessna St

104

147

105

121

140

110

122

145–46

142

143–44

128

129–30

123–24

125–26

127

109

111

132–33

117

136

137

138

134–35

131

141

113

116

139

118

112

106

149-51

148

107

102–03

114–15

100–01

119–20

152–53

108

134°36' 134°35'30" 134°35'

58°

21'

58°

22'

EXPLANATION

Cross sections and map ID number 101

Stream segment in study area

0

0

.2 MILES

.2 KILOMETERS

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

A.

Figure 6. Locations of modeled and surveyed cross sections along (A-D) Duck Creek and (E-F) Jordan Creek, Juneau, Alaska.

Methods of Analysis 13
ak20

0003fig06B

Mall Access Rd

Teslin St

Atlin Dr

Hurlock Ave

Egan Drive

Marsha

Ave

James Blvd

Sasha Ave

JORDAN

CREEK

Nancy St

Breese St

Skywood Lane Glacierwood

Court

Lori Ave

Mountainwood Circle

Jerry Dr

7

Riverside Dr

Cinema Dr

Gail Ave

Linda Ave

Hayes Way

Riverwood Dr

Glacierwood Dr

Rivercourt Way

Parkwood Dr

Kodzoff Dr

Kodzoff Acres

Nancy

St

D

U

CK

CREEK

Park

Pl

B.

154

149–51

156

157–58

159–61

162–63

164–67

168–70

171–72

173–74

178–79

180–81

182–83

184–85

187–89

175

176

177

186

187

148

155

152–53

134°35'30" 134°35' 134°34'30"

0

0

.2 MILES

.2 KILOMETERS

58°

22'

30"

58°

22'

15"

58°

22'

45"

EXPLANATION

Cross sections and map ID number 203

Stream segment in study area

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

Figure 6.—Continued

14  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Riverside Dr

Gee St

Tongass Blvd

Aspen Ave

Dudley St

Duran St

Cinema Dr

Nugget Dr

Tanis Dr

Longrun Dr

Portage Blvd

Sharon St

Jennifer Dr

Valley Blvd

Stephen Richards Dr

Forest Lane

McGinnis Dr

Hayes Way

Diane Dr Deborah

Dr

Kiowa St

Glacierwood Dr

Amalga St

Trinity Dr

Haloff Way

Parkwood Dr

Evergreen Park Rd

Division St

El Camino

Lower

El Camino

Upper

Sesame

St

JORDAN

CREEK

D

U

CK

CREEK

DUCK

CREEK

Unnamed tributary 

to Duck Creek

186

187

190

191

192

193

196

194

195

197

198

199–01

202–04

207–08

209–10

214–15

216–17

218–19

220–21 222–23

224–25

226–27

212–13

211

205

206

188–89

228–29

230–31

232–33

234–35

C.

0

0

.2 MILES

.2 KILOMETERS

134°35' 134°34'30"W 134°34'

58°

23'

58°

23'

30"

EXPLANATION

Cross sections and map ID number 217

Stream segment in study area

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

Spruce Lane

Figure 6.—Continued

Methods of Analysis 15
ak20

0003fig06DJulep St

Aspen Ave

Poplar Ave

Delta Dr

Thunder

Mt Rd

Cedar St

Birch Lane

Portage Blvd

Valley Blvd

Diane Dr

Deborah Dr

Kimberly St

Conifer

Lane

Division St

Sesame St

Dogwood Lane

Blvd

Mendenhall

DUCK

CREEK

Unnamed tributary 

to Duck Creek

Taku Blvd

Columbia Blvd

Wood Duck Ave

Decoy Blvd

Pinewood Dr

Ptarmagin St

Fireweed Lane

Ichabod Lane

Teel Court

Sleepy Court

Mitchell

Way

Cedar Court

Snipe Court

East

Valley

Court

246

241

238

237

236

232–33

234-35

239–240

242–43 244–45

0

0

.2 MILES

.2 KILOMETERS

134°34'45" 134°34'30" 134°34'15" 134°34'

58°

23'

30"

58°

23'

45"

EXPLANATION

Cross sections and map ID number 234

Stream segment in study area

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

D.

Figure 6.—Continued

16  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
ak20_0003_fig06_E

Yandukin Dr

Crest St

Old Dairy Rd

Egan Drive

Teal St

Airport Blvd

Mallard St

Livingston Way

Alpine

Ave

Jordan Ave

JORDAN

CREEK

Cascade

St

Glacier Highway

North

Airport Boundary

Float Plane

Access Rd

Shell Simmons Drive

7

Juneau International Airport

Float Plane Basin

304

300–01

306–07

309–12

313–14

316–19

302–03

321

305

315

308

320

323

322

324

326 325

134°35' 134°34'30"

58°

21'

58°

21'

30"

58°

20'

30”

0

0

.2 MILES

.2 KILOMETERS

EXPLANATION

Cross sections and map ID number 304

Stream segment in study area

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

E.

