U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004–5272

Monitoring Channel Morphology and Bluff Erosion 

at Two Installations of Flow-Deflecting Vanes, 

North Fish Creek, Wisconsin, 2000–03

In cooperation with the Wisconsin Department of Natural Resources
Monitoring Channel Morphology and 

Bluff Erosion at Two Installations of 

Flow-Deflecting Vanes, North Fish Creek, 

Wisconsin, 2000–03

By Faith A. Fitzpatrick, Marie C. Peppler, Heather E. Schwar, John A. Hoopes, 

and Matthew W. Diebel

In cooperation with the Wisconsin Department of Natural Resources 

Scientific Investigations Report 2004−5272

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.
iii

Contents

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

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

Purpose and Scope ............................................................................................................................. 3

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

Methods ......................... 4

Vane Design, Layout, and Installation .............................................................................................. 5

Channel Cross-Section Surveys and Sediment Volume Estimates ............................................. 8

Bluff Erosion Monitoring ..................................................................................................................... 9

Streamflow and Stage Monitoring .................................................................................................... 9

Hydrologic Conditions During the Monitoring Period ........................................................................... 12

Observations at Site 16.4 ........................................................................................................................... 15

Channel Morphology ......................................................................................................................... 15

Bluff Erosion ....... 23

Observations at Site 12.2 ........................................................................................................................... 23

Channel Morphology ......................................................................................................................... 23

Bluff Erosion ....... 30

Future Monitoring and Suggestions for Further Study ......................................................................... 30

Summary and Conclusions ........................................................................................................................ 30

Acknowledgments ...... 31

References Cited ........ 34
iv

Figures

1. Map showing location of North Fish Creek, Wis., and eroding bluff sites 

where channel and bluff changes were monitored after installation of 

flow-deflecting vanes ................................................................................................................. 2

2. Diagram showing annual sediment budget for North Fish Creek, Wis. ............................. 3

3. Longitudinal profile for North Fish Creek, Wis., from its headwaters to mouth 

at Chequamegon Bay, Lake Superior ....................................................................................... 4

4. Flow-deflecting vanes and resulting flow vortexes, A, diagram, and B, 

photographs. . 6

5. Diagram showing changes in the channel and thalweg caused by 

flow-deflecting vanes ................................................................................................................. 7

6. Diagrams showing final layout of vane arrays and channel cross sections at A, 

site 16.4, and B, site 12.2, on North Fish Creek, Wis. ........................................................... 10

7. Photograph showing vanes being installed at site 16.4, summer 2000, North 

Fish Creek, Wis. .......................................................................................................................... 12

8. Hydrographs of instantaneous streamflow from North Fish Creek, Wis. 

streamgage: A, 1990–2003, B, April 2001, C, April/May 2002, and 

D, April/May 2003 ....................................................................................................................... 14

9. Photographs of the channel and bluff at site 16.4, 1993–2004, North Fish 

Creek, Wis. . 16

10. Photograph of block failure from eroding bluff near cross-section 5, site 16.4, 

April 27, 2001, North Fish Creek, Wis. ..................................................................................... 17

11. Photograph of damaged vanes near cross-section 6 following April 2001 flood, 

site 16.4, North Fish Creek, Wis. .............................................................................................. 17

12. Stage data from the streamgage and from the stage recorder at site 16.4, 

April 2001, North Fish Creek, Wis. ........................................................................................... 17

13. Stage data from the streamgage and from the stage recorders at sites 16.4 

and 12.2, April 2002 to September 2003, North Fish Creek, Wis. ........................................ 18

14. Photographs of North Fish Creek at sites 16.4 and 12.2 during the April 2003 

snowmelt, North Fish Creek, Wis. ........................................................................................... 19

15. Graphs showing the change in channel and bluff locations along monitored 

cross sections at site 16.4 from April 2000 to September 2003, North Fish 

Creek, Wis. .. 20

16. Photographs of the channel and bluff at site 12.2, 2001–04, North Fish 

Creek, Wis. .. 26

17. Graphs showing the change in channel and bluff locations along monitored 

cross sections at site 12.2, from August 2001 to September 2003, North Fish 

Creek, Wis. .. 27
v

Tables

1. Sequence of events for vane installation and channel and bluff monitoring 

at sites 16.4 and 12.2, North Fish Creek, Wis. ......................................................................... 5

2. Design specifications and actual values for vanes recommended from 

Odgaard and Wang and actual values used at sites 16.4 and 12.2 on North 

Fish Creek, Wis. .......................................................................................................................... 7

3. Changes in the volume of sediment from banks, streambed, and bars 

associated with cross sections at site 16.4, North Fish Creek, Wis., April 2000 

to September 2003 ..................................................................................................................... 19

4. Results from monitoring bluff-top erosion at site 16.4 from 2000 to 2003 in 

relation to previous (1994) data, North Fish Creek, Wis. .................................................... 24

5. Changes in the volume of sediment from banks, streambed, and bars 

associated with cross sections at site 12.2, North Fish Creek, Wis., June 

and August 2001 to September 2003 ...................................................................................... 26

6. Bluff erosion monitoring results for site 12.2, North Fish Creek, Wis. from 

2002 to 2003 32
vi

Conversion Factors, Vertical Datum and Abbreviated Units 

of Measurements

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3) 0.02832 cubic meter (m3) 

 Precipitation and Flow Rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

inch per hour (in/h) 2.54 centimeter per hour (cm/h)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

ton, short (2,000 lb) 0.9072 metric ton

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

 °F=(1.8×°C)+32

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29).

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

Flow-deflecting vanes were installed in the streambed along two meander bends with eroding bluffs in 2000 

and 2001 in the upper main stem of North Fish Creek, a 

tributary to Lake Superior in Wisconsin. About 45 vanes 

were arranged in 15 arrays at each site to deflect the flow 

away from the eroding toe or base of the bluff (outside of a 

bend) and toward the point bar (inside of a bend). Channel cross-section and bluff-erosion surveys were done 

and streamflow and stage were measured before, during, 

and after vane installation to monitor changes in channel 

morphology and bluff erosion in the context of hydrologic 

conditions. There were two large floods in the study area 

in spring 2001 (recurrence interval of approximately 100 

years) and in spring 2002 (recurrence intervals of approximately 50 years). Some maintenance and replacement of 

vanes were needed after the floods. Most of the channelmorphology changes resulted from the large floods, and 

fewer changes resulted from near-bankfull or at-bankfull 

flows (one in October 2002 and four in April and May 

2003). At the bluff located 16.4 river miles upstream 

of the creek mouth (site 16.4), the vanes deflected flow 

and caused the channel to migrate away from the base 

of the bluff and toward the point bar, allowing sediment 

to deposit along the bluff base. The 361-foot reach at 

site 16.4 had a net gain of 6,740 cubic feet of sediment 

over the entire monitoring period (2000–03). Deposition 

(10,660 cubic feet) occurred mainly along the base of the 

bluff in the downstream part of the bend. Erosion occurred 

at site 16.4 along the streambed, the point bar side of the 

channel, and along a midchannel bar (1,220, 1,610, and 

1,090 cubic feet, respectively). Less channel migration 

was observed during 2001-03 at another bluff located 12.2 

river miles upstream of the creek mouth (site 12.2), which 

had a net loss of sediment through the 439-foot reach of 

2,800 cubic feet over the monitored time period. The main 

volume of sediment was lost from the bluff toe in the 

downstream part of the bend (7,100 cubic feet). Monitored 

channel-morphology changes at site 12.2 were less than 

at site 16.4, most likely because installation was done 

after the April 2001 flood, which caused major changes in 

channel morphology at site 16.4, and because the monitoring period was shorter than at site 16.4. Bluff-erosion 

data from both sites indicate that mass wasting and block 

failures from the bluff top occur episodically and will 

continue to occur for decades or more. 

Introduction

A demonstration study of the effectiveness of flowdeflecting vanes in a stream channel for reducing streambank erosion and improving aquatic habitat was done on 

North Fish Creek, a Wisconsin tributary to Lake Superior 

(fig. 1). Vanes are vertical plates that are installed on a 

streambed at specific angles and designed to deflect the 

flow in a bend away from the base of an eroding bank. The 

monitoring and installation of the vanes was done through 

the cooperative efforts of the Wisconsin Department of 

Natural Resources (DNR), Civil and Environmental Engineering (CEE) Department of the University of Wisconsin 

(UW)-Madison, U.S. Fish and Wildlife Service (USFWS), 

and U.S. Geological Survey (USGS). 