Figure 6.—Continued

Methods of Analysis 17
ak20_0003_fig06_F

Airport Boundary

Crest St

Miner Dr

Old Dairy Rd

Egan Drive

Glacier Hwy

Nugget

O'Day Dr

Lee Smith Dr

Teslin St

Hurlock Ave

Aurora Dr

Trout St

Jordan Ave

Cascade

St

JORDAN

CREEK

Shell Simmons

Dr

Ka-See-An Dr

Sheiye Way

Miner Court

Aurora

Court

Cessna Dr

7

7

341

323

329

330

340

346

359

360

322

334

335

331

324

326

327–28

338–39

336–37

342–43

344–45

347–48

349–50

351–54

355–58

332–33

325

134°35' 134°34'45" 134°34'30" 134°34'15"

58°

21'

30"

58°

22'

58°

22'

30"

0

0

.2 MILES

.2 KILOMETERS

EXPLANATION

Cross sections and map ID number 358

Stream segment in study area

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska, Federal Aviation Administration, Juneau International Airport; various scales. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

F.

Figure 6.—Continued

18  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Table 6. Index to cross section identifiers, Duck and Jordan Creeks, Juneau, Alaska.

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Lower Duck Creek main stem

100 D.RC.XS1 A

101 D.RC.XS2 B

102 D.RC.XS3 C

103 D.RC.XS4

104 D.RC.XS30 D

105 D.RC.XS50 E

106 D.CS.XS1 F

107 D.CS.XS2

108 D.CS.XS2-5 G

109 D.CS.XS3 H

110 D.CS.XS4

111 D.CS.XS50

112 D.BN.XS1 I

113 D.BN.XS2

114 D.BN.XS3 J

115 D.BN.XS4

116 D.BN.XS50

117 D.PP.XS1

118 D.PP.XS2 K

119 D.PP.XS3 L

120 D.PP.XS4

121 D.PP.XS50

122 D.BB.XS1

123 D.BB.XS1-5 M

124 D.BB.XS2

125 D.BB.XS3 N

126 D.BB.XS4

127 D.VP.XS1 O

128 D.VP.XS2 P

129 D.VP.XS3 Q

130 D.VP.XS4

131 D.VP.XS50 R

132 D.FA.XS1

133 D.FA.XS2 S

134 D.FA.XS3

135 D.FA.XS4 T

136 D.FA.XS50

137 D.GH.XS1

138 D.GH.XS2 U

139 D.GH.XS3 V

140 D.GH.XS4

141 D.GH.XS40

142 D.GH.XS60 W

143 D.DR.XS1 X

144 D.DR.XS2 Y

145 D.DR.XS3 Z

146 D.DR.XS4

147 D.DR.XS40 AA

148 D.DR.XS60

149 D.EG.XS0

150 D.EG.XS1

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Lower Duck Creek main stem—Continued

151 D.EG.XS2 AB

152 D.EG.XS3

153 D.EG.XS4 AC

154 D.EG.XS50 AD

155 D.MA.XS1 AE

156 D.MA.XS2 AF

157 D.MA.XS3

158 D.MA.XS4 AG

159 D.MJ.XS0

160 D.MJ.XS1 AH

161 D.MJ.XS2

162 D.MJ.XS3 AI

163 D.MJ.XS4 AJ

164 D.MJBR1.XS1 AK

165 D.MJBR1.XS2

166 D.MJBR1.XS3 AL

167 D.MJBR1.XS4

168 D.MJBR2.XS1 AM

169 D.MJBR2.XS2

170 D.MJBR2.XS3 AN

171 D.MJBR2.XS4 AO

172 D.MJBR2.XS50

173 D.MN.XS1 AP

174 D.MN.XS2

175 D.MN.XS3 AQ

176 D.MN.XS4 AR

177 D.MN.XS30 AS

178 D.KA1.XS1 AT

179 D.KA1.XS2

180 D.KA1.XS3 AU

181 D.KA1.XS4

182 D.KA2.XS1 AV

183 D.KA2.XS2

184 D.KA2.XS3 AW

185 D.KA2.XS4 AX

186 D.KA2.XS50-5 AY

187 D.KA2.XS50 AZ

188 D.CI.XS1 BA

189 D.CI.XS2

190 D.CI.XS3 BB

191 D.CI.XS4

192 D.CI.XS40 BC

193 D.CI.XS60 BD

194 D.SR.XS1

195 D.SR.XS2 BE

196 D.SR.XS3

197 D.SR.XS4 BF

198 D.SRPB1.XS1

199 D.SRPB1.XS2

200 D.SRPB1.XS3 BG

201 D.SRPB1.XS4

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Lower Duck Creek main stem—Continued

202 D.SRPB2.XS1 BH

203 D.SRPB2.XS2

204 D.SRPB2.XS3 BI

205 D.SRPB2.XS4 BJ

206 D.SRPB2.XS50

207 D.MG.XS1 BK

208 D.MG.XS2

209 D.MG.XS3 BL

210 D.MG.XS4 BM

Unnamed Tributary to Duck Creek

211 D.ES.XS0 A

212 D.ES.XS1 B

213 D.ES.XS2

214 D.ES.XS3

215 D.ES.XS4 C

216 D.EN.XS1 D

217 D.EN.XS2

218 D.EN.XS3

219 D.EN.XS4 E

220 D.SP.XS1 F

221 D.SP.XS2

222 D.SP.XS3

223 D.SP.XS4 G

224 D.VB.XS1 H

225 D.VB.XS2

226 D.VB.XS3

227 D.VB.XS4 I

Upper Duck Creek main stem

228 D.DU.XS1 BN

229 D.DU.XS2 BO

230 D.DU.XS3 BP

231 D.DU.XS4 BQ

232 D.AS.XS1

233 D.AS.XS2 BR

234 D.AS.XS3 BS

235 D.AS.XS4

236 D.AS.XS50 BT

237 D.MB.XS1 BU

238 D.MB.XS2

239 D.MB.XS3 BV

240 D.MB.XS4

241 D.MB.XS50 BW

242 D.TK.XS1 BX

243 D.TK.XS2

244 D.TK.XS3 BY

245 D.TK.XS4 BZ

246 Copy of D.TK.XS4, used 

to extend model to match 

previous study

Methods of Analysis 19
Table 6. Index to cross section identifiers, Duck and Jordan Creeks, Juneau, Alaska.—Continued

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Jordan Creek

300 J.CS.XS1 A

301 J.CS.XS2

302 J.CS.XS3 B

303 J.CS.XS4

304 J.YD.XS1

305 J.YD.XS2 C

306 J.YD.XS3

307 J.YD.XS4 D

308 J.YD.XS50

309 J.YDPB1.XS1 E

310 J.YDPB1.XS2

311 J.YDPB1.XS3

312 J.YDPB1.XS4 F

313 J.YDPB2.XS2 G

314 J.YDPB2.XS3

315 J.YDPB2.XS4 H

316 J.YDPB3.XS1 I

317 J.YDPB3.XS2

318 J.YDPB3.XS3

319 J.YDPB3.XS4 J

320 J.YDPB3.XS40

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Jordan Creek—Continued

321 J.YDPB3.XS60 K

322 J.GH.XS1 L

323 J.GH.XS2 M

324 J.GH.XS3 N

325 J.GH.XS4

326 J.GH.XS50

327 J.GHPB1.XS1

328 J.GHPB1.XS2 O

329 J.GHPB1.XS3 P

330 J.GHPB1.XS4

331 J.GHPB2.XS1 Q

332 J.GHPB2.XS2

333 J.GHPB2.XS3

334 J.GHPB2.XS4 R

335 J.GHPB2.XS50

336 J.JA.XS1 S

337 J.JA.XS2

338 J.JA.XS3

339 J.JA.XS4 T

340 J.JA.XS40 U

341 J.JA.XS60

Map 

identifier

Survey and 

model identifier

Letter 

identifier

Jordan Creek—Continued

342 J.TR.XS1 V

343 J.TR.XS2

344 J.TR.XS3

345 J.TR.XS4 W

346 J.TR.XS50

347 J.TRPB1.XS1 X

348 J.TRPB1.XS2

349 J.TRPB1.XS3

350 J.TRPB2.XS1

351 J.TRPB2.XS2 Y

352 J.TRPB2.XS3

353 J.EG.XS1

354 J.EG.XS2 Z

355 J.EG.XS3 AA

356 J.EG.XS4 AB

357 J.EGPB1.XS2

358 J.EGPB1.XS3

359 J.EGPB1.XS4 AC

360 Section 1 above 

split

AD

LIDAR Elevation Data

The City and Borough of Juneau provided Light 

Detection and Ranging (LIDAR) elevation data (fig. 5) that 

were used to supplement the survey data for selected locations. 