North Fish Creek is similar to many northern Wisconsin tributaries to Lake Superior in providing some of the 

highest sediment loads observed in the Great Lakes (Rose 

and Graczyk, 1996; Robertson, 1996). Results from a 

historical geomorphic study of North Fish Creek (Fitzpatrick and others, 1999) indicated that the majority of the 

total sediment load of North Fish Creek (67 percent, about 

Monitoring Channel Morphology and Bluff Erosion 

at Two Installations of Flow-Deflecting Vanes, 

North Fish Creek, Wisconsin, 2000–03

By Faith A. Fitzpatrick, Marie C. Peppler, Heather E. Schwar, John A. Hoopes1, and Matthew W. Diebel

1 University of Wisconsin-Madison, Civil and Environmental 

Engineering Department
15,000 tons per year) originates from 17 eroding bluffs, 

60 to 160 ft high, along meander bends through the upper 

main stem (fig. 2). Channel down-cutting (incision) also 

is a problem along the upper main stem and contributes 

18 percent of the total sediment load. Upland erosion only 

contributes a small amount of sediment to the main stem (5 

percent) because the watershed is mainly forest and grassland (fig. 1). Even though the amount of upland erosion is 

small, flood peaks are possibly 2.5 times higher and runoff 

volumes larger than when the watershed was completely 

forested before European settlement (Fitzpatrick and others, 1999). Bluff erosion occurred before European settlement, but appears to be accelerated because of increased 

flood peaks, runoff volumes, and related channel incision 

rates (Fitzpatrick and others, 1999).

The upper main stem of North Fish Creek is an 

important fishery resource for native brook trout and 

introduced potamodromous Coho salmon and steelhead. 

(Potamodromous means that the fish species live entirely 

within freshwater systems and exhibit seasonal return 

movements to spawning areas, usually located upstream 

in rivers.) Upstream controls on bluff erosion were needed 

to reduce downstream sediment transport (potential scour 

effects) and sedimentation (covering of spawning beds). 

Bluff failures typically are rotational or translational 

landslides but also have characteristics of debris avalanches and earth flows depending on the amount of clay 

and water content in the failing section and trees near the 

top edge of the bluff (Highland, 2004). Failures occur 

episodically and are related to flood events, freeze/thaw 

cycles, or periods of intense rainfall or snowmelt. During 

floods, the base, or toe, of the bluff is eroded by flowing 

water, which causes the bluff face to steepen and the upper 

part of the bluff to eventually fail from mass wasting and 

gravitational forces. 

Figure 1. Location of North Fish Creek, Wis., and eroding bluff sites where channel and bluff changes were monitored after 

installation of flow-deflecting vanes. 

2 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
 Past efforts to stabilize the bluffs on North Fish 

Creek through bioengineering efforts alone (using living 

plants to protect stream banks) had various success rates. 

Failures occurred because the plantings were mainly along 

the bluff toe and were covered by mass-wasted material 

from the upper part of the bluff, or were inadequate for 

stopping toe erosion along the base of the bluffs. 

Tributaries to Lake Superior are typically hard to 

access because of steep topography, lack of roads, thick 

brush and forest, and swampy valley bottoms. Techniques 

for stabilizing the bluffs and reducing erosion for these 

types of streams needed to be appropriate for remote areas 

and for minimal disturbance of the channel and spawning 

beds. The vanes were thought to be cost-effective alternatives to traditional, bank-hardening structures or other 

management techniques that would reduce flood peaks, 

such as detention basins. Vanes may be environmentally 

less intrusive because the bank is left in its natural state 

and the vanes can be installed by hand, minimizing compaction and disturbance from large earth-moving equipment.

The immediate goal of this demonstration study was 

to collect quantitative monitoring data in order to evaluate 

the capability of an instream restoration technique (flowdeflecting vanes on the streambed) to reduce bluff erosion 

along a flashy, high-energy stream. Results from this study 

will be used to guide watershed-based management decisions that are geared toward reducing erosion problems in 

other tributaries to Lake Superior, improving fish habitat 

and spawning areas, and reducing the amount of sediment 

transported downstream to Lake Superior.

Vanes were designed and installed at two eroding 

bluff sites on North Fish Creek in 2000 and 2001, mainly 

by the UW. Monitoring of channel and bluff conditions by 

the USGS and maintenance of the vanes by the UW continued through 2004 and will continue at both sites.

Purpose and Scope

The purpose of this report is to present the results 

from monitoring changes in channel morphology and bluff 

erosion following installation of flow-deflecting vanes at 

two eroding bluff sites along North Fish Creek, Wisconsin. Results from the monitoring data are grouped by site 

and mainly cover the period 2000–03. Channel and bluff 

changes are described in the context of hydrologic conditions. Changes in channel morphology (based on changes 

in cross-section profiles) were quantified in terms of volume of sediment removed or deposited from the point bar, 

streambed, bars, and bluff toe. Occurrence of block failure 

from the top of the bluffs also was monitored.

Description of Study Area

North Fish Creek generally flows from southwest to 

northeast, emptying into a coastal wetland at the head of 

Chequamegon Bay, Lake Superior, approximately 1 mi 

west of Ashland, Wis. The drainage area of North Fish 

Creek at its mouth is approximately 47 mi2 (surface-watercontributing area only). Average annual precipitation is 30 

in., with 16 in. of average annual evapotranspiration and 

14 in. of runoff (Young and Skinner, 1974). Mean daily 

maximum air temperatures range from 22oF in January to 

78oF in July (Eichenlaub, 1979). In 1992–93, land cover 

in the basin consisted of 58 percent forest, 31 percent pasture/grassland, 5 percent wetland, 3 percent cropland, and 

3 percent barren (Reese and others, 2002). 

The meandering reach along North Fish Creek with 

eroding bluffs extends from about river mile 10 to 18 (fig. 

1). The two monitored eroding bluff sites are at river miles 

16.4 and 12.2 (drainage areas of 19.8 and 25.1 mi2, respectively). A streamgage (USGS station number 040263491) 

is on North Fish Creek at river mile 10.5 (drainage area of 

38.3 mi2) at the downstream end of the reach with eroding 

bluffs. 

Surficial deposits in the North Fish Creek Basin consist mainly of clayey, lake-modified glacial deposits associated with the Miller Creek Formation (Clayton, 1984). 

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Figure 2. Annual sediment budget for North Fish Creek, Wis. 

(Fitzpatrick and others, 1999). All inputs and outputs are in 

tons per year. Arrow thickness is proportional to the amount of 

sediment input or output.

Introduction 3
The basin is rimmed on the northern and western side by 

sand and (or) sand and gravel associated with nearshore, 

wave-modified deposits from high stages of Lake Superior 

following deglaciation of the region (Clayton, 1984). Discontinuous sand, gravel, silt, and clay deposits associated 

with the Copper Falls Formation are present beneath the 

Miller Creek clay and are exposed in many of the 100-fthigh eroding bluffs. Soils developed in the Miller Creek 

clay have low infiltration rates (median of 0.1 in/h; Krug 

and others, 1992). The low infiltration rates result in high 

runoff rates. Sandy deposits exposed in the eroding bluffs 

are noncohesive and particularly prone to collapse. The 

instability of the bluffs is aggravated by seeps and springs 

along the base of the bluffs. 

The eroding bluffs along North Fish Creek are in a 

steep, incised reach of the stream that cuts through waveplaned topography associated with higher levels of Lake 

Superior following deglaciation (fig. 3) (Clayton, 1984). 

The slope in this reach averages 37 ft/mi or 0.7 percent. 

Substrate in the eroding-bluff reach changes from boulder/cobble/sand in upstream areas to cobble/gravel/sand in 

downstream areas. This reach is used by coho salmon and 

steelhead for spawning (fig. 3) (Dennis Pratt, Wisconsin 

Department of Natural Resources, oral commun., 2004). 

Before European settlement in the late 1800s, the entire 

length of North Fish Creek was populated by native brook 

trout. Brook trout currently are found only in headwater 

reaches and tributaries (Dennis Pratt, Wisconsin Department of Natural Resources, oral commun., 2003). 

Methods

The study began when vanes were installed at site 

16.4 in summer 2000 (table 1). Out of the 17 documented 

eroding bluffs, this site had the most previous data (channel cross-section and bluff surveys and profile of bluff stratigraphy; Fitzpatrick, 1998), and the best access (located 

near U.S. Highway 2 and on public land). In 2001, vanes 

were installed at a second site 4.2 mi downstream from site 

16.4 at site 12.2. The eroding bluff at site 12.2 was similar 

in size to the eroding bluff at site 16.4; site 12.2 had an 

actively eroding toe and also was on public land. No previous data were available for site 12.2. 

Channel cross-section and bluff surveys began before 

vane installation (site 16.4) or during vane installation 

(site 12.2) (table 1). The streamgage at river mile 10.5 was 

reactivated in June 2000 to monitor streamflow during the 

study. In addition, stage recorders were installed at each 

site to monitor at-site changes in water depth. Channel 

cross-section and bluff surveys were done two to three 

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Figure 3. Longitudinal profile for North Fish Creek, Wis., from its headwaters to mouth at Chequamegon Bay, Lake Superior. 

(Altitude and distance data generated from U.S. Geological Survey 7.5-minute topographic maps.)

4 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
times a year after vane installation, depending on the timing of floods. 

Vane Design, Layout, and Installation

The detailed design and layout of the vanes for each 

site is given in Whitman (2002). A summary of the design 

and layout follows here. 