Discrepancies between the field-surveyed elevations and 

LIDAR-obtained elevations were on the order of 0.5–1.0 ft, 

generally showing the LIDAR data at a lower elevation, 

limiting the use of LIDAR data to applications insensitive to 

exact elevations. Most commonly, LIDAR data were used to 

extend cross sections where an obvious, topographic feature 

was present. LIDAR data were also used to produce an extra 

cross section upstream from the upstream-most surveyed 

cross section on Jordan Creek to accommodate a lateral weir 

simulating overflow from the Jordan Creek network. Review 

of LIDAR data helped conceptualize inter-basin flow paths 

near Egan Drive and Glacier Highway.

Channel Roughness (Manning’s n)

Flood profile models require an estimate of channel 

and overbank roughness, which provide resistance to flow. 

Hydraulic roughness is characterized commonly by Manning’s 

n, a coefficient that cannot be measured directly. Estimates 

of Manning’s n reflect the boundary roughness generated by 

bed materials, vegetation, pavement, or other surface material 

present, as well as other types of roughness generated by 

obstacles and variations in channel parameters over short 

distances. Empirically derived tables (for example, U.S. 

Army Corps of Engineers [2002b]) list Manning’s n for 

surfaces common to a developed environment, and various 

publications show photographs of measurement sites for the 

natural riverine environment (for example, Barnes [1967]). 

Initial estimation of Manning’s n for this study relied on 

comparison of published values for various surfaces to field 

observations and photographs of the channel and hydraulic 

20 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Table 7. Range of Manning’s n for Duck and Jordan Creeks, 

Alaska.

Stream reach Range of Manning’s n

for channel areas

Range of Manning’s n 

for overbank areas

Duck Creek main stem 0.030–0.060 0.040–0.070

Unnamed tributary to 

Duck Creek 0.030–0.035 0.040–0.060

Jordan Creek 0.040–0.060 0.035–0.080

structures. Final values were obtained from the calibration 

process, which involved adjustments of initial values to obtain 

a reasonable match of simulated water surfaces with measured 

water surfaces during a small flood on November 21, 2005. 

Final values determined from calibration were used for the full 

range of discharges analyzed.

The range of values of Manning’s n used in the model 

is presented in table 7. In-channel values are relatively high 

in many locations to reflect the presence of dense in-channel 

vegetation. In some locations, dense vegetation was present in 

the channel, but channel sideslopes were lightly vegetated and 

sloped up to paved sidewalks and roadways. In these instances, 

the channel is rougher than the overbank areas.

Starting Water-Surface Elevation

Flood conditions are conservatively assumed to coincide 

with a high tide. The starting water-surface elevation in the 

model for Duck and Jordan Creeks at the downstream end 

of the study reach is the high-tide elevation of 20 ft, based 

on analysis from the previous FIS (Federal Emergency 

Management Agency, 1990). This is the high tide expected 

during a month when the 10-, 50-, 100-, or 500–year floods 

are likely to occur.

Model simulation results show backwater effects from 

a high tide as far as 720 ft upstream from Berners Avenue 

on Duck Creek and 750 ft upstream from Yandukin Drive 

on Jordan Creek during a 100-year flood. Water-surface 

elevations downstream from these locations would be lower 

than the simulated flood profile if the 100-year flood coincides 

with a lower tide.

Calibration to Known Water-Surface Elevations

Water-surface elevations were not available to rigorously 

calibrate the model to the high flows for which it was 

designed. However, water-surface elevations surveyed for a 

small flood on November 21, 2005, provided an opportunity 

to calibrate in-channel roughness values for a lower flow. The 

poor results of this calibration led to a downward adjustment 

of final values to within published ranges for the measured 

conditions.

Model calibration involves adjusting roughness 

coefficients to match simulated water-surface elevations as 

closely as possible to measured water-surface elevations. 

Measured discharges during the November 21, 2005, flood 

were 40.9 ft3/s at the USGS gaging station on Duck Creek, 

just greater than the 2-year flood magnitude, and 138 ft3

/s at 

the gaging station on Jordan Creek, between the 2- and 5-year 

flood magnitudes. For both streams, the model accounted for 

sediment that partially blocks the culverts (standard practice 

assumes sediment is scoured out for high flow, but sediment 

was present for the November 2005 flow). Despite the 

adjustment for partially blocked culverts, calibrating the model 

to the measured water-surface elevations required raising 

roughness coefficients to 0.09, a value exceeding generally 

accepted published ranges of roughness coefficients for the 

channel conditions present.

Finalizing roughness coefficients for the desired higher 

flows required balancing the calibration results from the lower 

flow with generally accepted published ranges. Roughness 

coefficients were reduced to within accepted ranges while 

minimizing the difference in simulated and measured water 

levels. The maximum final in-channel roughness coefficient 

was 0.06. Final simulated water-surface elevations for the 

November 21, 2005, flood were an average of 0.7 ft less than 

measured water-surface elevations on Duck and Jordan Creeks 

(fig. 7). The final simulated 100-year water-surface elevation 

was 0.4 ft lower than the calibrated model’s 100-year watersurface elevation simulation. Although this drop is within 

a 0.5 ft tolerance for the model, it indicates that the actual 

100-year water-surface elevations could be slightly higher than 

simulated water-surface elevations.

Methods of Analysis  21
ak20_0003_fig07

2,000 3,000 4,000 5,000 6,000

15

20

25

30

MAIN CHANNEL DISTANCE, IN FEET

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

Simulated water surface, November 21, 2005

Cross-section location and identification number 

Ground elevation

Measured water surface, November 21, 2005

106Cessna Drive110111112Berners Avenue116

116

private driveway119122private driveway127private driveway131132private driveway136Glacier Highway141142143Del Rae Road147148149Egan Drive

5,000 5,500 6,000 6,500 7,000 7,500 8,000

15

20

25

30

MAIN CHANNEL DISTANCE, IN FEET

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

321322325326327private driveway331private driveway335336Jordan Ave340341342Trout Street346347pedestiran brdigepedestrian bridgeEgan Drivepedestrian bridge360

JORDAN CREEK MAIN STEM

Open water passage

Solid structure

DUCK CREEK MAIN STEM

Glacier Highway

Overflow swale

Overflow swale

Figure 7. Profile of simulated water-surface elevations and measured water-surface elevations for flow in Duck 

and Jordan Creeks, Juneau, Alaska, November 21, 2005.

22  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Flood Profiles

Flood profiles computed for Duck Creek and Jordan 

Creek downstream from Egan Drive consist of the watersurface elevation for the 10-, 50-, 100-, or 500-year floods 

(fig. 8A-E). The model assumes Duck and Jordan Creeks peak 

simultaneously, and flooding coincides with a 20 ft high tide. 

Sensitivity analysis indicates the accuracy of the water-surface 

elevations is within the required tolerance of 0.5 ft.

Actual flooding conditions can damage bridges, culverts, 

and roadways, and debris obstructions can increase local 

flooding. However, this study assumes that all structures 

included in the model maintain their integrity during floods, 

that no road failures occur, and that structures remain 

unobstructed. For most culverts, the model assumes sediment 

observed during field investigations is washed out during 

flooding.

The steady-state model used does not address the possible 

attenuating effects of the numerous ponds within the Duck and 

Jordan Creek corridors. The likely effect of an unsteady-flow 

analysis, which would address storage, would be a reduction 

in water-surface elevations.

Generally, the lateral extent of the water-surface for 

the cross sections adequately delineates the flood plain. 

However, cross sections do not extend to the full extent of the 

500-year flood plain in areas where it was impractical to do 

so and the extension would not affect the model hydraulics. 

In particular, cross sections do not extend fully at locations 

where the channel flows over roadways and along Jordan 

Creek between Egan Drive and Glacier Highway, where watersurface elevations exceed the elevation of the surrounding land 

surface. Flood plains in these areas may be delineated on the 

basis of elevations generated in the model.

Simulated water-surface profiles generally are higher than 

those published previously (Federal Emergency Management 

Agency, 1990), showing a 1- to 3-ft discrepancy in elevation 

at the limits of the study areas for the 100-year flood (table 8). 

Possible reasons for this discrepancy include new hydrologic 

data, different assumptions regarding storage, different 

survey datum, and land-surface elevation change over time. 

A re-analysis of Jordan Creek upstream from Egan Drive 

will be necessary to match the profiles shown in this report. 

The profiles downstream from the underground pipe for the 

tributary named East Fork Duck Creek in the previous FIS will 

need adjustment because the simulated water surface at the 

confluence is about 3 ft higher than in the previous FIS.

Inter-Basin Flow

The Duck and Jordan Creek flood plains merge 

downstream from Egan Drive for the 50-, 100-, and 500-year 

floods. The LIDAR data show a low area along the east bank 

of Duck Creek about 500 ft downstream from Egan Drive 

(fig. 9). Floodwaters exceeding the elevation of this area 

(modeled as 29.0 ft) will not return to Duck Creek, but instead 

will flow across a residential landscape to Jordan Creek. The 

simulated 100-year flood conditions show a flow of 22 ft3/s 

exiting Duck Creek and entering Jordan Creek upstream from 

Jordan Avenue (table 5).

A topographic low between the base of the Mendenhall 

Valley wall and Egan Drive extends to the southeast from 

Jordan Creek for about 4,000 ft (fig. 9). Floodwaters 

exceeding the elevation of this low (simulated as 29.5 ft) will 

exit the Jordan Creek system entirely and drain into salt water. 