Vanes are vertical plates that protrude from a streambed about one-third of the bankfull depth, are oriented at 

an angle to the local stream velocity, and are distributed in 

arrays (groups) along part of the channel. When the vanes 

are submerged, they induce a transverse force and torque 

on the flow and cause a longitudinal vortex at their tops 

(fig. 4); this vortex is similar to the vortex from the wingtip 

of an airplane. This modified flow field causes (1) erosion 

of the streambed on the side opposite the angle of the vane 

into the flow and (2) deposition of sediment carried by the 

flow (and eroded from the bank) on the other side. Two 

small horseshoe vortexes near the bed cause local scour 

(the extent depends on the angle of the vane into the flow). 

In a bend, the vane-induced torque and tip vortexes from 

the arrays of vanes counter the secondary flow caused by 

the bend. Erosion of the streambed by these tip vortexes 

moves the thalweg away from the outside of the bend (cut 

bank) and toward the point bar, causing the channel radius 

to increase (flattening the bend) and channel cross sections 

to become more symmetrical (fig. 5). Thus, placing arrays 

of vanes along the outside of a bend causes sedimentation 

at the toe of the cut bank, which prevents further undercutting and helps to stabilize the bank (Whitman, 2002). 

Eventually, the vanes are buried by depositing sediment.

Vane dimensions and layout for the two North Fish 

Creek sites were based upon previous experiments and 

field studies, mainly those done by Odgaard and others at 

the Iowa Institute of Hydraulic Research (IIHR) (Odgaard 

and Kennedy, 1983; Odgaard and Mosconi, 1987; Odgaard 

and Wang, 1991a,b). The design procedure in Odgaard and 

Wang (1991b) was used to plan the size, shape, number, 

and layout of the vanes for the two North Fish Creek sites 

(table 2). Specific data needed for the design included 

bankfull depth and channel geometry and planform. Previous data (Fitzpatrick, 1998) and data from the April 2000 

field survey for bankfull depth and channel geometry and 

planform were used to determine the height and width of 

the vanes at site 16.4. For site 12.2, channel cross-section 

Table 1. Sequence of events for vane installation and channel and bluff monitoring at sites 16.4 and 12.2, North Fish Creek, Wis.

Date Event Site 16.4 Site 12.2

July 1994 Bluff-top survey 

April 2000 Channel cross-section survey 

July 2000 Streamgage reactivated

Summer 2000 Vanes installed 

August 2000 Bluff-top survey 

March 2001 Stage recorder installed 

April 2001 75- to 100-year flood

April 2001 Channel cross-section survey 

June 2001 Channel cross-section survey 

July 2001 Bluff-top survey, vane maintenance 

August 2001 Channel cross-section survey 

Summer 2001 Vanes maintained and some replaced 

September/October 2001 Vanes installed 

April 2002 Stage recorders installed 

May 2002 Channel cross-section and bluff-top surveys, vanes maintained  

August 2002 Channel cross-section and bluff-top surveys  

January 2003 Channel cross-section survey  

April 2003 Bluff-top survey  

May 2003 Channel cross-section survey  

June 2003 Bluff-top survey  

September 2003 Channel cross-section and bluff-top survey  

Methods 5
and bankfull-depth data were collected in fall 2001 just 

prior to vane installation (table 1). 

The most critical measurement for vane design is 

bankfull depth, which is used to determine vane height. A 

combination of field indicators were used to identify the 

bankfull depth and included the top of the coarse deposits associated with point bars (minimum elevation); the 

occurrence of a sharp break in slope of the bank above 

the low-flow water surface where the slope changes from 

vertical to more horizontal; changes in vegetation, such as 

a change from herbaceous to tree species; and for undercut 

banks, the top of the undercut (minimum bankfull elevation) (Harrelson and others, 1994; Fitzpatrick and others, 

1998). The vane height, in turn, is used to determine the 

vane width, lateral spacing of each vane within an array, 

streamwise spacing (longitudinal distance between arrays), 

and vane-to-bank distance. For the design, vane height was 

determined by multiplying the bankfull depth by 0.3. At 

site 16.4, the average bankfull depth was 4.6 ft; therefore, a 

typical vane height was 1.4 ft. To accommodate the uneven 

and undulating streambed at both North Fish Creek sites, 

the top of each vane was set to 0.6 times the estimated 

average bankfull depth at that section.

Design values for vane width were determined to be 2 

to 3 times vane height. For the North Fish Creek sites, the 

vane width used was 3 ft, except for some wider 4-ft vanes 

that were placed in the thalweg in a deep hole along the 

cut-bank side of site 16.4. All the vanes at site 12.2 had a 

width of 3 ft; wider vanes were not needed because there 

were no deep holes. 

In the design, lateral spacing among vanes within an 

array was determined to be 2 to 3 times the vane height. 

For the North Fish Creek sites, a spacing of 3 ft (+ 0.6 ft to 

avoid large cobbles and boulders) between vanes was used, 

which is generally 2 times the vane height. The low end of 

the recommended range was used to maximize the vortex 

effect. The number of vanes in each array was based on the 

amount of channel shift necessary to move flow away from 

the eroding bluff. 

The design angle of the vanes to bankfull flow direction can range from 13° to 40°. For the North Fish Creek 

sites, the chosen angle was 15-20° based on results from 

previous studies by Odgaard and Wang (1991a,b) and 

Hoopes and others (1999). 

Streamwise spacing of the arrays for design purposes 

was determined to be 10 to 30 times the vane height. For 

site 16.4, the streamwise array spacing was between 12 

and 15 ft. This short spacing, slightly less than the typical 

design value, tightens the vortex field and more dramatically disrupts the horizontal circulation of flow through 

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Figure 4. Flow-deflecting vanes and resulting flow vortexes, 

A, diagram (modified from Whitman, 2002), and B, photographs.

6 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 5. Changes in the channel and thalweg caused by flow-deflecting vanes (modified from Whitman, 2002).

Table 2. Design specifications and actual values for vanes recommended from Odgaard and Wang (1991b) and actual values 

used at sites 16.4 and 12.2 on North Fish Creek, Wis. 

[X, times; °, degree; ft, foot]

Vane parameter Design specifications 

(Odgaard and Wang, 1991b)

Site 16.4 

actual values

Site 12.2 

actual values

Height 0.2 to 0.4X average bankfull depth 0.3X average bankfull depth 

at the array location

0.3X average bankfull depth 

at the array location

Width 2–3X vane height 3 ft (4 ft in deep hole) 3 ft

Lateral spacing 2–3X vane height 3 ft (±0.6 ft to avoid obstacles) 3 ft (±0.6 ft to avoid obstacles)

Angle to estimated 

bankfull flow pattern

13–40° 15–20° 15–20°

Streamwise spacing of 

array

10–30X vane height 12–15 ft (to avoid obstacles) 20 ft (±3 ft to avoid obstacles)

Vane-to-bank distance Not to exceed 1–4X vane height Close to bank or on bank if 

possible

Close to bank or on bank if 

possible

Number of vane arrays Enough to cover entire meander 14 15

Total number of vanes About 20 vanes placed in arrays 

along entire meander

43 49

Methods 7
a bend (Odgaard and Wang, 1991a). The array spacing at 

site 12.2 was about 20 ft because the channel is narrow 

(less than 30 ft wide) through the sharply angled bend and 

a smaller streamwise spacing would cause the arrays to be 

close to each other along the point-bar side of the channel. Additional single vanes and a vane array were added 

later to the reach on the cut bank side between arrays. The 

streamwise spacing varied slightly at both sites to avoid 

immovable obstacles, such as large boulders. 

Design values of vane-to-bank distance should not 

exceed 1 to 4 times the vane height. For both North Fish 

Creek sites, a small vane-to-bank distance was used, similar to that in the vane study done on Pheasant Branch, Wis. 

(Hoopes and others, 1999). Vanes were placed as close to 

a bank as possible—or on the bank if possible—to make 

sure that the flow would not cut around the vanes and 

erode more of the bluff toe. 

The length of the bend determined the number of 

arrays because the arrays should extend through the 

entire bend. Site 16.4 had 14 arrays and site 12.2 had 15 

arrays. The arrays extend through the bends at both sites, 

upstream and downstream from the eroding bluffs (fig. 

6). The total number of vanes (including those buried or 

removed) in September 2003 was 43 at site 16.4 and 49 

at site 12.2. The number of vanes in each array was based 

on the amount of channel shift necessary to achieve the 

desired channel alignment away from the bluff. More 

vanes were used in the center of the bends and through the 

bends by the toe of the eroding bluff. 

The vanes were installed under normal flow conditions at both sites. Installation of the vanes at site 16.4 

started in summer 2000 and was completed in summer 

2001. Installation of the vanes at site 12.2 started in 

September and October 2001 and continued into summer 

2003. 

Complete installation plans and procedures are given 

by Whitman (2002). Materials and tools needed for the 

construction of the vanes were carried into each site. The 

vanes were cut onsite to the correct size from 4-ft by 8-ft 

sheets of 0.375-in.-thick, white, high-density polyethylene (HDPE). The vanes were held in place by driving two 

0.75-in.-diameter steel reinforcing bars into the streambed 

about 2 to 3 ft and fastening the vanes to the bars with Ubolts (fig. 7). 

Updates were made to the vane layout at site 12.2 in 

summers 2002 and 2003. Some vanes had to be replaced 

after floods in 2001, 2002, and 2003. Not every vane 

or array that was designed was installed, owing to local 

obstacles in the channel such as boulders, logs, or bed 

features. 