Model simulation results show a flow of 104 ft3

/s would exit 

Jordan Creek during the 100-year flood.

Discussion

Combined flows at the mouths of Duck and Jordan 

Creeks for the 100-year flood are 467 ft3/s, with 106 ft3/s 

leaving the Jordan Creek network upstream from Egan Drive 

(table 5). This is considerably less than the 699 ft3/s simulated 

in the previous FIS (Federal Emergency Management Agency, 

1990). However, simulated profiles generally are higher than 

those for the previous study. The effect of these differences on 

the areal extent of the flood plain depends on the topographic 

data used during flood plain delineation and cannot be 

predicted from this study alone.

The strong influence of culverts and bridges can be 

seen in the stair-step profiles for the 100-year flood on Duck 

Creek, which are influenced by backwater from near Berners 

Avenue upstream to Cinema Drive (fig. 8A-B). As viewed 

moving upstream over this 1.5 mi reach, the water-surface 

elevation increases at culverts and bridges, then remains flat 

until the next structure is reached. Under the influence of this 

backwater, the presence of some smaller structures has no 

noticeable effect on the water-surface profile. A similar effect 

can be seen at culverts at Glacier Highway and Egan Drive 

along Jordan Creek (fig. 8E).

Flood Profiles  23
A(100) B(101) C(102)

D(104)

E(105)

F(106)

G(108)

H(109)

I(112)

J(114)

K(118)

L(119)

M(123)

N(125)

O(127)

P(128)

Q(129)

R(131)

S(133)

T(135)

U(138)

V(139)

W(142)

X(143)

Y(144)

Z(145)

AA(147)

AB(151)

A.

STREAM DISTANCE, IN FEET ABOVE ORIGIN OF STUDY (40 FEET DOWNSTREAM FROM RADCLIFFE ROAD)

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

 0 5

 10 15 20 25 30

354045

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,

CESSNA DRIVE

BERNERS AVENUE

PRIVATE DRIVEWAY

PRIVATE DRIVEWAY

PRIVATE DRIVEWAY

PRIVATE DRIVEWAY

GLACIER HIGHWAY

DEL RAE ROAD

OVERFLOW SWALE

RADCLIFFE ROAD

DUCK CREEK

EXPLA

Le

M

StrCro

50

Flood 

105010

AA

(147)

Cu

Figure 8. Flood profiles for Duck and Jordan Creeks, and unnamed tributary to Duck Creek, Juneau, Alaska.
AH(160)

AI(162)

AJ(163)

AK(164)

AL(166)

AM(168)

AN(170)

AO(171)

AP(173)

AQ(175)

AR(176)

AS(177)

AT(178)

AU(180)

AV(182)

AW(184)

AX(185)

AY(186)

AZ(187)

BA(188)

BB(190)

BC(192)

BD(193)

BE(195)

DUCK CREEK

B.

STREAM DISTANCE, IN FEET ABOVE ORIGIN OF STUDY (40 FEET DOWNSTREAM FROM RADCLIFFE ROAD)

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

 10 15 20 25 30 35 40

455055

6,500 7,000 7,500 8,000 8,500 9,000 9,500 10,000 10,500 11,000 11,500 12

STEPHEN RICHARDS DRIVE

CINEMA DRIVE

ABANDONED PEDESTRIAN BRIDGE

ABANDONED ROADWAY

MENDENHALL LOOP

MENDENHALL LOOP

PEDESTRIAN BRIDGE

PEDESTRIAN BRIDGE

EXPLA

Le

M

StrCro

50

Floo

105010

AA

(147)

CuBri

Figure 8.—Continued.
ak20_0003_figure08_C C.

STREAM DISTANCE, IN FEET ABOVE ORIGIN OF STUDY (40 FEET DOWNSTREAM FROM RADCLIFFE ROAD)

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

MCGINNIS DRIVE

DURAN STREET

ASPEN AVENUE

MENDENHALL BOULEVARD

TAKU BOULEVARD

 25 30 35 40 45 50 55 60 65 70

13,000 13,500 14,000 14,500 15,000 15,500 16,000 16,500 17,000 17,500 18,000 18,

EXPLA

Le

M

StrCro

50

Flood 

105010

AA

(147)

Cul

BL(209)

BM(210)

BN(228)

BO(229)

BP(230)

BQ(231)

BR(233)

BS(234)

BT(236)

BU(237)

BV(239)

BW(241)

BX(242)

BY(244)

BZ(245)

DUCK CREEK

Figure 8.—Continued.
ak20_0003_fig08_D

A(211)

B(212)

C(215)

D(216)

E(219)

F(220)

G(223)

H(224)

I(227)

EXPLANATION

Letter Identifier

Map ID number (figure 6)

Stream bedCross section location

500-year flood

Flood profiles

100-year flood50-year flood10-year flood

AA

(147)

Culvert

D.

STREAM DISTANCE, IN FEET ABOVE CONFLUENCE

WITH DUCK CREEK

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

 25 30 35 40 45 50 55 60 65 70

EL CAMINO SOUTH

EL CAMINO NORTH

SPRUCE LANE

VALLEY BOULEVARD

0 500 1,000 1,500 2,000

UNNAMED TRIBUTARY TO DUCK CREEK

Figure 8.—Continued.
ak20

0003fig08E JORDAN CREEK

A (300)

B (302)

C (305)

D (307)

E (309)

F (312)

G (313)

H (315)

I (316)

J (319)

K (321)

L (322)

M (323)

N (324)

O (328)

P (329)

Q (331)

R (334)

S (336)

T (339)

U (340)

V (342)

W (345)

X (347)

Y (351)

Z (354)

E.

05

1015202530354045

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,5

ELEVATION, IN FEET ABOVE MEAN LOWER LOW WATER

5,000

CREST STREET

YANDUKIN DRIVE

PEDESTRIAN BRIDGE

PEDESTRIAN BRIDGE

PEDESTRIAN BRIDGE

GLACIER HIGHWAY

PRIVATE DRIVEWAY

PRIVATE DRIVEWAY

JORDAN AVE

TROUT STREET

PEDESTRIAN BRIDGE

PEDESTRIAN BRIDGE

STREAM DISTANCE, IN FEET ABOVE ORIGIN OF STUDY (50 FEET DOWNSTREAM FROM CREST STREET)

EXPLANA

Stream b

500-yea

Flood pr

100-yea50-yea10-yea

AA FEMA 

Map ID 

Cross se

(147)

Culvert

Bridge

Figure 8.—Continued.
ak20_0003_fig09

Berners Ave

La Perouse St

Crest St

Muir St

Miner Dr

Old Dairy Rd

Glacier Hwy

Nugget

Berners Ave

O'Day Dr

Eagle St

Mallard St

Lee Smith Dr

Teslin St

Hurlock Ave

Aurora Dr

Del Rae Rd

Trout St

La Perouse St Sunset Dr

Alpine Ave

Jordan Ave

Cascade

St

JORDAN

CREEK

Glacier Hwy

North

Shell Sim

mons Dr

Thunder Mountain

(elevations greater

than 100 ft truncated)

DUCK

CREEK

Egan Drive

Glacier Highway

134°35'30" 134°35' 134°34'30"

58°

21'

30"

58°

22'

58°

22'

30"

EXPLANATION

0

0

.25 MILE

.25 KILOMETER

Elevation, in feet

24.5 26.0 28.0 30.0 32.0

Direction of inter-basin flow

Base map data modified from U.S. Geological Survey, Census Bureau, University of 

Alaska; various scales. LIDAR data (2002) from the City and Borough of Juneau, AK. 

Projection: NAD_1983_StatePlane_Alaska_1_FIPS_5001_Feet, North American Datum 

1983.

Figure 9. Modeled stream center lines, roads, general elevation data, and direction of inter-basin flow for Duck and Jordan 

Creeks between Egan Drive and Glacier Highway in Juneau, Alaska.

Flood Profiles  29
Summary

Duck and Jordan Creeks are small, urban streams that 

flow through closely-spaced engineered bridges and culverts 

in Juneau’s Mendenhall Valley before draining into salt 

water. Both streams drain areas along the steep eastern flank 

of the valley. However, Jordan Creek extends farther up the 

mountainside and collects more mountainous drainage than 

Duck Creek, which first becomes channelized in the valley 

floor and is more influenced by ground-water conditions. 

Jordan Creek’s drainage area is 2.6 square miles, twice the size 

of Duck Creek’s drainage area, and its peak flows are about 3 

times larger than Duck Creek’s.

To provide information for updating Juneau’s most recent 

flood insurance study, this study determined flood magnitudes 

for floods with a 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year 

recurrence interval on Duck and Jordan Creeks. Computations 

from 11 and 8 years of streamflow data on Duck and Jordan 

Creeks, respectively, were weighted with results from 

regional regression equations for southeast Alaska. The flood 

discharges were used together with field surveys of channel 

geometry and details of culverts and bridges to construct a 

steady-state hydraulic model using the U.S. Army Corps of 

Engineers’ HEC-RAS software. Simulated reaches include 

3.4 miles of main stem Duck Creek, 0.3 mile of an unnamed 

tributary to Duck Creek near McGinnis Street, and 1.1 miles 

of Jordan Creek downstream from Egan Drive. Additional 

work will be required to update Jordan Creek upstream from 

Egan Drive. The model was calibrated by adjusting Manning’s 

roughness coefficients so water-surface elevations more 

closely matched measured elevations from a small 2005 flood. 