Channel Cross-Section Surveys and 

Sediment Volume Estimates

Eight channel cross sections were established at site 

16.4 in 2000 and five cross sections were established at 

site 12.2 in 2002 (fig. 6, table 1). The most upstream and 

downstream cross sections were just outside the arrays 

(fig. 6). The cross sections are perpendicular to the estimated bankfull channel and extend into the flood plain on 

the point-bar side and up the eroding bluff to elevations 

above bankfull. Steel reinforcing bars were driven into 

the ground at the endpoints of each transect (at the top of 

the bluff along the steep, eroding part of the bluff) and 

also were used for benchmarks. Multiple benchmarks are 

located on the point bar and bluff sides of the stream at 

both sites. Surveys were done with an electronic theodolite 

(Harrelson and others, 1994). Subsequent surveys were 

referenced to the same coordinate system by initially 

setting up the theodolite over a known base point and 

backsighting to a known benchmark. Each transect was 

surveyed with 20 to 30 points, a number adequate to detect 

small changes in bank and channel elevations.

Northing and easting coordinates were transformed 

into distances along a cross section by use of the following 

equation

where

dt is the distance along a cross section from the transect endpoint,

xe is the easting coordinate of the transect endpoint,

xs is the easting coordinate of the survey point,

ye is the northing coordinate of the transect endpoint, and 

ys is the northing coordinate of the survey point.

This transformation allowed subsequent surveys to 

be overlain for display of cross-section change and for 

calculation of sediment fluxes The midchannel distance 

between the upstream and downstream cross sections is 

361 ft at site 16.4 and 439 ft at site 12.2.

The volume of sediment lost and gained along the 

banks, bed, and bars from each site was estimated by quantifying the differences in cross-section profiles before and 

after the vanes were installed. Surveys done in September 

2003 were compared to those done in April 2000 for site 

16.4 and surveys done in September 2003 were compared 

to those done in May 2002 for site 12.2. Profile data from 

the selected surveys from each cross section were plot-

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8 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
ted on graphs with equal horizontal and vertical scales. 

The cross-section profiles were hand digitized, and area 

changes between the two surveys were calculated by use 

of a geographic information system. Area estimates were 

converted to volume estimates by multiplying the respective area by the representative left-bank, midchannel, and 

right-bank distances between each cross section. These 

lengths were estimated as the sum of half the distance to 

the next upstream cross section and half the distance to the 

next downstream cross section.

Bluff Erosion Monitoring

In 1994 during a geomorphic assessment of North 

Fish Creek (Fitzpatrick, 1998; Fitzpatrick and others, 

1999), eight reference points were established on the 

upland surface along the top of the eroding bluff at site 

16.4 to monitor mass wasting (slumping) from the top 

overhanging edge of the eroding bluff. The reference 

points were evenly spaced from the upstream to downstream side above the actively eroding part of the bluff 

(fig. 6), where there was little or no vegetation. A perpendicular distance was measured from the reference point to 

the bluff edge (first occurrence of a slope break or edge in 

the upland surface), and the azimuth of the measurement 

line recorded so that subsequent measurements could be 

done along the same line. All the reference points from 

1994 were found in good condition in 2000 and were used 

as a basis for monitoring bluff erosion at site 16.4 (table 

1). At site 12.2, nine reference points were established 

along the bluff top in 2002 in the same fashion as at site 

16.4 (table 1). 

Measured over time, the perpendicular distances 

measured are used to determine when and where blocks of 

upland material are lost from the top edge of the bluff. If 

blocks of soil are lost, the distances become shorter. Distances also may become slightly longer over time because 

the number and width of tension cracks may increase and 

soil may creep before a block failure. Tension cracks, 

slumping, and soil creep were common features along the 

top edge of the bluffs at both sites.

Streamflow and Stage Monitoring

Stage (water-surface elevation) was recorded at the 

streamgage at river mile 10.5 starting in June 2000 and 

is ongoing (table 1). Historical stage data (1990–91 and 

1994–97) were available for the streamgage. Stage data 

were collected continuously at 15-minute intervals. North 

Fish Creek remains ice-free during winter months at the 

streamgage because of the close proximity of springs 

and high base flow. Discharge (flow) measurements 

were made at a variety of stages throughout the year by 

use of standard USGS methods (Buchanan and Somers, 

1984). Empirical relations between stage and flow were 

determined (a rating curve), allowing flow to be directly 

determined from stage. These data were used to monitor 

hydrologic conditions, particularly the size of resulting 

floods after the vanes were installed. Peak flows from runoff events measured at the North Fish Creek streamgage 

from 2000 to 2003 were compared to peak flows from 

two nearby USGS streamgages with longer records—the 

Bois Brule River (25 mi west, drainage area of 118 mi2, 

1942–2003), and the Bad River (20 mi east, drainage area 

of 597 mi2, 1914–22, 1948–2003). Peak flows from the 

crest-stage partial-record station on the Sioux River (10 mi 

northeast, drainage area of 13.6 mi2, 1959–2003) also were 

compared to North Fish Creek.

Remote stage recorders with data loggers also were 

installed at both vane sites to monitor local changes in 

stage. At site 16.4, a submersible pressure transducer was 

installed just downstream from cross-section 4 on the 

point-bar side of the channel between vane arrays 7 and 

8 in late March 2001 (fig. 6). This stage recorder had an 

arbitrary altitude of about 99.15 ft and measured stage at 

30-minute intervals from March 20 to May 15, 2001. The 

recorder filled with sediment and stopped working after 

the record April 23, 2001 flood and was replaced by a 

second pressure transducer, with data-collection intervals 

of 1 hour from June 19, 2001, to April 3, 2002; 15 minutes 

for spring and summer, and 1 hour for fall and winter from 

April 4, 2002, to September 22, 2003. 

At site 12.2, two stage recorders were installed on 

April 4, 2002, at the upstream and downstream ends of the 

vanes reach (fig. 6). The stage recorder at the upstream end 

was a submersible pressure transducer (the repaired unit 

used in April 2001 at site 16.4) and was installed on the 

left side of the channel near cross-section 1 and upstream 

from vane array 1. The intake orifice on the pressure transducer had an arbitrary altitude of 99.45 ft in May 2002. 

The downstream recorder was a capacitance probe that was 

installed on the point-bar side near vane array 15 between 

cross-sections 4 and 5 on the right side. The arbitrary 

altitude of the capacitance probe was 98.89 ft. Data were 

recorded at 15-minute intervals for the pressure transducer 

and 1-hour intervals for the capacitance probe from April 

2002 to September 2003. The capacitance probe was used 

as a backup for the pressure transducer and for potentially 

calculating water-surface slope at various stages through 

the reach. 

Methods 9
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Figure 6. Final layout of vane arrays and channel cross sections at A, site 16.4, and B, site 12.2, on North Fish Creek, Wis. (modified from Whitman, 2002).

10 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 6. Final layout of vane arrays and channel cross sections at A, site 16.4, and B, site 12.2, on North Fish Creek, Wis. (modified from Whitman, 2002)—Continued.

Methods 11
Hydrologic Conditions During the 

Monitoring Period

The North Fish Creek streamgage was operated 

sporadically over 14 years from 1990 to 2003. About 6 

years of data were missing from two periods, October 

1991 to September 1994 and October 1997 to May 2000. 

During the 8-year combined period of available streamflow data (1990–91, 1995–97, and 2000–03), 17 flows 

greater than 900 ft3/s (stage of 10.0 ft and considered to 

be bankfull flow) were recorded (fig. 8A). Most of these 

flows occurred in the spring months; some were as little 

as 2 days apart, such as in April 2001 and April 2002, and 

others were about 1 year apart, such as from April 2001 to 

April 2002 (figs. 8A-D). The clustering of multiple floods 

within short spans of time within a year made it necessary 

to examine hydrographs based on stage data collected at 

15-minute intervals. Because of the flashiness of North 

Fish Creek, use of annual time series or mean daily flow 

data would not have been adequate for monitoring and 

describing hydrologic conditions before, during, and after 

vane installation.

 Streamflows larger than 1,520 ft3/s (stage of 12.0 ft 

and considered a flood by the National Weather Service) 

included two in 1991, four in 1996 (one in April and three 

clustered closely at the end of June and beginning of July), 

four in April 2001, and two in April/May 2002 (figs. 8AC). These floods were caused by spring snowmelt, spring 

snowmelt combined with rainfall, and rainfall alone in the 

spring, summer, and fall. The typical duration for a flood 

from a single summer rainstorm is only about 2 days, with 

stages rising and falling sharply in less than 12 hours (figs. 

8B-D). The hydrograph for April 10–18, 2002 (fig. 8C), 

reflects a combination of rainfall on snow (large peak) followed by snowmelt (smaller diurnal peaks). 

A closer look at the spring floods from 2001 to 2003 

gives an indication of the type of events that occurred after 

the vanes were installed (fig. 8B-D). After the vanes at 

site 16.4 were installed in summer 2000, a small rainstorm produced a below-bankfull flow of about 500 ft3

/s 

in November 2000 (fig. 8A). The next flood was in April 

2001 (fig. 8B), a record flood with an estimated recurrence 

interval of close to 100 years, based on flood-frequency 

regression equations for rural Wisconsin streams (Walker 

and Krug, 2003). On April 23, 2001, snowmelt combined 

with rainfall produced a peak flow of 3,420 ft3/s. This 

flood occurred 9 months after vanes were installed at site 

16.4 and 5 months before the vanes were installed at site 

12.2. The snowmelt with rainfall that caused this flood on 

North Fish Creek also caused the largest recorded floods in 

the Brule and Sioux Rivers, but flooding on the Bad River 

corresponded to only a 5- to 10-year recurrence interval 

(Walker and Krug, 2003). No floods occurred during the 

rest of 2001 (fig. 8A). 

On April 11, 2002, a sequence of events similar 

to those that produced the April 2001 flood produced a 

peak flow of 2,290 ft3/s at the streamgage (fig. 8C). This 

flood had an estimated recurrence interval of 25–50 years 

(Walker and Krug, 2003). Two days later, additional rain 

on snow produced a second flow of about 1,500 ft3/s. 

April 2002 floods on the Brule, Sioux, and Bad Rivers 

were smaller than on North Fish Creek and had recurrence 

intervals of 5–10 years (Walker and Krug, 2003). As in 

2001, no floods occurred in summer and fall 2002 (fig. 

8A), except for an October rainstorm that produced a flow 

of about 1,000 ft3/s. 

Peak flows for North Fish Creek in spring 2003 were 

small compared to spring 2001 and 2002, with no flows 

near flood stage (fig. 8A). Flows of 1,000 and 800 ft3/s 

occurred in April (the first from a fast snowmelt without 

rainfall and the second from a rainstorm), and two more 

rainfall-related flows of 1,300 to 1,000 ft3/s occurred in 

May (fig. 8D). Summer and early fall 2003 were flood free 

(fig. 8A).

Figure 7. Vanes being installed at site 16.4, summer 2000, 

North Fish Creek, Wis. (Installer is David Poggi, University of 

Wisconsin-Madison).

12 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 8. Hydrographs of instantaneous streamflow from North Fish Creek, Wis. streamgage: A, 1990–2003, B, April 2001, 

C, April/May 2002, and D, April/May 2003. 

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Hydrologic Conditions During the Monitoring Period 13
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Figure 8. Hydrographs of instantaneous streamflow from North Fish Creek, Wis. streamgage: A, 1990–2003, B, April 2001, 

C, April/May 2002, and D, April/May 2003—Continued.

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14 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
Observations at Site 16.4

A series of photographs of the channel and bluff 

at site 16.4 show how the site changed over 10 years in 

response to floods and the presence of the vanes (fig. 9). 

Photographs at site 16.4 extend back 7 years before the 

vanes were installed because the site was part of the previous geomorphic assessment of North Fish Creek (Fitzpatrick, 1998). Before vane installation, the face of the bluff 

changed over time as blocks of the top and upper part of 

the bluff failed, and failed debris built up along the bottom 

half of the bluff during low-flow periods between large 

floods (June 1994 as an example). During large floods, 

such as the April 1996 flood, loose sediment was removed 

from the lower half and toe of the bluff, making the bluff 

face more vertical (November 1996 as an example). The 

channel migrated toward the eroding bluff from 1993 to 

2000 and formed a midchannel bar by 2000.

In April 2001 during the record flood event, a block 

failure occurred from the top of the bluff near cross-section 5 (figs. 9 and 10). The block remained at the toe of 

the bluff and was not washed away during the flood or any 

subsequent floods through September 2003. Boulders also 

fell from the upper half of the bluff and hit some of the 

vanes, bending them out of alignment (fig. 11). The damaged vanes were replaced in summer 2001.

Water levels at site 16.4 increased about 4 ft above 

normal stage during the April 2001 flood (fig. 12). After 

the flood, trash lines from the flood were observed in trees 

about 5 ft above normal stage. The stage reached an elevation of about 3.4 ft above the top of the vanes (Whitman, 

2002). The stage recorder data also showed a rise in the 

channel bottom at the recorder location (inside of the bend 

near cross-section 4). The normal stage rose from between 

-1 and 0 ft in early April, to 0 ft by mid-April, and then 

to almost 1 ft after the April 23 flood. The stage recorder 

filled with sediment and stopped recording at the end of 

April. 

At the streamgage 5.9 mi downstream, the stage 

increased 10 ft during the April 2001 flood from a normal level of about 7 ft to 17 ft. Stage increases at the 

streamgage are about 2.5 times those at site 16.4 because 

the drainage area at the streamgage is larger and the valley 

is constricted near the gage by a roadway embankment and 

bridge. During the April 2002 flood, the stage rose 3 ft at 

site 16.4, with a corresponding rise in stage of more than 7 

ft at the streamgage (fig. 13). Whitman (2002) determined 

from correlation analysis that stage at the streamgage 

lagged about 2 hours behind stage at site 16.4.

After the April 2001 flood, the bluff toe appeared 

to extend into the channel more than before the flood, 

and mass-wasted material from the top part of the bluff 

accumulated along the bluff toe. The channel had migrated 

toward the point-bar side, concurrent with erosion of the 

midchannel bar. A photo taken during the April 2003 

snowmelt event (fig. 14) shows a natural foam trail 

(marking the center of flow) along the point-bar side and 

away from the bluff toe. The photo was taken on April 

10, 2003, at 9 a.m. (a point on the rising limb of the flood 

hydrograph) at a stage of approximately 0.9 ft on the stage 

recorder.

Channel Morphology

Results from surveys of the eight cross sections at 

site 16.4 from April 2000 to September 2003 are shown 

in figure 15. Similar to the photographs, the time series 

of cross sections also show channel migration toward the 

inside of the bend and point bar (left bank) after the April 

2001 snowmelt/rainfall event. This event produced the 

most channel migration. From 2000 to 2003, erosion was 

measured on the inside of the bend and deposition was 

measured on the toe of the eroding bluff at cross-sections 

1, 3, 4, 5, and 8. The channel location remained relatively constant at cross-section 2. Some material was lost 

from the lower part of the bluff at cross-section 4, but the 

bluff toe gained material. Erosion of the midchannel bar 

(upstream end) is shown in cross-section 5. At cross-section 6, no point-bar erosion was measured, but deposition 

was measured on the bluff toe. The channel at cross-section 7 became narrower and deeper, with some deposition 

on both sides. 

Results from calculations of the volume of sediment 

eroded and deposited along each cross section from April 

2000 to September 2003 are shown in table 3 for site 16.4. 

Approximately 1,610 ft3 of sediment was eroded from the 

point-bar side of the channel, and 10,660 ft3 of sediment 

was deposited at the base of the eroding bluff over the 361-

ft long reach. The channel morphology at cross-section 5 

changed the most of all the cross sections. This cross section is near where a block from the bluff top failed and was 

deposited at the base of the bluff during the April 2001 

flood (fig. 10). Assuming that the density of the sediment 

(a mixture of sand, silt, and clay) is 80 lb/ft3 (U.S. Department of Agriculture Soil Conservation Service, 1983), 

about 425 tons of sediment was deposited along the bluff 

toe over the 3 years that were monitored. There was a total 

net gain in sediment in the monitored 361-ft reach of 6,740 

ft3, or about 270 tons. This gain indicates that sediment 

Observations at Site 16.4 15
Figure 9. Photographs of the channel and bluff at site 16.4, 1993–2004, North Fish Creek, Wis. Flow direction is from lower left to 

upper left. Photographs were taken from bluff top on the upstream side of the meander bend.

November 1993 June 1994

November 1996 May 1998

March 2000 July 2001

August 2002 May 2004

Photo by J.C. Knox

16 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
Figure 10. Block failure from eroding bluff near cross-section 5, site 16.4, April 27, 2001, North Fish Creek, Wis. 

Photograph was taken from edge of bluff top looking down at 

cross-section 5. 

Figure 11. Damaged vanes near cross-section 6 following 

April 2001 flood, site 16.4, North Fish Creek, Wis.

Figure 12. Stage data from the streamgage and from the stage recorder at site 16.4, April 2001, North Fish Creek, Wis.

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Observations at Site 16.4 17
Figure 13. Stage data from the streamgage and from the stage recorders at sites 16.4 and 12.2, April 2002 to September 2003, 

North Fish Creek, Wis.

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18 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
Figure 14. North Fish Creek at sites 16.4 and 12.2 during the April 2003 snowmelt, North Fish Creek, Wis. Photograph of site 16.4 

is from the bluff top on the upstream end of the bend looking downstream. Photograph of site 12.2 is from the bluff top on the 

downstream end of the bend looking upstream.

Site 16.4 Site 12.2

Table 3. Changes in the volume of sediment from banks, streambed, and bars associated with cross sections at site 16.4, North 

Fish Creek, Wis., April 2000 to September 2003

[A positive value (+) indicates a net gain (accretion) of sediment and a negative value (-) indicates a net loss (depletion) of sediment; na, not applicable]

Cross section

Volume of sediment moved (cubic feet)

Left bank (point bar) Streambed Bar Right bank (bluff) Total

1 -676 +375 na +168 -133

2 -63 -238 na +278 -23

3 -353 -3 na +736 +381

4 -158 -191 na -1,409 -1,757

5 -364 -448 -924 +6,839 +5,103

6 +111 -299 +40 +3,074 +2,926

7 +188 -351 -202 +491 +125

8 -299 -69 na +485 +117

Total -1,614 -1,223 -1,086 +10,663 +6,740

Observations at Site 16.4 19
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Figure 15. Change in channel and bluff locations along monitored cross sections at site 16.4 from April 2000 to September 2003, North Fish Creek, Wis.

20 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 15. Change in channel and bluff locations along monitored cross sections at site 16.4 from April 2000 to September 2003, North Fish Creek, Wis.—Continued

Observations at Site 16.4 21
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Figure 15. Change in channel and bluff locations along monitored cross sections at site 16.4 from April 2000 to September 2003, North Fish Creek, Wis.—Continued

22 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
from upstream sources was deposited in the reach. In addition, the reach is less of a potential source of sediment to 

downstream reaches, as shown in the series of photographs 

of the reach and bluff from before and after vane installation (fig. 9).

Bluff Erosion

Surveys of the distances from eight reference points 

along the upland to the top edge of the bluff originally 

were done in 1994, during the geomorphic study of North 

Fish Creek (Fitzpatrick, 1998). These points were along 

the part of the bluff with minimal to no vegetation (longitudinal distance, measured along the top edge of the bluff, 

is about 300 ft). Distances from the reference points to the 

bluff edge were measured seven times from 2000 to 2003 

(table 4). Negative changes in distance reflect a loss of 

material from the bluff top. The results from the surveys 

only were useful for determining the occurrence of large 

block failures from the top of the bluff because accuracy of 

the measurements was approximately 1.5 ft. 

Between 1994 and 2000, before vane installation, a 

13.5-ft piece of the bluff top failed near the downstream 

end of the eroding bluff at reference point T8. Two points 

had differences in distance of 1.7 and 2.3 ft (T7 and T5, 

respectively) that may indicate small block failures from 

the bluff top. Two additional points had negative differences for 1994–2000 but were in the possible range of 

measurement error. Reference point T6 had a positive distance change; the top of the bluff is slumped at this location with some small breaks in slope, making it difficult to 

pinpoint the exact edge of the bluff top.

After vane installation, two blocks from the top of 

bluff failed, one during the April 2001 flood at T9 and 

another between April and June 2003 at T11. No other 

large block failures were measured; however, the nearvertical angle of the bluff face, tension cracks on the bluff 

top, rills along the bluff face, and overhanging vegetation 

on the downstream side of the bluff from T6 to T9 make it 

highly probable of more failures in the future. 

A slope-stability model and a bank-toe-erodibility 

model were done for site 16.4 by Whitman (2002). Results 

indicated that the top part of the bluff is stable as long as 

the water table is greater than 33 ft below the bluff top. 

Model results also indicated that the bluff toe erodes even 

at low flow. The bluff may fail at flows with a corresponding stage more than 6.6 ft. Model-simulation results 

indicate that in order for the bluff to stabilize, the toe needs 

to be protected and built out so that slumped materials 

will remain in place. Flow-deflecting vanes appear to be 

an adequate technique at this site for protecting the toe by 

causing the channel to move toward the point bar. Additional monitoring of the water table would be needed to 

verify model-simulation results.

Observations at Site 12.2

No previous geomorphic study was done at site 12.2, 

so the time period for the photos is much shorter than that 

for site 16.4 and starts in June 2001 (fig. 16). The photo 

vantage points at this site are not as encompassing or consistent as the vantage points at site 16.4. The photos show 

the upstream part of the bluff and bed. The eroding bluff 

face was virtually vertical to slightly convex from 2001 to 

2003, with minimal or no vegetation. Rills were common 

in the face of the bluff, and the toe of the bluff was eroded.

After installation, two floods occurred that were 

greater than bankfull (in April and May 2002) and five 

floods occurred that were near bankfull (one in October 

2002 and four in April and May 2003). During the first 

flood on April 11, 2002 (fig. 8), the stage at site 12.2 rose 

4 ft above normal levels (fig. 13) compared to 3 ft at site 

16.4 and 7 ft at the streamgage. As stated earlier, the April 

2002 flood had a probability of occurrence of roughly 

2 percent (recurrence interval of 50 years). The April 5, 

2002, photo of the bluff was taken before the flood event 

(fig. 16). 

The series of four floods in April and May 2003 were 

near or at bankfull. The stage rose about 2 ft during these 

events, compared to just below 2 ft at site 16.4 and about 4 

ft at the streamgage. A photo taken during the first of these 

floods (April 10, 2003; from rapid snowmelt) shows the 

center of flow (concentration of natural foam) toward the 

left side of midchannel on the upstream side of the bluff, 

but near the eroding bluff toe at the downstream end of 

the bluff (fig. 14). This result was an indication that more 

vanes probably were needed. Vanes were added in array 

14 and between arrays 8 and 9, 9 and 10, and 10 and 11 

in summer and fall 2003. In addition, a vane was removed 

from array 15. 

Channel Morphology

Results from the survey of the five cross sections at 

site 12.2 from June and August 2001 to September 2003 

are shown in figure 17. The April and May 2002 floods 

caused erosion along the channel (left bank) at cross-section 1, deposition along the channel (left bank) at crosssection 2, erosion of the bluff toe at cross-section 4, and 

Observations at Site 12.2 23
Table 4. Resul 

[A negative change in distance over time (-) indicates loss of sediment; a positive change in distance over time (+) indicates soil creep or expansion of tension cracks; ft, feet; ns, not surveyed; veg, vegetation; lg, large; %, percent; in, inch; diam, diameter; us, upstream; ds, downstream]

Reference 

points T3 T4 T5 T6 T7 T8 T11 T9

July 1994Distance (ft) 54.5 95.1 77.8 63.3 68.6 69.9 ns 65.0August 2000Distance (ft) 53.1 94.5 75.5 68.2 66.9 56.4 ns 65.0July 2001Distance (ft) 53.5 95.1 76.4 70.5 64.6 56.7 78.4 51.2Remarks No erosion No erosion No erosion Bluff slumped 

at top, hard to define edge

Us near lg block 

failure from 4/01 storm

Us near lg block 

failure from 4/01 storm, previous failure prior to 8/00

Very unstable, 1-ft 

diam ash leaning and ready to fall, 3-ft us is source of block failure

Center of lg 

failure block from 4/01 storm

May 2002Distance (ft) 53.5 93.5 76.1 69.6 65.9 56.8 78.4 50.9Remarks Stable, no loss 

of banks, vegetated

Some washout directly beneath 

bluff, mainly vegetated

Fir just below 

slope break, mainly vegetated

Unstable, toe 

eroded, few pieces of veg

Unstable, recent 

loss of block, no toe, no veg

Unstable angle, no 

veg, toe present

Very unstable, 

vertical drop

Very unstable, toe 

is building

August 2002Distance (ft) 53.8 91.5 76.8 68.6 66.3 57.4 78.1 50.9Remarks No erosion Some washout directly beneath 

bluff, 50% vegetated, stable toe, slump

50% vegetated, 

stable toe, overhanging top

Sparse veg, seeps 

at the toe, unstable bluff angle

No change Rills, tension cracks, 

toe with seeps and delta, unstable angle, overhang, creep

Overhanging edge, 

vertical slope, abundant rills, 2.5-in. diam fir leaning over, no veg

Similar to T11, 

rills common halfway down

April 2003Distance (ft) 53.8 92.2 76.4 68.9 65.3 57.1 79.1 51.5Remarks Bluff is snow 

covered, vegetated, same, small gully, no change

No change, 

covered in snow

Bluff same, snow 

covered, fir in same spot, overhang same

One third snow, 

overhanging edge, toe with seeps, unstable angle

Vertical bluff, 

same, no veg, toe starting to build out, toe present at near bankfull stage

Completely vertical, 

mass wasted, still has overhang, no veg, no rills, no snow, good toe, recent debris, delta from seep

Unstable, vertical, 

same rills, possible upland piece fell in, us toe looks good, chunk still at base

Vertical, no veg, 

overhanging edge, stable toe, no rills, debris pile on toe

24 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
Reference 

points T3 T4 T5 T6 T7 T8 T11 T9

June 2003Distance (ft) ns 93.5 76.8 68.2 66.9 55.4 73.5 51.5Remarks Could not find 

rebar, bluff unchanged

90% brush, 

washout directly below top, alder at top rotated out nearly horizontal

Bluff same, 

gully us slightly deeper

Same edge, 

vertical two thirds up, rills, gully just us, small pine on slump (20% vegetated) that makes upper third

Similar, 1.5 by 

6.5 ft piece of bluff at top then near vertical face to flat toe, rills, 10% vegetated

Slumped at top, near 

vertical bluff face, no veg, no rills, blocky face

Unstable, vertical, 

recent slump on upper bluff, toe has rills from runoff and seeps, mass wasted blocks near top of bluff, us 33-ft block in place, mass wasted pine growing near toe

Overhanging 

edge, near vertical bluff, no veg, blocky face, mass wasting, debris pile on toe, 43 ft ds to vegetated bluff face

September 2003Distance (ft) ns 92.9 75.1 67.9 65.9 55.1 72.8 50.5Remarks No change No change Bluff same, more 

veg on us. gully, rounded lip of veg at slope break

No change Piece of bluff top 

has fallen, toe 

developing, steep bluff face, 10% vegetated with yellow flowering plant, many rills

Overhang at top, 

near vertical face with rills, yellow flowering plant and moss grass growing from toe (20% vegetated), lg toe

Undercut at top 

bluff, mass wasted blocks near top of bluff are gone, recent mass wasting us of transect ~10 ft, pine and moss growing near toe

Recent erosion at 

top, very undercut lip, toe has recent debris covering moss/grass and veg, lots of sediment in stream, 42 ft distance ds to vegetated bluff face

Distance change (ft) before vane installation (1994-2000):

-1.4 -0.6 -2.3 +4.9 -1.7 -13.5 ns 0

Distance change (ft) after vane installation (2000-03):

1+0.7 +1.6 -0.4 -0.3 -1.0 -1.3 -5.6 -14.5

1 Calculated only through April 2003

Table 4. Results from mo [A negative change in distance over time (-) indicates loss of sediment; a positive change in distance over time (+) indicates soil creep or expansion of tension cracks; ft, feet; ns, not surveyed; veg, vegetation; lg, large; %, percent; in, inch; diam, diameter; us, upstream; ds, downstream]

Observations at Site 12.2 25
deposition along the left and center part of the channel at 

cross-section 5. Deposition occurred along the bluff toe at 

cross-section 3 after the April and May 2003 floods. The 

inside of the bend or point-bar side of the channel stayed 

in the same location at cross-section 1, with some erosion 

at cross-sections 2 and 3 after the April/May 2002 flood. 

Erosion on the point-bar side occurred between the May 

2003 and September 2003 surveys at cross-section 4. The 

channel at cross-section 5 remained in the same location.

Results from the compilation of volume changes in 

the banks and channel from May 2002 to September 2003 

indicate that the installation of the vanes at site 12.2 did not 

cause as much channel change as at site 16.4 (table 5). The 

channel (left bank) and bluff toe at cross-sections 2 and 3 

had deposition, but the left bank of the channel and bluff 

toe eroded at cross-sections 1, 4, and 5, with a net erosion 

of 3,870 ft3 or about 155 tons (assuming an average sediment density of 80 lb/ft3

). The channel incised at cross-section 2 as the thalweg moved away from the eroding bluff; 

Table 5. Changes in the volume of sediment from banks, 

streambed, and bars associated with cross sections at site 

12.2, North Fish Creek, Wis., June and August 2001 to 

September 2003 

[A positive value (+) indicates a net gain (accretion) of sediment and a 

negative value (-) indicates a net loss (depletion) of sediment.]

Cross

section

Volume of sediment moved (cubic feet)

Left bank

(bluff) Streambed

Right bank

(point bar) Total

1 -1,459 -97 0 -1,556

2 +3,586 -1,726 +282 +2,142

3 +1,148 -592 +325 +880

4 -7,072 +882 -847 -7,037

5 -72 +1,878 +990 +2,795

Total -3,870 +345 +749 -2,776

July 2001 April 2002

March 2003 May 2004

Figure 16. Channel and bluff at site 12.2, 2001–04, North Fish Creek, Wis. Flow direction is generally from left to right or from the 

bottom to the center of the image. Photographs were taken from the left bank, upstream of the bluff, at cross-section 1.

26 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 17. Change in channel and bluff locations along monitored cross sections at site 12.2, from August 2001 to September 2003, North Fish Creek, Wis.

Observations at Site 12.2 27
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Figure 17. Change in channel and bluff locations along monitored cross sections at site 12.2, from August 2001 to September 2003, North Fish Creek, Wis.—Continued

28 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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Figure 17. Change in channel and bluff locations along monitored cross sections at site 12.2, from August 2001 to September 2003, North Fish Creek, Wis.—Continued

Observations at Site 12.2 29
however, sediment was deposited in the channel at crosssection 5, resulting in a negligible change in the amount 

of channel erosion or deposition for the entire reach. The 

point-bar eroded at cross-section 4 from channel widening; otherwise there were no detectable channel, left bank 

(bluff), or right bank (point bar) changes with more than 

1,000 ft3 of sediment deposition or erosion. 

In contrast to site 16.4, there was net erosion (2,780 

ft3 or 110 tons) in the 439-ft reach at site 12.2 (table 5). 

Part of the explanation for the contrasting results between 

the two sites may be that the vanes were installed at site 

16.4 before the large April 2001 flood. This flood produced the largest changes in channel morphology at site 

16.4; however, the vanes were installed after the April 

2001 flood at site 12.2. Only two of the five cross sections at site 12.2 (cross-sections 2 and 3) have indications 

of deposition along the bluff toe, and the loss of bluff-toe 

material at cross-section 4 possibly indicated that more 

vane arrays were needed at the downstream end of the 

bluff to help build a bluff toe along the entire reach; as 

mentioned earlier, additional vanes were added in summer and fall 2003 in the center and downstream end of the 

bend. It is not known whether the amount of erosion has 

decreased or increased in this reach after vane installation. 

Bluff Erosion

Surveys of the distances from nine reference points 

along the upland to the top edge of the bluff started in May 

2002 and continued through September 2003 (table 6). The 

reference points extend along the top edge of the mainly 

unvegetated part of the bluff, along a longitudinal distance 

of about 450 ft (fig. 6). No major block failures occurred 

during the short monitoring period (16 months); however, 

tension cracks at the top, overhanging vegetation at bluff 

top, unstable angle, and lack of a bluff toe along much of 

the bluff indicate the future potential for mass wasting and 

block failure.

Future Monitoring and Suggestions 

for Further Study

The installation of vanes for this study has created 

opportunities for future investigations. Channel morphology, bluff erosion, and streamflow on North Fish Creek 

could continue to be monitored to further evaluate the 

positive and negative effects from large floods, the longevity of the vanes, and the possible need for maintenance and 

replacement of the vanes. Additional cross sections could be 

established at site 12.2 to better monitor changes in channel 

conditions on the downstream end of the bend. Future monitoring efforts could include more accurate measurements 

of mass wasting from the bluffs by extending the cross 

sections from the channel surveys up the bluff face as far as 

safely possible. Improvements to bluff erosion monitoring 

could be made by surveying the land surface from the reference point to the edge of the bluff, and down the bluff face 

as far as safely possible. Sediment-load sampling during 

flood events could be done at the streamgage and compared 

to previous sediment-load data to determine whether sediment loads have changed because of the vane installation.

Another possible extension of the current study would 

be installation and monitoring of vanes at other appropriate 

sites on North Fish Creek and other Wisconsin tributaries 

to Lake Superior with similar erosion problems. At these 

sites, different array spacing, vane angles, dimensions, 

shapes, and materials could be investigated. The effectiveness and longevity of vanes made out of natural materials 

could be studied. Changes in the direction of flow and 

effectiveness of vortex fields caused by the vanes could be 

measured by use of a three-dimensional acoustic Doppler 

velocity meter suitable for shallow water (1–3 ft deep). 

These data could be used to determine the optimum spacing, angle, dimension, and shape of the vanes. 

Piezometers could be installed to measure water-table 

changes in the bluffs. Water-table data could be used to 

improve the accuracy of the results from the bank-stability 

model. Mass-wasting, sloughing, and bluff erosion occurs 

episodically; this requires observations over long periods 

(decades) to determine erosion rates.

Summary and Conclusions

Flow-deflecting vanes were installed in the streambed 

at two eroding bluff sites along the upper main stem of 

North Fish Creek, Wis. The vanes were designed to deflect 

flow away from the base of the bluff and reduce bank 

erosion. Vanes were installed in 2000 at site 16.4 (16.4 

river miles upstream of the mouth) and in 2001 at site 12.2 

(12.2 river miles upstream of the mouth). The demonstration study was done through a cooperative effort by the 

UW-Madison, who mainly did the design and installation, the USGS, who mainly did the monitoring, and the 

DNR, who provided the funding. Monitoring consisted of 

repeated channel cross-section and bluff-erosion surveys, 

and streamflow and stage monitoring before, during, and 

after vane installation through September 2003. This report 

describes the monitoring results at both sites from vane 

installation through September 2003.

30 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
bluff; thus, this technique for toe stabilization is useful for 

reducing bluff erosion in flashy, high-energy, meandering 

streams. 

If monitoring continues at site 16.4, investigators 

could determine whether the observed expansion of the 

bluff toe is a permanent feature or whether future floods 

erode the toe. If monitoring continues at site 12.2, investigators could determine whether additional vanes and time 

will help reduce bluff toe erosion. Vanes at both sites also 

could be checked after floods for maintenance or replacement needs. 

Acknowledgments

Vane installation and channel and bluff monitoring 

would not have been possible without the help of numerous able and willing students from the CEE Department 

of the UW-Madison, personnel at the WDNR and USGS, 

and volunteers from county, State, and Federal agencies 

in Wisconsin. We are especially appreciative of all the 

time and commitment given by David Poggi (UW-Madison, Wis.) for vane installation and cross-section surveys. 

Bernard Lenz (USGS, Rice Lake, Wis.), David Housner (USGS, Middleton, Wis.), Krista Stensvold (USGS, 

Middleton, Wis.), and Ryan Jirik (USGS, Middleton, Wis.) 

assisted with vane installation, cross-section surveys, and 

collection of stage data. Andrew Veine, Kent Brander, 

Matt Hoffmann, Joshua Katt, Michael Schwar, Jay Stahl, 

Todd Shoemaker, Matthew Van Lieshout, and Yang Yang 

(all current or former UW-Madison students) assisted with 

vane installation and cross-section surveys. James Kennedy (USGS, Middleton, Wis.) assisted with cross-section 

surveys. Thomas Popowski (USGS, Rice Lake, Wis.) operated and maintained the streamgage. Dennis Pratt (WDNR, 

Superior, Wis.) provided assistance with site selection and 

insights about fish habitat and spawning. 

The efforts of Kimberly Walz (WDNR, Madison, 

Wis.) in project management and grant writing are greatly 

appreciated. Professor Kenneth Potter (UW-Madison) 

helped with proposal writing. 

The authors are very appreciative of access to site 

16.4 granted by Mr. Robert Dufek and to site 12.2 granted 

by Mr. Andrew Mihalek and Mr. Gary Johanik. 

Technical reviews by Janet Curran (USGS, Anchorage, 

Alaska) and Bernard Lenz (USGS, Rice Lake, Wis.) greatly 

improved the content of this report. Leah Hout and Michael 

Eberle (USGS, Columbus, Ohio) did the editorial review. 

Michelle Greenwood, Susan Jones, and Jennifer Bruce 

(USGS, Middleton, Wis.) completed the final report layouts.

The vanes survived the April 2001 flood (recurrence interval of approximately 100 years) at site 16.4 and 

the April and May 2002 floods (recurrence intervals of 

approximately 50 years) at both sites. The vanes at both 

sites required some maintenance and replacement after the 

floods. After the April and May 2002 floods, five nearbankfull or at-bankfull floods occurred (one in October 

2002 and four in April and May 2003).

At site 16.4, channel cross-section data from 2000 

to 2003 indicate that the vanes have caused the channel to 

move away from the base of the bluff (outside of the bend) 

and toward the point bar (inside of the bend), allowing 

sediment to deposit at the base of the bluff. Much of the 

channel-morphology change resulted from the April 2001 

flood. Over the entire monitoring period (2000–03), the 

361-ft reach at site 16.4 had a net gain of 6,740 ft3 of sediment. Deposition along the base of the bluff was 10,660 

ft3, mainly through the downstream half of the reach. In 

contrast, the left-bank or point bar side of the channel 

(1,610 ft3), channel streambed (1,220 ft3), and a midchannel bar (1,090 ft3

) eroded. 

Less change in channel morphology was measured at 

site 12.2 than at site 16.4, which had a net loss of sediment 

through the 439-ft reach of 2,780 ft3. The main volume 

of sediment was lost from the bluff toe at cross-section 4 

near the downstream end of the bend (7,040 ft3). Two cross 

sections showed a net gain in sediment along the bluff toe 

near the upstream side of the reach. The net gain along the 

point-bar side of the reach was 750 ft3. Channel changes 

at site 12.2 have been less than at site 16.4 most likely 

because the vanes were installed in the summer of 2001 

after the April 2001 flood and the monitoring period for 

site 12.2 (2001-03) is shorter than for site 16.4 (2000–03).

Bluff erosion data from both sites indicate that mass 

wasting is episodic and will likely occur for decades or 

more even after an adequate bluff toe has been established. Long-term monitoring data (observations that span 

decades) are needed to determine accurate bluff erosion 

rates. However, the extension of the bluff toe from vane 

installation should help to hold mass-wasted material 

from above and eventually allow the bluff to become more 

vegetated over time.

The monitoring results from this study indicate the 

importance of monitoring hydrologic conditions, as well as 

channel-morphology changes after use of erosion-control 

techniques. Much of the channel-morphology change and 

channel migration resulted from large floods, with minimal 

or small changes during bankfull flows. The vanes at site 

16.4 withstood a record flood with only minor damage 

and initiated channel migration away from the eroding 

Acknowledgments 31
Table 6. Bluff erosion monitoring results for site 12.2, North Fish Creek, Wis. from 2002 to 2003 

[A negative change in distance over time (-) indicates loss of sediment; a positive change in distance over time (+) indicates soil creep or expansion of tension cracks; ft, feet; veg, vegetation; lg, large; us, upstream; ds, downstream; %, percent; <, less than]

Reference

Points T1 T2 T3 T4 T5 T6 T7 T8 T9

May 2002

Distance (ft) 30.5 38.4 43.0 24.9 11.2 45.9 27.9 9.8 35.4Remarks Veg, no bluff 

erosion

50% veg, 

undercut at top

Not veg, 

undercut at top

60% veg above 

slump, <50% veg below slump, undercut at top

Slump starting, 

unstable slope below, debris flow, toe forming

No veg, no 

toe, failure impending

No veg, unstable, 

vertical for bottom third

<10% veg on 

upper third, no veg below, no toe

General slope 

down, 30-40% veg

August 2002

Distance (ft) 30.5 38.4 42.6 24.9 11.2 45.9 27.6 9.1 34.4Remarks All veg Undercut, 

20% veg at top, 90% veg at bottom

Toe at bottom, 

lg overhang, big cracks on top half

Same slope, 

little veg

Veg slump at top, 

start of toe

Clean break at 

overhang, no veg, vertical

Slumping, 50% 

veg at break in slope

No change No change

April 2003

Distance (ft) 29.5 38.4 42.6 25.9 11.2 45.9 27.8 9.1 36.1Remarks Gully at 

bottom has turbid flow

Same veg Lg overhang 

still present, slump at base, flow not directed away

Toe present, but 

flow is right against toe

Slump at base, 

toe built out, 1% veg at top, lg boulder with debris

No toe, main 

flow at base of bluff, concave, unveg, unstable

No veg, deer trail 

more slumped, cracks on top third, gully in lower two thirds, flow against toe

Seep/wet at top 

along bluff face, deep rills with trickles, unstable and convex, eddy at bottom

Seep area (upper 

quarter), new gully in lower three quarters with trickle in it

June 2003

Distance (ft) 31.8 37.7 42.0 25.9 10.8 45.9 28.2 9.8 37.1Remarks Well veg Same well 

veg

Lg overhang, 

same as before, slump at base now just remaining rock/dirt washed away

Sharp drop to 

slump with veg a quarter of the way down, steep unveg bluff face to flat toe

Slump with veg 

just below base, flat toe, lg boulder still in place

No toe, main 

flow at base of bluff, concave, unveg, unstable

Cracks with veg 

on top third, gully in lower two thirds, with debris fan partially washed away

Blocky mass 

wasting, unstable convex shape, no toe, near vertical at river, gullies us and ds of face

Seep area in upper 

quarter, new gully in lower three quarters, very wet

32 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
Reference

Points T1 T2 T3 T4 T5 T6 T7 T8 T9

September 2003

Distance (ft) 32.2 37.7 41.7 25.6 11.5 45.9 28.5 11.2 37.1Remarks Well vegetated, maybe 

new sand from river at toe

Well vegetated Lg overhang, slump 

at base, remaining rock has been filled in half with sand

Sharp drop to 

slump with veg a quarter of the way down, rest is near vertical and unvegetated face to flat toe, some slump is piled halfway down the face

Slump with veg 

near top, erosion at base, lg boulder now in river, lg flat toe created by debris from gully, no veg below lg blocks which came from the middle

Tip of bluff 

sticking out has slumped 2-3 ft at 42.3 ft and outheld in place by tree, slope near vertical halfway down, little veg, no toe

Small alder at 

slope break is holding bluff, but erosion has removed deer trail on both sides, cracks with veg on top third, gully bottom 2/3 is deeper and more debris fan has washed

Recent blocky 

mass wasting, unstable convex shape, 5% veg on top third, no veg and near vertical lower two thirds, flat toe at water surface

Near vertical drop 

at alder clump at top slope break, gentle fault bowl is seep area (upper quarter), 27 ft across bowl to start of gully (lower 3⁄4) that extends from T8, debris fan at base of gully

Distance change (ft) after vane installation (2002-03)

1.7 -0.7 -1.3 0.7 0.3 0 0.6 1.4 1.7

Table 6. Bluff erosion monitoring results for site 12.2, North Fish Creek, Wis. from 2002 to 2003 —Continued[A negative change in distance over time (-) indicates loss of sediment; a positive change in distance over time (+) indicates soil creep or expansion of tension cracks; ft, feet; veg, vegetation; lg, large; us, upstream; ds, downstream; %, percent; <, less than]

Acknowledgments 33
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34 Monitoring Channel Morphology and Bluff Erosion at Two Installations of Flow-Deflecting Vanes, North Fish Creek, Wis.
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