Resulting flood profiles provide water-surface elevations for 

the 10-, 50-, 100-, and 500-year floods. These flood profiles 

are strongly affected by backwater from the 30 culverts and 

bridges on Duck Creek and the 14 culverts and bridges in 

the study area on Jordan Creek. Backwater conditions over 

much of the study area create a stair-step profile with watersurface elevations rising at the culvert or bridge and a flat 

water-surface profile extending upstream. Inter-basin flow 

was simulated in two locations, one leaving Duck Creek 

downstream from Egan Drive and entering Jordan Creek 

upstream from Jordan Avenue, and another leaving the Jordan 

Creek system entirely in a southeast trending depression along 

the upstream side of Egan Drive.

References Cited

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

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

1849, 213 p.

City and Borough of Juneau, Alaska, 2001, Community 

demographics 2001 Juneau population map: City and 

Borough of Juneau, Alaska, accessed March 2, 2006, at 

http://www.juneau.org/cddftp/demographics/2001_CBJ_

Pop_map.pdf

Curran, J.H., Meyer, D.F., and Tasker, G.D., 2003, Estimating 

the magnitude and frequency of peak streamflows for 

ungaged sites on streams in Alaska and conterminous 

basins in Canada: U.S. Geological Survey Water-Resources 

Investigations Report 03-4188, 101 p., accessed October 3, 

2006, at http://pubs.water.usgs.gov/wri034188

Federal Emergency Management Agency, 1990, Flood 

insurance study, City and Borough of Juneau, Alaska: 

Federal Emergency Management Agency, 42 p., 36 p. figs.

Interagency Advisory Committee on Water Data, 1982, 

Guidelines for determining flood flow frequency: 

Hydrology Subcommittee Bulletin 17B, 28 p., 14 app.

Flood profile

Water-surface 

elevation in current 

study (ft)

Water-surface 

elevation in FEMA, 

1990 (ft)

Duck Creek, downstream from confluence with 

tributary near Nancy Street (15053200)

500-year 31.5 29.8

100-year 30.7 29.4

50-year 30.4 29.1

10-year 29.1 28.2

Jordan Creek, upstream from Egan Drive (15052475)

500-year 31.5 29.8

100-year 30.7 29.4

50-year 30.4 29.1

10-year 29.1 28.2

Table 8. Comparison of flood profiles at limits of study area to 

adjacent published profiles, Duck and Jordan Creeks, Juneau, 

Alaska.

[Abbreviations: FEMA, 1990, Federal Emergency Management Agency, 

1990; ft, foot]

30 Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Jones, S.H., and Fahl, C.B., 1994, Magnitude and frequency of 

floods in Alaska and conterminous basins of Canada: U.S. 

Geological Survey Water-Resources Investigations Report 

93-4179, 122 p., 2 pls.

National Geodetic Survey, 2006, NGS datasheet page: 

National Geodetic Survey data available on the Web, 

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[abs.]: Anchorage, Alaska, Proceedings of the 2006 

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Neal, E.G., and Host, R.H., Hydrology, geomorphology, and 

flood profiles of the Mendenhall River, Juneau Alaska: U.S. 

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99-4150, 35 p.

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References Cited  31
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32  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Appendix A. Description of Temporary Benchmarks Placed for Survey, and 

Benchmarks Placed by Others and Used in Survey

Appendix A data are available in an Excel data base for download at URL:

 http://pubs.water.usgs.gov/sir20065323/ sir20065323_appa.xls.

Appendix A.  33
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34  Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska
Appendix B. Coordinates and Elevations for Surveyed Points, Duck and Jordan 

Creeks, Alaska

Appendix B data are available in an Excel data base for download at URL: 

 http://pubs.water.usgs.gov/sir20065323/ sir20065323_appb.xls.

Appendix B.  35
Manuscript approved for publication, December 28, 2006

Prepared by the USGS Publishing Network, 

Publishing Service Center, Tacoma, Washington

Bill Gibbs 

Debra Grillo

Jacqueline Olson

Bobbie Jo Richey

Sharon Wahlstrom

Cheri Yoesting

For more information concerning the research in this report, contact the 

Alaska Science Center

U.S. Geological Survey

4230 University Drive, Suite 201

Anchorage, Alaska 99508-4664

http://alaska.usgs.gov
SIR 2006–5323 Curran Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska