U.S. Department of the Interior

U.S. Geological Survey

Stream Bank Stability in Eastern Nebraska

By Philip J. Soenksen, Mary J. Turner, Benjamin J. Dietsch, U.S. Geological Survey, 

and Andrew Simon, National Sedimentation Laboratory, U.S. Department of Agriculture

Water-Resources Investigations Report 03-4265

Prepared in cooperation with the

Nebraska Department of Roads,

Nebraska Department of Natural Resources,

Lower Platte South Natural Resources District,

Papio-Missouri River Natural Resources District,

U.S. Army Corps of Engineers, and the 

National Sedimentation Laboratory of the U.S. Department of Agriculture

Lincoln, Nebraska

2003
ii

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement 

by the U.S. Geological Survey.

For additional information write to: Copies of this report can be purchased from:

District Chief

U.S. Geological Survey U.S. Geological Survey

406 Federal Building Branch of Information Services

100 Centennial Mall North Box 25286

Lincoln, Nebraska 68508 Denver, CO 80225-0286

http://www.usgs.gov
Contents iii

CONTENTS

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

Introduction .................................................................................................................................................................... 2

Purpose and Scope................................................................................................................................................ 4

Description of Study Area .................................................................................................................................... 4

Acknowledgments................................................................................................................................................ 7

Data Collection and Description..................................................................................................................................... 7

Topographic Data ................................................................................................................................................. 7

Surveying.................................................................................................................................................... 7

Average Channel Site Geometry ................................................................................................................ 8

Geotechnical Data................................................................................................................................................. 8

Soil Testing and Sampling.......................................................................................................................... 8

Laboratory Soil Analyses ........................................................................................................................... 9

Evaluation of Borehole Shear Tests.......................................................................................................... 10

Generalization of Shear Strength Data ..................................................................................................... 12

Bank Stability ............................................................................................................................................................... 14

Shear Strength and Pore Pressure ....................................................................................................................... 14

Culmann Method—Planar Failure...................................................................................................................... 15

Approach .................................................................................................................................................. 16

Results ...................................................................................................................................................... 17

ARS Method—Planar Failure ............................................................................................................................ 17

Approach .................................................................................................................................................. 21

Results ...................................................................................................................................................... 22

Indirect Method—Rotational Failure ................................................................................................................. 22

Approach .................................................................................................................................................. 22

Analyses for Idealized Straight Banks............................................................................................ 23

Effects of Bank Shape .................................................................................................................... 23

Application to Studied Bank Sections............................................................................................ 30

Results ...................................................................................................................................................... 30

Bank Stability Assessment at New Sites............................................................................................................ 31

Culmann Method—Planar Failure............................................................................................................ 33

Indirect Method—Rotational Failure ....................................................................................................... 33

Other Considerations................................................................................................................................ 33

Summary and Conclusions........................................................................................................................................... 34

Selected References...................................................................................................................................................... 36

Supplemental Data........................................................................................................................................................ 41
iv

Figures

1. Location of loess area of the Midwestern United States and thickness of loess..................................................... 3

2. Location of study area showing river basins and sampling sites in Nebraska. ....................................................... 5

3. Generalized classification of soil parent materials showing study area and river basins, Nebraska. ..................... 6

4. Examples of borehole shear test data and interpretations, and values of moisture content and degree 

of saturation at time of tests. ................................................................................................................................. 11

5. Distribution of soil cohesion (A) and friction angle (B) data from borehole shear tests (BSTs) in the study 

described in this report compared to corresponding data for loess and alluvial soils from other studies............. 13

6. Conceptual diagram of a bank section and the forces acting on a potential planar failure surface that were 

used in the Culmann method of stability analysis................................................................................................. 16

7. Culmann failure-envelope curves for soil group 1, using median parameters and selected soil moisture and 

tension crack conditions, compared to average channel bank geometry for sites (bank angles, vertically 

weighted)............................................................................................................................................................... 18

8. Culmann failure-envelope curves for soil group 2, using median parameters and selected soil moisture and

tension crack conditions, compared to average channel bank geometry for sites (bank angles, vertically 

weighted)............................................................................................................................................................... 18

9. Culmann failure-envelope curves for soil group 3-4, using median parameters and selected soil moisture and

tension crack conditions, compared to average channel bank geometry for sites (bank angles, vertically 

weighted)............................................................................................................................................................... 19

10. Conceptual diagram of a bank section and the forces acting on a potential planar failure surface that were 

used in the ARS method of stability analysis........................................................................................................ 20

11. Example of rotational failures and minimum factors of safety for ambient (unsaturated) channel-bank 

sections differing only in cross-sectional shape between the top and toe—(A) convex elliptical, (B) straight, 

and (C) concave elliptical...................................................................................................................................... 24

12. Example of rotational failures and minimum factors of safety for saturated channel-bank sections differing 

only in cross-sectional shape between the top and toe—(A) convex elliptical, (B) straight, and (C) concave

elliptical................................................................................................................................................................. 25

13. Examples of factors of safety for (A) ambient (unsaturated) and (B) saturated elliptical (convex and concave)

banks from detailed analyses (REAME computer program and actual cross sections) compared to those 

from the indirect method (straight-bank tables using unweighted and vertically weighted average bank 

angles) over a range of bank angles. ..................................................................................................................... 27

14. Factors of safety against rotational failure for 30 randomly selected bank sections under ambient 

(unsaturated) conditions comparing those determined from the indirect method, using the straight-bank 

tables with (A) unweighted and (B) vertically weighted average bank angles as inputs, to those from 

detailed analysis, using the REAME computer program with actual surveyed bank section points as 

inputs. .................................................................................................................................................................... 28

15. Factors of safety against rotational failure for 30 randomly selected bank sections under saturated 

conditions comparing those determined from the indirect method, using the straight-bank tables with (A)

unweighted and (B) vertically weighted average bank angles as inputs, to those from detailed analysis, 

using the REAME computer program with actual surveyed bank section points as inputs.................................. 29

16. Soil cohesion relative to borehole depth for sites with more than one borehole shear test (BST) considered

useable................................................................................................................................................................... 32

Tables 

1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 

1995 to 1999.......................................................................................................................................................... 43

2. Channel-geometry data collected at study sites in eastern Nebraska, 1995 to 1999............................................. 50

3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999 .............................. 54

4. Results of Culmann, ARS, and indirect methods of bank-stability analysis......................................................... 62

5. Number and percent of bank sections for each method of analysis by stability category and soil group ............ 89

6. Factors of safety from REAME analysis of idealized straight banks ................................................................... 90
Contents v

Elevation, as used in this report, refers to distance above the National Geodetic Vertical Datum of 1929 (NGVD 29).

CONVERSION FACTORS AND VERTICAL DATUM

Multiply By To obtain

centimeter (cm) 0.394 inch (in)

meter (m) 3.28 foot (ft)

kilometer (km) 0.622 mile (mi)

square meter (m2

) 10.8 square foot (ft2)

square kilometer (km2) 0.386 square mile (mi2)

cubic meter (m3

) 35.3 cubic foot (ft3)

centimeter per hour (cm/hr) 0.3937 inch per hour (in/hr)

meter per year (m/yr) 3.28 foot per year (ft/yr)

cubic meter per second (m3/s) 35.3 cubic foot per second (ft3

/s)

gram (g) 0.03527 ounce avoirdupois (oz avdp)

kilopascal (kPa) 0.145 pound per square inch (lb/in2)

kilonewton per meter (kN/m) 68.6 pound per foot

kilonewton per cubic meter (kN/m3

) 6.37 pound per cubic foot (lb/ft3)
Abstract 1

Stream Bank Stability in Eastern Nebraska 

By Philip J. Soenksen, Mary J. Turner, Benjamin J. Dietsch, and Andrew Simon

Abstract

Dredged and straightened channels in eastern Nebraska have experienced degradation leading to channel widening by bank failure. 

Degradation has progressed headward and 

affected the drainage systems upstream from the 

modified reaches. This report describes a study 

that was undertaken to analyze bank stability at 

selected sites in eastern Nebraska and develop a 

simplified method for estimating the stability of 

banks at future study sites. Bank cross sections 

along straight reaches of channel and geotechnical 

data were collected at approximately150 sites in 

26 counties of eastern Nebraska. The sites were 

categorized into three groups based on mapped 

soil permeability. With increasing permeability of 

the soil groups, the median cohesion values 

decreased and the median friction angles 

increased. Three analytical methods were used to 

determine if banks were stable (should not fail 

even when saturated), at risk (should not fail 

unless saturated), or unstable (should have already 

failed). The Culmann and Agricultural Research 

Service methods were based on the Coulomb 

equation and planar failure; an indirect method 

was developed that was based on Bishop’s simplified method of slices and rotational failure. The 

maximum angle from horizontal at which the bank 

would be stable for the given soil and bank height 

conditions also was computed with the indirect 

method. Because of few soil shear-strength data, 

all analyses were based on the assumption of 

homogeneous banks, which was later shown to be 

atypical, at least for some banks. 

Using the Culmann method and assuming 

no soil tension cracks, 67 percent of all 908 bank 

sections were identified as stable, 32 percent were 

at risk, and 1 percent were unstable; when tension 

cracks were assumed, the results changed to 

58 percent stable, 40 percent at risk, and 1 percent 

unstable. Using the Agricultural Research Service 

method, 67 percent of all bank sections were identified as stable and 33 percent were at risk. Using 

the indirect method, 62 percent of all bank sections were identified as stable and 31 percent were 

at risk; 3 percent were unstable, and 3 percent 

were outside of the range of the tables developed 

for the method. For each of the methods that were 

used, the largest percentage of stable banks and the 

smallest percentage of at risk banks was for the 

soil group with the lowest soil permeability and 

highest median cohesion values.

A comparison of the expected stable bank 

angles for saturated conditions and the surveyed 

bank angles indicated that many of the surveyed 

bank angles were considerably less than the maximum expected stable bank angles despite the 

banks being classified as at risk or unstable. For 

severely degraded channels along straight reaches 

this was not expected. It was expected that they 

would have angles close to the maximum stable 

angle as they should have been failing from an 

oversteepened condition. Several explanations are 

possible. The channel reaches of some study sites 

have not yet been affected to a significant degree 

by degradation; study sites were selected throughout individual basins and severe degradation has 

not yet extended to some sites along upper 

reaches; and some reaches have experienced 
2 Stream Bank Stability in Eastern Nebraska

aggradation as degradation progresses upstream. 

Another possibility is that some bank sections 

have been affected by lateral migration processes, 

which typically result in shallow bank angles on 

the inside bend of the channel. 

Another possibility is that the maximum 

expected stable bank angles are too steep. The stability methods used were well established and in 

essential agreement with each other, and there was 

no reason to question the geometry data. This left 

non-representative soil data as a probable reason 

for computed stable bank angles that, at least in 

some cases, are overly steep. Based on an examination of the cohesion data, to which the stable 

bank-angle calculations were most sensitive, both 

vertical and horizontal variability in soil properties 

appeared likely for many of the sites. Because a 

weak soil area or an interface of two differing soil 

areas in a bank can determine where the failure 

plane will be and what the factor of safety might 

be, it is not likely that the few soil tests done at 

each of the sites identified the critical soil parameters needed to accurately assess bank stability or to 

determine the expected stable bank angle for each 

bank section. At least for some bank sections, it 

appears that the summary results of bank stability 

for this study are overly optimistic. Although some 

individual bank sections may be accurately portrayed, it is not known which or how many bank 

sections are accurately classified without more 

extensive data to determine variability in soil shear 

strength.

If the variability of soil parameters, especially cohesion, can be determined for a site, and if 

the variability is small so that average or weakest 

values can be used to represent the banks, any of 

the methods demonstrated in this report can be 

used to make preliminary assessments of channel 

bank stability at future study sites. An electronic 

spreadsheet, developed for use with the indirect 

method, is included on a compact disk at the back 

of this report and can be used to make preliminary 

assessments of existing bank stability at study sites 

or to assess future bank stability under assumptions of degradation or aggradation by imposing 

projected changes on the existing bank geometry. 

The user needs cross-section data and estimates of 

the soil parameters—cohesion, friction angle, and 

ambient and saturated unit weight—to make the 

assessments. In addition, the spreadsheet can automatically compute the maximum uniform angle at 

which a bank section would be expected to be stable, for a given factor of safety, bank height, and 

soil parameters. For a bank with extensive variability in soil shear-strength, a method needs to be 

used that can account for multiple soil areas with 

differing parameters. 

INTRODUCTION

Land-use changes in the loess area of the 

Midwestern United States (fig. 1) , resulted in stream 

channels becoming filled with sediment and debris by 

the early 1900s. This increased flooding of fertile 

bottomlands and affected the livelihoods of those 

trying to farm them. To alleviate frequent and 

prolonged flooding of these bottomlands, many stream 

channels, including thousands of kilometers in eastern 

Nebraska, were dredged and straightened to increase 

capacity and speed runoff (Speer and others, 1965). 

Although the original intent was realized, this engineering practice also reduced stream lengths, which 

increased channel gradients and stream power, and 

increased the ability of the flow to erode channel sediments. As a result, the modified channels of eastern 

Nebraska have experienced degradation, which heightened and steepened channel banks. Eventually, many 

banks reached a point where they became unstable and 

failed, thus widening the channel. This commonly 

occurs when banks become saturated during floods. As 

modified channels degraded, new oversteepened 

reaches formed at the upstream ends of the modified 

reaches and at the mouths of tributary channels along 

the modified reaches, thus initiating headwardprogressing degradation and subsequent bank failures. 

Eventually, this process can affect an entire drainage 

system upstream from the original channel modification. 

These channel responses have resulted in 

damage to highway structures, pipelines, and fiberoptic lines, and in the loss of land and the loss of access 

where structures were too expensive to justify repair or 

replacement (Simon and Rinaldi, 2000). Streambed 

degradation caused by straightening also is believed to 

have accelerated the drainage of saline wetlands along 
Introduction 3

Little Salt Creek (Farrar and Gersib, 1991) and Rock 

Creek (Natural Resources Conservation Service, 1996) 

in Nebraska. Degradation and channel widening in the 

loess area of the Midwestern United States has led to 

the collapse of bridges in West Tennessee (Robbins and 

Simon, 1983), southwest Mississippi (Wilson, 1979), 

Missouri (Emerson, 1971), and southeast Nebraska 

(Jerry Wallin, Nebraska Natural Resources Commission, oral commun., 1994). In western Tennessee, it 

was estimated that, on average, about 20 percent of the 

material eroded from stream channels was from the bed 

and 80 percent was from the banks (Simon, 1989a), 

which emphasizes the need to understand the bank-failure process. Large floods throughout the Midwestern 

United States in 1993 adversely affected many channels and caused the failure or closure of many bridges 

in Nebraska because of bed erosion and bank failure. 

To address the need for information on bank 

stability, the U.S. Geological Survey (USGS), in cooperation with the Nebraska Department of Roads, 

Nebraska Natural Resources Commission (now part of 

the Nebraska Department of Natural Resources), 

Lower Platte South Natural Resources District, (NRD), 

Papio-Missouri River NRD, U.S. Army Corps of Engineers (USACE), and the U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), 

National Sedimentation Laboratory (NSL), has 

completed a study to characterize and analyze the 

stability of stream channels in eastern Nebraska.

In addition to an analysis of stream bank stability, the study encompassed several other components. 

A database was created from the assessment of nearly 

1,000 bridges for potential scour-critical conditions 

(U.S. Army Corps of Engineers, 1999). Aerial reconFigure 1. Location of loess area of the Midwestern United States and

thickness of loess (modified from Luttenegger, 1987b).

SouthDakota

NorthDakota

Nebraska

Kansas

Oklahoma

Texas

Arkansas

Louisiana

Missouri

Iowa

Alabama

Mississippi

Tennessee

Kentucky

Indiana

Illinois

Ohio

Georgia

Minnesota

Michigan

Wisconsin

43o

37o

97o 89o

2 LINE OF EQUAL THICKNESS OF LOESS—Dashed where

approximately located. Hachures indicate depression.

Interval is variable, in feet

0 200 MILES 100

0 100 200 KILOMETERS

EXPLANATION
4 Stream Bank Stability in Eastern Nebraska

naissance was used to estimate the stage of channel 

evolution, based on the work of Simon (1989b) for 

many channels in the study area (U.S. Army Corps of 

Engineers, 1998a). Trends in the water-surface elevation for a given discharge were examined at 145 

stream-gaging stations in Nebraska (Chen and others, 

1999). Channel evolution models were developed for 

two streams in the study area (North Branch West 

Papillion Creek and Little Salt Creek) to assess the 

effects of mitigation measures and urbanization 

(Langendoen and Simon, 2000). Streambed adjustment 

and channel widening in eastern Nebraska were documented by Rus and others (2003).

Purpose and Scope

The purpose of this report is to present the 

summary results for three methods of analyzing bank 

stability at approximately 150 sites in eastern Nebraska 

and to present a simplified method for estimating the 

stability of banks at future study sites. The report also 

includes average channel geometry data, and soil property data from field measurements and laboratory analysis, which were collected during 1995–99. Tables for 

this report are located in the Supplemental Data section 

at the back of this report.

Description of Study Area

The study area initially consisted of 23 counties 

in eastern Nebraska based on the interests of the cooperators. The area was later expanded to 26 counties 

(fig. 2)—adding Madison, Platte, and Saline—when 

sites considered beneficial to the study were selected in 

those counties. Eastern Nebraska is a glaciated region 

characterized by rolling hills, covered by easily erodible soil. Almost all of the study area lies within the 

Dissected Till Plains of the Central Lowland physiographic province (Fenneman, 1946); the western part 

of Butler County is in the High Plains of the Great 

Plains province. Loess deposits in eastern Nebraska are 

among the thickest in the Midwestern United States 

(fig. 1) and are primarily from the Gilman Canyon 

Formation, Loveland Formation, and Peoria Loess 

(Mandel and Bettis, 1995, 2000). Glacial till composed 

of poorly sorted materials lies beneath the loess mantle 

throughout much of the region and is exposed on lower 

slopes in some areas. Bedrock occurs in parts of the 

region, especially in southeastern Nebraska, but most 

streambeds lack bedrock control. 

The dominant soil parent material is loess in 

most of the study area. In smaller areas, soils are primarily derived from loess and drift in the south and southwest, and from alluvium along some of the larger 

streams (fig. 3). Sites along smaller drainages in the 

uplands are likely to have loess-derived soils; sites 

along the larger drainages also could have soils derived 

from the underlying till or from alluvial deposits of silt, 

sand or gravel. Alluvial soil types vary in the region but 

generally consist of silt, silt loam, and silty-clay loam 

(Nebraska Soil and Water Conservation Commission, 

1968; Soil Conservation Service, 1975). In the Elkhorn 

River Basin, western streambanks are sandy materials 

while streambanks in the eastern part of the basin are 

silty loess (Soil Conservation Service, 1971). The alluvial stratigraphy of the fine-grained deposits found in 

eastern Nebraska stream valleys are similar to those 

found in the De Forest Formation of western Iowa 

(Mandel and Bettis, 1995; 2000). 

The study area (fig. 2) is included in parts of four 

major land-resource areas (MLRAs) (Soil Conservation Service, 1981). The Iowa and Missouri Loess Hills 

(MLRA 107) area has rolling-to-hilly topography that 

is highly dissected; the erosion hazard from runoff is 

severe on the uplands. The Loess Uplands and Till 

Plains (MLRA 102B) have well-defined drainages in 

the uplands while the till plains are level to gently rolling with less defined drainages. The Nebraska and 

Kansas Loess-Drift Hills (MLRA 106) have steep and 

strongly sloping areas generally consisting of glacial 

till, while the areas with flatter slopes consist of loess. 

The remaining part of the study area lies in the Central 

Loess Plains (MLRA 75). In the study area, these 

plains are gently rolling and mantled by loess, with the 

older Loveland loess exposed along the streams in 

some places. 

All basins in the study area are part of the 

Missouri River Basin, and study sites were grouped 

according to smaller basins within it. Six stream 

basins were used for identification of most sites in the 

study area: Papillion Creek, Elkhorn River, Salt 

Creek, Little and Big Nemaha River, and Big Blue 

River Basins (fig. 2). The remaining sites were in 

smaller tributary basins of the Platte and Missouri 

Rivers and were grouped into the Missouri River tributary basins and the Platte River tributary basins. 
Introduction 5

Figure 2. Location of study area showing river basins and sampling sites in Nebraska.

97°

42°

96°

41°

40°

0 10 20

0 KILOMETERS 10 30 20

30 MILES

Study sites

Surface water

Big Blue River Basin

Big Nemaha River Basin

Nebraska counties

Study area Elkhorn River Basin

Little Nemaha River Basin

Selected Missouri River tributary basins

Selected Platte River tributary basins

Papillion Creek Basin

Salt Creek Basin

EXPLANATION

Missouri Rive r

v a e h

L

m

i

ittle N a e r R

Bi i g

R B e lu ve r

e ek

S alt Cr

r i

h E or R ve

lk n

Big Nemaha River

Papillion Creek

Platte Rive r

Location Map

South Dakota

NebraskaNebraska

Iowa

Missouri

Kansas

Colorado

Wyoming

Major Land Resource Areas (MLRA)

(Soil Conservation Service, 1981)

102B

107

106

Central

loess plains

Loess uplands

and till plains

Iowa and Missouri

loess hills

Nebraska

and Kansas

loess drift hills

75

Base from U. S. Geological Survey

1:100,000 digital data

Albers Equal-Area Conic projection

Standard parallels 29o30' and 45o30'

Central meridian -96o
6 Stream Bank Stability in Eastern Nebraska
Data Collection and Description 7

Acknowledgments

The findings presented in this report are the 

culmination of a cooperative effort among several 

agencies and individuals whose assistance was vital 

and greatly appreciated. The authors thank the landowners for permission to collect data on their property. 

The authors also would like to thank representatives 

from each of the cooperating agencies, specifically 

Don Jisa (Nebraska Department of Roads), Randy 

Behm (U.S. Army Corps of Engineers), Dan Schulz 

(Lower Platte South Natural Resources District), 

Marlin Petermann (Papio-Missouri River Natural 

Resources District), Andrea Curini (formerly of the 

National Sedimentation Laboratory), and Jerry Wallin 

(formerly of the Nebraska Natural Resources Commission) for their support and knowledge and for providing 

access to historical data. Thanks also go to colleagues 

and student interns in the USGS who provided assistance in collecting and analyzing data, and reviewing 

this report. 

DATA COLLECTION AND 

DESCRIPTION

To analyze for bank stability, topographic and 

geotechnical data were collected along channel reaches at 

145 sites in eastern Nebraska during 1995–99 (table 1). 

For this report, a reach was a section of stream channel as 

much as several hundred meters in length. Five 

sites—MRT 14, PC 6, ER 1, ER 2, and SC 20—did not 

have sufficient topographic data for use in bank stability 

analysis but were used in the streambed adjustment analysis presented by Rus and others (2003). Topographic 

surveys were made to obtain stream channel cross 

sections, field tests in boreholes were made to obtain shear 

strength parameters of the channel bank material, and 

samples of the channel banks were collected for laboratory analysis to obtain other engineering properties. Sites 

were selected based on the need to analyze for streambed 

adjustment and channel widening, as reported by Rus and 

others (2003), as well as to analyze for channel bank 

stability. Sites were distributed among the major drainage 

basins of the study area and were individually selected 

based on the availability of historic streambed-elevation 

data. All of the sites were located at bridges or culverts 

because the majority of historical data were associated 

with them. These structures were good landmarks for 

isolating streambed data from several sources into one 

location and for establishing reference points for future 

comparisons and surveys. 

Topographic Data

A topographic survey of at least one streamchannel reach at each site was made to obtain multiple 

channel cross sections for bank-stability analyses.

Surveying

Channel-reach surveys were performed using a 

Sokkia Set II B electronic total station. A local coordinate system of northing, easting, and elevation was 

referenced to horizontal and vertical control points 

established at each site; this allowed each site to be 

surveyed later on the same coordinate system. The 

surveying instrument was approximately referenced to 

north by means of a magnetic compass with adjustments for declination as determined from USGS 

1:100,000-scale topographic maps. After the topographic survey was made, the control points were 

surveyed again to confirm that the instrument was still 

measuring within 1 centimeter (0.03 feet) of the known 

coordinates. All survey points were corrected for the 

effects of temperature and atmospheric pressure, and 

for curvature and refraction. 

The initial channel-reach surveys generally 

consisted of a combination of channel cross sections 

and selected ground and channel-bed shots not on the 

cross sections to define the top of the channel bank, and 

the thalweg, which is the deepest point in the channel. 

The reaches surveyed were typically three to four channel widths long; and all surveys included a cross 

section at either the upstream or downstream edge of 

the bridge or culvert structure for use in the streambedadjustment analysis. Most surveys were made on one 

side of the structure with about four cross sections; 

some surveys were made both upstream and downstream from the structure with as many as 20 cross 

sections. Because of time constraints or dense foliage, 

some later surveys consisted only of channel cross 

sections. This report focused on channel widening 

caused by streambed adjustment rather than by lateral 

channel migration; therefore, straight reaches were 

preferred for surveying. However, in some cases, no 

straight reaches were present.
8 Stream Bank Stability in Eastern Nebraska

Average Channel Site Geometry

Bank heights, bank angles for left and right 

banks, and channel width at the top and toe of the banks 

were determined from the cross-section data. Bank 

heights in this report are defined as the vertical distance 

from the toe of the bank to the top edge of the same 

bank. Bank angles, referenced to horizontal, were characterized from the top of the bank to the toe of the bank 

in four ways—unweighted, and weighted vertically, 

horizontally, and linearly. Unweighted bank angles 

were computed as the angle from the point at the top of 

bank directly to the toe of the bank regardless of the 

points between. For weighted angles, the angles 

between each set of adjacent surveyed points along the 

bank section were multiplied by the vertical, horizontal, or linear distance between the points. The sums of 

the resulting values were divided by the total vertical, 

horizontal, or linear distance from the top to the toe of 

the bank to find the corresponding weighted angles. 

The different weighted angle calculations were done to 

provide several measures of individual bank-section 

angles for use in the development of a simplified 

method of bank analysis that could be used at future 

sites of interest. Channel widths were computed as the 

distances between the left and right top-of-bank and 

toe-of-bank points for each cross section. For summary 

purposes, the average (mean) values for each of the 

above measures of bank height, bank angle, and channel width were computed (table 2). Geometry data 

from both the site averages and the individual bank 

sections were used in later analyses. Because bank 

stability related to degradation and not to meandering 

or lateral migration was analyzed, cross sections on 

channel bends were not used. 

Geotechnical Data

Geotechnical properties of the channel banks 

and streambeds were determined for 147 of the study 

sites by in-place soil testing and laboratory analyses of 

soil samples. Only geotechnical data for the channel 

banks were used for the analyses documented in this 

report.

Soil Testing and Sampling

Information about the shear-strength properties 

of the soil is essential for the analysis of channel-bank 

stability. Using an Iowa Borehole Direct-Shear Device 

(Spangler and Handy, 1973, p. 470–472) and the multistage method (Lutenegger and Hallberg, 1981; 

Lutenegger, 1987a), one or more Borehole Shear Tests 

(BSTs) were done in the channel banks at 147 study 

sites. The BST instrument does direct-shear tests on the 

walls of a borehole to determine values of total shear 

strength for corresponding values of applied normal 

stress. From a plot and regression of the data points, 

cohesion and friction angle, the individual components 

of total shear strength, were computed.

Boreholes of 7.6 centimeter (3-inch) nominal 

diameter were prepared manually for testing and 

sampling at most sites using a bucket auger and a 

reamer. Using a core sampler with a slide-hammer 

attachment, soil samples to be analyzed for soil unitweight, moisture content, and degree of saturation were 

obtained from the bottom of each borehole at 147 sites; 

sample volumes were 93.4 cubic centimeters (cm3). 

The samples were placed in metal containers and 

sealed with tape to preserve the ambient moisture 

representing existing conditions. At 91 sites, samples 

to be analyzed for particle size were obtained from the 

augered material taken at the depth of the BST; at 28 of 

those sites, a part of those samples also were analyzed 

to determine plasticity index. Logs of the bank material 

were made based on inspection of the soil as it was 

removed from the borehole and by examining nearby 

exposed bank faces; these were used in later evaluations of the BSTs.

For sites with the highest banks, a small trailermounted auger-drill rig was used to drill boreholes to 

depths not practical for hand augering. After the 

desired depth was nearly reached by drilling, a Shelby 

tube was pushed down about 15 to 30 centimeters (6 to 

12 inches) into the bottom of the borehole to prepare it 

for the BST and to obtain material from which the soil 

samples were collected. BSTs and soil samples to a 

depth of 7.4 meters were obtained this way. 

BSTs were done near the bottom of the boreholes. Using gas pressure, an outward (normal) force 

was applied to two conventional-style, 32 square centimeter (5 square inch), serrated shear plates suspended 

on opposite sides of the borehole. Time was allowed for 

the soil to consolidate (typically 15 to 30 minutes) and 

for pore water to dissipate out of the zone in proximity 

to the plates where shearing of the soil would occur. 

Then the plates were pulled axially along the borehole 

with increasing force until the soil next to the plates 

was sheared; the measured shear stress at failure (maxi-
Data Collection and Description 9

mum applied axial force) and the applied normal stress 

were recorded. This represented a single stage of the 

BST, which usually was repeated six to eight times in 

the same location with incrementally larger normal 

stresses and with fairly uniform consolidation times 

(typically 7 to 8 minutes) between stages. With each 

stage of the test, the shear zone should occur The data 

were plotted after corrections were made to compensate for any non-zeroing of the stress-gage dials. BSTs 

that appeared questionable usually were repeated after 

the shear head was rotated 90 degrees (°) or was moved 

vertically to test fresh material. Preliminary results 

from the BSTs were computed in the field; final results 

were computed in the office after the analytical results 

from the soil samples were received.

Laboratory Soil Analyses

Samples to be analyzed for soil unit weight, soil 

moisture, degree of saturation, and particle size were 

delivered to the Soil and Plant Analytical Laboratory at 

the University of Nebraska–Lincoln. The soil unitweight samples were weighed in the container, dried, 

and reweighed in the container; the containers then 

were cleaned and weighed. All measurements were in 

grams (g) as mass. The mass quantities of the ambient 

and dry soil sample and of the sample water were 

derived from the measurements.

The ambient soil unit weight (table 3) represents 

the soil condition at the time of sampling; values for the 

samples were computed using equations from Coduto 

(1999, p. 100):

(1)

where ρamb is the density of the ambient soil, in 

grams (mass) per cubic centimeter,

Mamb is the mass of the ambient soil, in 

grams, and 

V is the total volume of the soil, in cubic centimeters;

(2)

where γamb is the unit weight of the ambient soil, in 

kilonewtons per cubic meter, and 

g is the acceleration due to gravity, 9.81 

meters per second squared.

The saturated soil unit weight (table 3) represents the soil condition when all the voids in the soil 

become filled with water; values for the samples were 

computed using an equation modified from Lambe 

(1951, p. 12; used density in place of unit weight of 

water and mass in place of weight of dry sample), and 

an equation from Dunn and others (1980, p.17):

(3)

where e is the void ratio or relative volumes of voids 

(air and water) and solids of the soil, 

dimensionless,

Gs is the specific gravity of the soil solids, 

assumed to be 2.70 based on the range 

for moist soils (Coduto, 1999, p. 101) 

and the value for Iowa loess soil (Spangler and Handy, 1973, p. 166), dimensionless, 

ρw is the density of water, 1.00 grams per 

cubic centimeter, and 

Ms is the mass of the soil solids, in grams;

(4)

where γsat is the unit weight of the soil when saturated with water, in kilonewtons per 

cubic meter, and 

γw is the unit weight of water, 9.81 kilonewtons per cubic meter.

The moisture content (table 3) of the soil samples 

was computed using an equation from Coduto (1999, 

p. 97):

(5)

where w is the moisture content of the ambient soil, 

in percent, and

Mw is the mass of the soil water, in grams.

The degree of saturation (table 3) of the soil 

samples was computed using an equation modified 

from Coduto (1999, p. 106): 

ρamb Mamb

V

=

γ amb ρ amb = g

e

GsρwV

Ms

= ----------------- – 1

γ sat

Gs ( ) + e

1 + e ------------------- γ w =

w

Mw

Ms

= ------- × 100
10 Stream Bank Stability in Eastern Nebraska

(6)

where SD is the degree of saturation of the ambient 

soil, in percent.

Particle-size distribution, as percentages of 

gravel, sand, silt and clay, was determined by a 4-point 

hydrometer test. If the sample contained sufficient 

coarse material, a sieve analysis also was done. The 

laboratory made a determination of soil textural classification based on the USDA system (Schoeneberger 

and others, 1998) with National Soil Information 

System (NASIS) codes (table 3).

Samples to be analyzed for Atterburg limits 

(liquid limit, plastic limit, and plasticity index) were 

delivered to the National Soil Survey Laboratory of the 

Natural Resources and Conservation Service (NRCS) 

in Lincoln. Sample volumes of 500 grams or more 

were sieved, and the liquid limit was established by 

determining the moisture content in which the sample 

was able to close a groove under standard shaking 

(Lambe, 1951). The plastic limit was found by determining the moisture content in which a thread of the 

sample (of standard size) began to crumble when rolled 

(Lambe, 1951). The plasticity index then was 

computed as the liquid limit minus the plastic limit. 

Values for 28 sites were determined (table 3). 

Evaluation of Borehole Shear Tests

Pore-water pressure (u) can affect the total shear 

strength measured by the BST (Spangler and Handy, 

1973; Lutenegger and Hallberg, 1981). In such cases, 

the computed values of cohesion and friction angle are 

referred to as apparent values. The effective values of 

cohesion (c′) and friction angle (φ′) are those attributed 

only to the soil structure and are the values needed for 

channel-bank stability analysis. If pore water dissipates 

out of the shearing zone during the consolidation time 

between individual stage tests, the BST should not be 

affected by the effects of positive pore-water pressure. 

This should be especially true for sands and dry cohesive soils (Lutenegger and Hallberg,1981). If that is the 

case, the BST is a drained test, and the apparent shear 

stress measured is equal to the effective strength of the 

soil. The friction angle of the soil is lowered based on 

the degree of saturation of the soil and goes to zero 

when completely saturated (Lutton, 1974). If the 

excess pore water cannot be drained quickly enough, as 

can happen with saturated or high-plasticity clays, pore 

pressure is positive, and the BST is an undrained test 

with apparent strength parameters (Lutenegger and 

Hallberg, 1981). Generally, the greater the degree of 

saturation or the more clay in the soil, the greater the 

consolidation time needs to be to dissipate the excess 

pore water. Alternatively, some soil, such as silt and 

clay, can develop a high apparent cohesion from negative pore-water pressure through the process of drying 

(Spangler and Handy, 1973, p. 441; Simon and others, 

1999a). 

Preliminary manual calculations of cohesion (yintercept) and friction angle (slope) were made at the 

site by a least-squares regression on the range of data 

that appeared to define a relation known as the MohrCoulomb failure envelope for the soil (Lutenegger and 

Hallberg, 1981). The BSTs later were recalculated after 

a calibration adjustment for the instrument was incorporated and other independent results were examined 

to infer possible effects of positive or negative porewater pressures. These other results included moisture 

content, degree of saturation, and particle size of the 

soil; borehole logs; BST consolidation times; sorption 

curves of soils, and other BSTs. Sorption 

curves—negative pore-water pressure or capillary 

potential as related to moisture content or degree of 

saturation—for different textural classes of soils (Spangler and Handy, 1973, p. 222-231) were used as a guide 

to estimate possible effects of negative pore water pressure on BSTs.

According to Lutenegger and Hallberg (1981), 

interpretation of BSTs to determine effective strength 

parameters “should be based on judgement of the drainage characteristics of the soil and test conditions.” For this 

report points for regression were selected, or BST results 

were not used, based on guidelines given by Lutenegger 

(1987a) and Lutenegger and Hallberg (1981). Low initial 

points sometimes were eliminated because of apparent 

inadequate seating of the shear plates (figs. 4C and 

4D)—caused by inadequate normal stress for the given 

soil condition. The local slope of such points commonly 

will project to a negative cohesion, which is a physical 

impossibility. Although Lutenegger (1987a) suggests not 

using the first point routinely, many were found to fit a 

regression line consistent with other points. Data points at 

high values of normal stress sometimes were eliminated 

because of the apparent effects of positive pore-water 

pressures or because the expansion limits of the BST 

device appeared to have been reached (figs. 4B and 4D). 

These situations were identified by a flattening of the 

slope or a negative slope at the upper end of the data. 

SD

wGs

e = ----------
Evaluation of Borehole Shear Tests 11

160

140

120

100

80

60

40

20

0

160

140

120

100

80

60

40

20

0

160

180

140

120

100

80

60

40

20

-20

0

0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 200

A B

C D

E F

Cole Cr at Ames Ave, Omaha

(Site ID PC-10)

Stevens Cr at Havelock Ave, Lancaster Co

(Site ID SC-23)

Weeping Water Cr at US 75

(Site ID MRT-16)

Little Nemaha R at N67 near Talmage

(Site ID LNR-14)

M Br Big Nemaha R at S34B

(Site ID BNR-2)

N Br Big Blue R at CR "J", Butler Co

(Site ID BBR-4)

All points used

Apparent effects of inadequate initial shear

plate seating at low normal stress

Inadequate number of points, if any, only

representing drained condition—longer

consolidation times required

Test not used

Apparent effects of "stiff" soil

(slippage noted) causing nonseating

of conventional shear plates—

modified high-pressure shear

plates required

Test not used,

not considered

valid

Combination of B and C

Apparent effects of positive pore-water pressure

(undrained strength) or expansion limits of

instrument at high normal stress

NORMAL STRESS, IN KILOPASCALS

SHEARING STRENGTH, IN KILOPASCALS

Not used (test 1)

Used (test 1)

Not used (test 2)

Used (test 2)

EXPLANATION

Regression (test 1)

Regression (test 2)

w Moisture content

S Degree of saturation D

Negative cohesion Negative cohesion

Figure 4. Examples of borehole shear test data and interpretations, and values of moisture content and degree

of saturation at time of tests.

SD = 80.0%

w = 25.7%

SD = 82.9%

w = 27.2%

SD = 37.1%

w = 11.6%

SD = 97.5%

w = 27.4%

SD = 96.0%

w = 29.9%

SD = 29.7%

w = 10.9%
12 Stream Bank Stability in Eastern Nebraska

For some tests, positive pore-water pressure or 

inadequate seating of the plates appeared to affect most 

or all of the data points (figs. 4E and 4F) to such an 

extent that the test results were not used in the bankstability analysis. Based on sorption curves, results of a 

few BSTs with apparently high cohesions and low 

values of moisture content or degree of saturation also 

were considered questionable. The sorption curves 

showed that for the loess and clay loam soil the capillary potential increased rapidly with decreasing values 

of moisture content below about 25 percent of dry 

weight (or degree of saturation below about 55 percent 

for clay loam soil). 

A summary of the BST status, except for those 

not considered valid (such as fig. 4-F), are listed in 

table 3. Results considered questionable (such as 

fig. 4-E) are listed, but are noted as not being used for 

further analysis. Cumulative frequency diagrams of the 

BST results considered useable for bank-stability analysis show that most of the sites had cohesions between 

6 and 18 kPa (kilopascals) and friction angles between 

24 and 37o (fig. 5). For comparison, average (mean) 

values for loess in western Iowa (Lohnes and Handy, 

1968) and western Tennessee (Simon and Hupp, 1992), 

and a range of values for Kansas and Nebraska loess, 

cited from other sources by Lohnes and Handy (1968), 

indicated cohesions and friction angles generally in the 

same range as that found in this report, with the exception of cohesions ranging from 34.5 to 69.0 kPa cited 

by Lohnes and Handy (1968) (see fig. 5). The data from 

western Iowa and western Tennessee are from BSTs 

and were considered to represent drained conditions. 

Shear-strength data from BSTs also were 

collected from alluvial channel banks for three bridge 

site studies in Mississippi (Turnipseed and Wilson, 

1992; Turnipseed and Baldwin, 1992; and Wilson and 

Turnipseed, 1993). Excluding sand material, of which 

little was encountered in eastern Nebraska, average 

cohesion from the Mississippi studies was 13.8 kPa 

with a range of 9.2 to 17.7 kPa. Average friction angle 

was 27° with a range of 16 to 35°. The authors of the 

Mississippi reports noted that “Shear-strength data 

obtained using the BST have compared reasonably well 

with the results of triaxial shear-strength tests ...”; this 

assertion was based on work by Thorne and others 

(1981) and on tests made by the Mississippi Department of Transportation. Regarding the BST results for 

western Iowa, Lohnes and Handy (1968) note that the 

“... data are substantially in agreement with laboratory 

direct-shear and triaxial-shear-test results of Olsen 

(1958) and Akiyama (1963) for Iowa loess.” Except for 

the Kansas and Nebraska data cited by Lohnes and 

Handy (1968), data for all of the other studies were 

known to have been used for bank-stability analyses 

similar to those described in this report. 

Generalization of Shear Strength Data

Lohnes and Handy (1968) used the mean of their 

measured cohesion and friction angle value data in 

their slope-stability analysis of western Iowa loess. 

They also suggested using the mean values for design 

purposes. Attempts were made to group the site data in 

this report by stream basin, by Quarternary geology 

(Swinehart and others, 1994), by stratigraphy, by 

geographic area (proximity), and by soil groups with 

similar hydrologic characteristics as developed by 

Dugan (1984). After testing the alternatives, the sites 

were separated into three groups for this report based 

on the average mapped permeability of the 60-inch soil 

profile from Dugan (1984). 

The permeabilities of soil in Nebraska range from 

less than 0.06 inches per hour (in/hr) for clay soil, to 

more than 16.0 in/hr for sandy soil. Dugan defined five 

permeability groups—group 1, less than 1.0 in/hr; group 

2, 1.0 to 2.0 in/hr; group 3, 2.0 to 5.0 in/hr; group 4, 5.0 

to 10.0 in/hr; and group 5, more than 10.0 in/hr. Based 

on Dugan’s maps, permeability values of the sites in the 

study area ranged from groups 1 through 4, with the 

majority in group 2. Only two sites with acceptable BST 

data were in group 4, so groups 3 and 4 were combined 

for this report, hereafter referred to as group 3-4. Of the 

908 bank sections in the study, 72 were in soil group 1, 

724 were in soil group 2, and 112 were in soil group 3-4.

To evaluate whether cohesion values between each 

combination of groups were statistically different, twosample t-tests were done on the rank-transformed values 

(Iman and Conover, 1983). Groups 1 and 2 were both 

statistically different from group 3-4 at an alpha of 0.010 

for the two-tailed test. Groups 1 and 2 were not statistically 

different from each other at the same alpha; however, the 

ranges and median values of cohesion decreased with 

increasing permeability, as would be expected. The highest 

median cohesion was 13.6 kPa in soil group 1, with 12 

BST samples from 12 sites. The median cohesion for soil 

group 2 was 10.8 kPa, with 119 BST samples from 98 

sites. The median cohesion for soil group 3-4 was 6.7 kPa, 

with 19 BST samples from 18 sites. The corresponding 

median values of friction angle were about 26o, 28o, and 

30o.
Evaluation of Borehole Shear Tests 13

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60 70

COHESION, IN KILOPASCALS (kPa)

0

10

20

30

40

50

60

70

80

90

100

A

Western Iowa loess 9.0 kPa (average of 14) from Lohnes and Handy (1968)

Measured with BST device without pore pressure corrections

Assumed to represent drained conditions

Western Tennessee loess 15.1 kPa (average of 3) from Lohnes and Handy (1968)

Measured with BST device without pore pressure corrections

Assumed to represent drained conditions

Western Tennessee loess tributary streams 6.8 kPa (average of 53) from Simon and Hupp (1992)

Measured with BST device equipped with pore pressure sensor

Considered to represent drained conditions

Kansas and Nebraska loess 34.5–69.0 kPa from Bureau

of Reclamation studies cited by Lohnes and Handy (1968)

Method and conditions unknown

Mississippi alluvial bank material (no sand) 13.8 kPa (average of 9) from Turnipseed and Wilson (1992),

Turnipseed and Baldwin (1992), and Wilson and Turnipseed (1993)

Measured with BST device; apparently assumed to represent drained conditions

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30 40 50 60 70

FRICTION ANGLE, IN DEGREES

FREQUENCY

0

10

20

30

40

50

60

70

80

90

100

CUMULATIVE FREQUENCY

Frequency

Cumulative frequency

Literature value of friction angle

Kansas and Nebraska loess 31–33 degrees from Bureau of

Reclamation studies cited by Lohnes and Handy (1968)

Method and conditions unknown

Western Tennessee loess 29 degrees (average of 4)

from Lohnes and Handy (1968)

Measured with BST device without pore pressure corrections

Assumed to represent drained conditions

Western Iowa loess 25 degrees (average of 14) from Lohnes and Handy (1968)

Measured with BST device without pore pressure corrections

Assumed to represent drained conditions

Western Tennessee loess tributary streams 31 degrees

(average of 53) from Simon and Hupp (1992)

Measured with BST device equipped with pore

pressure sensor

Considered to represent drained conditions

Mississippi alluvial bank material (no sand) 27 degrees (average of 9) from

Turnipseed and Wilson (1992), Turnipseed and Baldwin (1992), and Wilson and

Turnipseed (1993)

Measured with BST device; apparently assumed to represent drained conditions

B

Frequency

Cumulative frequency

Literature value of friction angle

Figure 5. Distribution of soil cohesion (A) and friction angle (B) data from borehole shear tests (BSTs) in the study described

in this report compared to corresponding data for loess and alluvial soils from other studies.
14 Stream Bank Stability in Eastern Nebraska

BANK STABILITY

Cohesive channel banks tend to fail in large 

blocks with material sliding along a well-defined slip 

surface; investigations by Simon (1989b) have shown 

that these mass failures generally occur during stormflow recessions when banks are saturated and the water 

level in the channel is relatively low so that it provides 

little support. According to Spangler and Handy 

(1973), most failures usually occur along curved rather 

than planar surfaces; however, evidence for bank failures along both types of failure surfaces were observed 

during the study described in this report. In some cases, 

it was evident that the failure planes had intersected 

vertical tension cracks running parallel to the banks. 

From a concurrent study of the Wehrspann watershed, 

within the Papillion Creek Basin, Zellars (1996) noted 

that “... plane failures were observed to be the dominate [dominant] failure mode.” According to Thorne 

(1998), planar failures tend to occur more on steep 

banks, while failures along a curved surface (rotational 

failures) occur on steep and shallow banks; these statements are in agreement with the observations in this 

report. Some failure surfaces were accompanied by 

vertical sections at the top indicating the occurrence of 

tension cracking in conjunction with shearing along the 

failure surface. 

Three methods were used to analyze the bank 

stability for this report—(1) the Culmann method 

(Spangler and Handy, 1973); (2) a method developed 

by the Agricultural Research Service (ARS) (Andrea 

Curini, written communication, 1999); and (3) an indirect assessment based on Bishop’s simplified method 

of slices (Bishop, 1955) as contained in a computer 

program by Huang (1996)—Rotational Equilibrium 

Analysis of Multilayered Embankments (REAME). 

The Culmann and ARS methods are based on planar 

failures, and the indirect assessment is based on rotational failures. All three analyses required the use of the 

shear-strength parameters—cohesion and friction 

angle—and incorporate the effects of positive porewater pressure (saturated banks) on those parameters. 

The ARS analysis also can incorporate the effects of 

negative pore-water pressure (suction) that develops as 

soil dries. Due to few data, all analyses were based on 

the assumption of homogeneous banks. The occurrence 

of heterogeneous banks could significantly alter the 

results that were obtained. 

Shear Strength and Pore Pressure

The stability of a stream channel bank is based 

primarily on its shear strength (Spangler and Handy, 

1973; Simon and Hupp, 1992). When forces acting 

along a potential slip surface exceed the shear strength 

(resisting forces) of the soil, the channel bank will fail. 

The Coulomb equation, modified from Spangler and 

Handy (1973, p. 442), expresses the shearing strength 

of a drained soil as the sum of the forces generated from 

cohesion and from normal stress (forces acting perpendicular to a potential slip surface):

(7)

where s is the shear strength,

c is the total or apparent cohesion (cohesive 

shear strength) of the soil, 

σ is the total normal stress on the slip surface, and 

φ is the internal friction angle of the soil.

Resisting forces, from friction and the interlocking of soil grains, are generated along a potential slip 

surface (failure plane) in proportion to the normal 

stress applied to the potential slip surface. The coefficient of internal friction, or friction angle, is the property of a soil that is used as the limiting value that those 

forces can attain. For a granular soil, this property is 

primarily influenced by the soil density and grain packing (Spangler and Handy, 1973, p. 434-435). The 

normal stress, also referred to as consolidating pressure, serves to force the soil together along the potential 

slip surface. For planar slip surfaces, its magnitude is 

determined by the weight of the material above the slip 

surface and the angle of the potential slip plane. The 

steeper the angle, the more the weight is converted to 

force along the slip plane (to cause failure) and the less 

the weight is converted to force that is normal to the slip 

plane (to resist failure). Cohesion represents the soil’s 

ability to retain internally some of a previous consolidating pressure (preconsolidation) and is defined as the 

soil’s shearing strength in the absence of any normal 

stress. Sand does not have this ability and is considered 

cohesionless. 

Pore-water pressure can decrease or increase the 

shear strength of soil, depending on whether the pressure is positive or negative (the pore pressure from air 

is assumed to be negligible). Positive pore-water pressure will reduce the frictional component of shear 

s c += σ φ tan
Bank Stability 15

strength, as in the adjusted Coulomb equation modified 

from Spangler and Handy (1973, p. 442): 

(8)

where cr is the effective cohesion of the soil,

uw is the pore-water pressure on the slip surface, and 

φr is the effective internal friction angle of 

the soil.

When pore-water pressure is negative, it will increase 

the cohesive shear strength as in the adjusted Coulomb 

equation modified from Fredlund (1987): 

(9)

where ua is the pore-air pressure on the slip surface 

(considered negligible), and 

φ b is the angle used to determine the rate of 

increase in shear strength caused by 

matric suction (ua - uw).

Culmann Method—Planar Failure

The Culmann analysis of bank stability (Lohnes 

and Handy, 1968; Spangler and Handy, 1973, p. 487–

490; Simon and others, 1999a, p. 125–127) is based on 

the assumption that failure occurs along a plane 

through the toe of a homogeneous bank (fig. 6). The 

shearing (Ss) and resisting (Sr) forces along the length 

(L) of a potential failure plane are determined and set 

equal to each other—Ss is computed from the weight of 

the material above the potential failure plane, and Sr is 

computed from equation 7 for unsaturated conditions 

and from equation 8 for saturated conditions. For given 

soil properties of friction angle and cohesion, and for a 

given bank slope, the maximum bank height that can be 

attained before failure would occur can be computed 

(equation modified from Lohnes and Handy, 1968, 

p. 249; and Spangler and Handy, 1973, p. 489):

(10)

where Hc is the critical bank height at which the 

shearing forces equal the resisting 

forces, in meters,

c is the cohesion of the soil, in kilopascals,

α is the bank angle, in degrees,

φ is the internal friction angle of the soil, in 

degrees, and 

γ is the unit weight of the soil, in kilonewtons 

per cubic meter.

For drained conditions the effective shear strength 

parameters, c′ and φ′ , can be substituted in equation 10 

for c and φ. 

At the critical bank height, the angle of the plane 

at which failure would occur can be computed (equation modified from Lohnes and Handy, 1968, p. 250; 

and Spangler and Handy, 1973, p. 489):

(11)

where β is the failure plane angle at which the 

shearing forces equal the resisting 

forces, in degrees.

Because soil is weak in tension, vertical cracks 

often develop on the tops of steep banks; this reduces 

the critical bank height that can be attained by the depth 

of the tension crack (equation from Simon and others, 

1999a, 1999b):

(12)

where Hcz is the critical height of a bank with a tension crack, in meters, and 

z is the depth of the tension crack, in meters.

Tension crack depth can be calculated from the properties of the soil (equation from Lohnes and Handy, 1968, 

p. 251; and Simon and others, 1999b, p. 140) :

(13)

For saturated conditions, the friction angle is assumed 

to go to zero, leaving only the effective cohesion to 

resist failure. Therefore, the most stable bank condition

s c′ σ uw ( ) – φ′ += tan

s c′ ua uw ( ) – φ b tan σ ua ( ) – φ′ = + + tan

Hc

4c sinα φ cos

γ[ ] 1 – cos( ) α φ – = -------------------------------------------

β α φ +

2 ------------=

Hcz Hc –= z

z

2c′

γ

------ 45 φ′

2

----+ ⎝ ⎠ ⎛ ⎞ = tan
16 Stream Bank Stability in Eastern Nebraska

is dry soil without tension cracks, and the least stable 

condition is saturated soil with tension cracks. 

Approach

Two types of analyses were done for each site 

using the Culmann method—average bank geometry 

for each site with the median soil parameters from the 

corresponding soil group (see Generalization of Shear 

Strength Data section) and individual bank section 

geometry with soil parameters for that site. For banks 

that did not conform to the idealized straight-bank 

shape (fig. 6), average vertically weighted bank angles 

were used in equations 10 through 12 (see Effects of 

Bank Shape section).

Failure envelopes of critical bank heights and 

corresponding bank angles were developed from equations 10, 11, and 12 using the median shear strength 

and soil-unit-weight parameters for each soil group for 

four conditions—ambient (condition at time of 

sampling) and saturated soil moisture, each with and 

without tension cracks (figs. 7 through 9). For each 

tension crack condition (with and without), the ambient 

and saturated failure envelopes divide the plot into 

three areas—stable, at risk, and unstable. Any combination of bank angle and height below the saturated 

failure envelope is considered stable, and any point 

above the ambient failure envelope is considered unstable. Points between the two failure envelopes are 

considered at risk, meaning that the bank section is 

stable at ambient soil moisture but unstable if saturated. The average bank geometry (angle and height) 

for each site is shown on the appropriate plots to enable 

a visual determination of the expected stability status.

EXPLANATION

H

L

Failure

plane

Bank

face

Streambed

Bank top

Sr

Sr

Ss

Ss

L

H

Figure 6. Conceptual diagram of a bank section and the forces acting on a potential planar failure

surface that were used in the Culmann method of stability analysis.

Failure plane length, in meters

Bank height, in meters

Shearing forces, in kilonewtons per meter

Resisting forces, in kilonewtons per meter

Bank angle, in degrees

Failure plane angle, in degrees
ARS Method—Planar Failure 17

To the extent that the median parameters for the 

soil groups represent bank soil conditions at each site, 

the Culmann failure envelopes provide a general overview of the bank stability for average conditions at the 

sites within each of the soil groups. The proportion of 

stable sites is largest for soil group 1 (lowest permeability and highest cohesion), smallest for soil group 

3-4 (highest permeability and lowest cohesion), and 

intermediate for soil group 2 (figs. 7 through 9).

For a given failure envelope, any one site could 

have individual bank sections that are more or less 

stable than for the average channel reach because of 

different bank geometry. Also, any one site could have 

several different failure envelopes, depending on the 

variability of the soil parameters at the site that could 

indicate more or less stable conditions than those for 

the median soil group values. Therefore, individual 

bank sections were analyzed using their specific angles 

and heights, and the site-specific soil parameters for the 

four combinations of soil moisture (ambient and saturated) and tension cracking (with and without) 

(table 4). These analyses assume that the few soil data 

for each site are representative of the whole reach that 

was surveyed. 

As the measured bank angle (α) approaches the 

friction angle (φ), the quantity [1-cos(α−φ)]

approaches zero and the value of critical bank height 

(Hc) goes to infinity in equation 10; this is illustrated by 

the steepening of the ambient failure envelopes as they 

approach the value of the friction angle (φ) (figs. 7 

through 9). This situation resulted in some values of Hc

for ambient conditions that were much larger than any 

known bank heights in eastern Nebraska. For practicality, any values of Hc larger than 50 meters (an arbitrary 

value) were listed as “>50.0” (table 4). If the measured 

bank angle is less than the friction angle, the failure 

angle (β) in equation 11 will be greater than the 

measured bank angle (α) and the bank should be stable

for any bank height. Under those circumstances, 

however, equation 10 will still produce a finite result 

because the cosine of a negative angle is the same as an 

equal positive angle; therefore, equation 10 is not applicable and was not used. When the measured bank angle 

was less than the friction angle of the soil, values of Hc

were listed as “>50.0” and the stability results were 

listed as stable. Neither of these situations applies for 

saturated conditions because the friction angle (φ ) is 

assumed to be zero for that condition. 

Results

Summary results for the Culmann method were 

compiled (table 5) and are discussed in this section. For 

the condition with no soil tension cracks, 611 of all 908 

bank sections (67 percent) were listed as stable and 290 

(32 percent) were at risk; when tension cracks were 

assumed, 528 bank sections (58 percent) were listed as 

stable and 367 (40 percent) were at risk (table 4). For 

soil group 1 without tension cracks, 67 of 72 bank 

sections (93 percent) were listed as stable and 5 

(7 percent) were at risk; with tension cracks, 66 (92 

percent) were listed as stable and 6 (8 percent) were at 

risk. For soil group 2 without tension cracks, 470 of 

724 bank sections (65 percent) were listed as stable and 

248 (34 percent) were at risk; with tension cracks, 402 

(56 percent) were listed as stable, and 312 (43 percent) 

were at risk. For soil group 3-4 without tension cracks, 

74 of 112 bank sections (66 percent) were listed as 

stable and 37 (33 percent) were at risk; with tension 

cracks, 60 (54 percent) were listed as stable and 49 (44 

percent) were at risk. The largest percentage of stable

banks and the smallest percentage of at risk banks were 

for soil group 1, which had the lowest soil permeability 

and the highest median cohesion of all the soil groups. 

Theoretically, no actual bank section should fall 

into the unstable category because any such bank 

should have already failed. However, a few bank 

sections for soil groups 2 and 3-4 were listed as unstable based on the Culmann analysis (table 4); in actuality, these probably represent banks that are nearly 

unstable. For the condition without soil tension cracks, 

7 of 908 bank sections (1 percent) were listed as unstable; none of 72 bank sections for soil group 1, 6 of 724 

(1 percent) for soil group 2, and 1 of 112 (1 percent) for 

soil group 3-4. For the condition with tension cracks, 

13 bank sections (1 percent) were listed as unstable; 

none for soil group 1, 10 (1 percent) for soil group 2 

and 3 (3 percent) for soil group 3-4.

ARS Method—Planar Failure

The Agricultural Research Service (ARS) developed a method of bank stability analysis that incorporates the effects of positive and negative pore-water 

pressure from water in the bank, variable levels of 

water in the channel, and variations of bank material. 

Similar to the Culmann method, the forces along a
18 Stream Bank Stability in Eastern Nebraska

1

10

100

0 10 20 30 40 50 60 70 80 90

BANK ANGLE, IN DEGREES

BANK HEIGHT, IN METERS

Ambient without crack

Ambient with crack

Saturated without crack

Saturated with crack

Average channel-bank geometry

UNSTABLE

STABLE

AT RISK

Cohesion = 13.6 kilopascals

Friction angle = 26.0 degrees

Unit weight (ambient) = 15.9 kN/m3

Unit weight (saturated) = 17.6 kN/m3

(kN/m3, kilonewtons per cubic meter)

One site not shown

(bank angle 47.0 degrees, bank height 0.9 meter )

Figure 7. Culmann failure-envelope curves for soil group 1, using median soil group parameters and selected soil

moisture and tension crack conditions, compared to average channel-bank geometry for sites (bank angles, weighted

vertically).

SOIL PARAMETERS

1

10

100

0 10 20 30 40 50 60 70 80 90

BANK ANGLE, IN DEGREES

BANK HEIGHT, IN METERS

Ambient without crack

Ambient with crack

Saturated without crack

Saturated with crack

Average channel-bank geometry

UNSTABLE

STABLE

AT RISK

Cohesion = 10.8 kilopascals

Friction angle = 27.9 degrees

Unit weight (ambient) = 16.37 kN/m3

Unit weight (saturated) = 17.88 kN/m3

(kN/m3, kilonewtons per cubic meter )

Figure 8. Culmann failure-envelope curves for soil group 2, using median soil group parameters and selected soil

moisture and tension crack conditions, compared to average channel-bank geometry for sites (bank angles, weighted

vertically).

SOIL PARAMETERS
ARS Method—Planar Failure 19

1

10

100

0 10 20 30 40 50 60 70 80 90

BANK ANGLE, IN DEGREES

BANK HEIGHT, IN METERS

Ambient without crack

Ambient with crack

Saturated without crack

Saturated with crack

Average channel-bank geometry

UNSTABLE

STABLE

AT RISK

Cohesion = 6.7 kilopascals

Friction angle = 30.4 degrees

Unit weight (ambient) = 16.51 kN/m3

Unit weight (saturated) = 18.13 kN/m3

(kN/m3, kilonewtons per cubic meter)

Figure 9. Culmann failure-envelope curves for soil group 3-4, using median soil group parameters and selected soil

moisture and tension crack conditions, compared to average channel-bank geometry for sites (bank angles, weighted

vertically).

SOIL PARAMETERS
20 Stream Bank Stability in Eastern Nebraska

EXPLANATION

Bank top

Streambed

U

U

P

P

hp

hp

W

W

hs

hs

hu

hu

H

H

c

c

S

S

Bank

face

Failure

plane

Bank angle, in degrees

Failure plane angle, in degrees

Weight of failure block, in kilonewtons per meter

Negative pore-water pressure (suction) distribution from bank soil moisture,

in kilonewtons per meter

Height of unsaturated bank above bank-water level, in meters

Cohesion, in kilopascals

Bank height, in meters

Height of channel water above streambed level, in meters

Hydrostatic pressure distribution from channel water, in kilonewtons per meter

Positive pore-water pressure distribution from bank water, in kilonewtons per meter

Height of saturated bank above streambed level, in meters; and

Water surface

Figure 10. Conceptual diagram of a bank section and the forces acting on a potential planar failure surface

that were used in the ARS (Agricultural Research Service) method of stability analysis.
ARS Method—Planar Failure 21

potential failure plane are determined and summed to analyze for stability (fig.10). Several forces are accounted 

for differently or in addition to those in the Culmann method (Simon and others, 1999a):

1. The matric suction force (negative pore-water pressure) on the unsaturated part of the failure plane (S);

2. the hydrostatic-uplift force (U) from positive pore-water pressure in the saturated part of the failure 

surface; and

3. the hydrostatic-confining force from the water in the channel (P) (Casagli and others, 1997; Curini, 1998; 

Simon and Curini, 1998; and Casagli and others, 1999).

The distribution of the pore-water pressure forces is based on the position of the water table in the bank. The 

pressure from water in the channel serves to confine the bank and help resist failure; its computation is based on 

the level of the channel water. Variations in soil-bank parameters can be accounted for because the method allows 

the forces to be summed for various layers of soil. The ratio of the resisting forces (numerator) to the shearing or 

driving forces (denominator) is used to determine a factor of safety (FS) (Simon and others, 1999a, p. 138):

(14)

where ct is the effective cohesion of the soil, in kilopascals,

i is the layer number,

L is the length of the failure surface, in meters,

S is the force produced by matric suction on the unsaturated part of the failure surface, in kilonewtons 

per meter,

φ b is the angle used to determne the rate of increase in shear strength related to matric suction, in 

degrees, 

W is the weight of the failure block, in kilonewtons per meter,

β is the failure plane angle (=1/2(α+φ)), in degrees,

U is the hydrostatic uplift force acting on the saturated part of the failure surface, in kilonewtons per 

meter,

P is the hydrostatic confining force due to external water level, in kilonewtons per meter,

α is the bank angle, in degrees, and 

φr is the effective internal friction angle of the soil, in degrees.

A factor of safety less than 1 indicates an unstable bank and a value greater than 1 indicates a stable bank for the 

condition being analyzed.

As with the Culmann analysis, homogeneous banks were assumed because of the few, available soil data at 

each site. Therefore, only a single layer was used, and equation 14 becomes:

(15)

FS

c′iLi Si φb

i ( ) tan Wi β Ui [ ] cos – + Pi cos( ) α β – φ ′

i ∑ + + tan

Wi ∑ sinβ – Pisin( ) α β – = -------------------------------------------------------------------------------------------------------------------------------------------------

FS

c′L S φb + + ( ) tan [ ] ( ) Wcosβ – U + Pcos( ) α β – tanφ′

Wsinβ – Psin( ) α β – = -----------------------------------------------------------------------------------------------------------------------------

Approach

For each of the soil groups, bank analyses were 

done using a Microsoft EXCEL 2000® spreadsheet 

modified from A. Curini (ARS, written comm., 1999) 

that was developed by the ARS based on equation 15. 

For φ b, a constant value of 17 was used based on 

preliminary results of other ongoing research by the 

ARS. Two types of analyses were done for each site 

using the ARS method—average bank geometry for 

each reach with the median soil parameters from the 

corresponding soil group (see preceding section, 
22 Stream Bank Stability in Eastern Nebraska

Generalization of Shear Strength Data) and individual 

bank section geometry with soil parameters for that 

site. In all cases the average bank angles were based on 

vertical weighting (see Effects of Bank Shape section). 

To compare with the Culmann analyses, banks were 

analyzed for the same two conditions—ambient and 

saturated banks with no support from channel water 

(P = 0) (table 4). 

Banks were considered unstable if the factor of 

safety for the ambient condition was less than one 

(FS < 1), and banks were considered at risk if the factor 

of safety was greater than or equal to one (FS ≥ 1) for 

the ambient condition but was less than one (FS < 1) for 

the saturated condition. Banks were considered stable

if the factor of safety for the saturated condition was 

greater than or equal to one (FS ≥ 1). For banks considered at risk additional computations were done to 

determine at what percentage of bank saturation (up 

from the toe) the factor of safety would just equal one 

(FS = 1) (table 4); saturation above that level should 

result in a failure. The Solver tool in Microsoft EXCEL 

2000® was used to iteratively solve equation 15 with 

varying levels of bank saturation until it converged on 

a solution. Other factors being equal, banks requiring 

lower percentages of bank saturation (for FS = 1) will 

be at greater risk than those requiring higher percentages.

Results

Summary results for the ARS method were 

compiled (table 5) and are discussed in this section. For 

the ARS method, 612 of all 908 bank sections 

(67 percent) were listed as stable and 296 (33 percent) 

were at risk (table 4). For soil group 1, 67 of 72 bank 

sections (93 percent) were listed as stable and 5 

(7 percent) were at risk. For soil group 2, 471 of 724 

bank sections (65 percent) were listed as stable and 253 

(35 percent) were at risk. For soil group 3-4, 74 of 112 

bank sections (66 percent) were listed as stable and 38 

(34 percent) were at risk. The largest percentage of 

stable banks and the smallest percentage of at risk

banks were for soil group 1, which had the lowest soil 

permeability and the highest median cohesion of all the 

soil groups. 

Unlike the Culmann analysis for ambient banks, 

no unstable banks (FS < 1) for ambient banks were 

determined with the ARS analysis. This could be 

caused by the effects of negative pore-water pressure 

(suction) that are estimated in the ARS analysis, but not 

in the Culmann analysis. Also, there was no provision 

made for the adverse effects of tension cracks in the 

ARS analysis.

Indirect Method—Rotational Failure

An indirect method was developed to allow for 

rapid assessment of bank stability against rotational 

failure using a minimum amount of data. It is based on 

Bishop’s simplified method of slices (Bishop, 1955), as 

contained in the computer program Rotational Equilibrium Analysis of Multilayered Embankments 

(REAME) by Huang (1996)—a DOS/Windows 

computer program. It was used to analyze for rotational 

failures in this report.

For a given bank section, REAME simulates a 

series of circular failure arcs of varying radii that intersect the bank section from various points of origin 

within a search grid specified by the user. The program 

automatically expands the grid, as needed, to find a 

point with a factor of safety less than those for 

surrounding points on the grid. The program then 

subdivides the grid around that point and searches for 

points with lower factors of safety; this process is 

repeated several times before the point with the lowest 

factor of safety is selected. For each trial failure arc, the 

assumed failure block is divided into a series of vertical 

slices and the forces acting on each slice are calculated. 

An equilibrium equation is developed from which a 

factor of safety is calculated. The critical slip surface is 

the one with the minimum factor of safety. A factor of 

safety of one, where the resisting forces are equal to the 

driving forces, indicates the threshold of bank stability. 

For a more thorough explanation of the theory of the 

simplified method of slices, the reader is referred to 

Huang (1996), and Fredlund and Rahardjo (1993). 

Approach

Using REAME to analyze bank stability for each 

of the study sites would have provided results for those 

specific bank sections, but would not have provided a 

method for rapid assessment of banks to be studied in 

the future. Therefore, REAME was used to analyze a 

series of idealized straight banks (uniform slope from 

top-to-toe of bank) with various combinations of bank 

height, bank angle, and soil parameters (soil unit 

weight, cohesion, and friction angle) for both ambient 

and saturated soil moisture conditions. From these 
Indirect Method—Rotational Failure 23

idealized straight-bank analyses, factors of safety for 

the actual bank sections at each of the study sites were 

determined by interpolation from the straight-bank 

analyses using the appropriate bank heights, bank 

angles, and soil parameters.

A uniform bank angle was needed to represent 

each of the actual studied sections to do the interpolation; the same would be needed for any banks to be 

assessed in the future. For reasons explained in a 

following section (Effects of Bank Shape) the average, 

vertically weighted angle from the top to the toe of the 

bank was used for this report. A Microsoft EXCEL 

2000® spreadsheet, on the compact disk at the back of 

this report, was developed to do the five-way interpolation of the factor of safety for both ambient and saturated soil-moisture conditions. 

Analyses for Idealized Straight Banks

Bank stability was evaluated for 2,100 idealized 

straight bank sections using REAME. For each of 

seven combinations of soil-moisture (ambient and saturated) and soil unit-weight (ambient:12, 15, 18, and 

20 kN/m3; saturated: 16, 18, and 20 kN/m3), 300 analyses were done for all combinations of five soil cohesion values (0, 1, 8, 15, and 30 kPa), three soil friction 

angles (10ο, 25ο, and 40ο), four bank heights (1, 3, 6, 

and 12 m), and five bank angles (15ο, 30ο, 50ο, 70ο, and 

90ο). These values cover the range of actual data for all 

but a relatively few of the 908 study banks. 

A flat top, a uniform bank-face slope, and a flat 

streambed were assumed for all idealized straight bank 

sections. The water level in the channel was set equal 

to the bed level for all analyses. For the ambient soilbank moisture condition (unsaturated bank) the water 

level in the bank was set equal to the water level in the 

channel (fig. 11B). For the saturated soil-bank moisture 

condition, the water level in the bank was set equal to 

the bank profile (fig. 12B) to simulate the worst-case 

condition—completely saturated banks with no 

support from water in the channel. To prevent evaluation of failures that intersected only the bank face or 

widened the bank minimally, the failure arcs were 

forced to intersect the top of the bank at a distance from 

the edge equal to at least 10 percent of the bank height. 

Thus, only failures that widened the bank by at least 10 

percent of the bank height were evaluated. Factors of 

safety for each of the above conditions were calculated 

and compiled (table 6).

A Microsoft EXCEL 2000® spreadsheet was 

then developed to interpolate a factor of safety for 

conditions between the results obtained from the analyses for idealized straight banks. The spreadsheet 

contains the results shown in table 6 and uses linear 

interpolation, as needed, to determine the factors of 

safety for both ambient and saturated soil-moisture 

conditions from user-input soil parameters and bank 

geometry. Interpolation is done in the following order 

of parameter inputs: soil unit weight, bank height, 

cohesion, friction angle, and bank angle. The factor of 

safety is much more sensitive to changing input at low 

bank heights and is assumed to be less accurate than at 

higher bank heights because the relations are not as 

linear as those for soil unit weight, cohesion, and friction angle. Generally, this is not a problem, because 

lower banks tend to have relatively high factors of 

safety anyway. 

Finally, the spreadsheet also estimates the maximum angle at which each bank section would be stable 

under both ambient and saturated soil-bank conditions 

with no support from water in the channel. This was 

done by setting the factor of safety equal to zero and 

inputting the known or assumed values of ambient and 

saturated soil unit weight, effective cohesion, friction 

angle, and bank height. The spreadsheet outputs the 

bank angles for both ambient and saturated conditions. 

Because it is the worst case condition, only the bank 

angle for the saturated soil-bank condition was 

reported in table 4. Actual bank angles greater than this 

value should be considered at risk. By default, the 

interpolation spreadsheet uses a design factor of safety 

of one (FS = 1) to estimate the stable straight-bank 

angle; however, this can be reset to whatever value the 

user might desire to provide a margin safety.

Effects of Bank Shape 

Most natural banks do not conform to the straight 

banks assumed for the Culmann and ARS planar-failure analyses and used for the preceding rotational-failure REAME analyses. A channel that has degraded but 

whose banks have not yet failed could have bank faces 

that project outward between the top and the toe with 

the steepest section nearest the toe (convex). Banks that 

have already failed, either by planar failure with tension 

cracks or by rotational failure, could have banks that 

project inward between the top and the toe with the 

steepest section nearest the top (concave). Therefore, 

tests were done to determine the effects that 
24 Stream Bank Stability in Eastern Nebraska

-2

0

2

4

6

8

10

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 1.4

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.7

Vertically weighted angle (60.3 degrees), 1.5

Failure arc center at point

-7.38 from bank toe and

14.25 above channel bed

A CONVEX ELLIPTICAL BANK FACE

AMBIENT BANK-SOIL MOISTURE

Minimum widening allowed

(10 percent of bank height)

-2

0

2

4

6

8

10

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 1.7

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.7

Vertically weighted angle (50 degrees), 1.7

B STRAIGHT BANK FACE

AMBIENT BANK-SOIL MOISTURE

Minimum widening allowed

(10 percent of bank height)

-2

0

2

4

6

8

10

-14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 1.6

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.7

Vertically weighted angle (60.3 degrees), 1.5

Minimum widening allowed

(10 percent of bank height )

C CONCAVE ELLIPTICAL BANK FACE

AMBIENT BANK-SOIL MOISTURE

Failure arc from detailed analysis

Failure arc center

EXPLANATION

Water line

Channel bank section Minimum widening allowed

ELEVATION ABOVE CHANNEL BED, IN METERS

Figure 11. Example of rotational failures and minimum factors of safety for ambient (unsaturated) channel-bank sections

differing only in cross-sectional shape between the top and toe—(A) convex elliptical, (B) straight, and (C) concave elliptical.

Factors of safety from detailed analyses (REAME computer program and actual bank cross sections) are compared to those

from the indirect method (straight-bank tables using unweighted and vertically weighted average bank angels); both are based

on Bishop's simplified method of slices. Soil parameters are as follows: ambient unit weight, 15 kilonewtons per cubic meter;

saturated unit weight (below the water line), 18 kilonewtons per cubic meter; cohesion, 15 kilopascals; and friction angle,

25 degrees.

DISTANCE FROM BANK TOE, IN METERS
Indirect Method—Rotational Failure 25

-2

0

2

4

6

8

10

-14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 0.9

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.0

Vertically weighted angle (60.3 degrees), 0.8

Minimum widening allowed

(10 percent of bank height)

C CONCAVE ELLIPTICAL BANK FACE

SATURATED BANK-SOIL MOISTURE

DISTANCE FROM BANK TOE, IN METERS

-2

0

2

4

6

8

10

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 1.0

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.0

Vertically weighted angle (50 degrees), 1.0

Minimum widening allowed

(10 percent of bank height)

B STRAIGHT BANK FACE

SATURATED BANK-SOIL MOISTURE

-2

0

2

4

6

8

10

FACTORS OF SAFETY

Detailed analysis

REAME computer program, 0.7

Indirect method straight-bank tables

Unweighted angle (50 degrees), 1.0

Vertically weighted angle (60.3 degrees), 0.8

Failure arc center at point

-5.12 from bank toe and

11.00 above channel bed

Minimum widening allowed

(10 percent of bank height)

A CONVEX ELLIPTICAL BANK FACE

SATURATED BANK-SOIL MOISTURE

Failure arc from detailed analysis

Failure arc center

EXPLANATION

Water line

Channel bank section Minimum widening allowed

ELEVATION ABOVE CHANNEL BED, IN METERS

Figure 12. Example of rotational failures and minimum factors of safety for saturated channel-bank sections differing only in

cross-sectional shape between the top and toe—(A) convex elliptical, (B) straight, and (C) concave elliptical. Factors of safety

from detailed analyses (REAME computer program and actual bank cross sections) are compared to those from the indirect

method (straight-bank tables using unweighted and vertically weighted average bank angels); both are based on Bishop's

simplified method of slices. Soil parameters are as follows: saturated unit weight (below the water line), 18 kilonewtons per

cubic meter; cohesion, 15 kilopascals; and friction angle, 25 degrees.
26 Stream Bank Stability in Eastern Nebraska

bank shape have on bank stability, compared to straight 

banks, and to determine how any effects might be 

compensated for in the various types of analyses.

A series of analyses were done for idealized straight 

banks, for elliptically shaped convex, and for concave 

banks using the REAME computer program. Standardized convex and concave banks were developed using a 

quarter of an ellipse, defined by six points between the top 

and the toe of the bank (1/4, 1/2, and 2/3 bank width; and 

1/3, 1/2, and 3/4 bank height). This shape was fit to a given 

bank height such that angles formed by the two end points 

at the top and the toe (unweighted average bank angles) 

were the same although the shape between the endpoints 

was different. A detailed analysis using the REAME 

computer program was done on each set of banks, with all 

of the soil parameters being kept the same. For an example set of 6-m high, 50 degree banks, results show that 

convex and concave banks have reduced factors of safety 

compared to the straight banks for both ambient (fig. 11) 

and saturated (fig. 12) soil moisture. For convex banks, 

this can be attributed to the steepened section on the upper 

part of the bank, which is where the failures occurred in 

the examples (figs. 11 and 12). 

With all other parameters unchanged, convex and 

concave banks had reduced factors of safety compared to 

straight banks for unweighted average bank angles of 15, 

30, 70, and 90 degrees (fig. 13). Other sets of analyses, not 

shown, for other bank heights and soil conditions 

produced similar results. Therefore, if the indirect method 

is used with the unweighted average bank angle to assess 

natural banks with a convex or concave shape, the factors 

of safety will likely be overestimated.

To compensate for the effects of convex and 

concave bank shape when using the straight-bank tables of 

the indirect method, and angle larger than the unweighted 

bank must be used. Computing the vertically-weighted 

average angle from the actual bank-section data produces 

such a result. For straight banks, the vertically weighted 

angle is the same as the unweighted angle; therefore, the 

vertically weighted angle also can be used without affecting the results for straight banks. For the conditions given 

in figure 13, use of the indirect method (straight-bank 

tables) with vertically weighted average bank angle overcompensated for the concave banks at all bank angles, less 

so at the high bank angles, for both ambient and saturated 

conditions. For the convex banks, use of the indirect 

method with vertically weighted average bank angle overcompensated for bank angles less than about 45 degrees 

and under-compensated at bank angles higher than about 

45 degrees for both ambient and saturated conditions. 

Analyses for other bank heights and angles, based mostly 

on median soil parameters, produced similar results.

A final test of the indirect method was made using 

actual bank-section data. Thirty bank sections were 

randomly selected from those used in this report. For both 

ambient (unsaturated) and saturated soil moisture conditions and assuming no water in the channel, detailed 

REAME analyses were done to determine the minimum 

factors of safety using site-specific data for each selected 

bank section. Then, using the interpolation spreadsheet, 

the straight-bank tables were used to compute the factors 

of safety for the same bank sections using both the 

unweighted and the vertically weighted average bank 

angles. Results from the indirect method for both types of 

average bank angles and both soil conditions were 

compared to the corresponding results from the detailed 

REAME analysis (figs. 14 and 15).

Results to the left (or above) the 1:1 reference line 

(figs. 14 and 15) indicate that the indirect method produces 

a higher factor of safety than does the corresponding 

REAME detailed analysis. Assuming the detailed analyses to be correct, such results mean that the indirect 

method indicates a more stable bank than it should. 

Conversely, results to the right (or below) the 1:1 reference 

line (figs. 14 and 15) indicate that the indirect method 

produces a lower factor of safety than does the corresponding REAME detailed analysis; such results mean that the 

indirect method indicates a less stable bank than it should. 

For design purposes or for purposes of identifying banks 

that are nearing instability, the latter type of result from the 

indirect method is preferable because it errs on the side of 

safety.

For both ambient and saturated bank soil moisture 

conditions, the results for the indirect method with 

unweighted average bank angles (figs. 14A and 15A) are, 

generally, to the left (or above) the 1:1 reference line. 

Results for the indirect method with vertically weighted 

average bank angles (figs. 14B and 15B) are, generally, to 

the right (or below) the 1:1 reference line. Therefore, it 

was decided to use the vertically weighted angles with the 

indirect method to estimate factors of safety for actual 

bank angles for this report to compensate for the effects of 

convex- and concave-shaped banks, as much as possible, 

without affecting results for straight banks. 

Although the preceding tests for the effects of 

bank shape were done specifically for the indirect 

method and rotational failure, the rationale behind how 

bank shape affects stability is the same for planar failure. Therefore, because the Culmann and ARS methods also required average bank angles, vertically
Indirect Method—Rotational Failure 27

Detailed analysis of convex elliptical bank faceDetailed analysis of concave elliptical bank faceStraight-bank tables using unweighted average bank angleStraight-bank tables using vertically weighted average bank angle

EXPLANATION

Figure 13. Example of factors of safety for (A) ambient (unsaturated) and (B) saturated elliptical (convex and concave) banks from detailed analyses

(REAME computer program and actual cross sections) compared to those from the indirect method (straight-bank tables using unweighted and vertically weighted average bank angles) over a range of bank angles. Bank parameters were as follows: bank height, 6 meters; ambient soil unit weight,15 kilonewtons per cubic meter; saturated soil unit weight, 18 kilonewtons per cubic meter; soil cohesion, 15 kilopascals; and soil friction angle,25 degrees.

UNWEIGHTED (TOP-TO-TOE) BANK ANGLE, IN DEGREES

FACTOR OF SAFETY

AMBIENT BANK-SOIL MOISTURE6-METER BANK HEIGHT

0

3.53.02.52.01.51.00.5

A

SATURATED BANK-SOIL MOISTURE6-METER BANK HEIGHT

15 30 45 60 75 90 15 30 45 60 75 90

B
28 Stream Bank Stability in Eastern Nebraska 543

210

Note—Unweighted bank anglesfor two bank sections were toolow to estimate a factor of safetyusing the straight-bank tables.

FA

CT

OR

Ambient Bank ConditionsUnweighted AverageBank Angles

A

FACTOR OF SAFETY FROM DETAILED ANALYSIS

FACTOR OF SAFETY FROM STRAIGHT-BANK TABLES

0 1 234 5

Reference line (1:1)

Ambient Bank ConditionsVertically WeightedAverage Bank Angles

B

0 1 234 5

Figure 14. Factors of safety against rotational failure for 30 randomly selected bank sections under ambient (unsaturated) conditions comparing those determined

from the indirect method, using the straight-bank tables with (A) unweighted and (B) vertically weighted average bank angles as inputs, to those from detailed

analysis, using the REAME computer program with actual surveyed bank section points as inputs. All analyses were based on Bishop's simplified method of slices

and site-specific soil data.

Factor of safety

EXPLANATION
Indirect Method—Rotational Failure 29

543210

Note—Unweighted bank anglesfor two bank sections were toolow to estimate a factor of safetyusing the straight-bank tables.

FACTOR OF SAFETY FROM DETAILED ANALYSIS

FACTOR OF SAFETY FROM STRAIGHT-BANK TABLES

0 1 234 5

FACTORe Saturated Bank Conditions Unweighted Average Bank Angles

A

0 1 234 5

Saturated Bank ConditionsVertically WeightedAverage Bank Angles

B

Factor of safety

EXPLANATION

Figure 15. Factors of safety against rotational failure for 30 randomly selected bank sections under saturated conditions comparing those determined from theindirect method, using the straight-bank tables with (

A) unweighted and (

B) vertically weighted average bank angles as inputs, to those from detailed analysis,

using the REAME computer program with actual surveyed bank section points as inputs. All analyses were based on Bishop's simplified method of slices and

site-specific soil data.

Reference line (1:1)
30 Stream Bank Stability in Eastern Nebraska

weighted average bank angles were used in the analyses for planar failures as well.

Application to Studied Bank Sections

To determine factors of safety for the actual bank 

sections in this report using the indirect method, the 

spreadsheet was used to interpolate between the results 

obtained from the analyses for idealized straight banks. 

As with the Culmann and ARS methods, two types of 

analyses were done for each site—average bank geometry for each reach with the median soil parameters 

from the corresponding soil group (see preceding 

section, Generalization of Shear Strength Data) and 

individual bank section geometry with soil parameters 

for that site. In all cases the average bank angles were 

based on vertical weighting. To compare with the 

Culmann and ARS analyses, banks were analyzed for 

the same two soil moisture conditions—ambient 

(unsaturated) and saturated banks with no support from 

channel water.

Like the ARS analyses, banks were considered 

unstable if the factor of safety for the ambient condition 

was less than one (FS < 1), and banks were considered 

at risk if the factor of safety was greater than or equal 

to one (FS >1) for the ambient condition but was less 

than one (FS < 1) for the saturated condition. Banks 

were considered stable if the factor of safety for the 

saturated condition was greater than or equal to one 

(FS >1). For each average bank reach and each bank 

section, bank stability was classified as previously 

described based on factor of safety values, and the 

maximum stable bank angles were computed from the 

interpolation spreadsheet using the saturated soil 

parameters and the known bank heights. Results for all 

analyzed bank sections were compiled in table 4. 

Results

Summary results for the indirect method were 

compiled (table 5) and are discussed next. For the indirect method, 563 of all 908 bank sections (62 percent) 

were listed as stable, 286 (31 percent) were at risk, and 

31 (3 percent) were outside of the range of the tables 

developed for the method (table 4). For soil group 1, 58 

of 72 bank sections (81 percent) were listed as stable, 6 

(8 percent) were at risk, and 8 (11 percent) had input 

data out of the range of the straight-bank tables. For 

soil group 2, 439 of 724 bank sections (61 percent) 

were listed as stable, 247 (34 percent) were at risk, and 

22 (3 percent) had input data out of the range of the 

straight-bank tables. For soil group 3-4, 66 of 112 bank 

sections (59 percent) were listed as stable, 33 

(29 percent) as at risk, and 7 (6 percent) had input data 

out of the range of the straight-bank tables. The largest 

percentage of stable banks was for soil group 1, which 

had the lowest soil permeability and the highest median 

cohesion of all the soil groups. 

There were 28 bank sections (3 percent) that 

were assessed as unstable (FS <1 for the ambient 

condition; tables 4 and 5). As any unstable bank should 

have already failed, these results probably represent 

banks that are nearly unstable; they also are an indication of the approximate nature of the methodology and 

the overall conservative bias of using the vertically 

weighted average bank angle (see preceding section, 

Effects of Bank Shape). There were no bank sections 

that were unstable for soil group 1, 22 (3 percent) for 

soil group 2, and 6 (5 percent) for soil group 3-4.

Several banks, 31 (3 percent) were outside of the 

range of the tables developed for the method (tables 4 

and 5). Most of the out-of-range sites had input data 

lower than the defined range for the bank height (less 

than 1 m) or bank angle (less than 15ο). One site, 

LNR-10, had a cohesion of 36.5 kPa, greater than the 

maximum of the range (30 kPa) of the tables. Another 

site, BNR-3, had a saturated soil unit weight of 

18.1 kN/m3, greater than the maximum of the range 

(18 kN/m3) of the tables. 

The stable bank angles computed from the 

straight-bank tables using the interpolation spreadsheet 

(FS =1 for saturated banks and no channel water) were 

compared to the vertically weighted, average bank 

angles computed from the survey data. The comparison indicated that many of the surveyed bank angles 

were considerably less than the maximum expected 

stable bank angles (table 4). For severely degraded 

channels along straight reaches this would not be 

expected. As such reaches degrade, the bank heights 

and angles increase until the banks become at risk or 

eventually even unstable—at which point the bank 

would immediately fail; more typically the bank would 

become sufficiently saturated and fail before becoming 

unstable. In either case the banks would not be 

expected to fail well below the maximum stable angle.

For the banks with relatively low bank angles, it 

is possible that their channels have not yet been 

affected to a significant degree by degradation. Study 

sites were selected so that they were located throughout 

eastern Nebraska and throughout individual basins; this 
Bank Stability Assessment at New Sites 31

was done for the purpose of trying to develop basinwide streambed adjustment models (Rus and others, 

2003). Degradation may not yet have extended to sites 

along upper reaches, or lower reaches might be experiencing aggradation, which reduces a bank’s height and 

can help to stabilize it, as degradation progresses 

upstream. Another possible explanation for bank 

angles less than the maximum stable angle is that some 

sections may be affected by lateral migration 

processes. Although efforts were made to avoid such 

sections, straight reaches could not always be found at 

the study sites. Typically along curving reaches, the 

bank angle on the inside bend is relatively shallow and 

the bank angle on the outside bend is relatively steep 

compared to straight reaches with similar bank material. 

Another possibility is that the maximum 

expected stable bank angles are too steep—at least for 

some bank sections this is probably true. This would 

indicate that either the methods for analysis of bank 

stability are inaccurate or that the data used with the 

methods are not representative of actual conditions. 

The latter seems most likely as the methods are well 

established, and for the same data the results are in 

essential agreement. The bank geometry data were 

determined directly from topographic surveys and 

should not be a source of significant error. This leaves 

non-representative soil data as a probable reason for 

computed stable bank angles that in some cases are 

overly steep. Because the bank stability analyses are 

most sensitive to the values of soil cohesion, especially 

for saturated conditions, the limitations of the BSTs 

and the assumption of homogeneous banks are probably the main factors contributing to soil parameters that 

are not representative of those controlling bank stability.

The assumption of homogeneous banks was 

shown to be atypical, at least for those few sites for 

which more than one BST was made and considered 

useable (fig. 16). Although several sites have cohesion 

values that are fairly uniform, most of the sites show 

considerable vertical variability. The cohesion values 

for site MRT-10, the only site with useable BSTs at 

three depths, shows cohesion increasing with depth by 

more than 250 percent and then decreasing by more 

than 30 percent to the deepest test. Many of the other 

sites, for which only one BST was made or was 

useable, probably have actual variability in cohesion 

similar to that shown in figure 16. Horizontally, along 

and transverse to the banks there also may be considerable variability in cohesion. 

Similar to how a weak link in a chain will determine when it fails, a weak soil area or an interface of 

two differing soil areas in a bank can determine where 

the failure plane will be and what the factor of safety 

might be. It is not likely that the few soil tests done at 

each of the sites identified the critical soil parameters 

needed to accurately determine bank stability or to 

determine the stable bank angle for each bank section. 

For those sites that did not have homogeneous banks 

and for which the critical soil parameters were not 

identified, the results would indicate that the banks are 

more stable than they really are. Although not as likely, 

the opposite could also be true. If a weak soil area was 

tested that did not extend to other bank sections the 

analyses for those banks would indicate less stability 

than might be warranted. It is apparent that more extensive soil testing than was done for this report is required 

before an accurate assessment of bank stability can be 

made at a site. 

Because the BSTs require interpretation and are 

based on several assumptions, incorrect values of shear 

strength (soil cohesion and friction angle) computed 

from the BST measurements are possible. For example, 

at site BNR-7 the maximum expected stable bank 

angles for all sections were greater than the surveyed 

angles and the cohesion values for both depths tested 

were fairly uniform (fig. 16). However, re-interpretation of both BSTs indicated that both could have been 

discounted. 

At least for some sites, it appears that the results 

of bank stability in table 4 are overly optimistic. 

Although some individual bank sections may be accurately portrayed, without more extensive data to determine variability or non-variability in soil shear 

strength, it is not known which or how many bank 

sections this would include.

Bank Stability Assessment at New 

Sites

Any of the methods demonstrated in this report 

can be used to make preliminary assessments of bank 

stability at new sites. The uncertainty in the bank stabiity results appears to be the result of few data on soil 

shear strength and the assumption of homogeneous 
32 Stream Bank Stability in Eastern Nebraska

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25

SOIL COHESION, IN KILOPASCALS

BOREHOLE DEPTH, IN METERS

MRT-10 PC-2 ER-14 ER-20

SC-23 SC-25 SC-26 LNR-16

BNR-7 BNR-8 BNR-14 BBR-10

Figure 16. Soil cohesion relative to borehole depth for sites with more than one borehole shear test (BST)

considered useable.
Bank Stability Assessment at New Sites 33

banks, not because of problems with the methods themselves. If the variability of soil parameters, especially 

cohesion, can be determined for a site, and if the variability is small so that average or weakest values can be 

used to represent the banks, the methods should be 

useable to make preliminary assessments of stability. If 

the variability is more extensive, a computer program 

such as REAME that can account for multiple soil 

types and parameters is needed. 

The potential for planar failure at a bank section 

can be evaluated using the Culmann or ARS methods. 

The ARS method is still under development, and the 

current version of the spreadsheet and documentation 

would need to be obtained from ARS before using this 

method (Andrew Simon, National Sedimentation 

Laboratory, Agricultural Research Service, Oxford, 

Miss.). The potential for rotational failure can be evaluated using the indirect method. For preliminary 

assessments with either method, the user needs crosssection data and estimates of the soil parameters—cohesion, friction angle, and ambient and saturated unit weight. The vertically weighted average bank 

angle, or whatever average bank angle the user considers appropriate, can be computed from the crosssection data. If multiple estimates or measurements of 

cohesion, friction angle, and soil unit weight are made, 

the various combinations of parameters can be used to 

estimate the lowest factor of safety. 

Culmann Method—Planar Failure

The critical bank height for the four conditions of 

ambient and saturated soil, with and without tension 

cracks, can be computed using equations 10, 12, and 13 

with the data for the site; for saturated conditions the 

soil friction angle is assumed to be zero. Failure-envelope curves (figs. 7 through 9) can be developed by 

computing the critical bank heights for various assumed 

average bank angles, in addition to the actual values for 

the bank section being studied, and plotting the results. 

If the average bank angle is less than the soil friction 

angle, the bank should be stable and equation 10 is not 

applicable. The stability for saturated conditions should 

be less than for ambient conditions, and stability when 

tension cracks occur should be less than when tension 

cracks do not occur. These results can then be compared 

to the actual bank height and average bank angle to 

determine whether the bank is stable, at risk, or unstable as shown in this report.

Indirect Method—Rotational Failure

The indirect method can be used to make preliminary assessments of bank stability against rotational 

failure at new sites without having to run the REAME 

program for each new bank section. This can allow the 

user to separate bank sections that might require more 

extensive detailed analyses from those that are probably stable and should not require further study. The user 

can select whatever factor of safety criteria is desired to 

make such a separation for both ambient and saturated 

soil-moisture conditions. For convenience, the interpolation spreadsheet, provided on the compact disk at the 

back of this report, can be used to speed the interpolation process; any results appearing questionable should 

be checked manually against the values in table 6, 

which were used in the spreadsheet. When the soil and 

bank geometry data are entered into the interpolation 

spreadsheet, or when an input file is submitted with the 

data for multiple bank sections or combinations of soil 

parameters, the spreadsheet automatically computes 

the factor of safety for both ambient and saturated 

conditions for each section or combination of parameters.

In addition, the spreadsheet automatically 

computes the angle at which a bank section would be 

stable, for the given conditions of bank height and 

ambient and saturated soil parameters. For the latter 

computation, the spreadsheet uses a design factor of 

safety of one (FS = 1) by default. However, this can be 

reset to whatever value the user desires. Because the 

interpolation spreadsheet was based on analyses of 

straight banks, the computed stable angle also would be 

for straight banks. All results from this method should 

be considered as preliminary assessments to be 

followed by more detailed analyses for any sites requiring design work or appearing to be at risk or nearly 

unstable.

Other Considerations

Bank sections also could be assessed under 

assumptions of future degradation or aggradation. For 

example, actual bank geometry could be artificially 

altered to represent a selected amount of degradation. 

This would change (increase) both the average bank 

angle and height. These assumed values can then be 

used in place of the actual values to plot on the failureenvelope curve (Culmann method) or to compute new 

factors of safety and new stable bank angles (indirect 

method).
34 Stream Bank Stability in Eastern Nebraska

For some bank sections, it may be necessary to 

assess the stability of part of the bank section rather 

than the entire section. This could be especially true for 

banks that are relatively high with steep upper sections 

and shallow slopes on the lower part. Under these 

conditions, the vertically weighted average angle may 

not represent the failure potential of the upper part of 

the bank. For such banks, it might be necessary to 

analyze only a part of the upper bank section, with 

corresponding changes to the average bank angle and 

height.

SUMMARY AND CONCLUSIONS

To alleviate frequent and prolonged flooding of 

fertile bottomlands, many stream channels in eastern 

Nebraska were dredged and straightened, beginning 

around the early 1900s. This practice reduced stream 

lengths, which increased channel gradients and stream 

power, and increased the ability of the flow to erode 

channel sediments. These modified channels have 

experienced streambed degradation, which has caused 

banks to became unstable and fail, resulting in channel 

widening. Degradation has progressed headward and 

affected the drainage systems upstream from the modified reaches. 

In cooperation with local, State, and other 

Federal agencies, the U.S. Geological Survey began a 

study to characterize and analyze the stability of stream 

channels in eastern Nebraska. This report presents the 

data and summary results for the part of the study that 

used three methods for analyzing bank stability at 

selected sites in eastern Nebraska and presents a 

simplified method for estimating the stability of banks 

at new sites. 

Topographic and geotechnical data were 

collected at approximately 150 sites among major 

drainage basins in 26 counties of eastern Nebraska and 

were selected on the basis of available historic streambed-elevation data, required for other aspects of the 

study. Topographic surveys to determine bank heights 

and angles were made upstream or downstream from 

bridges or culverts, primarily along straight reaches of 

channel to focus on bank stability related to degradation rather than to lateral stream migration. Borehole 

Shear Tests (BSTs) were done to determine the shearstrength properties of the banks. Soil samples were 

collected from the banks and were analyzed in the laboratory to determine soil unit weight, moisture content, 

and degree of saturation. Cumulative frequency 

diagrams of the cohesion and friction angle data for this 

report were compared to ranges of values for similar 

soil from other studies. Sites were separated into three 

soil groups based on the average mapped permeability 

of the 60-inch soil profile. The ranges and median 

values of cohesion decreased with increasing permeability, as was expected. 

Three methods—Culmann, Agricultural 

Research Service (ARS), and an indirect assessment—were used to analyze banks for stability under 

both ambient (unsaturated) and saturated soil moisture 

conditions with no support from water in the stream 

channel; the latter condition represents the worst-case 

scenerio. Because of few data, all analyses were based 

on the assumption of homogeneous banks. The occurrence of heterogeneous banks could significantly alter 

the results that were obtained. 

The Culmann and ARS methods assume failure 

along a linear plane (planar failure) through the toe of 

the bank. The Culmann method was used to determine 

critical bank heights above which banks would be 

expected to fail. These calculations were made for both 

presence and absence of vertical tension cracks in the 

top of the banks. The ARS method was used to 

compute a factor of safety (FS), which is the ratio of 

forces resisting failure to those driving failure. The 

ARS method can account for positive and negative 

pore-water pressure from water in the banks. 

The indirect assessment assumes rotational failure and is based on Bishop’s simplified method of 

slices as contained in the computer program Rotational 

Equilibrium Analysis of Multilayered Embankments 

(REAME). Factors of safety were computed for 2,100 

idealized, uniform-angle (straight) banks for all combinations of 7 soil unit weights (4 ambient and 3 saturated), 5 cohesions, 3 soil friction angles, 4 bank 

heights, and 5 bank angles. Factors of safety for the 

studied banks were then estimated from the results for 

the idealized straight banks by interpolation. A 

Microsoft EXCEL 2000® spreadsheet, included on a 

compact disk at the back of this report, was developed 

for the factor-of-safety interpolation and to estimate the 

stable bank angle for given soil conditions and a 

desired factor of safety. Because most natural banks do 

not conform to the idealized straight banks assumed for 

the three methods, a series of analyses was done to test 

for the effects of bank shape. It was found that the average, vertically weighted bank angle approximately 

compensates for the effects of convex and concave 
Summary and Conclusions 35

bank shape without affecting the results for straight 

banks. An additional test of the indirect method was 

made by comparing results to those computed from 

detailed REAME analyses using actual cross-section 

data. For both ambient and saturated bank soil, factors 

of safety for unweighted average bank angles were, 

generally, overestimated compared to the detailed 

REAME analyses. Conversely, the factors of safety for 

vertically weighted average bank angles were, generally, underestimated compared to those for the detailed 

REAME analyses. The latter is preferable because it 

errs on the side of safety.

For each average bank reach and each bank 

section, the maximum expected stable bank angles 

were computed from the interpolation spreadsheet 

using the saturated soil parameters, the known bank 

heights, and a factor of safety of one. A bank was 

considered stable if the critical bank height was greater 

than the actual bank height or if the factor of safety was 

greater than or equal to one for the saturated soil-moisture condition. A bank was considered at risk if the critical bank height was greater than the actual bank height 

or if the factor of safety was greater than or equal to one 

for the ambient condition, but not for the saturated 

condition, meaning that the bank should fail when it 

becomes saturated. A bank was considered unstable if 

the critical bank height was less than the actual bank 

height or if the factor of safety was less than one for the 

ambient soil-moisture condition; theoretically, any 

such bank should have already failed. Results indicated 

that the three methods were in essential agreement with 

about two thirds of the sections classified as stable and 

less than one third classified as at risk unless tension 

cracks were assumed, then the at risk category 

increased to about 40 percent. For each of the methods, 

the largest percentage of stable banks and the smallest 

percentage of at risk banks was for soil group 1, which 

had the lowest soil permeability and the highest median 

cohesion of the three soil groups. 

The stable bank angles computed from the 

straight-bank tables using the interpolation spreadsheet 

(FS =1 for saturated banks and no channel water) were 

compared to the vertically weighted, average bank 

angles computed from the survey data. The comparison 

indicated that many of the surveyed bank angles were 

considerably less than the expected stable bank angles. 

For severely degraded channels along straight reaches 

this was not expected. As such reaches degrade, the 

bank heights and angles increase until the banks 

become at risk or eventually even unstable—at which 

point the bank would immediately fail; more typically 

the bank would become sufficiently saturated and fail 

before becoming unstable. In either case the banks 

would not be expected to fail well below the maximum 

stable angle.

For the banks with relatively low bank angles, it 

is possible that their channels have yet to be affected to 

a significant degree by degradation. Study sites were 

selected so that they were located throughout individual basins for the purpose of trying to develop basinwide streambed adjustment models. As such, degradation may not yet have extended to sites along upper 

reaches, or, lower reaches might be experiencing aggradation as degradation moves upstream—this can help 

to stabilize bank sections by reducing height. Another 

possible explanation for bank angles less than the 

maximum stable angle is that some sections may be 

affected by lateral migration processes. Although 

efforts were made to avoid such sections, straight 

reaches could not always be found at the study sites. 

Typically along curving reaches, the bank angle on the 

inside bend is relatively shallow and the bank angle on 

the outside bend is relatively steep compared to straight 

reaches with similar bank material. 

Another possibility is that the maximum 

expected stable bank angles are too steep. At least for 

some bank sections this is probably true and would 

seem to indicate that either the bank-stability methods 

were flawed or that the data used were not representative of actual bank conditions. The latter seems most 

likely as the methods are well established, and for the 

same data, the results are in essential agreement. The 

bank geometry data were determined directly from 

topographic surveys and should not be a source of 

significant error. This left non-representative soil data 

as a probable reason for computed stable bank angles 

that, at least in some cases, were overly steep. Because 

the bank stability analyses are most sensitive to the 

values of soil cohesion, especially for saturated conditions, the limitations of the BSTs and the assumption of 

homogeneous banks were probably the main factors 

contributing to soil properties that were not representative of those controlling bank stability. 

The assumption of homogeneous banks was 

determined to be atypical. Examination of the cohesion 

values compared to borehole/sample depth indicated 

considerable vertical variability for most sites with 

more than one useable BST. The potential for horizontal variability within a reach was indicated by the 

considerable variability in cohesion from site to site. A 
36 Stream Bank Stability in Eastern Nebraska

weak soil area or an interface of two differing soil areas 

in a bank can determine where the failure plane will be 

and what the factor of safety might be; therefore, it is 

not likely that the few soil tests done at each of the sites 

identified the critical soil parameters needed to accurately assess bank stability or to determine the expected 

stable bank angle for each bank section. Because BSTs 

require interpretation, there also exists the possibility 

of misinterpretation, which can result in incorrect 

values of shear strength (soil cohesion and friction 

angle) being computed from the BST measurements. 

At least for some bank sections, it appeared that the 

summary results of bank stability were overly optimistic. Although some individual bank sections may be 

accurately portrayed, without more extensive data to 

determine variability or non-variability in soil shear 

strength, it is not known which or how many bank 

sections this would include.

If the variability of soil parameters, especially 

cohesion, can be determined for a site, and if the variability is small so that average or weakest values can be 

used to represent the banks, any of the methods demonstrated in this report can be used to make preliminary 

assessments of channel bank stability at new sites. Critical bank height for the four conditions of ambient and 

saturated soil, with and without tension cracks, can be 

computed using the equations for planar failures listed 

in the Culmann method. Results can then be compared 

to the actual bank height to determine whether the bank 

is stable, at risk, or unstable. The potential for rotational failure at a bank section can be evaluated using 

the interpolation spreadsheet from the indirect method 

to estimate the factor of safety for both ambient and 

saturated soil-moisture conditions. In addition, the 

spreadsheet automatically computes the angles at 

which the bank section would be stable for the given 

bank height and soil parameters. Either method also 

could be used to assess future bank stability under 

assumptions of degradation by simply altering actual 

bank geometry and re-evaluating. For sites with extensive variability in soil shear-strength, a method needs to 

be used that that can account for multiple soil areas 

with differing parameters. 

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Supplement No. 9, p. 27–34.

Lutenegger, A.J., and Hallberg, G.R., 1981, Borehole 

shear test in geotechnical investigations, in Yong, 

R.N, and Townsend, F.C., eds., Laboratory shear 

strength of soil: Philadelphia, American Society 

for Testing and Materials, ASTM STP 740, 

p. 566–578.

Lutenegger, A.J., Remmes, B.D., and Handy, R.L., 

1978, Borehole shear test for stiff soil: Journal of 

the Geotechnical Engineering Division, Proceedings of the ASCE, v. 104, no. GT11, p. 1403–

1407.

Lutton, R.J., 1974, Use of loess soil for modeling rock 

mechanics: Vicksburg, U.S. Army Corps of Engineers Waterways Experiment Station, Report 

S–74–28.

Mandel, R.D., and Bettis, E.A., III, 1995, Late Quaternary landscape evolution and stratigraphy in eastern Nebraska—Field trip No. 7: University of 

Nebraska-Lincoln, Conservation and Survey Division Guidebook, v. 10, p. 77–90.

——— 2000, Late Quaternary landscape evolution in 

the South Fork of the Big Nemaha River Valley, 

southeastern Nebraska and northeastern Kansas: 

University of Nebraska-Lincoln, Conservation and 

Survey Division Guidebook, v. 11, 58 p.

Moore, C.T., 1915, Drainage districts of southeastern 

Nebraska, in Barbour, E.H., An account of the 

Nebraska Geological Survey to 1912: Nebraska 

Geological Survey Miscellaneous Papers, v. 7, 

p. 125–164.

Natural Resources Conservation Service, 1996, Rock 

Creek saline wetland cooperative river basin 

study: Lincoln, Nebr., U.S. Department of Agriculture, Natural Resources Conservation Service, 

85 p.

Nebraska Soil and Water Conservation Commission, 

1968, Big Blue River Basin: Lincoln, Nebr., State 

Water Plan Publication Number 201, 103 p.

Olson, G.R., 1958, Direct shear and consolidation tests 

of undisturbed loess: Ames, Iowa State University 

Library, M.S. thesis.

Piest, R.F., Beer, C.E., and Spomer, R.G., 1976, 

Entrenchment of drainage systems in western 

Iowa and northwestern Missouri: Proceedings, 

Third Federal Inter-Agency Sedimentation Conference, p. 5–48 to 5–60.

Piest, R.F., Elliot, L.S., and Spomer, R.G., 1977, Erosion of the Tarkio drainage system, 1845–1976: 

Transactions, American Society of Agricultural 

Engineers, v. 20, p. 485–488.

Robbins, C.H., and Simon, Andrew, 1983, Maninduced channel adjustment of Tennessee streams: 
38 Stream Bank Stability in Eastern Nebraska

U.S. Geological Survey Water-Resources Investigations Report 82–4098, 129 p.

Rus, D.L., Dietsch, B.J., and Simon, Andrew, 2003, 

Streambed adjustment and channel widening in 

eastern Nebraska: U.S. Geological Survey WaterResources Investigations Report 03–4003, 63 p., 

CD-ROM.

Rus, D.L., and Soenksen, P.J., 1998, Channel stability 

of Turkey Creek, Nebraska, in Abt, S.R., YoungPezeshk, Jayne, and Watson, C.C., eds., Water 

Resources Engineering 98—International Water 

Resources Engineering Conference, 

August 3–7, 1998, Memphis, Tenn., Proceedings: 

Reston, Va., American Society of Civil Engineers, 

v. 1, p. 423–428.

Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and 

Broderson, W.D., 1998, Field book for describing 

and sampling soils: U.S. Department of Agriculture, version 1.1.

Simon, Andrew, 1989a, The discharge of sediment in 

channelized alluvial streams: Water Resources 

Bulletin, v. 25, no. 6, p. 1177–1188.

Simon, Andrew, 1989b, A model of channel response 

in disturbed alluvial channels: Earth Surface Processes and Landforms, v. 14, p. 11–26.

——— 1994, Gradation processes and channel evolution in modified west Tennessee streams—process, response and form: U.S. Geological Survey 

Professional Paper 1470, 84 p.

———1998, Processes and forms of the Yalobusha 

River system—A detailed geormorphic evaluation: Oxford, Miss., U.S. Dept. of AgricultureAgricultural Research Service, 131 p., 1 app.

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suction, in Abt, S.R., Young-Pezeshk, Jayne, and 

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98—International Water Resources Engineering 

Conference, August 3–7, 1998, Memphis, Tenn., 

Proceedings: Reston, Va., American Society of 

Civil Engineers, v. 1, p. 358–363.

Simon, Andrew, and Hupp, C.R., 1992, Geomorphic 

and vegetative recovery processes along modified 

stream channels of West Tennessee: U.S. Geological Survey Open-File Report 91–502, 142 p. 

Simon, Andrew, and Rinaldi, Massimo, 2000, Channel 

instability in the loess area of the midwestern 

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Simon, Andrew, Curini, Andrea, Darby, S.E., and Langendoen, E.J., 1999a, Streambank mechanics and 

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channels in Darby, S.E., and Simon, Andrew, eds., 

Incised river channels: New York, Wiley, p. 123–

152.

Simon, Andrew, Shields, D.F., Ettema, Robert, Alonso, 

Carlos, Garsjo, M.M., Curini, Andrea, and Steffen, 

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——— 1971, Elkhorn River Basin, Nebraska—Water 

and related land resources: Lincoln, Nebr., U.S. 

Department of Agriculture, Soil Conservation Service.

——— 1975, Nemaha River Basin, Nebraska—Water 

and related land resources: Lincoln, Nebr., U.S. 

Department of Agriculture, Soil Conservation Service.

——— 1981, Land resource regions and major land 

resource areas of the United States: Washington, 

D.C., U.S. Department of Agriculture, Soil Conservation Service Agricultural Handbook 296, 

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Jeffery, H.G., 1965, Low-flow characteristics of 

streams in the Mississippi embayment in Tennessee, Kentucky, and Illinois: U.S. Geological Survey Professional Paper 448–H, 36 p.

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G.R., and Goebel, J.E., 1994, Quaternary geologic 

map of the Platte River 4o x 6 o quadrangle: U.S. 

Geological Survey Investigations Map I–1420 

(NK–14), scale 1:1,000,000.

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processes and mechanisms: Journal of Hydraulic 

Engineering, v. 124, no. 9, p. 881–902.

Thorne, C.R., Murphey, J.B., and Little, W.C., 1981, 

Stream channel stability, Appendix D, Bank stability and bank material properties in the bluffline 

streams of northwest Mississippi: Oxford, Miss., 
Selected Refeences 39

U.S. Department of Agriculture, Sedimentation 

Laboratory, 257 p.

Turnipseed, D.P., and Baldwin W.T., 1992, Channel 

and bank stability of Bakers Creek at State Highway 547 near Port Gibson, Claiborne County, Mississippi: U.S. Geological Survey Open-File Report 

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and bank stability of Standing Pine Creek at State 

Highway 488 near Freeny, Leake County, Mississippi: U.S. Geological Survey Open-File Report 

92–112, 18 p.

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Nebraska channel instability study—stream classification: Omaha, Nebr., U.S. Army Corps of 

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Army Corps of Engineers [Section 22 study], prepared for the Nebraska Department of Roads, 62 p.

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Omaha, Nebr., U.S. Army Corps of Engineers 

[Section 22 study], 148 p.

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study—evaluation of bridge and culvert structures: 

Omaha, Nebr., U.S. Army Corps of Engineers 

[Section 22 study], 7 p., 9 apps.

Wahl, K.L., and Weiss, L.S., 1995, Channel degradation in southeastern Nebraska rivers, in Ward, T.J., 

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21st Century, San Antonio, Tex., August 14–16, 

1995, Proceedings: New York, American Society 

of Civil Engineers, p. 250–259.

Wilson, K.V., 1979, Changes in channel characteristics, 

1938–1974, of the Homochotto River and tributaries, Mississippi: U.S. Geological Survey OpenFile Report 79–554, 18 p.

Wilson, K.V., Jr., and Turnipseed, D.P., 1993, Channelbed and channel-bank stability of Standing Pine 

Creek tributary at State Highway 488 at Free 

Trade, Leake County, Mississippi: U.S. Geological Survey Open-File Report 93–37, 20 p.

Zellars, J.A., 1996, Stability of alluvial incised stream 

channels in loess covered landscapes: University 

of Nebraska-Lincoln, M.S. thesis, 228 p.
SUPPLEMENTAL DATA

Table 1 43

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999[ID, identification; NDOR, Nebraska Department of Roads; No., number; Cr, Creek; N#, Nebraska State route; Nebr, Nebraska; W, west; US#, U.S. route; CR, Co

sec, section; T#X, township; N, north; R#X, range; E, east; NW, northwest; SE, southeast; S, south; St, Street; Rd, Road; Br, Branch; trib, tributary; L#X, State co

S#X, State spur; R, River; M, Middle; Fk, Fork; SW, southwest]

Site ID Station name1

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li

Missouri River Tributary Basins

MRT-1 Bow Cr at N84 S084 04362 110MRT-2 Bow Cr at N12

Bow Cr at St. James, Nebr 06478518)

S012 20744 111

MRT-3 W Bow Cr at US81 S081 20306 100MRT-4 Aowa Cr at CR, Dixon Co 

(near center sec 1, T30N, R5E)

C026 22325P 110

MRT-5 South Cr at CR, Dakota Co

(NW1/4 sec 10, T29N, R5E)

C026 13020 110

MRT-6 Aowa Cr at N12 S012 23427 100MRT-7 Otter Cr at CR, Dixon Co 

(SE1/4 sec33, T29N, R6E)

C026 13810P 100

MRT-8 Elk Cr at US20 S020 42270 110MRT-9 S Omaha Cr at N94

(S Omaha Cr at Walthill, Nebr 06600900)

S094 01301 221

MRT-10 Omaha Cr at Main St, Homer

(Omaha Cr at Homer, Nebr 06601000)

C022 23015 321

MRT-11 Elm Cr at US75 S075 14855 110MRT-12a New York Cr at New York Cr Rd, Washington Co

(New York Cr east of Spiker, Nebr 06608900)

C089 21910P 000

MRT-12b New York Cr at CR21, Washington Co unknown 110MRT-13 Weeping Water Cr at N1 S001 00266 110MRT-14 Weeping Water Cr at CR, Cass Co

(Weeping Water Cr at Weeping Water, Nebr 06806460)

C013 13710P 100

MRT-15 S Br Weeping Water Cr at N67 S067 06587 100MRT-16 Weeping Water Cr at US75

(Weeping Water Cr at Union, Nebr 06806500)

S075 05774 220

MRT-17 Honey Cr at N67 S067 02402 111
44 Stream Bank Stability in Eastern Nebraska Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea NDOR bridge ID Bank material No. of samples analyzed for soil unit weight No. of samples analyzed for particle size No. of samp

analyzed f

Atterburg li

Papillion Creek Basin PC-1 N Br W Papillion Cr at Fort St, Douglas Co C028 21415 221

PC-2 N Br W Papillion Cr at Blondo St, Douglas Co C028 21820 331

PC-3 W Papillion Cr at US275 S275 17757 100PC-4 S Papillion Cr trib at Cornhusker Rd, Sarpy Co C077 20620 100

PC-5 W Papillion Cr at Giles Rd, Sarpy Co C077 20435 110PC-6 Big Papillion Cr at 168th St, Douglas Co C028 13140 110

PC-7 Big Papillion Cr at Fort St, Omaha C028 21420 100

PC-8 Eagle Run at 120th St, Omaha C028 13910 100

PC-9 Little Papillion Cr at L28K SL28K 01578 110PC-10 Cole Cr at Ames Ave, Omaha C028 F1405 110

PC-11 Cole Cr at Blondo St, Omaha C028 31835 100

PC-12 Papillion Cr at Capeheart Rd, Bellevue C077 01205P 110

Platte River Tributary Basins

PRT-1 Shell Cr at CR, Platte Co

(SW1/4 sec 14, T18N, R1E)(Shell Cr near Columbus, Nebr 06795500)

C071 05705P 110

PRT-2 Shell Cr at US30 S030 39774 110PRT-3 Bone Cr at S12B SS12B 00427 1 1 0 PRT-4 Bone Cr at N15 S015 09916 110PRT-5 Skull Cr at CR, Butler Co (sec 22/27, T16N, R4E) C012 32035 110PRT-6 Skull Cr at S12A SS12A 00554 110PRT-7 Otoe Cr at US77 S077 10726 110PRT-8 Otoe Cr at S78J SS78J 00074 100PRT-9 Buffalo Cr trib at 192nd St, Sarpy Co C077 11310 100

PRT-10 Buffalo Cr at N50 S050 07970 111PRT-11 Springfield Cr at Platteview Rd, Sarpy Co C077 11640 100PRT-12 Fourmile Cr at N66 S066 10234 110PRT-13 Fourmile Cr at Bay Rd, Cass Co C013 00415 100
Table 1 45

Elkhorn River Basin

ER-1 Elkhorn R at US81

(Elkhorn R at Norfolk, Nebr 06799000)

S081 15491 000

ER-2 Union Cr at Main St (old US81), Madison

(Union Cr at Madison, Nebr 06799230)

C059 H3905 111

ER-3 Union Cr at CR, Stanton Co

(SE1/4 sec 15, T22N, R1E)

C084 13205 100

ER-4 Plum Cr at N15 S015 15738 100ER-5 Plum Cr at N51 S051 00598 110ER-6 Elkhorn R at N32

(Elkhorn R at West Point, Nebr 06799350)

S032 07316 110

ER-7 Pebble Cr at N32 S032 06215 210ER-8 Pebble Cr at N91 S091 19072 100ER-9 Pebble Cr at CR "G", Dodge Co

(Pebble Cr at Scribner, Nebr 06799385)

C027 02305P 111

ER-10 M Logan Cr at N57 S057 05119 110ER-11 Deer Cr at N57 S057 04075 111ER-12 S Logan Cr at N15 S015 16384 110ER-13 Logan Cr at N35 S035 04053 100ER-14 Logan Cr at N94

(Logan Cr at Pender, Nebr 06799450)

S094 00025 220

ER-15 Logan Cr at CR 22, Dodge Co

(Logan Cr near Uehling, Nebr 06799500)

C027 30645 220

ER-16 W Fk Maple Cr at N91 S091 17273 110ER-17 Dry Cr at N15 S015 11596 111ER-18 E Fk Maple Cr at N91 S091 17846 100ER-19 Maple Cr at N79 S079 05122 100ER-20 Maple Cr at CR20, Dodge Co 

(Maple Cr near Nickerson, Nebr 06800000)

C027 13910 220

ER-21 Maple Cr at US77

(former site of Maple Cr near Nickerson, Nebr 06800000)

S077 12173 000

ER-22 Bell Cr at N32 S032 09289 110

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li
46 Stream Bank Stability in Eastern Nebraska Elkhorn River Basin—Continued ER-23 Little Bell Cr at CR P11, Washington Co C089 01130 100

ER-24 Bell Cr at CR 26, Washington Co C089 02610 110ER-25 Elkhorn R at N64 (Elkhorn R at Waterloo, Nebr 06800500) S064 06033 220

Salt Creek Basin SC-1 Olive Br at SW 86th St, Lancaster Co C055 00910 110

SC-2 Hickman Br at S 110th St, Lancaster Co C055 03705 100

SC-3 Salt Cr at S55F

(Salt Cr at Roca, Nebr 06803000)

SS55F 00229 221

SC-4 Beal Slough at N2 S002 46092 110SC-5 Haines Br at Midway Rd, Lancaster Co C055 04405P 100

SC-6 S Br Middle Cr at SW 126th St, Lancaster Co C055 60315 110

SC-7 Middle Cr at US6 S006 30732 100SC-8 Middle Cr at SW 40th St, Lancaster Co

(Middle Cr at SW 40th St at Lincoln, Nebr 06803170)

C055 31520 1 00

SC-9 Oak Cr at N66 S066 05451 110SC-10 N Oak Cr at N66 S066 06060 100SC-11 Oak Cr at US34 S034 31754 110SC-12 W Oak Cr at US34 S034 31644 100SC-13 Salt Cr at N 27th St, Lincoln

(Salt Cr at Lincoln, Nebr 06803500)

C055 22535 110

SC-14 Little Salt Cr at Davey Rd, Lancaster Co unknown/Culvert 111

SC-15 Little Salt Cr at Branched Oak Rd, Lancaster Co C055 11215 100

SC-16 Little Salt Cr at NW 12th St, Lancaster Co C055 41935 110

SC-17 Deer Cr at Davey Rd, Lancaster Co C055 21013 311

SC-18 Deer Cr at Branched Oak Rd, Lancaster Co C055 11220 110SC-19 Little Salt Cr at Raymond Rd, Lancaster Co C055 11415 111

SC-20 Little Salt Cr at Waverly Rd, Lancaster Co C055 01815 211

SC-21 Little Salt Cr at Arbor Rd, Lancaster Co 

(Little Salt Cr near Lincoln, Nebr 06803510)

C055 02205P 410

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li
Table 1 47

Salt Creek Basin—Continued

SC-22 Salt Cr at 70th St, Lincoln

(Salt Cr at 70th St at Lincoln, Nebr 06803513)

C055 13120 111

SC-23 Stevens Cr at Havelock Ave, Lancaster Co

(Stevens Cr near Lincoln, Nebr 06803520)

C055 32815 221

SC-24 Rock Cr at Ashland Rd, Lancaster/Saunders Co C055 10230 100

SC-25 Rock Cr at Agnew Rd, Lancaster Co

(Rock Cr near Ceresco, Nebr 06803530)

C055 00650 220

SC-26 Salt Cr at CR, Cass Co

(Salt Cr at Greenwood, Nebr 06803555)

C013 01405P 211

SC-27 N Fk Wahoo Cr at N79 S079 02719 100SC-28 N Fk Wahoo Cr at N92 S092 44217 110SC-29 Cottonwood Cr trib at CR "S" 2200, Butler Co

(Cottonwood Cr trib above Dam 6B near Prague, Nebr 06803935)

C078 01805 111

SC-30 Cottonwood Cr at S78E SS78E 00387 100SC-31 Sand Cr trib at CR 24, Saunders Co C078 11765 100SC-32 Sand Cr at CR 22, Saunders Co C078 22150 110SC-33 Wahoo Cr at N63

(Wahoo Cr at Ithaca, Nebr 06804000)

S063 03460 211

SC-34 Johnson Cr at CR G, Saunders Co

(Johnson Cr near Memphis, Nebr 06804900)

C078 24260 100

Little Nemaha River Basin

LNR-1 Little Nemaha R at N43 S043 01441 100LNR-2 Silver Cr at S66A SS66A 00269 100LNR-3 Hooper Cr at N43 S043 02621 110LNR-4 Hooper Cr at N2 S002 48008 100LNR-5 Little Nemaha R at N50

(Little Nemaha R near Syracuse, Nebr 06810500)

S050 05049 000

LNR-6 Muddy Cr at CR "O", Otoe Co C066 13035 110LNR-7 S Fk Little Nemaha at CR "N", Otoe Co C066 02810 110

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li
48 Stream Bank Stability in Eastern Nebraska Little Nemaha River Basin—Continued LNR-8 S Fk Little Nemaha R at N50 S050 04149 100

LNR-9 Coon Cr at N50 S050 03929 100LNR-10 Spring Cr at US136 S136 21474 100LNR-11 Spring Cr at CR, Johnson Co (sec 5/8, T6N, R12E) C049 10445 110

LNR-12 N Fk Little Nemaha at N50 S050 05900 100LNR-13 N Fk Little Nemaha at CR "L", Otoe Co S002 49685 100

LNR-14 Little Nemaha R at N67 near Talmage S067 04771 200

LNR-15 Rock Cr at N128 S128 01489 100

LNR-16 Rock Cr at N67 S067 03578 221LNR-17 Little Nemaha R at US136

(Little Nemaha R at Auburn, Nebr 06811500)

S136 23131 220

LNR-18 Whiskey Run at CR, Nemaha Co

(sec 12/13, T4N, R15E)

C064 13060 100

LNR-19 Little Nemaha R at N67 near Nemaha S067 01234 100

Big Nemaha River Basin

BNR-1 N Fk Big Nemaha R at SE 148th St, Lancaster Co C055 04305 111BNR-2 M Br Big Nemaha R at S34B SS34B 004551 0 0 BNR-3 M Br Big Nemaha R at N41 S041 08540 100BNR-4 Yankee Cr at CR, Johnson Co

(near center of S 1/2, sec 8, T4N, R9E)

C049 00305P 220

BNR-5 Yankee Cr at US136 S136 20392 100BNR-6 N Fk Big Nemaha at US136 S136 20939 110BNR-7 Long Branch Cr at N62 S062 00820 221BNR-8 Kirkham Cr at CR, Richardson Co

(near center sec 32, T3N, R13E)

C074 00305P 220

BNR-9 N Fk Big Nemaha R at N105

(N Fk Big Nemaha R at Humboldt, Nebr 06814500)

S105 00703 221

BNR-10 Turkey Cr at CR, Pawnee Co (sec 3/4, T3N, R9E) C067 00735 100

BNR-11 Turkey Cr at N8 S008 11290 110

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li
Table 1 49

Big Nemaha River Basin—Continued

BNR-12 Johnson Ck at CR, Pawnee Co

(sec 25/30, T1N, R10/11E)

C067 02505 110

BNR-13 S Fk Big Nemaha at N8 S008 12578 220BNR-14 Big Nemaha R at US73

(Big Nemaha R at Falls City, Nebr 06815000)

S073 00248 221

BNR-15 Muddy Cr at N105 S105 02688 100BNR-16 Muddy Cr at US75 S075 01884 220BNR-17 Muddy Cr at US73 S073 01612 331

Big Blue River Basin

BBR-1 Big Blue R at CR "D", Butler Co

(Big Blue R at Surprise, Nebr 06879900)

C012 00705 111

BBR-2 N Br Big Blue R at S12E SS12E 00100 100BBR-3 Kezan Cr at N15 S015 08602 110BBR-4 N Br Big Blue R at CR "J", Butler Co C012 01915 100

BBR-5 Big Blue R at CR 2250, Saline Co

(Big Blue R near Crete, Nebr 06881000)

C076 14315P 110

BBR-6 Turkey Cr at N41 S041 05764 100BBR-7 Turkey Cr at N103 S103 02465 110BBR-8 Indian Cr trib at US77 S077 03378 110BBR-9 Indian Cr at US77

(Indian Ck at Beatrice 06881450)

S077 02364 100

BBR-10 Big Blue R at US77 S077 02160 220BBR-11 Big Indian Cr at CR, Gage Co

(sec 33/4, T2/11N, R5E)

C034 06210 110

BBR-12 Big Indian Cr at US77 S077 00775 100BBR-13 Big Blue R at N8

(Big Blue R at Barneston, Nebr 06882000)

S008 08619 110

a Naming convention for stations is as follows: Stream name; U.S. route, state route, county road, or municipal street. Where a county road or municipal stre

municipality name follows the site name. Where the county road or municipal street name is not known, the section, township, and range location are given. Where s

gaging station, the station name and number are listed in parenthesis.

b Dugan (1984).

Table 1. Study sites and types of soil data collected for analysis of channel-bank stability in eastern Nebraska, 1995 to 1999—Cont

Site ID Station namea

NDOR

bridge ID

Bank material

No. of samples 

analyzed for 

soil unit weight

No. of samples 

analyzed for 

particle size

No. of samp

analyzed f

Atterburg li
50 Stream Bank Stability in Eastern Nebraska

Table 2. Channel-geometry data collected at study sites in eastern Nebraska, 1995 to 1999

[ID, identification; m, meter; °, degree; --, insufficient data]

Site ID

Soil 

groupa

Average 

bank 

height

(m)

Average 

unweighted 

bank angle

(°)

Average 

vertically 

weighted 

bank angle

(°)

Average 

horizontally 

weighted 

bank angle

(°)

Average 

linearly 

weighted 

bank angle

(°)

Average 

bank to 

bank width

(m)

Average 

toe to toe 

width

(m)

Missouri River Tributary Basins

MRT-1 2 3.09 26.65 44.57 22.80 28.28 25.29 7.28

MRT-2 2 3.36 15.67 25.20 14.42 15.90 56.71 32.95

MRT-3 2 2.64 21.01 28.37 19.55 21.14 20.81 6.75

MRT-4 2 7.82 40.10 46.28 34.47 40.14 25.57 5.30

MRT-5 2 4.99 39.40 47.13 36.24 40.56 29.65 17.32

MRT-6 2 6.13 28.82 35.06 26.56 28.86 35.94 12.87

MRT-7 2 3.62 40.13 42.36 38.47 40.14 13.80 5.43

MRT-8 2 6.40 41.80 45.57 38.58 41.87 22.17 7.36

MRT-9 2 4.74 25.22 34.32 22.85 25.24 25.54 4.07

MRT-10 2 9.02 42.55 46.03 37.67 40.90 33.45 12.67

MRT-11 2 6.87 23.04 28.98 21.06 23.28 41.54 9.29

MRT-12b 2 5.82 34.38 40.10 30.98 34.56 23.74 5.31

MRT-13 2 3.05 25.49 30.22 24.27 25.53 19.55 5.33

MRT-14 2 -- -- -- -- -- -- --

MRT-15 2 5.06 26.95 35.53 23.70 26.58 28.16 7.57

MRT-16 2 6.52 25.05 31.58 23.20 25.02 43.37 10.31

MRT-17 2 5.41 44.96 52.51 35.94 44.83 18.72 7.39

Papillion Creek Basin

PC-1 2 3.91 31.41 36.05 29.40 31.48 16.41 2.66

PC-2 2 5.08 36.86 41.70 34.16 36.94 21.66 5.39

PC-3 2 3.46 26.15 31.30 24.81 26.15 20.19 4.35

PC-4 2 7.98 41.56 45.66 38.69 41.61 23.16 3.95

PC-5 2 8.44 23.18 27.33 22.16 23.25 51.31 9.89

PC-6 2 -- -- -- -- -- -- --

PC-7 2 7.42 22.66 33.99 21.23 24.24 40.89 4.59

PC-8 2 7.49 36.49 43.86 31.38 36.64 25.82 5.00

PC-9 2 3.74 33.18 38.13 30.30 33.27 16.64 3.79

PC-10 2 3.81 30.81 33.84 29.24 30.90 24.65 10.95

PC-11 2 6.13 36.52 38.12 35.40 36.55 22.07 5.00

PC-12 2 5.15 27.78 37.63 25.59 29.41 39.10 18.51

Platte River Tributary Basins

PRT-1 2 4.86 32.44 37.73 30.12 32.57 23.85 7.63

PRT-2 2 5.42 31.23 36.62 29.10 31.33 33.77 14.54

PRT-3 2 3.05 27.27 39.52 24.11 27.83 14.61 1.61

PRT-4 2 3.06 37.97 44.67 33.48 38.20 10.98 3.02

PRT-5 3 9.10 44.99 53.37 34.76 45.15 30.07 11.45

PRT-6 3 5.88 31.95 37.61 28.90 32.12 26.52 6.99

PRT-7 1 6.08 44.35 53.93 34.36 44.84 16.59 3.92

PRT-8 1 3.99 28.13 39.01 24.35 28.46 23.14 7.54

PRT-9 2 6.06 44.01 51.34 38.00 43.93 15.01 2.34
Table 2 51

Platte River Tributary Basins—Continued

PRT-10 2 6.24 30.00 33.99 28.81 30.02 30.90 5.68

PRT-11 2 6.01 39.03 42.26 38.54 39.03 25.65 4.74

PRT-12 2 6.64 38.85 43.75 35.78 38.93 24.27 7.02

PRT-13 2 5.15 42.31 47.63 37.50 42.39 32.74 20.99

Elkhorn River Basin

ER-1 4 -- -- -- -- -- -- --

ER-2 3 -- -- -- -- -- -- --

ER-3 3 4.64 36.79 40.30 33.68 36.82 36.07 23.42

ER-4 2 2.60 34.63 41.60 31.17 34.75 10.44 2.41

ER-5 2 5.77 34.35 44.71 27.60 34.65 26.02 6.19

ER-6 4 3.25 41.78 41.78 41.78 41.78 99.53 93.40

ER-7 2 4.54 32.73 34.46 30.17 32.01 17.88 3.78

ER-8 4 4.88 30.46 39.40 26.84 30.71 21.60 4.63

ER-9 2 5.08 29.43 36.61 26.49 29.66 31.29 12.75

ER-10 2 2.47 34.05 40.60 31.83 34.14 11.51 3.55

ER-11 2 0.64 21.03 24.19 20.74 21.07 6.05 2.29

ER-12 2 6.91 38.07 42.13 35.23 38.13 30.46 10.84

ER-13 2 5.99 35.04 38.92 34.58 36.06 38.79 21.01

ER-14 2 5.05 32.38 36.59 30.34 32.45 42.83 26.86

ER-15 2 4.92 32.35 40.28 28.54 32.52 41.22 24.35

ER-16 2 4.34 30.55 43.23 24.28 31.12 18.85 3.09

ER-17 2 4.56 31.98 36.94 30.31 32.04 18.19 2.71

ER-18 2 3.90 31.91 39.95 27.84 32.27 18.48 5.68

ER-19 2 4.74 33.77 38.22 31.05 33.94 33.60 18.68

ER-20 2 3.65 35.36 40.18 31.81 36.03 35.68 24.71

ER-21 2 2.94 39.84 42.27 38.17 36.13 24.77 17.28

ER-22 2 1.84 33.28 36.68 31.59 33.28 11.23 5.59

ER-23 2 3.56 31.57 36.80 29.68 31.67 15.70 3.96

ER-24 2 4.30 36.85 39.33 35.04 36.91 21.65 9.82

ER-25 4 4.17 31.03 35.01 29.67 26.96 84.49 69.79

Salt Creek Basin

SC-1 2 2.96 37.92 42.72 33.72 38.04 13.92 5.53

SC-2 2 3.62 46.03 50.05 40.54 46.13 11.24 4.15

SC-3 2 5.04 23.28 37.46 20.99 24.78 30.60 6.44

SC-4 2 2.71 29.67 32.44 28.62 29.73 17.25 3.84

SC-5 2 3.67 40.54 46.51 34.37 40.79 13.62 3.86

SC-6 2 8.34 29.20 33.84 27.88 29.24 38.35 6.81

SC-7 2 4.97 33.66 43.15 28.21 33.94 20.13 4.27

SC-8 2 6.04 33.26 40.44 31.26 35.22 28.11 9.64

SC-9 2 3.21 27.44 34.92 25.60 27.63 16.29 2.67

Table 2. Channel-geometry data collected at study sites in eastern Nebraska, 1995 to 1999—Continued

[ID, identification; m, meter; °, degree; --, insufficient data]

Site ID

Soil 

groupa

Average 

bank 

height

(m)

Average 

unweighted 

bank angle

(°)

Average 

vertically 

weighted 

bank angle

(°)

Average 

horizontally 

weighted 

bank angle

(°)

Average 

linearly 

weighted 

bank angle

(°)

Average 

bank to 

bank width

(m)

Average 

toe to toe 

width

(m)
52 Stream Bank Stability in Eastern Nebraska

Salt Creek Basin—Continued

SC-10 2 4.75 24.19 33.93 21.51 24.43 27.21 4.54

SC-11 2 7.92 24.05 33.44 21.79 24.28 48.09 11.43

SC-12 2 4.74 37.21 47.12 30.31 37.84 17.62 4.57

SC-13 2 9.59 24.45 31.82 22.10 24.66 90.84 39.98

SC-14 1 3.91 42.52 42.80 42.25 42.52 12.48 3.98

SC-15 1 2.84 27.90 39.59 24.12 28.36 12.05 1.08

SC-16 2 1.98 29.61 48.30 22.45 31.16 10.05 2.13

SC-17 1 1.96 38.62 48.33 31.57 38.88 6.77 1.84

SC-18 1 1.15 47.53 48.05 41.12 46.29 6.62 4.40

SC-19 1 2.65 31.46 37.51 28.06 31.91 10.43 1.37

SC-20 2 -- -- -- -- -- -- --

SC-21 2 6.73 39.69 44.48 35.99 39.80 25.88 9.66

SC-22 2 9.68 35.31 40.26 32.18 34.36 60.96 33.31

SC-23 2 4.94 29.29 39.03 26.16 29.87 24.02 6.00

SC-24 2 4.02 25.25 35.97 21.32 25.67 20.42 3.01

SC-25 2 5.44 38.21 42.50 35.24 37.98 25.37 10.81

SC-26 2 7.52 37.64 43.00 33.17 37.96 66.55 46.25

SC-27 2 6.14 28.21 40.53 24.26 29.40 29.57 6.21

SC-28 2 4.97 27.21 36.12 20.29 24.35 25.79 3.55

SC-29 1 4.33 36.43 42.68 32.16 36.48 14.75 2.47

SC-30 2 5.66 44.61 47.93 40.57 44.76 17.59 6.13

SC-31 3 1.54 27.83 30.82 25.32 27.79 7.23 2.00

SC-32 3 7.84 39.94 45.70 35.08 40.08 24.31 4.51

SC-33 2 5.13 23.27 35.84 20.46 24.11 30.60 6.20

SC-34 2 2.42 23.28 31.59 22.90 24.26 14.23 1.40

Little Nemaha River Basin

LNR-1 2 4.87 29.61 39.81 25.16 30.03 25.61 8.01

LNR-2 2 4.39 32.38 36.29 30.49 30.99 17.88 3.38

LNR-3 2 4.68 34.10 37.82 32.36 34.15 20.13 5.72

LNR-4 2 5.24 31.13 37.30 28.81 31.25 25.43 7.20

LNR-5 2 10.18 36.26 40.34 33.78 36.31 46.73 18.37

LNR-6 2 8.87 44.70 53.08 34.66 44.87 29.40 9.84

LNR-7 2 4.16 37.20 45.14 31.95 37.31 19.22 6.63

LNR-8 2 9.73 44.58 52.47 35.89 44.88 38.09 16.10

LNR-9 1 4.24 35.64 38.94 34.29 35.64 15.97 3.92

LNR-10 1 2.90 21.22 31.12 18.82 21.58 17.44 1.87

LNR-11 2 7.37 39.99 48.22 33.08 40.05 25.78 7.19

LNR-12 2 4.64 31.57 41.65 27.34 30.24 22.62 5.82

LNR-13 2 5.58 24.20 36.37 20.98 24.57 32.61 6.79

LNR-14 2 8.16 20.73 29.85 20.30 21.57 91.85 44.43

LNR-15 2 4.78 28.01 32.98 26.34 28.11 22.28 3.90

Table 2. Channel-geometry data collected at study sites in eastern Nebraska, 1995 to 1999—Continued

[ID, identification; m, meter; °, degree; --, insufficient data]

Site ID

Soil 

groupa

Average 

bank 

height

(m)

Average 

unweighted 

bank angle

(°)

Average 

vertically 

weighted 

bank angle

(°)

Average 

horizontally 

weighted 

bank angle

(°)

Average 

linearly 

weighted 

bank angle

(°)

Average 

bank to 

bank width

(m)

Average 

toe to toe 

width

(m)
Table 2 53

Little Nemaha River Basin—Continued

LNR-16 2 5.49 35.60 42.83 30.63 35.60 24.99 8.40

LNR-17 2 6.33 32.17 34.47 31.08 32.20 56.20 35.61

LNR-18 2 2.26 31.93 37.12 29.28 31.79 16.50 9.01

LNR-19 2 3.12 16.85 24.54 15.93 16.92 57.16 34.84

Big Nemaha River Basin

BNR-1 2 3.79 46.72 50.16 42.84 47.00 11.40 4.10

BNR-2 2 5.08 34.87 38.34 32.99 34.92 19.56 4.55

BNR-3 2 5.13 30.46 37.53 27.37 30.57 27.49 9.56

BNR-4 2 4.58 44.08 48.21 36.20 42.86 16.54 6.53

BNR-5 2 5.60 18.58 23.66 17.55 18.73 39.51 7.48

BNR-6 2 6.76 36.20 43.06 32.42 36.24 52.91 23.24

BNR-7 2 5.12 35.45 43.09 30.78 35.83 22.05 6.69

BNR-8 2 4.52 36.62 41.97 31.03 36.54 20.15 4.36

BNR-9 2 10.45 25.52 31.03 23.97 25.39 79.47 32.08

BNR-10 2 2.49 37.39 41.82 34.54 37.52 9.06 2.54

BNR-11 2 4.58 39.29 46.89 33.41 39.37 20.02 8.24

BNR-12 2 2.38 34.60 39.13 32.09 34.65 17.04 9.43

BNR-13 2 8.27 35.90 44.88 29.18 35.73 65.46 39.13

BNR-14 2 7.44 24.83 28.05 23.96 24.89 80.35 48.12

BNR-15 2 3.95 24.41 27.59 23.54 24.50 20.61 3.19

BNR-16 2 9.41 30.58 37.11 28.41 30.65 48.83 11.27

BNR-17 2 7.54 27.21 34.01 24.82 27.47 50.30 19.79

Big Blue River Basin

BBR-1 1 3.36 29.06 36.45 26.64 29.17 19.66 6.52

BBR-2 1 0.94 40.77 47.03 36.41 40.86 5.83 3.59

BBR-3 1 1.74 45.14 50.16 42.46 45.25 6.46 2.12

BBR-4 3 3.02 29.57 36.39 27.32 29.60 15.92 5.14

BBR-5 3 4.14 36.93 39.09 35.42 36.99 37.63 26.25

BBR-6 3 2.25 25.90 28.92 25.13 25.89 24.53 12.88

BBR-7 3 2.79 28.99 36.93 24.91 28.90 31.78 20.41

BBR-8 3 4.52 24.81 35.23 21.41 25.20 25.44 5.56

BBR-9 3 4.60 34.53 43.78 27.36 34.85 22.19 6.36

BBR-10 3 4.45 29.56 34.98 28.09 30.27 63.41 44.75

BBR-11 3 3.85 30.97 39.11 27.87 31.27 18.23 5.11

BBR-12 3 3.55 51.08 53.27 47.28 51.11 33.43 27.07

BBR-13 3 5.80 33.51 36.21 33.02 33.54 75.71 56.21

a

 Dugan (1984).

Table 2. Channel-geometry data collected at study sites in eastern Nebraska, 1995 to 1999—Continued

[ID, identification; m, meter; °, degree; --, insufficient data]

Site ID

Soil 

groupa

Average 

bank 

height

(m)

Average 

unweighted 

bank angle

(°)

Average 

vertically 

weighted 

bank angle

(°)

Average 

horizontally 

weighted 

bank angle

(°)

Average 

linearly 

weighted 

bank angle

(°)

Average 

bank to 

bank width

(m)

Average 

toe to toe 

width

(m)
54 Stream Bank Stability in Eastern Nebraska Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999 [ID, identification; m, meter; c, cohesion; kPa, kilopascals; φ, friction angel; °, degree; BST status, borehole shear test status: 1, used (good); 2, used (fair); 3, not used (q

kN/m3, kilonewtons per cubic meter; amb, ambient conditions; sat, saturated conditions; %, percent; NASIS, National Soil Information System: S, sand; LS, loamy sand

silt loam; CL, clay loam; SICL, silty clay loam; SIC, silty clay; GR, gravelly; GRV, very gravelly; GRX, extremely gravelly; --, no data] Site ID Sample depth (m) c (kPa) φ (°) BST status Soil unit weight (kN/m3) Moisture content (%) Degree of saturation (%) Particle-size distribution (%) 

t

m

Ambient (γamb) Saturated (γsat) Gravel Sand Silt Clay 

Missouri River Tributary Basins MRT-1 2.5 13.7 28.9 1 18.1 18.7 28.7 88.2 -- 9.4 54.1 37.6 S

MRT-2 1.8 3.2 27.9 2 17.5 17.6 42.1 99 -- 17.1 71.1 11.9 SMRT-3 2 2.5 32.2 1 17.9 18.6 28 84.7 -- -- -- -- MRT-4 1.1 4.8 30.7 1 18 19.2 20.3 71 -- 17.6 63.8 18.7 SMRT-5 1.4 27.3 21.3 3 17.3 18.9 20 64.4 -- 15.1 67.7 17.3 SMRT-6 2.3 8.1 29.7 2 18.5 18.9 28.5 91.2 -- -- -- -- MRT-7 1.7 3.3 25.2 1 17.3 18.3 28.7 79.9 -- -- -- -- MRT-8 1.4 8.7 26.6 2 17.2 17.9 33.9 86.3 -- 5 68.9 26.1 SMRT-9 0.7 23.6 15.7 3 16.6 18.2 25 67.7 -- 17.8 59.9 22.4 S

2.1 7.7 26.6 1 16.1 17.2 36.7 79.4 -- 7.1 68.6 24.3 S

MRT-10 1.9 6.6 39 1 17.5 19.2 17 59.9 -- 14.2 70.1 17.3 S

2.3 16.8 29.8 1 15.6 18 21 54.1 -- -- -- -- 6.1 11.3 34.6 1 16.1 18.1 22.6 60 -- 21.9 59 19.1 S

MRT-11 1.4 11.2 29.9 1 17.5 18.6 25.4 76.2 -- 6.7 71 22.8 SMRT-12b 1.1 10.7 27.9 1 17.7 18.7 25.1 77.4 -- 4.5 71.8 23.6 SMRT-13 1.6 7.7 24.1 1 16.9 17.9 32.3 81.2 -- 8.8 64.8 26.4 SMRT-14 1.5 3.5 23 2 16.7 17.8 31 77.6 -- -- -- -- MRT-15 1.1 13.5 27.2 1 16.9 18.3 25.6 71.3 -- -- -- -- MRT-16 2.3 8.6 31.6 3 17.9 18 37.3 98.1 -- 20.2 60.9 18.8 S

5.7 9.1 24.4 3 18.7 18.9 29.9 96 -- 28.2 55 16.8 S

MRT-17 3.6 16 27.6 2 18.6 19 28.1 92.3 -- 29.6 56.5 13.9 S
Table 3 55

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay

Papillion Creek Basin

PC-1 1.1 13 29.2 3 17.4 18.1 31.5 84.9 -- 8.9 66.2 24.9 S

1.7 12.4 29.4 1 17.3 18.5 24.5 72.8 -- 13.5 67.6 19 S

PC-2 0.8 23 17.7 2 13.7 16.2 34.7 58.7 -- 9.9 64.9 25.2 S

0.9 44.2 13.8 3 18.8 19.3 24.8 87.8 -- 11.2 67.7 21.1 S2.1 4 38.2 1 16.2 18.6 15.9 47.7 -- 4.3 67.2 28.5 

PC-3 1.4 12.3 23.4 2 17.2 18.3 27.9 77.3 -- -- -- -- PC-4 2.3 11.5 36.4 2 14.2 17.5 15.8 36.8 -- -- -- -- PC-5 1.6 14.5 25 1 17.7 18.6 26.7 80.6 -- 4.3 63.2 34.1 SPC-6 1.3 4.7 27.6 1 16.9 18.1 28.5 76.4 -- 3.1 75.1 21.8 SPC-7 1.6 11.4 20.6 1 17.2 17.9 34.3 86.5 -- -- -- -- PC-8 2.5 7.6 26 1 17.9 18.3 32.4 91.7 -- -- -- -- PC-9 1 24 21.8 1 15.8 17.4 30.6 69.3 -- 2.9 77.6 19.5 SPC-10 2.2 9.2 26 1 17.2 18.2 29.3 80 -- 2.2 76 21.9 SPC-11 1.7 8.9 23.8 1 18.5 19.3 23 82.1 -- -- -- -- PC-12 2.6 4.5 28.8 1 15.8 17.1 37.4 77.6 -- 2.8 64.5 32.8 S

Platte River Tributary Basins

PRT-1 1.2 14.9 22.6 3 18.3 19.1 23.8 81.6 -- 15.7 65.7 18.6 SPRT-2 1.7 12.3 30.5 1 14 17.6 12.6 30.1 -- 35.5 46 18.6 L PRT-3 1.1 3.6 30.1 3 17.8 18.5 28.5 84.2 -- 11.5 65.8 22.8 SPRT-4 0.7 4.2 27.5 1 17.9 18.6 28.4 84.8 -- 14.3 59.1 26.6 SPRT-5 2.6 7.1 30.4 2 15.2 18.3 13.6 37.8 -- 14.4 67 18.6 SPRT-6 1.5 15.8 29.3 1 17.2 18.5 25.3 73.6 -- 15.5 61.2 23.3 SPRT-7 1.4 12.8 29.5 2 15.4 17.8 21.9 53.9 -- 12.7 67.4 22 SPRT-8 1.7 16.9 25.4 1 16.4 18 26.6 68.9 -- -- -- -- 
56 Stream Bank Stability in Eastern Nebraska Platte River Tributary Basins—Continued PRT-9 1.5 4.5 33 2 15.9 17.7 26.9 65.1 -- -- -- -- 

PRT-10 1.5 6.5 29.1 1 17 18.3 25.7 72.8 -- 4.2 78.5 17.3 SPRT-11 2.1 14 21.5 1 17.2 17.8 34.7 86.8 -- -- -- -- PRT-12 1.7 4.7 24.6 1 17.6 18.3 30.4 85 -- 6.1 75.6 19.5 SPRT-13 1.7 6 25 1 15.7 17.2 34.4 73.3 -- -- -- -- 

Elkhorn River Basin

ER-2 1.3 4.1 22.9 1 17.4 18.2 30.4 83.9 -- 16.8 56.2 28.2 SER-3 3 4.2 33.6 1 17.1 19.5 11 41.4 -- -- -- -- ER-4 1.2 17 25 1 16.3 17.8 29.2 71.6 -- -- -- -- ER-5 1.9 19.4 28.4 1 13.8 17.2 18 38.2 -- 9.3 59.6 31.2 SER-6 0.3 0 32.8 2 20.2 22.4 0.9 7.4 -- 81.2 12.1 7 LER-7 1.1 9.1 33.1 1 15.1 18 15.9 41.6 -- 8 68.6 28.1 S

1.5 -- -- -- 15.9 17.5 30.7 70.4 -- -- -- -- 

ER-8 2.2 17 19.3 3 18.6 19 27.9 92.2 -- -- -- -- ER-9 1.3 9.5 31.7 1 14.5 17.1 24.9 52.4 -- 8.8 62.7 28.6 SER-10 1.3 12.5 26.6 1 17.2 18.2 28.7 79 -- 16.1 64.9 20.9 SER-11 1.2 14.6 28.1 1 17.7 18.8 24.7 77.4 -- 9.6 58.4 32.9 SER-12 1.5 10.3 26.5 2 18.7 19.1 26.6 90.9 -- 12.6 66.2 21.2 SER-13 1.6 23.4 29.2 2 15 17.8 17.6 44 -- -- -- -- ER-14 1.4 10.8 29.2 1 16.5 19.3 9.9 35.1 -- 55.3 31.4 13.3 S

3.8 17.5 24.6 1 18.5 19.2 23.8 83.7 -- 30.2 49.8 19.9 L 

ER-15 1.1 16.7 10.7 1 17 18.6 22.3 66.8 -- 12.5 59.5 28.9 S

3 -- -- -- 18.3 18.9 26.8 86.2 -- 26.1 48.1 27.2 C

ER-16 1.2 4.7 35 2 14.7 17.1 26.4 55.6 -- 7.6 63.5 28.9 SER-17 1.4 11 28.1 2 15.2 18.1 14.6 39.5 -- 9.3 63.4 27.3 S

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
Table 3 57

Elkhorn River Basin—Continued

ER-18 1.7 3.2 30.9 1 16.3 17.3 37 81.6 -- -- -- -- ER-19 1.7 5 30.3 2 14.5 17.6 17.1 40.7 -- -- -- -- ER-20 0.5 14.6 21.9 1 17.4 18.6 24.1 73.2 -- 10.4 65.3 24.3 S

2 20 22 2 17.5 18.7 24.6 75.4 -- 14.2 56.6 29.3 S

ER-22 1 17.3 20.1 2 17.5 17.9 35.7 91.6 -- 3.2 45.8 53.9 SER-23 1.1 5.7 31 1 18.4 19.3 22.7 80.1 -- -- -- -- ER-24 1.5 11 27.2 1 16.9 18.3 25.8 71.8 -- 5.3 70.9 23.9 SER-25 1 6.7 30.4 2 16.3 18.8 13.7 43.5 -- 45.1 43.9 26.3 L 

4.4 -- -- -- -- -- -- -- -- 84.2 11.6 5.8 L

Salt Creek Basin

SC-1 1.2 7.8 25.8 1 16.8 18.1 27.4 73.6 -- 12.8 63.4 23.8 SSC-2 1.3 2.5 37.1 1 14.6 17.5 20.5 47 -- -- -- -- SC-3 2.2 8.5 32.8 2 15.7 17.5 28.1 65.3 -- 20.6 57.4 22 S

4.5 9.3 16.4 3 17.5 17.8 37 93 -- 23.8 57.8 18.4 S

SC-4 1.2 2.7 34.3 2 15.6 18.2 16.7 46.1 -- 7.2 70.5 22.3 SSC-5 1.4 9.8 28.8 2 15.8 17.7 25.9 63 -- -- -- -- SC-6 1.7 5 32.7 1 14.6 18 12.6 32.5 -- 4 72.1 23.9 SSC-7 1.6 14 26.6 1 16.1 17.6 30.9 72.4 -- -- -- -- SC-8 1.5 12 31.4 1 16.6 18.3 23.6 65.4 -- -- -- -- SC-9 2.2 13 26.6 1 18.2 19 24.3 80.8 -- 33.7 59.9 21.9 SSC-10 1.1 11.7 23 1 17.7 18.2 31.8 88 -- -- -- -- SC-11 1.5 14.6 26 1 17.7 18.5 28 82.4 -- 5.9 52.3 41.8 SSC-12 2.5 8.6 27 1 17.4 18.3 29.2 81.8 -- -- -- -- SC-13 6.4 8.7 35.6 1 18 19 23.5 78 -- 18.8 61.8 19.4 SSC-14 1.4 15.1 36.9 2 16.3 18.4 20.3 57.7 -- 19.3 51.8 28.9 S

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
58 Stream Bank Stability in Eastern Nebraska Salt Creek Basin—Continued SC-15 1 12.8 14 3 18 18.6 28.4 85.7 -- -- -- -- 

SC-16 0.5 14.1 21.5 1 13.5 16.3 30.3 52.6 -- 18.2 65.3 16.5 SSC-17 1 13.8 26.6 2 -- -- -- -- -- -- -- -- 

1.4 16.3 13 3 17.2 18.1 31.5 83.4 -- 22.6 56.3 21 S1.5 7.7 17.7 3 17.1 18 31.5 82 -- -- -- -- 

SC-18 0.8 3.5 24.6 2 17.6 18.1 33.3 89.2 -- 41.1 42.5 16.4 L SC-19 1 36 15.3 3 16.7 17.8 31.8 78.8 -- 21.8 57.8 20.4 SSC-20 1.5 8.5 14 3 18.4 19.4 20.8 76.5 -- 42.2 43.5 14.3 L 

1.9 22.2 26.7 2 -- -- -- -- -- -- -- -- 

SC-21 2 -- -- -- 18.6 19.6 19.3 74.8 -- -- -- -- 

2 44.7 15.8 3 18.6 19.9 16.1 66.5 -- 25 56.2 18.9 S3.3 -- -- -- 17.2 18.5 24.6 72.4 -- -- -- -- 4 0 15.3 3 17.6 20.1 7.7 33.7 -- -- -- -- 

SC-22 2.4 8.1 35.9 1 18.4 19.5 18.8 71 -- 22.7 50.8 26.6 SSC-23 2.2 16 35.2 1 17.3 18.6 24 71.7 -- 18.2 45.2 36.7 S

4.4 7.1 28.4 1 19.2 19.3 27.4 97.5 -- 15.7 53.3 30.9 S

SC-24 1.1 11.2 20.3 2 17.8 18.6 26.9 81.3 -- -- -- -- SC-25 1.3 2.2 31.8 1 18.7 19.4 22.9 83.2 -- 6.8 69 24.1 S

2.2 7 21.8 2 18.7 19.1 26.8 90.8 -- 6.6 63.3 31.1 S

SC-26 2 10 42.1 1 15.9 18.5 14.5 43 -- 18.4 56 25.6 S

2.4 7 32.1 1 15.3 18.1 16.3 43.2 -- -- -- -- 

SC-27 1.1 15.7 21.8 2 16.5 18.4 20.6 59.5 -- -- -- -- SC-28 1.7 12.6 23.1 2 16.2 17.5 33 75.8 -- 32.2 53.8 22.4 SSC-29 1.7 20.4 19.3 1 15.2 17.2 30.3 64.6 -- 5.9 69.6 24.5 SSC-30 1.9 9.4 33.8 1 12.6 16.7 15.9 30 -- -- -- -- SC-31 0.6 3.1 27.9 1 16.7 17.6 34.9 82.9 -- -- -- -- 

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
Table 3 59

Salt Creek Basin—Continued

SC-32 2.8 6.5 30.6 1 18.3 19.5 18.9 71 -- 13.2 60.5 27.1 SSC-33 2.5 2.3 36.4 2 17.2 18.3 27.8 77.2 -- -- -- -- 

3.9 0 0 3 18.3 18.6 31.1 93.6 -- 80.7 7 12.2 S

SC-34 1.8 7.4 33.1 1 17.7 18.4 28.7 83.2 -- -- -- -- 

Little Nemaha River Basin

LNR-1 1.8 16.6 21 1 18.6 19.3 23.3 83.6 -- -- -- -- LNR-2 1.6 19.4 25.8 1 16.2 18.2 20.7 57.2 -- -- -- -- LNR-3 1.5 7.9 31.5 1 18 18.7 27.3 84.6 -- 17.1 60 22.9 SLNR-4 1.3 15.1 34 2 -- 18.5 -- -- -- -- -- -- LNR-5 -- 12.8 23 1 -- -- -- -- -- -- -- -- LNR-6 1.8 12.7 29.2 1 -- 17.2 -- -- -- 5.7 72.6 21.6 SLNR-7 0.9 8.8 22.5 2 17.4 18.5 25.8 75.9 -- 21.2 57.3 21.6 SLNR-8 1.5 6.5 33.5 1 15.8 18.8 10.4 33.3 -- -- -- -- LNR-9 1.4 13.3 26.5 2 18.5 19.3 22.3 80.2 -- -- -- -- LNR-10 0.9 36.5 15.3 2 16.4 18 25.5 67.2 -- -- -- -- LNR-11 3.2 19.6 34.4 3 19.2 20.5 13.3 63.4 -- 36.2 42.2 21.6 L LNR-12 1.3 7.7 26.2 2 18 19.1 21.4 73.3 -- -- -- -- LNR-13 1.5 12.8 24.7 1 15 17.4 24.3 55 -- -- -- -- LNR-14 1.7 -- -- -- 14.7 18.2 10.9 29.7 -- -- -- -- 

2.4 18.9 33.7 3 16.5 19 12.9 43.1 -- -- -- -- 

LNR-15 2 12.9 28.8 1 18.8 19.5 22.2 83 -- -- -- -- LNR-16 1 17.2 34.2 2 16 18.3 18.9 52.6 -- 3.2 70.7 26.1 S

4.7 3.1 38.7 2 17.7 18.4 29.5 84.5 -- 22.8 58.6 18.7 S

LNR-17 1.6 -- -- -- 18.1 19.6 16.8 64.3 -- 15.8 55.1 29.1 S

5.5 15.5 27.9 2 18.1 18.4 33 94.5 -- 20.5 61.2 18.2 S

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
60 Stream Bank Stability in Eastern Nebraska Little Nemaha River Basin—Continued LNR-18 1.3 12.2 23 1 17.6 18.2 32.3 88 -- -- -- -- 

LNR-19 1.1 23.8 19.6 1 18.3 19 25.2 84.1 -- -- -- -- 

Big Nemaha River Basin BNR-1 1.6 10.5 30.7 1 12.9 16.5 22 39.7 -- 1.1 63.2 35.7 S

BNR-2 1.9 7 33 1 16 18.8 11.6 37.1 -- -- -- -- BNR-3 1.1 5.4 32.1 1 18.9 20.1 16 69.5 -- -- -- -- BNR-4 0.9 -- -- -- 18.6 19.8 16.8 68.5 -- 16.6 62 23.8 SBNR-4 3.7 18.5 16.3 1 17.5 18.6 24.9 75.2 -- 41 43.9 20.5 L BNR-5 2.5 5.8 33 1 15.6 18.6 11.8 35.6 -- -- -- -- BNR-6 2 15.3 20.7 1 17.6 18.6 26.3 79.3 -- 34.4 51.7 18.2 SBNR-7 1.7 22.1 24.4 2 14.2 18.1 8 21.4 -- 24 57.9 18.1 S

4.7 19.8 30.1 2 18.4 19.6 17.6 68.4 -- 42.4 39.4 19.3 L 

BNR-8 1.5 19.7 20.8 2 18.2 19.2 22.9 78.8 -- 24.7 48.5 29.1 C

4.3 10.2 26.4 2 18.5 19 27.3 89.8 -- 16.8 49.4 35 S

BNR-9 2.2 44.1 17.7 3 19.3 19.7 22.8 89.5 -- 11.5 49.3 39.2 S

6.8 22.5 23.5 2 19 19.2 27.3 95 -- 10.8 47.7 41.5 S

BNR-10 1.3 11.7 19.6 1 15.5 17.3 30.9 67.6 -- -- -- -- BNR-11 3 20.3 23.8 1 16.6 18 28.1 73 -- 4.6 64.7 30.7 SBNR-12 1.1 12.4 32.8 1 18.6 19.7 19.2 74.7 -- 35.4 39.9 24.7 L BNR-13 0.5 10.1 24.5 1 18.6 18.8 29.7 94.3 -- 18.7 48.9 33.4 S

1.6 21.3 27 3 -- -- -- -- -- 16.5 53.4 30.2 S

BNR-14 2.2 14.3 35.7 1 16.9 18.4 23.5 67.9 -- 14.4 61.6 24 S

7.4 17.2 31.5 2 18.9 19 28.9 96.2 -- 38.5 41.2 20.4 L 

BNR-15 1.5 11.2 29.7 1 18.4 19.2 24 82.9 -- -- -- -- 

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
Table 3 61

Big Nemaha River Basin—Continued

BNR-16 1.1 7.6 33.1 2 17.4 18.6 24.6 74 -- 7.2 69.6 26 S

4.8 -- -- -- 17.7 18.7 24.8 77.2 -- 1.9 50.8 50.4 S

BNR-17 1.3 18.6 9.4 3 17.5 18.3 29.9 83.3 -- 2 45.4 57.3 S

4.1 21.7 20 3 17.7 18.6 26 78.9 -- 12.6 56.1 31.3 S5.9 7.8 24.3 1 16.9 17.8 33.8 83.6 -- 12.3 46 42.3 S

Big Blue River Basin

BBR-1 1.8 18 21.8 2 17.3 18.4 27.5 78.2 -- 12.2 64.5 23.3 SBBR-2 0.7 6.4 28.5 1 16 17.6 30.1 70.7 -- -- -- -- BBR-3 1.2 7.2 23.1 1 16.7 17.6 35.6 83.3 -- 8.5 67.8 23.7 SBBR-4 1.6 8.9 27.6 1 17.9 18.7 27.2 82.9 -- -- -- -- BBR-5 2.3 14.1 39.5 1 17.2 18.6 23.5 70.2 -- 18.4 55.5 26.1 SBBR-6 2.2 7 31.1 1 18.3 19.6 18.2 69.2 -- -- -- -- BBR-7 1.9 4.3 30.2 1 14.9 17.5 22.2 51.3 -- 3.5 89.7 6.7 SBBR-8 1 12.6 19 1 17.4 18.1 32 85.4 -- 7.2 76.8 16 SBBR-9 1.8 13.9 27.2 1 17.1 18.5 22.9 68 -- -- -- -- BBR-10 2 1.7 42.1 1 17.9 19.1 21.3 72.1 -- 15.7 49.3 35.1 S

4.7 3.3 32.9 2 18.8 19 28.2 94.7 -- 31.1 55.1 13.8 S

BBR-11 1.8 10.8 29.7 1 13.3 17.1 15.3 32.1 -- 4.5 69.1 26.4 SBBR-12 1.7 12.7 29.5 1 18 19 23.6 77.4 -- -- -- -- BBR-13 2.3 2.3 38 2 15.1 18.5 9.9 29.1 -- 29.1 54.6 16.3 S

Table 3. Soil-property data from samples collected at study sites in eastern Nebraska, 1995 to 1999—Continued

Site ID

Sample 

depth 

(m)

c 

(kPa)

φ 

(°)

BST 

status

Soil unit weight

(kN/m3)

Moisture 

content 

(%)

Degree of 

saturation 

(%)

Particle-size distribution 

(%)

t

m

Ambient

(γamb)

Saturated

(γsat) Gravel Sand Silt Clay
62 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

f

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

MRT-1 2 16.4 17.9 10.8 28 45 3.1 38.9 36.7 5.9 4.7 Stable Stable 4.0 1.9 

SS 18.1 18.7 13.7 29 53 4.6 24.6 22.0 5.9 4.4 Stable At Risk 2.9 1.3 SS 18.1 18.7 13.7 29 32 2.1 >50.0 >50.0 10.2 8.7 Stable Stable 7.8 4.8 SS 18.1 18.7 13.7 29 46 4.3 43.4 40.8 6.9 5.5 Stable Stable 3.5 1.6 SS 18.1 18.7 13.7 29 47 1.3 37.5 34.9 6.7 5.2 Stable Stable 7.1 5.1 

MRT-2 2 16.4 17.9 10.8 28 25 3.4 >50.0 >50.0 10.8 9.6 Stable Stable 7.1 3.2 

SS 17.5 17.6 3.2 28 29 4.3 >50.0 >50.0 2.9 2.5 At Risk At Risk 3.6 0.7 

SS 17.5 17.6 3.2 28 22 2.4 >50.0 >50.0 3.8 3.4 Stable Stable 5.5 1.5 

MRT-3 2 16.4 17.9 10.8 28 28 2.6 >50.0 >50.0 9.5 8.3 Stable Stable 7.1 3.6 

SS 17.9 18.6 2.5 32 32 2.9 >50.0 >50.0 1.9 1.6 At Risk At Risk 3.5 0.6 

SS 17.9 18.6 2.5 32 21 2.8 >50.0 >50.0 2.9 2.6 Stable At Risk 5.5 1.0 

SS 17.9 18.6 2.5 32 28 2.9 >50.0 >50.0 2.2 1.9 At Risk At Risk 4.1 0.8 SS 17.9 18.6 2.5 32 31 2.4 >50.0 >50.0 1.9 1.7 At Risk At Risk 3.8 0.8 SS 17.9 18.6 2.5 32 35 2.8 >50.0 >50.0 1.7 1.4 At Risk At Risk 3.2 0.6 

SS 17.9 18.6 2.5 32 23 2.2 >50.0 >50.0 2.6 2.4 Stable Stable 5.3 1.2 

MRT-4 2 16.4 17.9 10.8 28 46 7.8 33.0 30.8 5.6 4.4 At Risk At Risk 2.6 0.7 

SS 18.0 19.2 4.8 31 35 8.0 >50.0 >50.0 3.2 2.7 At Risk At Risk 2.9 0.4 SS 18.0 19.2 4.8 31 53 8.1 10.0 9.0 2.0 1.5 At Risk At Risk 1.8 0.2 

SS 18.0 19.2 4.8 31 30 7.9 >50.0 >50.0 3.7 3.2 At Risk At Risk 3.4 0.5 

SS 18.0 19.2 4.8 31 58 8.0 7.1 6.1 1.8 1.3 Unstable Unstable 1.6 0.2 

SS 18.0 19.2 4.8 31 44 7.1 22.7 21.8 2.5 2.0 At Risk At Risk 2.3 0.3 

SS 18.0 19.2 4.8 31 58 7.8 7.1 6.1 1.8 1.3 Unstable Unstable 1.6 0.2 

MRT-5 2 16.4 17.9 10.8 28 49 5.0 25.5 23.3 5.3 4.0 Stable At Risk 2.9 1.0 

2* 16.4 17.9 10.8 28 58 5.4 14.5 12.3 4.3 3.1 At Risk At Risk 2.3 0.8 

2* 16.4 17.9 10.8 28 47 4.6 31.9 29.7 5.6 4.4 Stable At Risk 3.2 1.2 

2* 16.4 17.9 10.8 28 43 5.1 44.5 42.3 6.1 4.9 Stable At Risk 3.3 1.2 

2* 16.4 17.9 10.8 28 40 4.9 >50.0 >50.0 6.6 5.4 Stable Stable 3.6 1.3 

[ID, identification; kN/m3, kilonewtons per cubic meter; kPa, kilopascals; ° , degrees; m, meters; CWxx , Channel-water level as a percentage (xx) of the bank height; BWyy , bank-w

height; F s , Factor of safety; Soil group: 1, 2, 3, and 4 as referenced in text; %, percent; SS, Site specific soil property data used; *, Sites without site-specific soil property data or w

using the median soil group data as needed. Indirect method: bh, bank height below range; ba, bank angle below range; c, cohesion above range; γsat, saturated soil unit weight a

or no data; For each site reach, the average channel geometry and soil group median parameters were used, and for the individual bank sections within each reach, the section bawere used (all bank angles were weighted vertically); Summary results listed as or equivalent to the at risk condition are in bold font and those listed as or representing the unstab

Expected stable bank angles greater than the vertically weighted bank angles are shown in bold italics font]

Summary resul

Culmann method ARS method 

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks

Missouri River Tributary Basins

Ambient conditions Saturated conditions Summary results
Table 4 63

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

MRT-6 2 16.4 17.9 10.8 28 35 6.1 >50.0 >50.0 7.6 6.4 Stable Stable 3.9 1.2 

SS 18.5 18.9 8.1 30 38 5.7 >50.0 >50.0 5.0 4.2 At Risk At Risk 3.2 0.9 

SS 18.5 18.9 8.1 30 40 9.8 >50.0 >50.0 4.7 3.9 At Risk At Risk 2.6 0.5 SS 18.5 18.9 8.1 30 30 4.9 >50.0 >50.0 6.4 5.5 Stable Stable 4.2 1.3 SS 18.5 18.9 8.1 30 49 6.0 20.9 19.4 3.8 2.9 At Risk At Risk 2.3 0.6 SS 18.5 18.9 8.1 30 28 4.5 >50.0 >50.0 7.0 6.1 Stable Stable 4.8 1.6 SS 18.5 18.9 8.1 30 44 6.0 32.8 31.3 4.2 3.4 At Risk At Risk 2.6 0.7 SS 18.5 18.9 8.1 30 27 5.8 >50.0 >50.0 7.0 6.2 Stable Stable 4.4 1.2 SS 18.5 18.9 8.1 30 24 6.5 >50.0 >50.0 8.0 7.2 Stable Stable 4.9 1.2 

MRT-7 2 16.4 17.9 10.8 28 42 3.6 49.5 47.4 6.2 5.0 Stable Stable 3.9 1.7 

SS 17.3 18.3 3.3 25 36 1.2 23.2 22.6 2.2 1.9 Stable Stable 4.2 1.9 SS 17.3 18.3 3.3 25 48 6.9 6.4 5.8 1.6 1.2 Unstable Unstable 1.8 0.2 

SS 17.3 18.3 3.3 25 48 5.5 6.7 6.1 1.6 1.3 At Risk At Risk 1.9 0.3 

SS 17.3 18.3 3.3 25 41 1.2 12.0 11.4 1.9 1.6 Stable Stable 3.7 1.6 

SS 17.3 18.3 3.3 25 39 4.1 16.0 15.4 2.1 1.7 At Risk At Risk 2.6 0.5 

SS 17.3 18.3 3.3 25 43 2.7 10.3 9.7 1.9 1.5 At Risk At Risk 2.5 0.7 

MRT-8 2 16.4 17.9 10.8 28 46 6.4 35.2 33.0 5.7 4.5 At Risk At Risk 2.8 0.9 

SS 17.2 17.9 8.7 27 43 6.9 30.4 28.8 4.9 4.0 At Risk At Risk 2.6 0.7 SS 17.2 17.9 8.7 27 51 5.7 15.4 13.7 4.0 3.1 At Risk At Risk 2.3 0.7 SS 17.2 17.9 8.7 27 43 6.8 31.5 29.9 5.0 4.0 At Risk At Risk 2.7 0.7 SS 17.2 17.9 8.7 27 48 5.9 19.1 17.4 4.3 3.4 At Risk At Risk 2.4 0.7 SS 17.2 17.9 8.7 27 37 6.6 >50.0 >50.0 5.9 4.9 At Risk At Risk 3.2 0.9 SS 17.2 17.9 8.7 27 52 6.4 15.2 13.5 4.0 3.1 At Risk At Risk 2.2 0.6 

MRT-9 2 16.4 17.9 10.8 28 34 4.7 >50.0 >50.0 7.8 6.6 Stable Stable 4.4 1.6 

SS 16.1 17.2 7.7 27 48 4.2 17.9 16.4 4.0 3.1 At Risk At Risk 2.7 0.9 

SS 16.1 17.2 7.7 27 39 5.0 47.0 45.4 5.1 4.2 Stable At Risk 3.3 1.0 

SS 16.1 17.2 7.7 27 39 4.0 46.3 44.8 5.1 4.2 Stable Stable 3.5 1.3 SS 16.1 17.2 7.7 27 36 5.2 >50.0 >50.0 5.6 4.7 Stable At Risk 3.5 1.1 SS 16.1 17.2 7.7 27 45 4.4 24.5 23.0 4.4 3.5 At Risk At Risk 2.9 1.0 

SS 16.1 17.2 7.7 27 21 5.0 >50.0 >50.0 9.9 9.0 Stable Stable 6.4 2.0 

SS 16.1 17.2 7.7 27 24 4.7 >50.0 >50.0 8.3 7.4 Stable Stable 5.5 1.8 SS 16.1 17.2 7.7 27 35 5.0 >50.0 >50.0 5.6 4.7 Stable At Risk 3.6 1.1 SS 16.1 17.2 7.7 27 30 5.0 >50.0 >50.0 6.8 5.9 Stable Stable 4.4 1.3 SS 16.1 17.2 7.7 27 40 5.0 41.2 39.6 4.9 4.0 At Risk At Risk 3.2 1.0 

SS 16.1 17.2 7.7 27 34 4.8 >50.0 >50.0 5.8 4.9 Stable Stable 3.8 1.2 

SS 16.1 17.2 7.7 27 31 5.1 >50.0 >50.0 6.4 5.5 Stable Stable 4.1 1.3 SS 16.1 17.2 7.7 27 44 3.9 27.1 25.5 4.5 3.6 Stable At Risk 3.2 1.2 

SS 16.1 17.2 7.7 27 29 5.0 >50.0 >50.0 7.0 6.1 Stable Stable 4.5 1.4 

SS 16.1 17.2 7.7 27 28 4.8 >50.0 >50.0 7.2 6.3 Stable Stable 4.7 1.5 SS 16.1 17.2 7.7 27 37 4.9 >50.0 >50.0 5.3 4.4 Stable At Risk 3.4 1.1 

SS 16.1 17.2 7.7 27 39 4.3 48.8 47.3 5.1 4.2 Stable At Risk 3.5 1.2 

SS 16.1 17.2 7.7 27 25 5.0 >50.0 >50.0 8.2 7.3 Stable Stable 5.3 1.7 SS 16.1 17.2 7.7 27 30 4.8 >50.0 >50.0 6.8 5.9 Stable Stable 4.4 1.4 SS 16.1 17.2 7.7 27 35 4.7 >50.0 >50.0 5.7 4.8 Stable Stable 3.7 1.2 

Missouri River Tributary Basins--Continued

Ambient conditions Saturated conditions Summary results Summary resul

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued
64 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued MRT-10 2 16.4 17.9 10.8 28 46 9.1 33.7 31.5 5.7 4.5 At Risk At Risk 2.5 0.6 

SS 16.4 18.4 11.6 35 30 8.6 >50.0 >50.0 9.4 8.1 Stable At Risk 4.6 1.1 

SS 16.4 18.4 11.6 35 56 9.3 27.8 25.2 4.7 3.5 At Risk At Risk 2.2 0.5 

SS 16.4 18.4 11.6 35 34 8.8 >50.0 >50.0 8.1 6.9 At Risk At Risk 3.9 0.9 

SS 16.4 18.4 11.6 35 53 9.1 36.7 34.0 5.1 3.8 At Risk At Risk 2.4 0.6 

SS 16.4 18.4 11.6 35 39 8.7 >50.0 >50.0 7.2 5.9 At Risk At Risk 3.5 0.8 SS 16.4 18.4 11.6 35 67 9.5 13.6 10.9 3.8 2.5 At Risk At Risk 1.8 0.4 SS 16.4 18.4 11.6 35 43 9.0 >50.0 >50.0 6.4 5.1 At Risk At Risk 3.1 0.7 SS 16.4 18.4 11.6 35 46 9.8 >50.0 >50.0 5.9 4.6 At Risk At Risk 2.8 0.6 

MRT-11 2 16.4 17.9 10.8 28 29 6.9 >50.0 >50.0 9.3 8.1 Stable Stable 4.5 1.4 

SS 17.5 18.6 11.2 30 21 5.5 >50.0 >50.0 12.8 11.6 Stable Stable 6.8 2.3 SS 17.5 18.6 11.2 30 37 8.3 >50.0 >50.0 7.3 6.1 At Risk At Risk 3.3 0.9 

MRT-12 2 16.4 17.9 10.8 28 40 5.8 >50.0 >50.0 6.6 5.4 Stable At Risk 3.4 1.1 

SS 17.7 18.7 10.7 28 43 6.0 41.8 39.8 5.8 4.7 At Risk At Risk 2.9 1.0 

SS 17.7 18.7 10.7 28 46 5.7 31.8 29.7 5.4 4.3 At Risk At Risk 2.8 0.9 SS 17.7 18.7 10.7 28 46 5.8 32.6 30.6 5.5 4.3 At Risk At Risk 2.8 0.9 SS 17.7 18.7 10.7 28 41 5.6 >50.0 >50.0 6.1 5.0 Stable At Risk 3.2 1.1 

SS 17.7 18.7 10.7 28 38 6.3 >50.0 >50.0 6.7 5.6 Stable At Risk 3.4 1.1 SS 17.7 18.7 10.7 28 53 5.4 18.1 16.1 4.6 3.4 At Risk At Risk 2.4 0.9 

SS 17.7 18.7 10.7 28 25 7.7 >50.0 >50.0 10.2 9.0 Stable Stable 4.8 1.3 SS 17.7 18.7 10.7 28 29 4.1 >50.0 >50.0 8.8 7.6 Stable Stable 5.3 2.2 

MRT-13 2 16.4 17.9 10.8 28 30 3.1 >50.0 >50.0 8.9 7.7 Stable Stable 6.2 2.9 

SS 16.9 17.9 7.7 24 21 3.0 >50.0 >50.0 9.4 8.6 Stable Stable 7.3 3.2 

SS 16.9 17.9 7.7 24 34 2.9 >50.0 >50.0 5.6 4.8 Stable Stable 4.4 1.9 SS 16.9 17.9 7.7 24 27 3.6 >50.0 >50.0 7.1 6.2 Stable Stable 5.0 2.0 SS 16.9 17.9 7.7 24 39 2.7 32.1 30.7 4.9 4.0 Stable Stable 3.9 1.8 

MRT-15 2 16.4 17.9 10.8 28 36 5.1 >50.0 >50.0 7.5 6.3 Stable Stable 4.1 1.5 

SS 16.9 18.3 13.5 27 33 4.7 >50.0 >50.0 10.1 8.6 Stable Stable 5.0 2.1 SS 16.9 18.3 13.5 27 32 5.2 >50.0 >50.0 10.3 8.8 Stable Stable 4.8 2.0 SS 16.9 18.3 13.5 27 42 5.1 >50.0 >50.0 7.8 6.3 Stable Stable 3.7 1.5 SS 16.9 18.3 13.5 27 36 5.2 >50.0 >50.0 9.1 7.6 Stable Stable 4.3 1.8 

MRT-16 2 16.4 17.9 10.8 28 30 6.8 >50.0 >50.0 9.1 7.9 Stable Stable 4.4 1.3 

2* 16.4 17.9 10.8 28 26 6.8 >50.0 >50.0 10.7 9.4 Stable Stable 5.2 1.6 2* 16.4 17.9 10.8 28 24 8.9 >50.0 >50.0 11.3 10.1 Stable Stable 5.1 1.3 2* 16.4 17.9 10.8 28 35 6.4 >50.0 >50.0 7.7 6.5 Stable Stable 3.8 1.2 2* 16.4 17.9 10.8 28 35 6.9 >50.0 >50.0 7.6 6.4 Stable At Risk 3.7 1.1 2* 16.4 17.9 10.8 28 30 6.4 >50.0 >50.0 9.0 7.8 Stable Stable 4.5 1.4 2* 16.4 17.9 10.8 28 28 5.3 >50.0 >50.0 9.8 8.6 Stable Stable 5.2 1.8 

Missouri River Tributary Basins--Continued
Table 4 65

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

B

f

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary result

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued

MRT-17 2 16.4 17.9 10.8 28 53 5.4 20.3 18.1 4.9 3.7 At Risk At Risk 2.6 0.9 

SS 18.6 19.0 16.0 28 28 3.9 >50.0 >50.0 13.5 11.8 Stable Stable 6.6 3.5 

SS 18.6 19.0 16.0 28 53 6.1 24.4 21.6 6.7 5.0 Stable At Risk 2.6 1.1 

SS 18.6 19.0 16.0 28 65 4.6 13.7 10.8 5.3 3.7 Stable At Risk 2.3 1.2 

SS 18.6 19.0 16.0 28 59 5.8 17.9 15.1 6.0 4.3 Stable At Risk 2.4 1.0 

SS 18.6 19.0 16.0 28 50 5.4 30.8 28.0 7.2 5.5 Stable Stable 2.9 1.3 

SS 18.6 19.0 16.0 28 60 6.6 17.0 14.2 5.9 4.2 At Risk At Risk 2.2 0.9 

PC-1 2 16.4 17.9 10.8 28 36 3.9 >50.0 >50.0 7.5 6.3 Stable Stable 4.6 1.9 

SS 17.3 18.5 12.4 29 39 3.7 >50.0 >50.0 7.5 6.1 Stable Stable 4.4 2.0 SS 17.3 18.5 12.4 29 20 2.9 >50.0 >50.0 15.6 14.2 Stable Stable 10.6 5.4 SS 17.3 18.5 12.4 29 32 3.7 >50.0 >50.0 9.4 8.1 Stable Stable 5.6 2.6 SS 17.3 18.5 12.4 29 38 3.9 >50.0 >50.0 7.7 6.4 Stable Stable 4.5 2.0 SS 17.3 18.5 12.4 29 34 4.5 >50.0 >50.0 8.7 7.3 Stable Stable 4.7 1.9 SS 17.3 18.5 12.4 29 33 4.2 >50.0 >50.0 9.0 7.7 Stable Stable 5.1 2.2 SS 17.3 18.5 12.4 29 36 3.7 >50.0 >50.0 8.3 6.9 Stable Stable 4.9 2.2 SS 17.3 18.5 12.4 29 41 4.0 >50.0 >50.0 7.2 5.9 Stable Stable 4.1 1.8 SS 17.3 18.5 12.4 29 47 3.9 40.7 38.3 6.2 4.9 Stable Stable 3.6 1.6 SS 17.3 18.5 12.4 29 31 3.9 >50.0 >50.0 9.8 8.4 Stable Stable 5.7 2.5 SS 17.3 18.5 12.4 29 35 4.4 >50.0 >50.0 8.4 7.1 Stable Stable 4.6 1.9 SS 17.3 18.5 12.4 29 34 3.6 >50.0 >50.0 8.8 7.5 Stable Stable 5.3 2.4 SS 17.3 18.5 12.4 29 34 3.8 >50.0 >50.0 8.8 7.4 Stable Stable 5.1 2.3 SS 17.3 18.5 12.4 29 46 3.9 42.6 40.2 6.3 4.9 Stable Stable 3.6 1.6 SS 17.3 18.5 12.4 29 33 3.9 >50.0 >50.0 9.2 7.8 Stable Stable 5.3 2.3 SS 17.3 18.5 12.4 29 37 4.2 >50.0 >50.0 8.1 6.7 Stable Stable 4.5 1.9 SS 17.3 18.5 12.4 29 34 4.4 >50.0 >50.0 8.6 7.3 Stable Stable 4.7 2.0 SS 17.3 18.5 12.4 29 46 4.1 43.1 40.6 6.3 5.0 Stable Stable 3.5 1.5 SS 17.3 18.5 12.4 29 30 3.8 >50.0 >50.0 9.9 8.5 Stable Stable 5.8 2.6 SS 17.3 18.5 12.4 29 35 3.8 >50.0 >50.0 8.6 7.2 Stable Stable 5.0 2.2 SS 17.3 18.5 12.4 29 28 3.2 >50.0 >50.0 10.7 9.4 Stable Stable 6.8 3.3 SS 17.3 18.5 12.4 29 41 4.6 >50.0 >50.0 7.2 5.9 Stable Stable 3.9 1.6 SS 17.3 18.5 12.4 29 25 3.2 >50.0 >50.0 11.9 10.5 Stable Stable 7.6 3.7 SS 17.3 18.5 12.4 29 51 4.5 27.9 25.4 5.6 4.3 Stable At Risk 3.0 1.2 SS 17.3 18.5 12.4 29 25 3.8 >50.0 >50.0 12.1 10.8 Stable Stable 7.2 3.2 SS 17.3 18.5 12.4 29 42 3.6 >50.0 >50.0 6.9 5.6 Stable Stable 4.1 1.9 SS 17.3 18.5 12.4 29 51 4.0 26.8 24.3 5.6 4.2 Stable Stable 3.2 1.4 SS 17.3 18.5 12.4 29 20 4.0 >50.0 >50.0 15.4 14.1 Stable Stable 8.8 3.8 SS 17.3 18.5 12.4 29 20 4.1 >50.0 >50.0 15.3 14.0 Stable Stable 8.7 3.8 SS 17.3 18.5 12.4 29 47 3.9 38.9 36.4 6.1 4.8 Stable Stable 3.5 1.6 SS 17.3 18.5 12.4 29 25 3.1 >50.0 >50.0 11.8 10.5 Stable Stable 7.8 3.8 SS 17.3 18.5 12.4 29 38 4.1 >50.0 >50.0 7.8 6.4 Stable Stable 4.4 1.9 SS 17.3 18.5 12.4 29 34 3.1 >50.0 >50.0 8.7 7.3 Stable Stable 5.7 2.8 SS 17.3 18.5 12.4 29 51 4.3 27.3 24.8 5.6 4.2 Stable At Risk 3.1 1.3 

Missouri River Tributary Basins--Continued

Papillion Creek Basin
66 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary re

Culmann method ARS meth

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued PC-2 2 16.4 17.9 10.8 28 42 5.1 >50.0 >50.0 6.3 5.1 Stable Stable 3.4 1.2 

SS 14.9 17.4 13.5 28 46 6.2 46.6 43.6 7.3 5.7 Stable At Risk 3.3 1.2 

SS 14.9 17.4 13.5 28 32 5.8 >50.0 >50.0 10.9 9.3 Stable Stable 5.1 1.9 

SS 14.9 17.4 13.5 28 83 4.4 7.4 4.4 3.5 2.0 At Risk At Risk 1.8 0.8 

SS 14.9 17.4 13.5 28 34 5.2 >50.0 >50.0 10.3 8.7 Stable Stable 5.1 2.0 SS 14.9 17.4 13.5 28 53 4.4 27.6 24.6 6.2 4.7 Stable Stable 3.3 1.4 

SS 14.9 17.4 13.5 28 34 6.0 >50.0 >50.0 10.0 8.5 Stable Stable 4.6 1.7 SS 14.9 17.4 13.5 28 25 3.3 >50.0 >50.0 14.1 12.5 Stable Stable 8.9 4.3 SS 14.9 17.4 13.5 28 40 5.7 >50.0 >50.0 8.5 6.9 Stable Stable 4.0 1.5 SS 14.9 17.4 13.5 28 33 3.6 >50.0 >50.0 10.4 8.8 Stable Stable 6.2 2.9 SS 14.9 17.4 13.5 28 43 5.3 >50.0 >50.0 7.8 6.2 Stable Stable 3.8 1.5 SS 14.9 17.4 13.5 28 34 4.5 >50.0 >50.0 10.2 8.7 Stable Stable 5.4 2.3 SS 14.9 17.4 13.5 28 37 5.5 >50.0 >50.0 9.2 7.6 Stable Stable 4.4 1.7 SS 14.9 17.4 13.5 28 26 5.3 >50.0 >50.0 13.5 12.0 Stable Stable 6.6 2.5 SS 14.9 17.4 13.5 28 49 5.7 35.8 32.8 6.8 5.2 Stable At Risk 3.2 1.2 SS 14.9 17.4 13.5 28 44 6.0 >50.0 >50.0 7.6 6.1 Stable Stable 3.5 1.3 SS 14.9 17.4 13.5 28 28 5.7 >50.0 >50.0 12.6 11.1 Stable Stable 6.0 2.2 SS 14.9 17.4 13.5 28 37 3.3 >50.0 >50.0 9.3 7.7 Stable Stable 5.8 2.8 SS 14.9 17.4 13.5 28 59 5.4 18.8 15.7 5.4 3.9 Stable At Risk 2.6 1.0 

SS 14.9 17.4 13.5 28 67 4.8 13.2 10.2 4.7 3.1 At Risk At Risk 2.4 1.0 

SS 14.9 17.4 13.5 28 29 5.5 >50.0 >50.0 12.0 10.5 Stable Stable 5.8 2.2 

PC-3 2 16.4 17.9 10.8 28 31 3.5 >50.0 >50.0 8.6 7.4 Stable Stable 5.6 2.5 

SS 17.2 18.3 12.3 23 38 4.0 >50.0 48.7 7.9 6.5 Stable Stable 4.2 2.0 SS 17.2 18.3 12.3 23 25 3.2 >50.0 >50.0 12.1 10.8 Stable Stable 7.2 3.8 

SS 17.2 18.3 12.3 23 23 3.9 >50.0 >50.0 13.0 11.6 Stable Stable 7.0 3.3 SS 17.2 18.3 12.3 23 24 3.5 >50.0 >50.0 12.8 11.5 Stable Stable 7.2 3.6 SS 17.2 18.3 12.3 23 27 3.2 >50.0 >50.0 11.2 9.9 Stable Stable 6.6 3.5 SS 17.2 18.3 12.3 23 51 2.9 18.2 16.0 5.7 4.3 Stable Stable 3.5 1.9 

PC-4 2 16.4 17.9 10.8 28 46 8.0 34.9 32.8 5.7 4.5 At Risk At Risk 2.6 0.7 

SS 14.2 17.5 11.5 36 52 8.0 >50.0 49.6 5.3 4.0 At Risk At Risk 2.8 0.7 SS 14.2 17.5 11.5 36 45 8.0 >50.0 >50.0 6.4 5.0 At Risk At Risk 3.4 0.8 SS 14.2 17.5 11.5 36 44 7.5 >50.0 >50.0 6.6 5.3 At Risk At Risk 3.6 0.9 SS 14.2 17.5 11.5 36 35 7.8 >50.0 >50.0 8.4 7.1 Stable At Risk 4.5 1.1 

SS 14.2 17.5 11.5 36 63 8.3 22.6 19.4 4.3 3.0 At Risk At Risk 2.2 0.5 

SS 14.2 17.5 11.5 36 36 8.3 >50.0 >50.0 8.1 6.8 At Risk At Risk 4.3 1.0 

PC-5 2 16.4 17.9 10.8 28 27 8.4 >50.0 >50.0 9.9 8.7 Stable Stable 4.5 1.2 

SS 17.7 18.6 14.5 25 35 8.7 >50.0 >50.0 9.9 8.4 Stable At Risk 3.5 1.1 SS 17.7 18.6 14.5 25 33 8.4 >50.0 >50.0 10.6 9.0 Stable Stable 3.7 1.3 SS 17.7 18.6 14.5 25 19 7.9 >50.0 >50.0 18.7 17.1 Stable Stable 6.8 2.4 SS 17.7 18.6 14.5 25 29 8.4 >50.0 >50.0 11.9 10.3 Stable Stable 4.2 1.4 SS 17.7 18.6 14.5 25 24 8.7 >50.0 >50.0 14.7 13.2 Stable Stable 5.1 1.7 SS 17.7 18.6 14.5 25 24 8.6 >50.0 >50.0 14.6 13.1 Stable Stable 5.1 1.7 

Papillion Creek Basin--Continued
Table 4 67

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued

PC-7 2 16.4 17.9 10.8 28 34 7.4 >50.0 >50.0 7.9 6.7 Stable At Risk 3.7 1.1 

SS 17.2 17.9 11.4 21 29 7.5 >50.0 >50.0 10.0 8.7 Stable Stable 3.9 1.3 SS 17.2 17.9 11.4 21 39 7.6 30.0 28.1 7.2 5.9 At Risk At Risk 2.8 0.9 

SS 17.2 17.9 11.4 21 29 7.4 >50.0 >50.0 9.9 8.6 Stable Stable 3.9 1.3 SS 17.2 17.9 11.4 21 29 7.4 >50.0 >50.0 10.0 8.7 Stable Stable 3.9 1.3 SS 17.2 17.9 11.4 21 37 7.5 36.1 34.2 7.6 6.3 Stable At Risk 3.0 1.0 

SS 17.2 17.9 11.4 21 41 7.1 25.5 23.6 6.8 5.5 At Risk At Risk 2.7 1.0 

PC-8 2 16.4 17.9 10.8 28 44 7.5 41.8 39.7 6.0 4.8 At Risk At Risk 2.8 0.8 

SS 17.9 18.3 7.6 26 46 7.8 17.7 16.3 3.9 3.0 At Risk At Risk 2.2 0.5 SS 17.9 18.3 7.6 26 40 7.6 34.0 32.6 4.6 3.8 At Risk At Risk 2.6 0.6 SS 17.9 18.3 7.6 26 37 8.0 >50.0 48.9 5.0 4.1 At Risk At Risk 2.8 0.6 SS 17.9 18.3 7.6 26 45 7.8 19.3 18.0 4.0 3.1 At Risk At Risk 2.2 0.5 SS 17.9 18.3 7.6 26 36 8.1 >50.0 >50.0 5.2 4.3 At Risk At Risk 2.9 0.6 SS 17.9 18.3 7.6 26 45 7.1 20.3 18.9 4.0 3.2 At Risk At Risk 2.3 0.6 SS 17.9 18.3 7.6 26 58 7.9 8.6 7.3 3.0 2.2 At Risk Unstable 1.7 0.4 

SS 17.9 18.3 7.6 26 44 7.5 20.7 19.3 4.1 3.2 At Risk At Risk 2.3 0.5 

SS 17.9 18.3 7.6 26 40 7.0 31.3 30.0 4.5 3.7 At Risk At Risk 2.6 0.6 SS 17.9 18.3 7.6 26 47 6.2 16.4 15.0 3.8 3.0 At Risk At Risk 2.2 0.6 

PC-9 2 16.4 17.9 10.8 28 38 3.7 >50.0 >50.0 7.0 5.8 Stable Stable 4.4 1.9 

SS 15.8 17.4 24.0 22 40 4.0 >50.0 >50.0 15.2 12.5 Stable Stable 6.2 3.8 SS 15.8 17.4 24.0 22 26 3.6 >50.0 >50.0 23.9 21.1 Stable Stable 10.5 6.7 SS 15.8 17.4 24.0 22 25 3.5 >50.0 >50.0 24.9 22.1 Stable Stable 11.1 7.1 SS 15.8 17.4 24.0 22 61 4.0 22.3 17.8 9.4 6.7 Stable Stable 3.8 2.4 SS 15.8 17.4 24.0 22 39 3.7 >50.0 >50.0 15.4 12.7 Stable Stable 6.6 4.2 SS 15.8 17.4 24.0 22 38 3.7 >50.0 >50.0 16.0 13.2 Stable Stable 6.8 4.3 

PC-10 2 16.4 17.9 10.8 28 34 3.8 >50.0 >50.0 7.9 6.7 Stable Stable 4.9 2.1 

SS 17.2 18.2 9.2 26 27 3.7 >50.0 >50.0 8.3 7.3 Stable Stable 5.4 2.3 SS 17.2 18.2 9.2 26 42 3.5 34.9 33.2 5.3 4.3 Stable Stable 3.6 1.5 SS 17.2 18.2 9.2 26 43 3.4 31.3 29.6 5.2 4.2 Stable Stable 3.5 1.5 SS 17.2 18.2 9.2 26 21 3.6 >50.0 >50.0 11.0 10.0 Stable Stable 7.3 3.0 SS 17.2 18.2 9.2 26 36 4.3 >50.0 >50.0 6.2 5.2 Stable Stable 3.8 1.4 SS 17.2 18.2 9.2 26 34 4.3 >50.0 >50.0 6.5 5.5 Stable Stable 4.0 1.5 

PC-11 2 16.4 17.9 10.8 28 38 6.1 >50.0 >50.0 7.0 5.8 Stable At Risk 3.5 1.1 

SS 18.5 19.3 8.9 24 39 5.6 32.1 30.6 5.2 4.3 At Risk At Risk 2.9 0.9 

SS 18.5 19.3 8.9 24 34 6.7 >50.0 >50.0 6.0 5.0 At Risk At Risk 3.1 0.9 SS 18.5 19.3 8.9 24 28 5.5 >50.0 >50.0 7.3 6.4 Stable Stable 4.1 1.3 SS 18.5 19.3 8.9 24 51 6.8 12.5 11.1 3.9 3.0 At Risk At Risk 2.0 0.6 SS 18.5 19.3 8.9 24 38 5.6 36.0 34.6 5.4 4.5 At Risk At Risk 3.0 1.0 SS 18.5 19.3 8.9 24 39 6.6 32.7 31.3 5.3 4.3 At Risk At Risk 2.7 0.8 

Papillion Creek Basin--Continued
68 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued PC-12 2 16.4 17.9 10.8 28 38 5.2 >50.0 >50.0 7.1 5.9 Stable Stable 3.8 1.4 

SS 15.8 17.1 4.5 29 36 4.9 >50.0 >50.0 3.2 2.7 At Risk At Risk 3.2 0.7 

SS 15.8 17.1 4.5 29 37 5.1 >50.0 >50.0 3.2 2.7 At Risk At Risk 3.1 0.6 SS 15.8 17.1 4.5 29 34 5.3 >50.0 >50.0 3.4 2.9 At Risk At Risk 3.3 0.7 SS 15.8 17.1 4.5 29 40 5.2 32.1 31.1 2.9 2.3 At Risk At Risk 2.8 0.5 SS 15.8 17.1 4.5 29 34 4.9 >50.0 >50.0 3.4 2.9 At Risk At Risk 3.4 0.7 SS 15.8 17.1 4.5 29 47 5.3 14.4 13.4 2.4 1.9 At Risk At Risk 2.3 0.5 SS 15.8 17.1 4.5 29 34 5.0 >50.0 >50.0 3.5 2.9 At Risk At Risk 3.4 0.7 SS 15.8 17.1 4.5 29 39 5.4 39.4 38.4 3.0 2.4 At Risk At Risk 2.8 0.5 

PRT-1 2 16.4 17.9 10.8 28 38 4.9 >50.0 >50.0 7.1 5.9 Stable Stable 3.9 1.5 

2* 16.4 17.9 10.8 28 46 4.0 32.4 30.2 5.6 4.4 Stable Stable 3.4 1.4 2* 16.4 17.9 10.8 28 32 4.2 >50.0 >50.0 8.5 7.3 Stable Stable 5.0 2.0 2* 16.4 17.9 10.8 28 44 5.4 41.6 39.4 6.0 4.8 Stable At Risk 3.2 1.1 

2* 16.4 17.9 10.8 28 34 4.5 >50.0 >50.0 7.9 6.7 Stable Stable 4.5 1.8 

2* 16.4 17.9 10.8 28 40 5.9 >50.0 >50.0 6.7 5.5 Stable At Risk 3.4 1.1 2* 16.4 17.9 10.8 28 31 5.1 >50.0 >50.0 8.8 7.6 Stable Stable 4.8 1.7 

PRT-2 2 16.4 17.9 10.8 28 37 5.4 >50.0 >50.0 7.3 6.1 Stable Stable 3.9 1.3 

SS 14.0 17.6 12.3 31 38 4.6 >50.0 >50.0 8.1 6.7 Stable Stable 4.9 1.8 SS 14.0 17.6 12.3 31 28 6.0 >50.0 >50.0 11.2 9.8 Stable Stable 5.9 1.8 SS 14.0 17.6 12.3 31 46 4.3 >50.0 >50.0 6.6 5.2 Stable Stable 4.1 1.5 SS 14.0 17.6 12.3 31 35 6.7 >50.0 >50.0 9.0 7.6 Stable Stable 4.6 1.3 

PRT-3 2 16.4 17.9 10.8 28 40 3.0 >50.0 >50.0 6.7 5.5 Stable Stable 4.7 2.3 

2* 16.4 17.9 10.8 28 40 3.0 >50.0 >50.0 6.6 5.4 Stable Stable 4.6 2.2 2* 16.4 17.9 10.8 28 43 3.0 45.1 42.9 6.1 4.9 Stable Stable 4.3 2.1 2* 16.4 17.9 10.8 28 34 2.9 >50.0 >50.0 7.8 6.6 Stable Stable 5.5 2.7 2* 16.4 17.9 10.8 28 35 2.9 >50.0 >50.0 7.6 6.4 Stable Stable 5.4 2.6 2* 16.4 17.9 10.8 28 50 2.9 24.0 21.8 5.2 3.9 Stable Stable 3.6 1.8 2* 16.4 17.9 10.8 28 30 3.0 >50.0 >50.0 9.1 7.9 Stable Stable 6.4 3.1 2* 16.4 17.9 10.8 28 40 3.0 >50.0 >50.0 6.7 5.5 Stable Stable 4.6 2.2 2* 16.4 17.9 10.8 28 44 3.0 43.0 40.8 6.0 4.8 Stable Stable 4.2 2.0 

PRT-4 2 16.4 17.9 10.8 28 45 3.1 38.5 36.3 5.9 4.7 Stable Stable 4.0 1.9 

SS 17.9 18.6 4.2 28 51 2.6 8.1 7.3 1.9 1.5 At Risk At Risk 2.3 0.7 

SS 17.9 18.6 4.2 28 44 2.7 14.4 13.6 2.3 1.8 At Risk At Risk 2.7 0.8 SS 17.9 18.6 4.2 28 50 3.1 8.3 7.5 1.9 1.5 At Risk At Risk 2.2 0.6 SS 17.9 18.6 4.2 28 40 3.2 22.5 21.8 2.5 2.0 At Risk At Risk 2.8 0.8 SS 17.9 18.6 4.2 28 39 3.2 28.0 27.3 2.6 2.1 At Risk At Risk 3.0 0.8 SS 17.9 18.6 4.2 28 43 3.3 15.6 14.8 2.3 1.8 At Risk At Risk 2.6 0.7 SS 17.9 18.6 4.2 28 46 3.0 11.6 10.9 2.1 1.7 At Risk At Risk 2.5 0.7 SS 17.9 18.6 4.2 28 45 3.3 12.3 11.6 2.2 1.7 At Risk At Risk 2.5 0.7 

Papillion Creek Basin--Continued

Platte River Tributary Basins
Table 4 69

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued

PRT-5 3 16.5 18.1 6.7 30 53 9.1 14.2 12.8 2.9 2.2 At Risk At Risk 1.9 0.3 

SS 15.2 18.3 7.1 30 43 8.3 45.9 44.3 4.0 3.2 At Risk At Risk 2.7 0.5 

SS 15.2 18.3 7.1 30 58 9.8 11.9 10.2 2.8 2.0 At Risk At Risk 1.8 0.3 

SS 15.2 18.3 7.1 30 39 9.1 >50.0 >50.0 4.3 3.6 At Risk At Risk 2.9 0.5 

SS 15.2 18.3 7.1 30 60 9.5 10.4 8.8 2.7 1.9 At Risk Unstable 1.7 0.3 

SS 15.2 18.3 7.1 30 61 9.0 10.2 8.6 2.7 1.9 At Risk Unstable 1.8 0.3 SS 15.2 18.3 7.1 30 58 8.9 11.6 10.0 2.8 2.0 At Risk At Risk 1.8 0.3 

PRT-6 3 16.5 18.1 6.7 30 38 5.9 >50.0 >50.0 4.3 3.6 At Risk At Risk 3.2 0.7 

SS 17.2 18.5 15.8 29 27 4.9 >50.0 >50.0 14.0 12.3 Stable Stable 6.4 2.9 SS 17.2 18.5 15.8 29 41 7.8 >50.0 >50.0 9.1 7.4 Stable At Risk 3.4 1.2 

SS 17.2 18.5 15.8 29 30 4.6 >50.0 >50.0 12.9 11.2 Stable Stable 6.1 2.8 SS 17.2 18.5 15.8 29 46 6.6 >50.0 >50.0 8.1 6.3 Stable At Risk 3.2 1.2 SS 17.2 18.5 15.8 29 30 5.0 >50.0 >50.0 12.8 11.1 Stable Stable 5.8 2.6 SS 17.2 18.5 15.8 29 51 6.4 34.2 31.0 7.1 5.4 Stable At Risk 2.9 1.1 

PRT-7 1 15.9 17.6 13.6 26 54 6.1 21.3 18.6 6.1 4.5 At Risk At Risk 2.6 1.0 

SS 15.4 17.8 12.8 30 54 6.2 26.6 23.8 5.7 4.3 At Risk At Risk 2.7 0.9 

SS 15.4 17.8 12.8 30 58 6.2 20.8 18.0 5.2 3.8 At Risk At Risk 2.5 0.8 SS 15.4 17.8 12.8 30 52 6.0 29.3 26.4 5.9 4.4 At Risk At Risk 2.8 1.0 SS 15.4 17.8 12.8 30 49 6.0 39.6 36.7 6.4 4.9 Stable At Risk 3.1 1.1 

SS 15.4 17.8 12.8 30 58 6.2 20.7 17.8 5.2 3.8 At Risk At Risk 2.5 0.8 

SS 15.4 17.8 12.8 30 54 5.9 26.1 23.3 5.7 4.2 At Risk At Risk 2.7 1.0 

PRT-8 1 15.9 17.6 13.6 26 39 4.0 >50.0 >50.0 8.7 7.2 Stable Stable 4.6 2.2 

SS 16.4 18.0 16.9 25 39 3.7 >50.0 >50.0 10.5 8.7 Stable Stable 5.2 2.8 SS 16.4 18.0 16.9 25 35 4.5 >50.0 >50.0 11.9 10.0 Stable Stable 5.2 2.6 SS 16.4 18.0 16.9 25 42 3.6 >50.0 >50.0 9.7 7.9 Stable Stable 4.9 2.7 SS 16.4 18.0 16.9 25 39 4.1 >50.0 >50.0 10.5 8.7 Stable Stable 5.0 2.6 

PRT-9 2 16.4 17.9 10.8 28 51 6.1 22.0 19.8 5.0 3.8 At Risk At Risk 2.5 0.8 

SS 15.9 17.7 4.5 33 53 6.1 12.3 11.3 2.0 1.5 At Risk At Risk 2.1 0.3 SS 15.9 17.7 4.5 33 56 6.1 9.6 8.5 1.9 1.4 At Risk At Risk 1.9 0.3 

SS 15.9 17.7 4.5 33 43 5.8 46.2 45.1 2.6 2.1 At Risk At Risk 2.7 0.5 

SS 15.9 17.7 4.5 33 53 6.3 12.5 11.4 2.0 1.5 At Risk At Risk 2.1 0.3 

PRT-10 2 16.4 17.9 10.8 28 34 6.2 >50.0 >50.0 7.9 6.7 Stable Stable 4.0 1.3 

SS 17.0 18.3 6.5 29 24 6.4 >50.0 >50.0 6.7 6.0 Stable At Risk 4.9 1.1 SS 17.0 18.3 6.5 29 38 6.7 >50.0 >50.0 4.1 3.4 At Risk At Risk 2.9 0.6 

SS 17.0 18.3 6.5 29 43 6.4 29.9 28.6 3.6 2.9 At Risk At Risk 2.6 0.6 SS 17.0 18.3 6.5 29 31 5.5 >50.0 >50.0 5.1 4.4 At Risk At Risk 3.8 0.9 

PRT-11 2 16.4 17.9 10.8 28 42 6.0 >50.0 47.9 6.2 5.0 Stable At Risk 3.2 1.0 

SS 17.2 17.8 14.0 22 61 5.5 11.8 9.4 5.4 3.8 At Risk At Risk 2.1 1.0 

SS 17.2 17.8 14.0 22 31 5.3 >50.0 >50.0 11.3 9.7 Stable Stable 4.6 2.1 

SS 17.2 17.8 14.0 22 28 8.2 >50.0 >50.0 12.4 10.8 Stable Stable 4.2 1.5 SS 17.2 17.8 14.0 22 49 5.1 20.4 18.0 6.9 5.3 Stable Stable 2.9 1.4 

Platte River Tributary Basins--Continued
70 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued PRT-12 2 16.4 17.9 10.8 28 44 6.6 42.3 40.2 6.0 4.8 At Risk At Risk 2.9 0.9 

SS 17.6 18.3 4.7 25 37 6.8 24.7 23.9 3.1 2.5 At Risk At Risk 2.5 0.5 SS 17.6 18.3 4.7 25 47 6.4 9.3 8.5 2.4 1.8 At Risk At Risk 2.0 0.4 

SS 17.6 18.3 4.7 25 47 6.7 9.3 8.5 2.4 1.8 At Risk At Risk 1.9 0.4 SS 17.6 18.3 4.7 25 38 6.5 21.3 20.5 3.0 2.4 At Risk At Risk 2.5 0.5 

SS 17.6 18.3 4.7 25 51 6.6 7.3 6.5 2.2 1.6 At Risk Unstable 1.8 0.3 

SS 17.6 18.3 4.7 25 42 6.8 14.2 13.4 2.7 2.2 At Risk At Risk 2.2 0.4 

PRT-13 2 16.4 17.9 10.8 28 48 5.2 29.3 27.1 5.5 4.3 Stable At Risk 2.9 1.1 

SS 15.7 17.2 6.0 25 50 5.1 11.6 10.4 3.0 2.3 At Risk At Risk 2.2 0.6 

SS 15.7 17.2 6.0 25 57 5.4 7.8 6.6 2.6 1.9 At Risk At Risk 1.9 0.5 

SS 15.7 17.2 6.0 25 39 5.2 29.2 28.0 3.9 3.2 At Risk At Risk 2.9 0.8 

SS 15.7 17.2 6.0 25 56 5.3 8.0 6.8 2.6 1.9 At Risk At Risk 1.9 0.5 

SS 15.7 17.2 6.0 25 41 5.0 24.3 23.1 3.8 3.1 At Risk At Risk 2.8 0.7 

SS 15.7 17.2 6.0 25 44 4.9 18.4 17.2 3.5 2.8 At Risk At Risk 2.6 0.7 

ER-3 3 16.5 18.1 6.7 30 40 4.6 >50.0 >50.0 4.0 3.3 At Risk At Risk 3.2 0.9 

SS 17.1 19.5 4.2 34 41 3.1 >50.0 >50.0 2.3 1.9 At Risk At Risk 3.2 0.8 SS 17.1 19.5 4.2 34 40 6.2 >50.0 >50.0 2.4 1.9 At Risk At Risk 2.8 0.4 

ER-4 2 16.4 17.9 10.8 28 42 2.6 >50.0 >50.0 6.4 5.1 Stable Stable 4.8 2.4 

SS 16.3 17.8 17.0 25 36 2.3 >50.0 >50.0 11.9 10.0 Stable Stable 8.0 5.2 

SS 16.3 17.8 17.0 25 39 2.5 >50.0 >50.0 10.8 8.9 Stable Stable 6.9 4.4 SS 16.3 17.8 17.0 25 30 2.5 >50.0 >50.0 14.1 12.2 Stable Stable 9.0 5.7 SS 16.3 17.8 17.0 25 45 2.9 45.5 42.2 9.3 7.4 Stable Stable 5.4 3.3 SS 16.3 17.8 17.0 25 55 2.4 22.6 19.3 7.3 5.4 Stable Stable 4.8 3.0 SS 16.3 17.8 17.0 25 44 3.1 46.9 43.6 9.4 7.5 Stable Stable 5.2 3.0 

ER-5 2 16.4 17.9 10.8 28 45 5.8 38.3 36.1 5.9 4.7 Stable At Risk 3.0 1.0 

SS 13.8 17.2 19.4 28 64 5.2 23.4 18.6 7.2 4.9 Stable At Risk 3.1 1.4 

SS 13.8 17.2 19.4 28 38 4.7 >50.0 >50.0 13.0 10.7 Stable Stable 6.0 2.8 SS 13.8 17.2 19.4 28 53 6.4 43.6 38.8 9.1 6.8 Stable Stable 3.5 1.4 SS 13.8 17.2 19.4 28 35 5.6 >50.0 >50.0 14.2 11.9 Stable Stable 5.9 2.5 SS 13.8 17.2 19.4 28 43 5.9 >50.0 >50.0 11.6 9.3 Stable Stable 4.7 1.9 SS 13.8 17.2 19.4 28 34 6.7 >50.0 >50.0 14.7 12.4 Stable Stable 5.6 2.2 

ER-6 4 16.5 18.1 6.7 30 41 2.4 >50.0 >50.0 3.9 3.2 Stable Stable 4.0 1.6 

4* 16.5 18.1 6.7 30 33 2.8 >50.0 >50.0 5.0 4.3 Stable Stable 4.8 1.8 4* 16.5 18.1 6.7 30 44 1.7 32.7 31.3 3.6 2.9 Stable Stable 4.4 2.1 4* 16.5 18.1 6.7 30 31 3.4 >50.0 >50.0 5.3 4.6 Stable Stable 4.7 1.6 4* 16.5 18.1 6.7 30 54 1.6 13.4 11.9 2.9 2.2 Stable Stable 3.6 1.8 4* 16.5 18.1 6.7 30 38 3.5 >50.0 >50.0 4.3 3.5 Stable Stable 3.7 1.2 4* 16.5 18.1 6.7 30 47 1.6 24.9 23.4 3.4 2.7 Stable Stable 4.2 2.1 4* 16.5 18.1 6.7 30 38 3.3 >50.0 >50.0 4.3 3.5 Stable Stable 3.8 1.3 4* 16.5 18.1 6.7 30 44 1.5 36.8 35.4 3.7 3.0 Stable Stable 4.8 2.4 

Platte River Tributary Basins--Continued

Elkhorn River Basin
Table 4 71

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued

ER-7 2 16.4 17.9 10.8 28 34 4.5 >50.0 >50.0 7.8 6.6 Stable Stable 4.4 1.7 

SS 15.1 18.0 9.1 33 37 5.1 >50.0 >50.0 6.0 5.0 Stable At Risk 4.1 1.2 

SS 15.1 18.0 9.1 33 32 4.0 >50.0 >50.0 7.1 6.1 Stable Stable 5.4 1.8 

ER-8 4 16.5 18.1 6.7 30 39 4.9 >50.0 >50.0 4.1 3.4 At Risk At Risk 3.2 0.8 

4* 16.5 18.1 6.7 30 42 5.1 48.0 46.6 3.9 3.1 At Risk At Risk 3.0 0.8 4* 16.5 18.1 6.7 30 40 5.3 >50.0 >50.0 4.0 3.3 At Risk At Risk 3.1 0.8 4* 16.5 18.1 6.7 30 35 4.4 >50.0 >50.0 4.8 4.0 Stable At Risk 3.8 1.1 

4* 16.5 18.1 6.7 30 44 5.1 34.6 33.1 3.7 2.9 At Risk At Risk 2.8 0.7 

4* 16.5 18.1 6.7 30 39 4.5 >50.0 >50.0 4.1 3.4 At Risk At Risk 3.3 0.9 4* 16.5 18.1 6.7 30 36 4.9 >50.0 >50.0 4.5 3.8 At Risk At Risk 3.5 0.9 

ER-9 2 16.4 17.9 10.8 28 37 5.1 >50.0 >50.0 7.3 6.1 Stable Stable 4.0 1.4 

SS 14.5 17.1 9.5 32 31 5.4 >50.0 >50.0 8.1 7.0 Stable Stable 5.1 1.5 SS 14.5 17.1 9.5 32 43 5.2 >50.0 >50.0 5.7 4.6 Stable At Risk 3.6 1.1 

SS 14.5 17.1 9.5 32 31 5.3 >50.0 >50.0 7.9 6.8 Stable Stable 5.0 1.5 

SS 14.5 17.1 9.5 32 38 4.4 >50.0 >50.0 6.5 5.4 Stable Stable 4.4 1.5 SS 14.5 17.1 9.5 32 32 5.1 >50.0 >50.0 7.7 6.6 Stable Stable 4.9 1.5 SS 14.5 17.1 9.5 32 43 4.6 >50.0 >50.0 5.6 4.5 Stable At Risk 3.8 1.2 SS 14.5 17.1 9.5 32 32 5.7 >50.0 >50.0 7.7 6.5 Stable Stable 4.7 1.3 SS 14.5 17.1 9.5 32 43 4.9 >50.0 >50.0 5.7 4.6 Stable At Risk 3.7 1.1 

ER-10 2 16.4 17.9 10.8 28 41 2.5 >50.0 >50.0 6.5 5.3 Stable Stable 5.1 2.6 

SS 17.2 18.2 12.5 27 36 2.1 >50.0 >50.0 8.5 7.1 Stable Stable 6.8 4.1 SS 17.2 18.2 12.5 27 41 1.8 >50.0 >50.0 7.3 6.0 Stable Stable 6.5 4.2 SS 17.2 18.2 12.5 27 44 2.6 37.8 35.4 6.7 5.3 Stable Stable 4.6 2.6 SS 17.2 18.2 12.5 27 44 3.1 37.9 35.6 6.7 5.3 Stable Stable 4.2 2.2 SS 17.2 18.2 12.5 27 40 2.7 >50.0 >50.0 7.6 6.2 Stable Stable 5.1 2.8 SS 17.2 18.2 12.5 27 38 2.6 >50.0 >50.0 7.9 6.5 Stable Stable 5.5 3.1 

ER-11 2 16.4 17.9 10.8 28 24 0.6 >50.0 >50.0 11.3 10.1 Stable Stable 23.2 17.7 

SS 17.7 18.8 14.6 28 17 0.6 >50.0 >50.0 20.3 18.7 Stable Stable 42.4 35.0 SS 17.7 18.8 14.6 28 19 0.8 >50.0 >50.0 18.4 16.9 Stable Stable 30.8 24.6 SS 17.7 18.8 14.6 28 15 0.6 >50.0 >50.0 23.0 21.4 Stable Stable 45.9 37.7 SS 17.7 18.8 14.6 28 26 0.5 >50.0 >50.0 13.6 12.0 Stable Stable 33.9 28.6 SS 17.7 18.8 14.6 28 32 0.5 >50.0 >50.0 10.9 9.4 Stable Stable 26.1 22.0 SS 17.7 18.8 14.6 28 31 0.4 >50.0 >50.0 11.4 9.8 Stable Stable 33.9 29.2 SS 17.7 18.8 14.6 28 26 0.8 >50.0 >50.0 13.7 12.1 Stable Stable 21.4 16.9 SS 17.7 18.8 14.6 28 28 1.0 >50.0 >50.0 12.6 11.1 Stable Stable 16.9 12.8 

ER-12 2 16.4 17.9 10.8 28 42 6.9 >50.0 48.7 6.3 5.1 At Risk At Risk 3.0 0.9 

SS 18.7 19.1 10.3 27 30 7.1 >50.0 >50.0 8.0 6.9 Stable At Risk 3.8 1.1 

SS 18.7 19.1 10.3 27 48 6.6 20.4 18.7 4.8 3.7 At Risk At Risk 2.3 0.7 

SS 18.7 19.1 10.3 27 30 6.6 >50.0 >50.0 8.0 6.9 Stable Stable 3.9 1.2 

SS 18.7 19.1 10.3 27 48 7.0 21.7 20.0 4.9 3.8 At Risk At Risk 2.3 0.7 

SS 18.7 19.1 10.3 27 42 7.2 37.3 35.6 5.7 4.6 At Risk At Risk 2.7 0.8 SS 18.7 19.1 10.3 27 55 7.0 13.3 11.5 4.1 3.1 At Risk At Risk 2.0 0.6 

Elkhorn River Basin--Continued
72 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued ER-13 2 16.4 17.9 10.8 28 39 6.0 >50.0 >50.0 6.8 5.6 Stable At Risk 3.5 1.1 

SS 15.0 17.8 23.4 29 42 7.3 >50.0 >50.0 13.7 11.1 Stable Stable 4.5 1.9 SS 15.0 17.8 23.4 29 31 5.4 >50.0 >50.0 19.0 16.3 Stable Stable 7.3 3.5 SS 15.0 17.8 23.4 29 44 5.5 >50.0 >50.0 13.1 10.4 Stable Stable 5.0 2.4 SS 15.0 17.8 23.4 29 34 5.4 >50.0 >50.0 17.3 14.7 Stable Stable 6.7 3.2 SS 15.0 17.8 23.4 29 50 6.8 >50.0 >50.0 11.2 8.6 Stable Stable 3.8 1.6 SS 15.0 17.8 23.4 29 33 5.4 >50.0 >50.0 17.7 15.1 Stable Stable 6.8 3.3 

ER-14 2 16.4 17.9 10.8 28 37 5.1 >50.0 >50.0 7.3 6.1 Stable Stable 4.0 1.4 

SS 17.5 19.3 14.2 27 40 5.8 >50.0 >50.0 8.2 6.7 Stable Stable 3.6 1.4 SS 17.5 19.3 14.2 27 30 4.4 >50.0 >50.0 10.9 9.4 Stable Stable 5.6 2.5 SS 17.5 19.3 14.2 27 40 4.3 >50.0 >50.0 8.0 6.6 Stable Stable 4.1 1.9 SS 17.5 19.3 14.2 27 37 5.7 >50.0 >50.0 8.9 7.4 Stable Stable 4.0 1.6 

ER-15 2 16.4 17.9 10.8 28 40 4.9 >50.0 >50.0 6.6 5.4 Stable Stable 3.6 1.3 

SS 17.0 18.6 16.7 11 34 5.5 26.7 24.4 11.8 10.0 Stable Stable 4.0 2.2 SS 17.0 18.6 16.7 11 46 4.8 15.1 12.8 8.5 6.7 Stable Stable 3.1 1.8 SS 17.0 18.6 16.7 11 36 4.6 23.9 21.5 11.1 9.3 Stable Stable 4.2 2.4 SS 17.0 18.6 16.7 11 45 5.1 15.7 13.3 8.7 6.9 Stable Stable 3.0 1.7 SS 17.0 18.6 16.7 11 26 4.7 45.8 43.4 15.3 13.5 Stable Stable 5.6 3.2 SS 17.0 18.6 16.7 11 40 5.2 19.0 16.7 9.8 8.0 Stable Stable 3.4 1.9 SS 17.0 18.6 16.7 11 38 4.6 21.0 18.7 10.4 8.6 Stable Stable 3.9 2.2 SS 17.0 18.6 16.7 11 57 4.8 10.6 8.2 6.7 4.9 Stable Stable 2.4 1.4 

ER-16 2 16.4 17.9 10.8 28 43 4.3 44.8 42.6 6.1 4.9 Stable Stable 3.5 1.4 

SS 14.7 17.1 4.7 35 41 4.4 >50.0 >50.0 3.0 2.4 At Risk At Risk 3.3 0.7 

SS 14.7 17.1 4.7 35 50 3.9 24.8 23.5 2.4 1.8 At Risk At Risk 2.8 0.6 SS 14.7 17.1 4.7 35 49 4.7 25.6 24.4 2.4 1.8 At Risk At Risk 2.6 0.5 SS 14.7 17.1 4.7 35 33 4.3 >50.0 >50.0 3.7 3.1 At Risk At Risk 4.2 0.8 

ER-17 2 16.4 17.9 10.8 28 37 4.6 >50.0 >50.0 7.2 6.0 Stable Stable 4.1 1.6 

SS 15.2 18.1 11.0 28 33 4.9 >50.0 >50.0 8.2 7.0 Stable Stable 4.8 1.7 

SS 15.2 18.1 11.0 28 44 4.4 46.6 44.2 6.0 4.8 Stable Stable 3.7 1.4 SS 15.2 18.1 11.0 28 36 4.7 >50.0 >50.0 7.4 6.2 Stable Stable 4.4 1.6 SS 15.2 18.1 11.0 28 36 4.4 >50.0 >50.0 7.5 6.3 Stable Stable 4.6 1.7 SS 15.2 18.1 11.0 28 43 4.6 >50.0 48.8 6.1 4.9 Stable Stable 3.7 1.3 SS 15.2 18.1 11.0 28 30 4.5 >50.0 >50.0 9.1 7.9 Stable Stable 5.6 2.0 

ER-18 2 16.4 17.9 10.8 28 40 3.9 >50.0 >50.0 6.6 5.4 Stable Stable 4.0 1.7 

SS 16.3 17.3 3.2 31 41 3.7 28.0 27.3 2.0 1.6 At Risk At Risk 2.8 0.5 

SS 16.3 17.3 3.2 31 44 3.8 17.6 16.9 1.8 1.5 At Risk At Risk 2.5 0.5 SS 16.3 17.3 3.2 31 34 3.5 >50.0 >50.0 2.4 2.0 At Risk At Risk 3.4 0.7 SS 16.3 17.3 3.2 31 34 3.7 >50.0 >50.0 2.4 2.1 At Risk At Risk 3.4 0.7 SS 16.3 17.3 3.2 31 38 4.4 >50.0 >50.0 2.2 1.8 At Risk At Risk 2.9 0.5 SS 16.3 17.3 3.2 31 48 4.3 11.0 10.3 1.7 1.3 At Risk At Risk 2.2 0.4 

Elkhorn River Basin--Continued
Table 4 73

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued

ER-19 2 16.4 17.9 10.8 28 38 4.7 >50.0 >50.0 7.0 5.8 Stable Stable 3.9 1.5 

SS 14.5 17.6 5.0 30 34 4.0 >50.0 >50.0 3.7 3.1 At Risk At Risk 3.9 0.9 

SS 14.5 17.6 5.0 30 42 4.9 40.7 39.5 3.0 2.4 At Risk At Risk 3.0 0.6 SS 14.5 17.6 5.0 30 29 5.0 >50.0 >50.0 4.3 3.8 At Risk At Risk 4.4 0.9 SS 14.5 17.6 5.0 30 47 5.1 19.7 18.5 2.6 2.0 At Risk At Risk 2.6 0.5 

ER-20 2 16.4 17.9 10.8 28 40 3.7 >50.0 >50.0 6.6 5.4 Stable Stable 4.2 1.8 

SS 17.5 18.7 17.3 22 39 3.6 >50.0 48.0 10.4 8.5 Stable Stable 4.9 2.8 SS 17.5 18.7 17.3 22 44 3.5 34.1 31.2 9.1 7.3 Stable Stable 4.4 2.6 SS 17.5 18.7 17.3 22 36 3.8 >50.0 >50.0 11.3 9.4 Stable Stable 5.2 3.0 SS 17.5 18.7 17.3 22 24 3.4 >50.0 >50.0 17.3 15.4 Stable Stable 8.7 5.1 SS 17.5 18.7 17.3 22 49 3.5 24.7 21.8 8.1 6.2 Stable Stable 3.9 2.3 SS 17.5 18.7 17.3 22 47 4.1 28.0 25.1 8.5 6.6 Stable Stable 3.8 2.1 

ER-21 2 16.4 17.9 10.8 28 43 3.1 46.7 44.5 6.1 4.9 Stable Stable 4.2 2.0 

2* 16.4 17.9 10.8 28 34 2.8 >50.0 >50.0 7.9 6.7 Stable Stable 5.7 2.8 2* 16.4 17.9 10.8 28 28 3.7 >50.0 >50.0 9.5 8.3 Stable Stable 6.0 2.6 

2* 16.4 17.9 10.8 28 55 2.5 17.5 15.3 4.7 3.4 Stable Stable 3.6 1.9 2* 16.4 17.9 10.8 28 54 3.4 18.3 16.1 4.7 3.5 Stable Stable 3.1 1.4 2* 16.4 17.9 10.8 28 49 2.9 25.7 23.5 5.3 4.1 Stable Stable 3.7 1.8 2* 16.4 17.9 10.8 28 42 4.2 50.0 47.8 6.2 5.0 Stable Stable 3.7 1.5 2* 16.4 17.9 10.8 28 40 2.8 >50.0 >50.0 6.6 5.4 Stable Stable 4.8 2.4 2* 16.4 17.9 10.8 28 53 3.0 19.6 17.4 4.8 3.6 Stable Stable 3.4 1.6 2* 16.4 17.9 10.8 28 30 2.8 >50.0 >50.0 8.9 7.7 Stable Stable 6.5 3.2 2* 16.4 17.9 10.8 28 30 2.9 >50.0 >50.0 9.1 7.9 Stable Stable 6.4 3.1 2* 16.4 17.9 10.8 28 44 2.8 40.2 38.0 5.9 4.7 Stable Stable 4.3 2.1 2* 16.4 17.9 10.8 28 31 3.0 >50.0 >50.0 8.8 7.6 Stable Stable 6.1 2.9 2* 16.4 17.9 10.8 28 42 3.1 49.5 47.3 6.2 5.0 Stable Stable 4.3 2.0 2* 16.4 17.9 10.8 28 52 3.4 21.4 19.2 5.0 3.8 Stable Stable 3.2 1.4 2* 16.4 17.9 10.8 28 49 2.9 25.7 23.5 5.3 4.1 Stable Stable 3.7 1.8 2* 16.4 17.9 10.8 28 51 2.7 22.6 20.5 5.1 3.9 Stable Stable 3.8 1.9 

ER-22 2 16.4 17.9 10.8 28 37 1.8 >50.0 >50.0 7.3 6.1 Stable Stable 6.8 4.0 

SS 17.5 17.9 17.3 20 47 1.7 24.5 21.7 8.8 6.9 Stable Stable 6.8 5.2 SS 17.5 17.9 17.3 20 43 2.0 31.3 28.4 9.7 7.8 Stable Stable 6.7 5.0 SS 17.5 17.9 17.3 20 22 1.4 >50.0 >50.0 19.8 17.9 Stable Stable 17.7 14.0 SS 17.5 17.9 17.3 20 42 2.4 34.0 31.2 10.0 8.1 Stable Stable 5.9 4.2 SS 17.5 17.9 17.3 20 32 1.4 >50.0 >50.0 13.4 11.4 Stable Stable 11.8 9.3 SS 17.5 17.9 17.3 20 33 2.1 >50.0 >50.0 13.1 11.2 Stable Stable 8.6 6.3 

ER-23 2 16.4 17.9 10.8 28 37 3.6 >50.0 >50.0 7.3 6.0 Stable Stable 4.6 2.0 

SS 18.4 19.3 5.7 31 40 4.0 >50.0 >50.0 3.3 2.7 At Risk At Risk 3.1 0.8 

SS 18.4 19.3 5.7 31 30 2.9 >50.0 >50.0 4.4 3.8 Stable Stable 4.6 1.5 SS 18.4 19.3 5.7 31 39 3.7 >50.0 >50.0 3.3 2.7 At Risk At Risk 3.2 0.9 SS 18.4 19.3 5.7 31 38 3.7 >50.0 >50.0 3.4 2.8 At Risk At Risk 3.3 0.9 

Elkhorn River Basin--Continued
74 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued ER-24 2 16.4 17.9 10.8 28 39 4.3 >50.0 >50.0 6.8 5.5 Stable Stable 3.9 1.6 

SS 16.9 18.3 11.0 27 31 4.5 >50.0 >50.0 8.6 7.4 Stable Stable 4.9 1.9 

SS 16.9 18.3 11.0 27 48 4.1 26.6 24.5 5.4 4.2 Stable Stable 3.2 1.3 SS 16.9 18.3 11.0 27 37 4.2 >50.0 >50.0 7.3 6.1 Stable Stable 4.2 1.7 SS 16.9 18.3 11.0 27 42 4.4 48.3 46.2 6.3 5.1 Stable Stable 3.6 1.4 

ER-25 4 16.5 18.1 6.7 30 35 4.2 >50.0 >50.0 4.7 4.0 Stable At Risk 3.9 1.1 

SS 16.3 18.8 6.7 30 22 3.9 >50.0 >50.0 7.2 6.5 Stable Stable 6.4 1.8 SS 16.3 18.8 6.7 30 49 3.7 20.0 18.5 3.1 2.4 At Risk At Risk 2.8 0.8 

SS 16.3 18.8 6.7 30 34 4.2 >50.0 >50.0 4.6 3.9 Stable At Risk 4.0 1.1 

SS 16.3 18.8 6.7 30 33 5.2 >50.0 >50.0 4.7 4.0 At Risk At Risk 3.8 0.9 

SS 16.3 18.8 6.7 30 40 4.5 >50.0 >50.0 3.9 3.2 At Risk At Risk 3.3 0.9 

SS 16.3 18.8 6.7 30 28 4.1 >50.0 >50.0 5.7 5.0 Stable Stable 4.9 1.4 SS 16.3 18.8 6.7 30 38 3.7 >50.0 >50.0 4.1 3.4 Stable At Risk 3.7 1.1 

SS 16.3 18.8 6.7 30 34 4.1 >50.0 >50.0 4.6 3.9 Stable At Risk 4.0 1.1 

SC-1 2 16.4 17.9 10.8 28 43 3.0 47.5 45.3 6.2 5.0 Stable Stable 4.3 2.1 

SS 16.8 18.1 7.8 26 47 2.6 18.5 17.0 4.0 3.1 Stable Stable 3.4 1.5 SS 16.8 18.1 7.8 26 39 2.9 40.8 39.3 4.9 4.0 Stable Stable 4.0 1.7 SS 16.8 18.1 7.8 26 25 2.9 >50.0 >50.0 7.6 6.8 Stable Stable 6.1 2.6 SS 16.8 18.1 7.8 26 50 3.1 15.0 13.5 3.7 2.9 Stable At Risk 2.9 1.2 

SS 16.8 18.1 7.8 26 42 2.9 27.5 26.0 4.5 3.6 Stable Stable 3.6 1.6 

SS 16.8 18.1 7.8 26 31 3.8 >50.0 >50.0 6.1 5.3 Stable Stable 4.4 1.6 SS 16.8 18.1 7.8 26 50 2.8 15.0 13.5 3.7 2.9 Stable Stable 3.1 1.3 SS 16.8 18.1 7.8 26 58 2.6 9.0 7.6 3.1 2.2 Stable At Risk 2.6 1.2 

SC-2 2 16.4 17.9 10.8 28 50 3.6 24.2 22.0 5.2 4.0 Stable Stable 3.3 1.4 

SS 14.6 17.5 2.5 37 52 3.3 13.0 12.3 1.2 0.9 At Risk At Risk 2.4 0.4 

SS 14.6 17.5 2.5 37 43 4.1 >50.0 >50.0 1.5 1.2 At Risk At Risk 2.9 0.4 SS 14.6 17.5 2.5 37 46 3.4 32.9 32.2 1.4 1.1 At Risk At Risk 2.8 0.4 SS 14.6 17.5 2.5 37 62 3.5 5.4 4.7 1.0 0.7 At Risk At Risk 1.9 0.3 

SS 14.6 17.5 2.5 37 50 3.7 15.7 15.0 1.2 0.9 At Risk At Risk 2.5 0.3 

SS 14.6 17.5 2.5 37 48 3.7 24.0 23.3 1.3 1.0 At Risk At Risk 2.6 0.4 

SC-3 2 16.4 17.9 10.8 28 37 5.0 >50.0 >50.0 7.1 5.9 Stable Stable 3.9 1.4 

SS 15.7 17.5 8.5 33 31 5.3 >50.0 >50.0 7.0 6.0 Stable Stable 4.7 1.3 SS 15.7 17.5 8.5 33 47 4.7 46.3 44.3 4.5 3.5 At Risk At Risk 3.1 1.0 

SS 15.7 17.5 8.5 33 38 5.0 >50.0 >50.0 5.6 4.7 Stable At Risk 3.8 1.1 

SS 15.7 17.5 8.5 33 45 5.0 >50.0 >50.0 4.7 3.8 At Risk At Risk 3.2 0.9 

SS 15.7 17.5 8.5 33 29 5.5 >50.0 >50.0 7.5 6.5 Stable Stable 5.0 1.4 

SS 15.7 17.5 8.5 33 43 4.3 >50.0 >50.0 5.0 4.0 Stable At Risk 3.6 1.1 SS 15.7 17.5 8.5 33 35 5.0 >50.0 >50.0 6.2 5.2 Stable Stable 4.2 1.2 SS 15.7 17.5 8.5 33 33 5.5 >50.0 >50.0 6.6 5.7 Stable Stable 4.4 1.2 

Elkhorn River Basin--Continued

Salt Creek Basin
Table 4 75

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued

SC-4 2 16.4 17.9 10.8 28 32 2.7 >50.0 >50.0 8.3 7.1 Stable Stable 6.1 3.1 

SS 15.6 18.2 2.7 34 14 1.9 >50.0 >50.0 4.7 4.5 Stable Stable 10.3 2.4 SS 15.6 18.2 2.7 34 18 2.5 >50.0 >50.0 3.7 3.4 Stable Stable 7.4 1.5 SS 15.6 18.2 2.7 34 15 2.2 >50.0 >50.0 4.4 4.1 Stable Stable 9.2 2.0 SS 15.6 18.2 2.7 34 22 2.8 >50.0 >50.0 3.1 2.8 Stable At Risk 6.1 1.1 SS 15.6 18.2 2.7 34 16 1.9 >50.0 >50.0 4.2 3.9 Stable Stable 9.1 2.2 SS 15.6 18.2 2.7 34 20 2.6 >50.0 >50.0 3.3 3.0 Stable Stable 6.6 1.3 SS 15.6 18.2 2.7 34 15 1.9 >50.0 >50.0 4.5 4.2 Stable Stable 9.8 2.3 SS 15.6 18.2 2.7 34 18 2.7 >50.0 >50.0 3.8 3.5 Stable Stable 7.5 1.4 SS 15.6 18.2 2.7 34 59 2.4 5.4 4.8 1.1 0.8 At Risk At Risk 2.1 0.4 

SS 15.6 18.2 2.7 34 41 2.8 >50.0 >50.0 1.6 1.3 At Risk At Risk 3.1 0.6 SS 15.6 18.2 2.7 34 44 3.4 29.3 28.6 1.5 1.2 At Risk At Risk 2.7 0.4 SS 15.6 18.2 2.7 34 45 3.4 23.8 23.2 1.4 1.1 At Risk At Risk 2.7 0.4 SS 15.6 18.2 2.7 34 45 3.6 22.2 21.6 1.4 1.1 At Risk At Risk 2.6 0.4 SS 15.6 18.2 2.7 34 82 3.8 1.7 1.1 0.7 0.4 Unstable Unstable 1.2 0.2 

SC-5 2 16.4 17.9 10.8 28 47 3.7 32.3 30.1 5.6 4.4 Stable Stable 3.5 1.5 

SS 15.8 17.7 9.8 29 39 4.5 >50.0 >50.0 6.2 5.1 Stable Stable 3.9 1.4 SS 15.8 17.7 9.8 29 49 2.5 26.2 24.1 4.8 3.7 Stable Stable 3.9 1.9 SS 15.8 17.7 9.8 29 34 4.6 >50.0 >50.0 7.3 6.2 Stable Stable 4.5 1.6 SS 15.8 17.7 9.8 29 53 2.6 19.9 17.8 4.4 3.3 Stable Stable 3.6 1.7 SS 15.8 17.7 9.8 29 52 4.8 20.8 18.7 4.5 3.4 At Risk At Risk 2.7 0.9 

SS 15.8 17.7 9.8 29 65 2.6 10.3 8.2 3.5 2.4 Stable At Risk 2.8 1.3 

SS 15.8 17.7 9.8 29 35 5.1 >50.0 >50.0 7.1 6.0 Stable Stable 4.2 1.4 SS 15.8 17.7 9.8 29 45 2.8 37.0 34.9 5.3 4.2 Stable Stable 4.1 1.9 

SC-6 2 16.4 17.9 10.8 28 43 5.0 45.2 43.0 6.1 4.9 Stable At Risk 3.3 1.2 

SS 14.6 18.0 5.0 33 36 5.2 >50.0 >50.0 3.4 2.9 At Risk At Risk 3.6 0.7 

SS 14.6 18.0 5.0 33 50 4.7 19.1 17.9 2.4 1.8 At Risk At Risk 2.5 0.5 SS 14.6 18.0 5.0 33 30 4.8 >50.0 >50.0 4.2 3.6 At Risk At Risk 4.5 0.9 

SS 14.6 18.0 5.0 33 56 5.1 11.6 10.3 2.1 1.5 At Risk At Risk 2.2 0.4 

SC-7 2 16.4 17.9 10.8 28 34 8.3 >50.0 >50.0 7.9 6.7 At Risk At Risk 3.6 1.0 

SS 16.1 17.6 14.0 27 38 8.3 >50.0 >50.0 9.4 7.8 Stable At Risk 3.5 1.1 

SS 16.1 17.6 14.0 27 28 8.4 >50.0 >50.0 12.7 11.1 Stable Stable 4.7 1.5 SS 16.1 17.6 14.0 27 32 8.4 >50.0 >50.0 11.2 9.6 Stable Stable 4.1 1.3 SS 16.1 17.6 14.0 27 28 8.4 >50.0 >50.0 12.9 11.3 Stable Stable 4.8 1.5 SS 16.1 17.6 14.0 27 33 8.7 >50.0 >50.0 10.9 9.3 Stable Stable 4.0 1.2 SS 16.1 17.6 14.0 27 45 7.8 43.3 40.4 7.7 6.1 At Risk At Risk 2.9 1.0 

SC-8 2 16.4 17.9 10.8 28 40 6.0 >50.0 >50.0 6.6 5.3 Stable At Risk 3.3 1.1 

SS 16.6 18.3 12.0 31 40 6.1 >50.0 >50.0 7.1 5.8 Stable At Risk 3.6 1.2 

SS 16.6 18.3 12.0 31 31 5.3 >50.0 >50.0 9.4 8.1 Stable Stable 5.0 1.8 

SS 16.6 18.3 12.0 31 45 6.3 >50.0 >50.0 6.3 5.0 At Risk At Risk 3.1 1.0 

SS 16.6 18.3 12.0 31 45 6.4 >50.0 >50.0 6.4 5.1 At Risk At Risk 3.2 1.0 

Salt Creek Basin--Continued
76 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturate

CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary re

Culmann method ARS meth

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued SC-9 2 16.4 17.9 10.8 28 35 3.2 >50.0 >50.0 7.7 6.5 Stable Stable 5.2 2.4 

SS 18.2 19.0 13.0 27 29 3.4 >50.0 >50.0 10.4 9.0 Stable Stable 6.0 3.0 SS 18.2 19.0 13.0 27 42 3.9 45.9 43.6 7.1 5.7 Stable Stable 3.8 1.8 SS 18.2 19.0 13.0 27 31 3.4 >50.0 >50.0 10.0 8.6 Stable Stable 5.8 2.9 SS 18.2 19.0 13.0 27 35 2.6 >50.0 >50.0 8.7 7.3 Stable Stable 5.9 3.4 SS 18.2 19.0 13.0 27 36 3.2 >50.0 >50.0 8.3 6.9 Stable Stable 5.0 2.6 SS 18.2 19.0 13.0 27 36 2.8 >50.0 >50.0 8.5 7.1 Stable Stable 5.5 3.0 

SC-10 2 16.4 17.9 10.8 28 34 4.7 >50.0 >50.0 7.9 6.7 Stable Stable 4.4 1.7 

SS 17.7 18.2 11.7 23 32 4.9 >50.0 >50.0 8.9 7.6 Stable Stable 4.2 1.8 SS 17.7 18.2 11.7 23 40 5.0 35.8 33.8 7.0 5.8 Stable Stable 3.3 1.4 SS 17.7 18.2 11.7 23 35 4.8 >50.0 >50.0 8.2 6.9 Stable Stable 4.0 1.7 SS 17.7 18.2 11.7 23 34 4.3 >50.0 >50.0 8.3 7.0 Stable Stable 4.2 1.9 SS 17.7 18.2 11.7 23 40 4.8 35.9 33.9 7.1 5.8 Stable Stable 3.4 1.5 SS 17.7 18.2 11.7 23 22 4.6 >50.0 >50.0 13.0 11.7 Stable Stable 6.4 2.8 

SC-11 2 16.4 17.9 10.8 28 33 7.9 >50.0 >50.0 8.0 6.8 Stable At Risk 3.7 1.0 

SS 17.7 18.5 14.6 26 31 6.8 >50.0 >50.0 11.4 9.8 Stable Stable 4.4 1.7 SS 17.7 18.5 14.6 26 36 8.3 >50.0 >50.0 9.6 8.0 Stable At Risk 3.4 1.2 SS 17.7 18.5 14.6 26 39 7.8 >50.0 >50.0 8.9 7.4 Stable At Risk 3.3 1.1 

SS 17.7 18.5 14.6 26 28 8.7 >50.0 >50.0 12.8 11.3 Stable Stable 4.5 1.5 

SC-12 2 16.4 17.9 10.8 28 47 4.7 30.6 28.4 5.5 4.3 Stable At Risk 3.1 1.2 

SS 17.4 18.3 8.6 27 50 4.5 17.4 15.8 4.1 3.1 At Risk At Risk 2.6 0.9 

SS 17.4 18.3 8.6 27 38 4.6 >50.0 >50.0 5.5 4.5 Stable At Risk 3.4 1.2 

SS 17.4 18.3 8.6 27 53 5.4 14.1 12.5 3.8 2.9 At Risk At Risk 2.2 0.7 

SS 17.4 18.3 8.6 27 48 4.5 19.4 17.8 4.2 3.3 At Risk At Risk 2.6 0.9 

SC-13 2 16.4 17.9 10.8 28 32 9.6 >50.0 >50.0 8.5 7.3 At Risk At Risk 3.7 0.9 

SS 18.0 19.0 8.7 36 38 9.5 >50.0 >50.0 5.3 4.3 At Risk At Risk 3.1 0.6 SS 18.0 19.0 8.7 36 25 8.6 >50.0 >50.0 8.3 7.4 At Risk At Risk 5.0 1.0 

SS 18.0 19.0 8.7 36 60 9.9 15.2 13.3 3.2 2.3 At Risk At Risk 1.8 0.3 

SS 18.0 19.0 8.7 36 15 9.1 >50.0 >50.0 14.2 13.2 Stable Stable 8.5 1.6 SS 18.0 19.0 8.7 36 25 5.9 >50.0 >50.0 8.1 7.2 Stable Stable 5.4 1.4 

SS 18.0 19.0 8.7 36 22 10.2 >50.0 >50.0 9.4 8.4 At Risk At Risk 5.5 0.9 

SS 18.0 19.0 8.7 36 29 10.7 >50.0 >50.0 7.2 6.3 At Risk At Risk 4.2 0.7 

SS 18.0 19.0 8.7 36 35 9.4 >50.0 >50.0 5.9 4.9 At Risk At Risk 3.5 0.6 

SS 18.0 19.0 8.7 36 34 10.0 >50.0 >50.0 6.0 5.1 At Risk At Risk 3.5 0.6 SS 18.0 19.0 8.7 36 29 10.8 >50.0 >50.0 7.0 6.1 At Risk At Risk 4.0 0.6 

SS 18.0 19.0 8.7 36 32 9.9 >50.0 >50.0 6.3 5.4 At Risk At Risk 3.7 0.6 

SS 18.0 19.0 8.7 36 37 11.1 >50.0 >50.0 5.4 4.5 At Risk At Risk 3.1 0.5 

Salt Creek Basin--Continued
Table 4 77

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued

SC-14 1 15.9 17.6 13.6 26 43 3.9 49.0 46.2 7.9 6.3 Stable Stable 4.2 2.0 

SS 16.3 18.4 15.1 37 41 3.5 >50.0 >50.0 8.8 7.1 Stable Stable 5.5 2.5 SS 16.3 18.4 15.1 37 45 4.3 >50.0 >50.0 8.0 6.4 Stable Stable 4.5 1.9 

SC-15 1 15.9 17.6 13.6 26 40 2.8 >50.0 >50.0 8.6 7.0 Stable Stable 5.5 3.0 

1* 15.9 17.6 13.6 26 43 2.7 48.7 46.0 7.9 6.3 Stable Stable 5.2 2.9 1* 15.9 17.6 13.6 26 28 2.9 >50.0 >50.0 12.5 11.0 Stable Stable 7.9 4.3 1* 15.9 17.6 13.6 26 38 2.6 >50.0 >50.0 9.1 7.5 Stable Stable 6.2 3.5 1* 15.9 17.6 13.6 26 45 2.6 40.6 37.9 7.5 6.0 Stable Stable 5.1 2.9 1* 15.9 17.6 13.6 26 44 2.9 42.3 39.6 7.6 6.0 Stable Stable 4.9 2.7 1* 15.9 17.6 13.6 26 40 3.1 >50.0 >50.0 8.6 7.0 Stable Stable 5.2 2.7 1* 15.9 17.6 13.6 26 37 3.1 >50.0 >50.0 9.1 7.6 Stable Stable 5.6 2.9 1* 15.9 17.6 13.6 26 42 2.8 >50.0 49.8 8.0 6.5 Stable Stable 5.2 2.9 

SC-16 2 16.4 17.9 10.8 28 48 2.0 27.7 25.5 5.4 4.2 Stable Stable 4.8 2.7 

SS 13.5 16.3 14.1 22 62 1.5 14.2 11.1 5.7 4.0 Stable Stable 6.0 3.9 SS 13.5 16.3 14.1 22 49 1.7 25.7 22.7 7.6 5.8 Stable Stable 7.0 4.4 SS 13.5 16.3 14.1 22 35 1.6 >50.0 >50.0 11.1 9.4 Stable Stable 11.0 7.0 SS 13.5 16.3 14.1 22 52 2.4 22.5 19.4 7.1 5.4 Stable Stable 5.2 3.0 SS 13.5 16.3 14.1 22 38 2.5 >50.0 >50.0 10.1 8.4 Stable Stable 7.2 4.1 SS 13.5 16.3 14.1 22 47 2.4 29.3 26.3 8.0 6.2 Stable Stable 5.8 3.3 SS 13.5 16.3 14.1 22 54 1.5 20.3 17.2 6.8 5.1 Stable Stable 6.9 4.5 SS 13.5 16.3 14.1 22 50 2.3 24.2 21.1 7.4 5.6 Stable Stable 5.5 3.2 

SC-17 1 15.9 17.6 13.6 26 48 2.0 30.6 27.9 6.9 5.3 Stable Stable 5.7 3.5 

SS 17.2 18.0 13.8 27 45 1.8 40.6 38.0 7.5 5.9 Stable Stable 6.3 4.2 SS 17.2 18.0 13.8 27 52 2.1 23.5 20.9 6.3 4.8 Stable Stable 4.7 2.9 

SC-18 1 15.9 17.6 13.6 26 48 1.2 31.3 28.5 6.9 5.4 Stable Stable 8.5 6.0 

SS 17.6 18.1 3.5 25 57 1.3 3.9 3.3 1.4 1.0 Stable At Risk 2.5 1.1 

SS 17.6 18.1 3.5 25 40 1.3 12.5 11.9 2.1 1.7 Stable Stable 3.7 1.7 

SS 17.6 18.1 3.5 25 54 0.9 4.5 3.8 1.5 1.1 Stable Stable 3.1 1.6 SS 17.6 18.1 3.5 25 41 1.2 12.1 11.5 2.1 1.7 Stable Stable 3.8 1.8 

SC-19 1 15.9 17.6 13.6 26 38 2.7 >50.0 >50.0 9.1 7.6 Stable Stable 6.1 3.4 

1* 15.9 17.6 13.6 26 45 2.8 39.8 37.1 7.5 5.9 Stable Stable 4.8 2.6 1* 15.9 17.6 13.6 26 41 2.6 >50.0 >50.0 8.4 6.8 Stable Stable 5.7 3.3 1* 15.9 17.6 13.6 26 27 2.9 >50.0 >50.0 12.7 11.1 Stable Stable 8.1 4.4 1* 15.9 17.6 13.6 26 27 2.7 >50.0 >50.0 12.8 11.3 Stable Stable 8.6 4.8 1* 15.9 17.6 13.6 26 35 2.6 >50.0 >50.0 9.9 8.4 Stable Stable 6.7 3.8 1* 15.9 17.6 13.6 26 52 2.4 24.0 21.2 6.3 4.8 Stable Stable 4.5 2.6 1* 15.9 17.6 13.6 26 36 2.7 >50.0 >50.0 9.5 7.9 Stable Stable 6.3 3.5 1* 15.9 17.6 13.6 26 37 2.4 >50.0 >50.0 9.1 7.6 Stable Stable 6.5 3.7 

SC-21 2 16.4 17.9 10.8 28 44 6.7 39.2 37.0 5.9 4.7 At Risk At Risk 2.9 0.9 

2 16.4 17.9 10.8 28 48 7.1 28.7 26.5 5.4 4.2 At Risk At Risk 2.6 0.8 2 16.4 17.9 10.8 28 41 6.4 >50.0 >50.0 6.4 5.2 Stable At Risk 3.2 1.0 

Salt Creek Basin--Continued
78 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued SC-22 2 16.4 17.9 10.8 28 40 9.7 >50.0 >50.0 6.6 5.4 At Risk At Risk 2.9 0.7 

SS 18.4 19.5 8.1 36 31 9.7 >50.0 >50.0 6.0 5.2 At Risk At Risk 3.8 0.6 

SS 18.4 19.5 8.1 36 41 9.9 >50.0 >50.0 4.5 3.6 At Risk At Risk 2.8 0.5 

SS 18.4 19.5 8.1 36 44 10.4 >50.0 >50.0 4.1 3.3 At Risk At Risk 2.6 0.4 SS 18.4 19.5 8.1 36 40 8.6 >50.0 >50.0 4.5 3.7 At Risk At Risk 3.0 0.5 SS 18.4 19.5 8.1 36 51 11.3 34.0 32.3 3.5 2.7 At Risk At Risk 2.1 0.3 SS 18.4 19.5 8.1 36 40 8.6 >50.0 >50.0 4.6 3.7 At Risk At Risk 3.0 0.5 SS 18.4 19.5 8.1 36 34 10.5 >50.0 >50.0 5.5 4.7 At Risk At Risk 3.5 0.5 SS 18.4 19.5 8.1 36 42 8.4 >50.0 >50.0 4.3 3.4 At Risk At Risk 2.8 0.5 

SC-23 2 16.4 17.9 10.8 28 39 4.9 >50.0 >50.0 6.8 5.6 Stable Stable 3.7 1.4 

SS 18.2 18.9 11.6 32 38 5.6 >50.0 >50.0 7.1 5.9 Stable Stable 3.7 1.3 SS 18.2 18.9 11.6 32 42 4.7 >50.0 >50.0 6.4 5.1 Stable Stable 3.6 1.4 SS 18.2 18.9 11.6 32 37 4.8 >50.0 >50.0 7.2 6.0 Stable Stable 4.0 1.5 SS 18.2 18.9 11.6 32 37 4.8 >50.0 >50.0 7.4 6.2 Stable Stable 4.1 1.6 SS 18.2 18.9 11.6 32 47 5.0 44.6 42.3 5.6 4.4 Stable At Risk 3.1 1.1 

SS 18.2 18.9 11.6 32 35 4.9 >50.0 >50.0 7.8 6.5 Stable Stable 4.3 1.6 

SS 18.2 18.9 11.6 32 44 5.2 >50.0 >50.0 6.1 4.8 Stable At Risk 3.3 1.2 SS 18.2 18.9 11.6 32 36 4.4 >50.0 >50.0 7.6 6.4 Stable Stable 4.4 1.7 SS 18.2 18.9 11.6 32 34 5.2 >50.0 >50.0 7.9 6.7 Stable Stable 4.3 1.5 SS 18.2 18.9 11.6 32 36 4.6 >50.0 >50.0 7.5 6.2 Stable Stable 4.2 1.6 SS 18.2 18.9 11.6 32 46 5.1 >50.0 49.6 5.8 4.6 Stable At Risk 3.1 1.1 SS 18.2 18.9 11.6 32 35 5.0 >50.0 >50.0 7.7 6.5 Stable Stable 4.2 1.5 

SC-24 2 16.4 17.9 10.8 28 36 4.0 >50.0 >50.0 7.4 6.2 Stable Stable 4.5 1.8 

SS 17.8 18.6 11.2 20 35 4.2 42.1 40.2 7.7 6.5 Stable Stable 3.9 1.8 SS 17.8 18.6 11.2 20 38 4.1 30.4 28.6 7.0 5.8 Stable Stable 3.6 1.7 SS 17.8 18.6 11.2 20 26 4.2 >50.0 >50.0 10.6 9.4 Stable Stable 5.4 2.5 SS 17.8 18.6 11.2 20 47 4.0 15.8 14.0 5.5 4.3 Stable Stable 2.9 1.4 SS 17.8 18.6 11.2 20 31 3.9 >50.0 >50.0 8.6 7.4 Stable Stable 4.6 2.2 SS 17.8 18.6 11.2 20 25 3.9 >50.0 >50.0 10.7 9.5 Stable Stable 5.7 2.7 SS 17.8 18.6 11.2 20 31 3.8 >50.0 >50.0 8.7 7.4 Stable Stable 4.7 2.3 SS 17.8 18.6 11.2 20 43 4.0 21.5 19.7 6.2 5.0 Stable Stable 3.3 1.6 SS 17.8 18.6 11.2 20 35 3.9 43.1 41.3 7.7 6.5 Stable Stable 4.1 2.0 SS 17.8 18.6 11.2 20 48 4.4 14.9 13.1 5.3 4.1 Stable At Risk 2.7 1.2 

SC-25 2 16.4 17.9 10.8 28 42 5.4 48.7 46.5 6.2 5.0 Stable At Risk 3.3 1.1 

SS 18.7 19.2 4.6 27 53 5.2 6.8 6.0 1.9 1.4 At Risk At Risk 1.8 0.4 

SS 18.7 19.2 4.6 27 39 5.9 25.1 24.3 2.7 2.2 At Risk At Risk 2.5 0.5 

SS 18.7 19.2 4.6 27 41 5.5 18.2 17.4 2.5 2.1 At Risk At Risk 2.3 0.5 SS 18.7 19.2 4.6 27 37 5.2 34.2 33.4 2.9 2.4 At Risk At Risk 2.7 0.6 

Salt Creek Basin--Continued
Table 4 79

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued

SC-26 2 16.4 17.9 10.8 28 43 7.5 46.0 43.8 6.1 4.9 At Risk At Risk 2.9 0.8 

SS 15.6 18.3 8.5 37 42 6.1 >50.0 >50.0 4.9 3.9 At Risk At Risk 3.5 0.8 SS 15.6 18.3 8.5 37 44 8.5 >50.0 >50.0 4.5 3.6 At Risk At Risk 3.0 0.5 SS 15.6 18.3 8.5 37 45 6.9 >50.0 >50.0 4.5 3.6 At Risk At Risk 3.1 0.7 SS 15.6 18.3 8.5 37 49 7.8 >50.0 >50.0 4.0 3.1 At Risk At Risk 2.7 0.5 SS 15.6 18.3 8.5 37 46 6.3 >50.0 >50.0 4.4 3.5 At Risk At Risk 3.1 0.7 SS 15.6 18.3 8.5 37 32 9.6 >50.0 >50.0 6.5 5.6 At Risk At Risk 4.2 0.7 

SC-27 2 16.4 17.9 10.8 28 41 6.1 >50.0 >50.0 6.5 5.3 Stable At Risk 3.3 1.1 

SS 16.5 18.4 15.7 22 44 7.8 34.0 31.2 8.5 6.8 Stable At Risk 2.9 1.1 SS 16.5 18.4 15.7 22 45 7.8 31.0 28.2 8.2 6.5 Stable At Risk 2.8 1.1 SS 16.5 18.4 15.7 22 39 4.3 >50.0 47.3 9.6 7.9 Stable Stable 4.5 2.3 

SS 16.5 18.4 15.7 22 38 5.6 >50.0 >50.0 9.9 8.2 Stable Stable 3.9 1.8 SS 16.5 18.4 15.7 22 44 5.8 32.0 29.2 8.3 6.6 Stable Stable 3.3 1.4 SS 16.5 18.4 15.7 22 33 5.5 >50.0 >50.0 11.4 9.7 Stable Stable 4.6 2.1 

SC-28 2 16.4 17.9 10.8 28 36 5.0 >50.0 >50.0 7.4 6.2 Stable Stable 4.1 1.5 

SS 16.2 17.5 12.6 23 33 5.2 >50.0 >50.0 9.7 8.2 Stable Stable 4.4 1.9 SS 16.2 17.5 12.6 23 31 4.8 >50.0 >50.0 10.3 8.8 Stable Stable 4.9 2.2 SS 16.2 17.5 12.6 23 31 4.9 >50.0 >50.0 10.5 9.1 Stable Stable 4.9 2.2 SS 16.2 17.5 12.6 23 40 4.8 44.2 41.8 8.0 6.6 Stable Stable 3.8 1.7 SS 16.2 17.5 12.6 23 53 5.4 17.0 14.7 5.8 4.3 Stable At Risk 2.6 1.1 

SS 16.2 17.5 12.6 23 29 4.8 >50.0 >50.0 11.3 9.8 Stable Stable 5.3 2.3 

SC-29 1 15.9 17.6 13.6 26 43 4.3 49.5 46.8 7.9 6.4 Stable Stable 4.0 1.8 

SS 15.2 17.2 20.4 19 38 4.8 >50.0 >50.0 13.8 11.5 Stable Stable 5.2 2.9 SS 15.2 17.2 20.4 19 41 3.3 47.4 43.6 12.8 10.4 Stable Stable 6.2 3.9 SS 15.2 17.2 20.4 19 45 4.6 36.8 33.0 11.6 9.2 Stable Stable 4.5 2.5 SS 15.2 17.2 20.4 19 36 4.5 >50.0 >50.0 14.7 12.3 Stable Stable 5.7 3.2 SS 15.2 17.2 20.4 19 37 4.4 >50.0 >50.0 14.3 11.9 Stable Stable 5.7 3.3 SS 15.2 17.2 20.4 19 60 4.3 18.2 14.4 8.2 5.9 Stable Stable 3.3 1.9 

SC-30 2 16.4 17.9 10.8 28 48 5.7 28.6 26.4 5.4 4.2 At Risk At Risk 2.8 1.0 

SS 12.6 16.7 9.4 34 52 6.0 39.2 36.4 4.6 3.5 At Risk At Risk 3.1 0.8 SS 12.6 16.7 9.4 34 44 5.3 >50.0 >50.0 5.6 4.5 Stable At Risk 3.9 1.1 

SC-31 3 16.5 18.1 6.7 30 31 1.5 >50.0 >50.0 5.4 4.6 Stable Stable 6.9 3.5 

SS 16.7 17.6 3.1 28 15 0.9 >50.0 >50.0 5.4 5.0 Stable Stable 12.5 6.1 SS 16.7 17.6 3.1 28 16 0.8 >50.0 >50.0 5.1 4.8 Stable Stable 12.4 6.2 SS 16.7 17.6 3.1 28 31 0.7 >50.0 >50.0 2.5 2.2 Stable Stable 6.6 3.5 SS 16.7 17.6 3.1 28 23 0.6 >50.0 >50.0 3.4 3.1 Stable Stable 10.5 6.2 SS 16.7 17.6 3.1 28 32 0.9 >50.0 >50.0 2.5 2.1 Stable Stable 5.6 2.7 SS 16.7 17.6 3.1 28 26 0.9 >50.0 >50.0 3.0 2.7 Stable Stable 7.1 3.5 SS 16.7 17.6 3.1 28 25 1.0 >50.0 >50.0 3.2 2.8 Stable Stable 6.8 3.1 SS 16.7 17.6 3.1 28 29 1.2 >50.0 >50.0 2.7 2.3 Stable Stable 5.3 2.2 SS 16.7 17.6 3.1 28 44 3.8 11.2 10.6 1.7 1.4 At Risk At Risk 2.3 0.5 

SS 16.7 17.6 3.1 28 67 4.6 2.7 2.1 1.1 0.7 Unstable Unstable 1.4 0.2 

Salt Creek Basin--Continued
80 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued SC-32 3 16.5 18.1 6.7 30 46 7.8 28.3 26.9 3.5 2.8 At Risk At Risk 2.4 0.4 

SS 18.3 19.5 6.5 31 48 8.4 20.4 19.1 3.0 2.3 At Risk At Risk 2.1 0.4 SS 18.3 19.5 6.5 31 31 7.7 >50.0 >50.0 4.7 4.1 At Risk At Risk 3.4 0.6 SS 18.3 19.5 6.5 31 39 7.4 >50.0 >50.0 3.8 3.1 At Risk At Risk 2.7 0.5 SS 18.3 19.5 6.5 31 52 7.5 13.6 12.3 2.7 2.0 At Risk At Risk 1.9 0.4 SS 18.3 19.5 6.5 31 50 8.5 16.0 14.8 2.8 2.2 At Risk At Risk 2.0 0.3 SS 18.3 19.5 6.5 31 53 7.5 12.5 11.3 2.6 2.0 At Risk At Risk 1.9 0.4 

SC-33 2 16.4 17.9 10.8 28 36 5.1 >50.0 >50.0 7.5 6.3 Stable Stable 4.0 1.5 

SS 17.2 18.3 2.3 36 32 4.6 >50.0 >50.0 1.8 1.5 At Risk At Risk 3.6 0.4 

SS 17.2 18.3 2.3 36 35 5.2 >50.0 >50.0 1.6 1.3 At Risk At Risk 3.2 0.3 SS 17.2 18.3 2.3 36 38 4.9 >50.0 >50.0 1.4 1.2 At Risk At Risk 2.9 0.3 SS 17.2 18.3 2.3 36 32 5.3 >50.0 >50.0 1.8 1.5 At Risk At Risk 3.5 0.3 SS 17.2 18.3 2.3 36 37 5.1 >50.0 >50.0 1.5 1.3 At Risk At Risk 3.0 0.3 SS 17.2 18.3 2.3 36 41 5.5 >50.0 >50.0 1.4 1.1 At Risk At Risk 2.7 0.2 SS 17.2 18.3 2.3 36 35 5.0 >50.0 >50.0 1.6 1.3 At Risk At Risk 3.1 0.3 SS 17.2 18.3 2.3 36 39 5.5 >50.0 >50.0 1.4 1.2 At Risk At Risk 2.8 0.3 SS 17.2 18.3 2.3 36 35 4.6 >50.0 >50.0 1.6 1.3 At Risk At Risk 3.2 0.3 SS 17.2 18.3 2.3 36 33 5.5 >50.0 >50.0 1.7 1.4 At Risk At Risk 3.3 0.3 

SC-34 2 16.4 17.9 10.8 28 32 2.4 >50.0 >50.0 8.5 7.3 Stable Stable 6.7 3.5 

SS 17.7 18.4 7.4 33 25 3.1 >50.0 >50.0 7.2 6.4 Stable Stable 6.3 2.3 SS 17.7 18.4 7.4 33 38 1.4 >50.0 >50.0 4.6 3.8 Stable Stable 6.1 3.4 SS 17.7 18.4 7.4 33 23 2.8 >50.0 >50.0 7.8 7.0 Stable Stable 7.2 2.8 SS 17.7 18.4 7.4 33 40 1.9 >50.0 >50.0 4.5 3.7 Stable Stable 4.9 2.3 SS 17.7 18.4 7.4 33 33 2.7 >50.0 >50.0 5.4 4.6 Stable Stable 5.1 2.0 SS 17.7 18.4 7.4 33 30 2.7 >50.0 >50.0 6.0 5.2 Stable Stable 5.6 2.2 

LNR-1 2 16.4 17.9 10.8 28 40 4.9 >50.0 >50.0 6.7 5.5 Stable Stable 3.7 1.4 

SS 18.6 19.3 16.6 21 43 4.6 31.0 28.4 8.7 7.0 Stable Stable 3.6 1.9 SS 18.6 19.3 16.6 21 36 5.3 >50.0 >50.0 10.7 9.0 Stable Stable 4.1 2.0 SS 18.6 19.3 16.6 21 50 4.8 20.9 18.3 7.5 5.7 Stable Stable 3.0 1.6 SS 18.6 19.3 16.6 21 31 4.8 >50.0 >50.0 12.4 10.7 Stable Stable 5.0 2.6 

LNR-2 2 16.4 17.9 10.8 28 36 4.4 >50.0 >50.0 7.4 6.2 Stable Stable 4.3 1.7 

SS 16.2 18.2 19.4 26 32 5.3 >50.0 >50.0 14.8 12.7 Stable Stable 5.8 2.8 SS 16.2 18.2 19.4 26 30 3.8 >50.0 >50.0 15.9 13.8 Stable Stable 7.7 4.2 SS 16.2 18.2 19.4 26 48 4.8 42.1 38.2 9.5 7.3 Stable Stable 3.9 2.0 SS 16.2 18.2 19.4 26 35 3.8 >50.0 >50.0 13.6 11.5 Stable Stable 6.5 3.6 SS 16.2 18.2 19.4 26 40 4.6 >50.0 >50.0 11.8 9.7 Stable Stable 5.1 2.6 SS 16.2 18.2 19.4 26 33 4.0 >50.0 >50.0 14.4 12.2 Stable Stable 6.6 3.6 

LNR-3 2 16.4 17.9 10.8 28 38 4.7 >50.0 >50.0 7.0 5.8 Stable Stable 4.0 1.5 

SS 18.0 18.7 7.9 32 33 5.5 >50.0 >50.0 5.7 4.9 Stable At Risk 3.8 1.0 SS 18.0 18.7 7.9 32 43 4.4 >50.0 >50.0 4.3 3.5 At Risk At Risk 3.1 1.0 

SS 18.0 18.7 7.9 32 39 4.8 >50.0 >50.0 4.7 3.9 At Risk At Risk 3.3 1.0 

SS 18.0 18.7 7.9 32 36 4.0 >50.0 >50.0 5.1 4.3 Stable Stable 3.8 1.3 

Salt Creek Basin--Continued

Little Nemaha River Basin
Table 4 81

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued

LNR-4 2 16.4 17.9 10.8 28 37 5.2 >50.0 >50.0 7.2 5.9 Stable Stable 3.8 1.4 

2* 16.4 17.9 15.1 34 39 5.5 >50.0 >50.0 9.6 7.9 Stable Stable 4.5 1.8 2* 16.4 17.9 15.1 34 38 4.6 >50.0 >50.0 9.7 8.0 Stable Stable 4.9 2.1 2* 16.4 17.9 15.1 34 33 5.8 >50.0 >50.0 11.4 9.7 Stable Stable 5.2 2.0 2* 16.4 17.9 15.1 34 41 4.5 >50.0 >50.0 9.1 7.4 Stable Stable 4.7 2.0 2* 16.4 17.9 15.1 34 37 5.6 >50.0 >50.0 10.1 8.4 Stable Stable 4.7 1.8 2* 16.4 17.9 15.1 34 36 5.4 >50.0 >50.0 10.4 8.7 Stable Stable 4.9 1.9 

LNR-5 2 16.4 17.9 10.8 28 40 10.2 >50.0 >50.0 6.6 5.4 At Risk At Risk 2.8 0.6 

2* 16.4 17.9 12.8 23 42 10.8 36.4 34.0 7.5 6.1 At Risk At Risk 2.6 0.7 2* 16.4 17.9 12.8 23 45 9.5 27.2 24.8 6.8 5.4 At Risk At Risk 2.4 0.7 2* 16.4 17.9 12.8 23 33 10.8 >50.0 >50.0 9.6 8.2 At Risk At Risk 3.3 0.9 2* 16.4 17.9 12.8 23 41 9.6 38.0 35.7 7.6 6.2 At Risk At Risk 2.7 0.8 

LNR-6 2 16.4 17.9 10.8 28 53 8.9 19.6 17.4 4.8 3.6 At Risk At Risk 2.1 0.5 

2* 16.4 17.9 12.7 29 51 8.9 28.7 26.1 5.9 4.5 At Risk At Risk 2.4 0.7 2* 16.4 17.9 12.7 29 36 9.6 >50.0 >50.0 8.7 7.3 At Risk At Risk 3.4 0.9 2* 16.4 17.9 12.7 29 57 8.5 19.2 16.5 5.2 3.8 At Risk At Risk 2.1 0.6 2* 16.4 17.9 12.7 29 61 8.6 16.0 13.3 4.8 3.4 At Risk At Risk 2.0 0.6 2* 16.4 17.9 12.7 29 70 8.9 10.3 7.7 4.0 2.6 At Risk Unstable 1.6 0.5 

2* 16.4 17.9 12.7 29 43 8.7 >50.0 >50.0 7.3 5.9 At Risk At Risk 3.0 0.8 

LNR-7 2 16.4 17.9 10.8 28 45 4.2 36.7 34.5 5.8 4.6 Stable Stable 3.4 1.4 

SS 17.4 18.5 8.8 23 52 4.8 11.6 10.1 3.9 3.0 At Risk At Risk 2.3 0.8 

SS 17.4 18.5 8.8 23 39 3.9 28.1 26.6 5.3 4.4 Stable Stable 3.3 1.4 

SS 17.4 18.5 8.8 23 28 3.4 >50.0 >50.0 7.7 6.8 Stable Stable 5.2 2.3 SS 17.4 18.5 8.8 23 65 5.2 6.5 5.0 3.0 2.0 At Risk Unstable 1.7 0.6 

SS 17.4 18.5 8.8 23 48 3.0 14.0 12.5 4.2 3.3 Stable Stable 3.0 1.4 

SS 17.4 18.5 8.8 23 39 4.7 28.0 26.5 5.3 4.4 Stable At Risk 3.1 1.1 

LNR-8 2 16.4 17.9 10.8 28 52 9.7 20.4 18.2 4.9 3.7 At Risk At Risk 2.1 0.5 

SS 15.8 18.8 6.5 34 58 9.3 13.0 11.4 2.5 1.8 At Risk At Risk 1.9 0.3 

SS 15.8 18.8 6.5 34 40 9.2 >50.0 >50.0 3.8 3.1 At Risk At Risk 2.9 0.4 

SS 15.8 18.8 6.5 34 62 10.4 9.7 8.2 2.3 1.6 Unstable Unstable 1.7 0.2 SS 15.8 18.8 6.5 34 49 10.1 26.9 25.4 3.0 2.3 At Risk At Risk 2.2 0.3 

LNR-9 1 15.9 17.6 13.6 26 39 4.2 >50.0 >50.0 8.7 7.2 Stable Stable 4.5 2.1 

SS 18.5 19.3 13.3 27 44 4.2 38.5 36.2 6.8 5.4 Stable Stable 3.5 1.6 

SS 18.5 19.3 13.3 27 39 4.0 >50.0 >50.0 7.7 6.4 Stable Stable 4.1 1.9 SS 18.5 19.3 13.3 27 38 4.3 >50.0 >50.0 7.9 6.6 Stable Stable 4.1 1.9 SS 18.5 19.3 13.3 27 34 4.4 >50.0 >50.0 8.9 7.5 Stable Stable 4.5 2.0 

LNR-10 1 15.9 17.6 13.6 26 31 2.9 >50.0 >50.0 11.1 9.6 Stable Stable 7.1 3.8 

SS 16.4 18.0 36.5 15 27 2.9 >50.0 >50.0 33.3 29.2 Stable Stable 14.9 11.4 SS 16.4 18.0 36.5 15 35 2.9 >50.0 >50.0 25.7 21.7 Stable Stable 11.7 8.9 

Little Nemaha River Basin--Continued
82 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued LNR-11 2 16.4 17.9 10.8 28 48 7.4 27.9 25.7 5.4 4.2 At Risk At Risk 2.5 0.7 

2* 16.4 17.9 10.8 28 47 7.2 30.5 28.3 5.5 4.3 At Risk At Risk 2.6 0.8 2* 16.4 17.9 10.8 28 61 7.5 12.8 10.6 4.1 2.9 At Risk At Risk 1.9 0.6 2* 16.4 17.9 10.8 28 42 7.6 >50.0 >50.0 6.3 5.1 At Risk At Risk 3.0 0.8 2* 16.4 17.9 10.8 28 44 7.3 43.4 41.3 6.0 4.8 At Risk At Risk 2.9 0.8 

LNR-12 2 16.4 17.9 10.8 28 42 4.6 >50.0 >50.0 6.3 5.1 Stable Stable 3.6 1.4 

SS 18.0 19.1 7.7 26 57 6.1 9.3 7.9 3.0 2.2 At Risk At Risk 1.8 0.5 

SS 18.0 19.1 7.7 26 32 5.2 >50.0 >50.0 5.6 4.8 Stable At Risk 3.7 1.1 

SS 18.0 19.1 7.7 26 40 4.6 33.0 31.7 4.4 3.6 At Risk At Risk 3.0 0.9 

SS 18.0 19.1 7.7 26 41 4.8 29.7 28.3 4.3 3.5 At Risk At Risk 2.9 0.9 SS 18.0 19.1 7.7 26 44 3.6 21.6 20.3 4.0 3.1 Stable At Risk 2.9 1.1 

SS 18.0 19.1 7.7 26 32 3.1 >50.0 >50.0 5.6 4.8 Stable Stable 4.5 1.8 SS 18.0 19.1 7.7 26 44 5.0 22.7 21.3 4.0 3.2 At Risk At Risk 2.6 0.8 

SS 18.0 19.1 7.7 26 43 4.7 25.6 24.2 4.1 3.3 At Risk At Risk 2.8 0.9 

LNR-13 2 16.4 17.9 10.8 28 36 5.6 >50.0 >50.0 7.3 6.1 Stable Stable 3.8 1.3 

SS 15.0 17.4 12.8 25 33 5.6 >50.0 >50.0 9.9 8.4 Stable Stable 4.6 1.8 SS 15.0 17.4 12.8 25 39 5.7 >50.0 >50.0 8.4 6.9 Stable Stable 3.9 1.5 SS 15.0 17.4 12.8 25 38 5.4 >50.0 >50.0 8.7 7.2 Stable Stable 4.1 1.6 SS 15.0 17.4 12.8 25 36 5.7 >50.0 >50.0 9.1 7.6 Stable Stable 4.2 1.6 

LNR-14 2 16.4 17.9 10.8 28 30 8.2 >50.0 >50.0 9.1 7.8 Stable At Risk 4.2 1.1 

SS 18.3 19.0 23.8 20 33 8.9 >50.0 >50.0 17.1 14.6 Stable Stable 4.1 1.9 SS 18.3 19.0 23.8 20 30 8.0 >50.0 >50.0 18.8 16.3 Stable Stable 4.8 2.4 

SS 18.3 19.0 23.8 20 22 8.2 >50.0 >50.0 25.4 22.9 Stable Stable 6.3 3.1 SS 18.3 19.0 23.8 20 29 7.0 >50.0 >50.0 19.2 16.7 Stable Stable 5.2 2.7 SS 18.3 19.0 23.8 20 39 8.6 >50.0 >50.0 14.1 11.6 Stable Stable 3.4 1.6 SS 18.3 19.0 23.8 20 26 8.3 >50.0 >50.0 21.4 18.9 Stable Stable 5.3 2.6 

LNR-15 2 16.4 17.9 10.8 28 33 4.8 >50.0 >50.0 8.2 6.9 Stable Stable 4.5 1.7 

SS 18.8 19.5 12.9 29 30 5.0 >50.0 >50.0 9.8 8.5 Stable Stable 4.9 2.0 SS 18.8 19.5 12.9 29 32 4.4 >50.0 >50.0 9.3 7.9 Stable Stable 4.9 2.1 SS 18.8 19.5 12.9 29 31 5.1 >50.0 >50.0 9.6 8.3 Stable Stable 4.8 1.9 SS 18.8 19.5 12.9 29 39 4.7 >50.0 >50.0 7.5 6.1 Stable Stable 3.8 1.6 

LNR-16 2 16.4 17.9 10.8 28 43 5.5 46.9 44.7 6.2 4.9 Stable At Risk 3.2 1.1 

SS 16.8 18.4 10.2 37 33 5.7 >50.0 >50.0 7.4 6.3 Stable Stable 4.6 1.3 SS 16.8 18.4 10.2 37 59 4.7 22.3 19.8 3.9 2.8 At Risk At Risk 2.6 0.8 

SS 16.8 18.4 10.2 37 43 5.8 >50.0 >50.0 5.7 4.6 At Risk At Risk 3.5 1.0 

SS 16.8 18.4 10.2 37 37 5.8 >50.0 >50.0 6.6 5.5 Stable At Risk 4.1 1.1 

SS 16.8 18.4 10.2 37 38 5.7 >50.0 >50.0 6.4 5.3 Stable At Risk 4.0 1.1 

SS 16.8 18.4 10.2 37 37 5.7 >50.0 >50.0 6.6 5.5 Stable At Risk 4.1 1.2 SS 16.8 18.4 10.2 37 32 5.5 >50.0 >50.0 7.6 6.5 Stable Stable 4.8 1.4 SS 16.8 18.4 10.2 37 42 4.4 >50.0 >50.0 5.8 4.7 Stable Stable 3.9 1.3 

SS 16.8 18.4 10.2 37 48 5.7 >50.0 >50.0 5.0 3.9 At Risk At Risk 3.0 0.9 

SS 16.8 18.4 10.2 37 59 5.8 22.0 19.6 3.9 2.8 At Risk At Risk 2.4 0.7 

Little Nemaha River Basin--Continued
Table 4 83

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary resu

Culmann method ARS method

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil data 

banks--Continued

LNR-17 2 16.4 17.9 10.8 28 34 6.3 >50.0 >50.0 7.8 6.6 Stable Stable 3.9 1.2 

SS 18.1 18.4 15.5 28 45 6.3 47.8 44.9 8.1 6.4 Stable Stable 3.1 1.3 SS 18.1 18.4 15.5 28 38 6.4 >50.0 >50.0 9.9 8.2 Stable Stable 3.8 1.6 SS 18.1 18.4 15.5 28 32 6.4 >50.0 >50.0 11.7 10.0 Stable Stable 4.5 1.8 SS 18.1 18.4 15.5 28 34 6.9 >50.0 >50.0 10.9 9.2 Stable Stable 4.1 1.6 SS 18.1 18.4 15.5 28 27 5.6 >50.0 >50.0 14.0 12.3 Stable Stable 5.7 2.5 SS 18.1 18.4 15.5 28 31 6.5 >50.0 >50.0 12.3 10.6 Stable Stable 4.7 1.9 

LNR-18 2 16.4 17.9 10.8 28 37 2.3 >50.0 >50.0 7.2 6.0 Stable Stable 5.9 3.2 

SS 17.6 18.2 12.2 23 53 2.4 15.2 13.1 5.4 4.0 Stable Stable 3.7 2.2 SS 17.6 18.2 12.2 23 28 2.0 >50.0 >50.0 10.8 9.4 Stable Stable 8.3 5.3 SS 17.6 18.2 12.2 23 41 2.4 34.8 32.7 7.2 5.9 Stable Stable 4.9 3.0 SS 17.6 18.2 12.2 23 27 2.1 >50.0 >50.0 11.4 10.0 Stable Stable 8.4 5.3 

LNR-19 2 16.4 17.9 10.8 28 25 3.1 >50.0 >50.0 11.1 9.9 Stable Stable 7.6 3.6 

2* 16.4 17.9 10.8 28 35 2.9 >50.0 >50.0 7.8 6.6 Stable Stable 5.5 2.7 2* 16.4 17.9 10.8 28 19 3.2 >50.0 >50.0 14.6 13.4 Stable Stable 9.8 4.5 2* 16.4 17.9 10.8 28 20 3.1 >50.0 >50.0 13.8 12.6 Stable Stable 9.5 4.4 2* 16.4 17.9 10.8 28 25 3.8 >50.0 >50.0 11.0 9.8 Stable Stable 6.9 2.9 2* 16.4 17.9 10.8 28 27 2.8 >50.0 >50.0 10.2 9.0 Stable Stable 7.5 3.7 2* 16.4 17.9 10.8 28 23 2.9 >50.0 >50.0 11.9 10.7 Stable Stable 8.4 4.0 

BNR-1 2 16.4 17.9 10.8 28 50 3.8 24.0 21.8 5.2 4.0 Stable Stable 3.2 1.4 

SS 12.9 16.5 10.5 31 41 3.8 >50.0 >50.0 6.8 5.5 Stable Stable 4.8 1.8 SS 12.9 16.5 10.5 31 60 3.6 18.9 16.0 4.4 3.1 Stable At Risk 3.2 1.2 

SS 12.9 16.5 10.5 31 42 3.8 >50.0 >50.0 6.6 5.3 Stable Stable 4.7 1.8 

SS 12.9 16.5 10.5 31 46 3.7 >50.0 >50.0 5.9 4.7 Stable Stable 4.2 1.6 SS 12.9 16.5 10.5 31 56 4.0 24.0 21.2 4.8 3.5 Stable At Risk 3.3 1.2 SS 12.9 16.5 10.5 31 55 3.9 25.8 23.0 4.9 3.6 Stable At Risk 3.4 1.3 

BNR-2 2 16.4 17.9 10.8 28 38 5.1 >50.0 >50.0 6.9 5.7 Stable Stable 3.8 1.4 

SS 16.0 18.8 7.0 33 31 5.3 >50.0 >50.0 5.4 4.7 Stable At Risk 4.4 1.0 SS 16.0 18.8 7.0 33 36 5.1 >50.0 >50.0 4.6 3.8 At Risk At Risk 3.8 0.9 SS 16.0 18.8 7.0 33 44 5.1 >50.0 >50.0 3.6 2.9 At Risk At Risk 3.0 0.7 

SS 16.0 18.8 7.0 33 42 5.2 >50.0 >50.0 3.9 3.2 At Risk At Risk 3.2 0.8 SS 16.0 18.8 7.0 33 36 4.9 >50.0 >50.0 4.5 3.8 At Risk At Risk 3.8 0.9 

SS 16.0 18.8 7.0 33 41 4.9 >50.0 >50.0 4.0 3.2 At Risk At Risk 3.3 0.8 

BNR-3 2 16.4 17.9 10.8 28 38 5.1 >50.0 >50.0 7.1 5.9 Stable Stable 3.8 1.4 

SS 18.9 20.1 5.4 32 34 4.6 >50.0 >50.0 3.5 2.9 At Risk At Risk 3.4 0.8 

SS 18.9 20.1 5.4 32 50 4.6 15.7 14.7 2.3 1.8 At Risk At Risk 2.2 0.5 SS 18.9 20.1 5.4 32 33 5.3 >50.0 >50.0 3.6 3.1 At Risk At Risk 3.4 0.7 SS 18.9 20.1 5.4 32 33 5.2 >50.0 >50.0 3.6 3.1 At Risk At Risk 3.4 0.7 SS 18.9 20.1 5.4 32 34 5.6 >50.0 >50.0 3.5 3.0 At Risk At Risk 3.3 0.6 SS 18.9 20.1 5.4 32 41 5.4 >50.0 >50.0 2.9 2.4 At Risk At Risk 2.7 0.5 

Little Nemaha River Basin--Continued

Big Nemaha River Basin
84 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued BNR-4 2 16.4 17.9 10.8 28 48 4.6 27.9 25.7 5.4 4.2 Stable At Risk 3.0 1.2 

SS 17.5 18.6 18.5 16 42 4.8 27.2 24.3 10.3 8.3 Stable Stable 3.8 2.1 

SS 17.5 18.6 18.5 16 43 4.7 26.3 23.4 10.1 8.2 Stable Stable 3.8 2.1 SS 17.5 18.6 18.5 16 60 4.2 12.9 10.0 6.9 5.0 Stable Stable 2.8 1.7 SS 17.5 18.6 18.5 16 48 4.6 20.1 17.3 8.9 6.9 Stable Stable 3.3 1.9 

BNR-5 2 16.4 17.9 10.8 28 24 5.6 >50.0 >50.0 11.5 10.3 Stable Stable 6.0 2.1 

SS 15.6 18.6 8.7 34 18 3.6 >50.0 >50.0 11.6 10.7 Stable Stable 9.7 3.3 SS 15.6 18.6 8.7 34 29 7.6 >50.0 >50.0 7.2 6.3 At Risk At Risk 4.6 0.9 

BNR-6 2 16.4 17.9 10.8 28 43 6.8 45.7 43.5 6.1 4.9 At Risk At Risk 3.0 0.9 

SS 17.6 18.6 15.3 21 22 6.4 >50.0 >50.0 17.0 15.3 Stable Stable 6.1 2.6 SS 17.6 18.6 15.3 21 64 6.5 10.8 8.3 5.3 3.6 At Risk At Risk 1.9 0.8 SS 17.6 18.6 15.3 21 33 7.5 >50.0 >50.0 10.9 9.3 Stable Stable 3.7 1.5 

SS 17.6 18.6 15.3 21 53 6.7 16.7 14.2 6.6 4.9 At Risk At Risk 2.3 1.0 

BNR-7 2 16.4 17.9 10.8 28 43 5.1 45.5 43.3 6.1 4.9 Stable At Risk 3.3 1.2 

SS 18.0 18.9 21.0 27 39 5.5 >50.0 >50.0 12.7 10.4 Stable Stable 4.6 2.3 SS 18.0 18.9 21.0 27 52 4.9 35.4 31.6 9.1 6.9 Stable Stable 3.5 1.9 SS 18.0 18.9 21.0 27 39 4.7 >50.0 >50.0 12.4 10.2 Stable Stable 4.9 2.6 SS 18.0 18.9 21.0 27 42 5.3 >50.0 >50.0 11.5 9.3 Stable Stable 4.2 2.2 

BNR-8 2 16.4 17.9 10.8 28 42 4.5 >50.0 49.7 6.3 5.1 Stable Stable 3.6 1.4 

SS 18.4 19.1 15.0 24 62 5.0 12.1 9.6 5.2 3.6 Stable At Risk 2.2 1.0 

SS 18.4 19.1 15.0 24 43 4.4 35.8 33.3 8.0 6.4 Stable Stable 3.6 1.8 

SS 18.4 19.1 15.0 24 16 4.2 >50.0 >50.0 22.8 21.3 Stable Stable 10.7 5.5 SS 18.4 19.1 15.0 24 47 4.6 27.0 24.5 7.3 5.7 Stable Stable 3.2 1.6 

BNR-9 2 16.4 17.9 10.8 28 31 10.5 >50.0 >50.0 8.7 7.5 At Risk At Risk 3.7 0.8 

SS 19.0 19.2 22.5 24 28 10.7 >50.0 >50.0 18.6 16.2 Stable Stable 4.4 1.7 SS 19.0 19.2 22.5 24 41 11.2 >50.0 >50.0 12.4 10.1 Stable At Risk 2.9 1.1 

SS 19.0 19.2 22.5 24 22 10.5 >50.0 >50.0 23.7 21.4 Stable Stable 5.7 2.3 SS 19.0 19.2 22.5 24 32 9.4 >50.0 >50.0 16.3 13.9 Stable Stable 4.1 1.7 

BNR-10 2 16.4 17.9 10.8 28 42 2.5 >50.0 >50.0 6.3 5.1 Stable Stable 4.9 2.5 

SS 15.5 17.3 11.7 20 41 2.5 26.7 24.5 7.2 5.9 Stable Stable 5.0 2.8 SS 15.5 17.3 11.7 20 40 2.1 29.1 27.0 7.4 6.1 Stable Stable 5.7 3.5 SS 15.5 17.3 11.7 20 41 2.6 26.8 24.7 7.2 5.9 Stable Stable 4.9 2.8 SS 15.5 17.3 11.7 20 37 2.2 36.0 33.9 8.0 6.6 Stable Stable 6.1 3.7 SS 15.5 17.3 11.7 20 44 2.8 22.6 20.5 6.8 5.4 Stable Stable 4.3 2.4 SS 15.5 17.3 11.7 20 48 2.7 17.9 15.8 6.1 4.8 Stable Stable 4.1 2.3 

BNR-11 2 16.4 17.9 10.8 28 47 4.6 31.2 29.0 5.6 4.4 Stable At Risk 3.1 1.2 

SS 16.6 18.0 20.3 24 48 4.3 38.7 34.9 10.2 8.0 Stable Stable 4.2 2.4 

SS 16.6 18.0 20.3 24 57 4.7 23.2 19.4 8.4 6.1 Stable Stable 3.3 1.8 SS 16.6 18.0 20.3 24 48 4.6 38.3 34.5 10.2 7.9 Stable Stable 4.0 2.2 SS 16.6 18.0 20.3 24 35 4.7 >50.0 >50.0 14.2 11.9 Stable Stable 5.5 3.0 

Big Nemaha River Basin--Continued
Table 4 85

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued

BNR-12 2 16.4 17.9 10.8 28 39 2.4 >50.0 >50.0 6.8 5.6 Stable Stable 5.4 2.9 

SS 18.6 19.7 12.4 33 42 2.2 >50.0 >50.0 6.6 5.3 Stable Stable 5.5 3.0 SS 18.6 19.7 12.4 33 37 3.7 >50.0 >50.0 7.5 6.3 Stable Stable 4.7 2.1 SS 18.6 19.7 12.4 33 53 2.4 28.0 25.6 5.0 3.8 Stable Stable 4.0 2.1 SS 18.6 19.7 12.4 33 23 2.1 >50.0 >50.0 12.2 11.0 Stable Stable 10.3 5.7 SS 18.6 19.7 12.4 33 38 2.2 >50.0 >50.0 7.4 6.1 Stable Stable 6.0 3.3 SS 18.6 19.7 12.4 33 41 1.7 >50.0 >50.0 6.7 5.4 Stable Stable 6.5 3.9 

BNR-13 2 16.4 17.9 10.8 28 45 8.3 37.7 35.5 5.8 4.6 At Risk At Risk 2.6 0.7 

SS 18.6 18.8 10.1 25 52 7.0 13.5 11.8 4.4 3.3 At Risk At Risk 2.0 0.6 SS 18.6 18.8 10.1 25 28 8.3 >50.0 >50.0 8.5 7.5 Stable At Risk 3.8 1.0 

SS 18.6 18.8 10.1 25 41 6.5 31.5 29.8 5.7 4.7 At Risk At Risk 2.7 0.9 

SS 18.6 18.8 10.1 25 59 9.6 9.7 8.0 3.8 2.7 At Risk Unstable 1.6 0.4 

SS 18.6 18.8 10.1 25 48 8.4 17.4 15.7 4.8 3.7 At Risk At Risk 2.1 0.6 

SS 18.6 18.8 10.1 25 41 9.7 33.2 31.5 5.8 4.7 At Risk At Risk 2.4 0.6 

BNR-14 2 16.4 17.9 10.8 28 28 7.4 >50.0 >50.0 9.7 8.5 Stable Stable 4.6 1.3 

SS 17.9 18.7 15.8 34 31 7.8 >50.0 >50.0 12.3 10.6 Stable Stable 4.8 1.6 SS 17.9 18.7 15.8 34 25 7.1 >50.0 >50.0 14.9 13.2 Stable Stable 6.1 2.1 

BNR-15 2 16.4 17.9 10.8 28 28 4.0 >50.0 >50.0 9.8 8.6 Stable Stable 6.0 2.5 

SS 18.4 19.2 11.2 30 28 4.0 >50.0 >50.0 9.3 8.1 Stable Stable 5.6 2.3 SS 18.4 19.2 11.2 30 27 3.9 >50.0 >50.0 9.7 8.6 Stable Stable 5.9 2.5 

BNR-16 2 16.4 17.9 10.8 28 37 9.4 >50.0 >50.0 7.2 6.0 At Risk At Risk 3.1 0.8 

SS 17.4 18.6 7.6 33 28 7.9 >50.0 >50.0 6.4 5.6 At Risk At Risk 4.2 0.8 

SS 17.4 18.6 7.6 33 36 9.7 >50.0 >50.0 5.1 4.3 At Risk At Risk 3.2 0.5 

SS 17.4 18.6 7.6 33 25 9.6 >50.0 >50.0 7.4 6.6 At Risk At Risk 4.7 0.8 

SS 17.4 18.6 7.6 33 46 9.3 43.6 42.0 3.9 3.1 At Risk At Risk 2.4 0.4 

SS 17.4 18.6 7.6 33 34 9.7 >50.0 >50.0 5.4 4.6 At Risk At Risk 3.4 0.6 SS 17.4 18.6 7.6 33 54 10.1 17.5 15.9 3.2 2.4 At Risk At Risk 1.9 0.3 

BNR-17 2 16.4 17.9 10.8 28 34 7.5 >50.0 >50.0 7.9 6.7 Stable At Risk 3.7 1.0 

SS 16.9 17.8 7.8 24 30 7.8 >50.0 >50.0 6.5 5.6 At Risk At Risk 3.5 0.8 

SS 16.9 17.8 7.8 24 35 8.5 >50.0 >50.0 5.5 4.6 At Risk At Risk 2.9 0.6 SS 16.9 17.8 7.8 24 27 6.6 >50.0 >50.0 7.4 6.5 Stable At Risk 4.1 1.1 

SS 16.9 17.8 7.8 24 33 7.3 >50.0 >50.0 6.0 5.1 At Risk At Risk 3.3 0.8 

SS 16.9 17.8 7.8 24 34 7.8 >50.0 >50.0 5.8 4.9 At Risk At Risk 3.1 0.7 SS 16.9 17.8 7.8 24 36 7.1 48.0 46.6 5.4 4.5 At Risk At Risk 3.0 0.8 SS 16.9 17.8 7.8 24 47 7.5 15.7 14.3 4.0 3.1 At Risk At Risk 2.2 0.5 SS 16.9 17.8 7.8 24 30 7.5 >50.0 >50.0 6.5 5.6 At Risk At Risk 3.5 0.9 SS 16.9 17.8 7.8 24 34 7.7 >50.0 >50.0 5.8 4.9 At Risk At Risk 3.1 0.7 SS 16.9 17.8 7.8 24 34 7.4 >50.0 >50.0 5.7 4.8 At Risk At Risk 3.1 0.8 

Big Nemaha River Basin--Continued
86 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturated CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued BBR-1 1 15.9 17.6 13.6 26 36 3.4 >50.0 >50.0 9.4 7.8 Stable Stable 5.5 2.8 

SS 17.3 18.4 18.0 22 36 4.2 >50.0 >50.0 12.2 10.2 Stable Stable 5.2 2.9 SS 17.3 18.4 18.0 22 29 2.9 >50.0 >50.0 14.9 13.0 Stable Stable 8.1 5.2 SS 17.3 18.4 18.0 22 50 3.6 25.5 22.4 8.5 6.5 Stable Stable 4.0 2.4 SS 17.3 18.4 18.0 22 21 3.2 >50.0 >50.0 20.7 18.7 Stable Stable 10.6 6.5 SS 17.3 18.4 18.0 22 58 3.3 17.2 14.2 7.1 5.2 Stable Stable 3.5 2.1 SS 17.3 18.4 18.0 22 31 2.7 >50.0 >50.0 14.0 12.0 Stable Stable 7.9 5.1 SS 17.3 18.4 18.0 22 30 3.4 >50.0 >50.0 14.8 12.8 Stable Stable 7.2 4.4 SS 17.3 18.4 18.0 22 42 3.1 40.5 37.5 10.1 8.1 Stable Stable 5.2 3.2 SS 17.3 18.4 18.0 22 39 3.4 >50.0 49.6 10.9 9.0 Stable Stable 5.3 3.2 SS 17.3 18.4 18.0 22 32 4.1 >50.0 >50.0 13.5 11.5 Stable Stable 5.9 3.3 SS 17.3 18.4 18.0 22 39 3.1 >50.0 49.8 11.0 9.0 Stable Stable 5.7 3.6 SS 17.3 18.4 18.0 22 25 3.4 >50.0 >50.0 17.7 15.7 Stable Stable 8.6 5.2 SS 17.3 18.4 18.0 22 51 3.3 24.1 21.0 8.3 6.3 Stable Stable 4.1 2.5 SS 17.3 18.4 18.0 22 27 3.4 >50.0 >50.0 16.5 14.6 Stable Stable 8.1 4.9 

BBR-2 1 15.9 17.6 13.6 26 47 0.9 33.8 31.0 7.1 5.6 Stable Stable 10.2 7.6 

SS 16.0 17.6 6.4 29 50 0.9 15.1 13.8 3.1 2.4 Stable Stable 5.6 3.5 SS 16.0 17.6 6.4 29 46 0.9 20.9 19.5 3.4 2.7 Stable Stable 6.3 4.0 SS 16.0 17.6 6.4 29 52 0.9 13.1 11.8 3.0 2.2 Stable Stable 5.2 3.1 SS 16.0 17.6 6.4 29 44 0.9 26.7 25.3 3.6 2.9 Stable Stable 6.6 4.1 SS 16.0 17.6 6.4 29 52 1.1 13.8 12.4 3.0 2.3 Stable Stable 4.7 2.7 

SS 16.0 17.6 6.4 29 38 0.9 >50.0 >50.0 4.3 3.6 Stable Stable 7.6 4.6 

BBR-3 1 15.9 17.6 13.6 26 50 1.7 27.0 24.2 6.6 5.1 Stable Stable 5.9 3.8 

SS 16.7 17.6 7.2 23 64 1.7 5.9 4.5 2.6 1.8 Stable Stable 2.8 1.6 SS 16.7 17.6 7.2 23 46 1.5 14.2 12.9 3.8 3.0 Stable Stable 4.3 2.5 SS 16.7 17.6 7.2 23 43 2.1 18.5 17.2 4.2 3.4 Stable Stable 3.9 2.0 SS 16.7 17.6 7.2 23 71 1.4 4.5 3.2 2.3 1.5 Stable Stable 2.8 1.7 SS 16.7 17.6 7.2 23 41 1.9 21.0 19.7 4.3 3.5 Stable Stable 4.3 2.3 SS 16.7 17.6 7.2 23 36 1.9 39.5 38.2 5.1 4.3 Stable Stable 5.0 2.7 

BBR-4 3 16.5 18.1 6.7 30 36 3.0 >50.0 >50.0 4.5 3.8 Stable Stable 4.2 1.5 

SS 17.9 18.7 8.9 28 37 2.8 >50.0 >50.0 5.7 4.7 Stable Stable 4.4 2.0 SS 17.9 18.7 8.9 28 40 3.2 47.1 45.4 5.2 4.3 Stable Stable 3.8 1.6 SS 17.9 18.7 8.9 28 32 2.9 >50.0 >50.0 6.7 5.7 Stable Stable 5.1 2.3 SS 17.9 18.7 8.9 28 35 3.4 >50.0 >50.0 6.1 5.2 Stable Stable 4.3 1.8 SS 17.9 18.7 8.9 28 38 2.8 >50.0 >50.0 5.5 4.6 Stable Stable 4.2 1.9 SS 17.9 18.7 8.9 28 41 2.9 42.9 41.2 5.1 4.2 Stable Stable 3.9 1.7 SS 17.9 18.7 8.9 28 37 3.0 >50.0 >50.0 5.8 4.8 Stable Stable 4.4 2.0 SS 17.9 18.7 8.9 28 32 3.1 >50.0 >50.0 6.8 5.8 Stable Stable 5.0 2.2 

Big Blue River Basin
Table 4 87

Site ID

Soil

group

Ambient

soil unit 

weight,

γ amb

Saturated

soil unit 

weight,

γ sat

Effective

cohesion,

c'

Friction

angle,

φ

Vertically

weighted

bank

angle

Bank

height

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Critical

bank

height,

H c

Critical bank 

height with 

tension

crack, H cz

Without

tension

cracks

With

tension

cracks

Ambient

CW0--

BW0

Saturated

CW0--

BW100

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary res

Culmann method ARS metho

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil dat

banks--Continued

BBR-5 3 16.5 18.1 6.7 30 39 4.1 >50.0 >50.0 4.2 3.4 Stable At Risk 3.4 1.0 

SS 17.2 18.6 14.1 40 40 3.9 >50.0 >50.0 8.4 6.9 Stable Stable 5.2 2.2 SS 17.2 18.6 14.1 40 38 4.1 >50.0 >50.0 8.8 7.3 Stable Stable 5.3 2.1 SS 17.2 18.6 14.1 40 33 5.0 >50.0 >50.0 10.4 8.9 Stable Stable 5.8 2.1 SS 17.2 18.6 14.1 40 40 4.6 >50.0 >50.0 8.4 6.9 Stable Stable 4.8 1.8 SS 17.2 18.6 14.1 40 48 3.3 >50.0 >50.0 6.9 5.4 Stable Stable 4.6 2.1 SS 17.2 18.6 14.1 40 37 3.9 >50.0 >50.0 9.1 7.6 Stable Stable 5.6 2.3 

BBR-6 3 16.5 18.1 6.7 30 29 2.3 >50.0 >50.0 5.7 5.0 Stable Stable 6.1 2.5 

SS 18.3 19.6 7.0 31 20 2.2 >50.0 >50.0 8.1 7.4 Stable Stable 8.7 3.7 SS 18.3 19.6 7.0 31 11 2.3 >50.0 >50.0 14.9 14.2 Stable Stable 15.7 6.6 SS 18.3 19.6 7.0 31 24 2.2 >50.0 >50.0 6.7 6.0 Stable Stable 7.2 3.0 SS 18.3 19.6 7.0 31 28 1.7 >50.0 >50.0 5.8 5.1 Stable Stable 7.1 3.5 SS 18.3 19.6 7.0 31 39 2.2 >50.0 >50.0 4.1 3.3 Stable Stable 4.4 1.9 SS 18.3 19.6 7.0 31 32 2.3 >50.0 >50.0 5.0 4.3 Stable Stable 5.2 2.2 SS 18.3 19.6 7.0 31 43 2.5 39.1 37.7 3.6 2.9 Stable Stable 3.6 1.4 SS 18.3 19.6 7.0 31 34 2.7 >50.0 >50.0 4.6 3.9 Stable Stable 4.5 1.7 

BBR-7 3 16.5 18.1 6.7 30 37 2.8 >50.0 >50.0 4.4 3.7 Stable Stable 4.3 1.6 

SS 14.9 17.5 4.3 30 42 2.8 31.2 30.2 2.6 2.1 At Risk At Risk 3.3 0.9 

SS 14.9 17.5 4.3 30 24 2.7 >50.0 >50.0 4.7 4.2 Stable Stable 6.2 1.8 

SS 14.9 17.5 4.3 30 43 3.1 28.4 27.4 2.5 2.0 At Risk At Risk 3.1 0.8 

SS 14.9 17.5 4.3 30 41 2.4 34.8 33.8 2.6 2.1 Stable At Risk 3.6 1.1 

SS 14.9 17.5 4.3 30 34 2.9 >50.0 >50.0 3.2 2.7 Stable At Risk 4.1 1.1 

SS 14.9 17.5 4.3 30 38 2.9 >50.0 >50.0 2.9 2.4 Stable At Risk 3.7 1.0 

BBR-8 3 16.5 18.1 6.7 30 35 4.5 >50.0 >50.0 4.7 3.9 Stable At Risk 3.7 1.0 

SS 17.4 18.1 12.6 19 46 5.0 17.8 15.7 6.5 5.1 Stable Stable 2.8 1.3 SS 17.4 18.1 12.6 19 21 4.3 >50.0 >50.0 14.8 13.4 Stable Stable 6.9 3.5 SS 17.4 18.1 12.6 19 38 3.7 31.0 29.0 8.1 6.7 Stable Stable 4.1 2.2 SS 17.4 18.1 12.6 19 33 5.3 >50.0 48.2 9.4 8.0 Stable Stable 3.9 1.8 SS 17.4 18.1 12.6 19 34 3.5 45.7 43.7 9.1 7.8 Stable Stable 4.8 2.6 SS 17.4 18.1 12.6 19 39 5.4 28.9 26.9 7.9 6.5 Stable Stable 3.3 1.4 

BBR-9 3 16.5 18.1 6.7 30 44 4.6 35.7 34.3 3.7 2.9 At Risk At Risk 2.9 0.8 

SS 17.1 18.5 13.9 27 46 5.6 39.1 36.4 7.1 5.6 Stable At Risk 3.2 1.3 

SS 17.1 18.5 13.9 27 26 5.8 >50.0 >50.0 13.0 11.5 Stable Stable 5.8 2.2 SS 17.1 18.5 13.9 27 63 3.2 13.7 11.0 4.9 3.4 Stable Stable 2.9 1.5 SS 17.1 18.5 13.9 27 40 3.8 >50.0 >50.0 8.2 6.7 Stable Stable 4.5 2.2 

Big Blue River Basin--Continued
88 Stream Bank Stability in Eastern Nebraska Site ID Soil group Ambient soil unit weight, γ amb Saturated soil unit weight, γ sat Effective cohesion, c' Friction angle, φ Vertically weighted bank angle Bank height Critical bank height, H c Critical bank height with tension crack, H cz Critical bank height, H c Critical bank height with tension crack, H cz Without tension cracks With tension cracks Ambient CW0-- BW0 Saturate

CW0-- BW100 

(kN/m3) (kN/m3) (kPa) (o) (o) (m) (m) (m) (m) (m) (F S ) (F S ) 

Ambient conditions Saturated conditions Summary results Summary re

Culmann method ARS meth

Table 4. Results of Culmann, Agricultural Research Service (ARS), and indirect methods of bank-stability analysis based on few soil da

banks--Continued BBR-10 3 16.5 18.1 6.7 30 35 4.5 >50.0 >50.0 4.7 4.0 Stable At Risk 3.8 1.1 

SS 18.3 19.1 2.5 38 31 4.4 >50.0 >50.0 1.9 1.6 At Risk At Risk 3.7 0.4 

SS 18.3 19.1 2.5 38 44 4.0 47.0 46.5 1.3 1.0 At Risk At Risk 2.5 0.3 SS 18.3 19.1 2.5 38 58 4.2 6.0 5.5 1.0 0.7 At Risk At Risk 1.8 0.2 

SS 18.3 19.1 2.5 38 28 6.0 >50.0 >50.0 2.1 1.9 At Risk At Risk 4.0 0.4 

SS 18.3 19.1 2.5 38 41 4.3 >50.0 >50.0 1.4 1.1 At Risk At Risk 2.7 0.3 SS 18.3 19.1 2.5 38 29 4.5 >50.0 >50.0 2.0 1.8 At Risk At Risk 4.0 0.5 SS 18.3 19.1 2.5 38 25 4.3 >50.0 >50.0 2.4 2.1 At Risk At Risk 4.7 0.6 

SS 18.3 19.1 2.5 38 25 3.8 >50.0 >50.0 2.4 2.1 At Risk At Risk 4.8 0.6 

BBR-11 3 16.5 18.1 6.7 30 39 3.9 >50.0 >50.0 4.2 3.4 Stable At Risk 3.5 1.1 

SS 13.3 17.1 10.8 30 47 4.8 47.4 44.6 5.9 4.6 Stable At Risk 3.7 1.2 SS 13.3 17.1 10.8 30 36 3.9 >50.0 >50.0 7.9 6.6 Stable Stable 5.4 2.0 SS 13.3 17.1 10.8 30 41 3.6 >50.0 >50.0 6.7 5.4 Stable Stable 4.8 1.9 SS 13.3 17.1 10.8 30 34 3.9 >50.0 >50.0 8.3 7.0 Stable Stable 5.7 2.1 SS 13.3 17.1 10.8 30 43 3.1 >50.0 >50.0 6.4 5.2 Stable Stable 5.0 2.1 SS 13.3 17.1 10.8 30 34 3.8 >50.0 >50.0 8.2 6.9 Stable Stable 5.7 2.2 

BBR-12 3 16.5 18.1 6.7 30 53 3.6 14.3 12.9 3.0 2.2 At Risk At Risk 2.6 0.8 

SS 18.0 19.0 12.7 30 67 2.9 10.8 8.4 4.0 2.7 Stable At Risk 2.6 1.4 

SS 18.0 19.0 12.7 30 43 3.2 >50.0 >50.0 6.8 5.5 Stable Stable 4.3 2.1 

SS 18.0 19.0 12.7 30 61 3.9 14.9 12.5 4.6 3.2 Stable At Risk 2.6 1.2 SS 18.0 19.0 12.7 30 42 4.2 >50.0 >50.0 6.9 5.6 Stable Stable 3.8 1.7 

BBR-13 3 16.5 18.1 6.7 30 36 5.8 >50.0 >50.0 4.5 3.8 At Risk At Risk 3.4 0.8 

SS 15.1 18.5 2.3 38 46 5.8 35.4 34.8 1.2 0.9 At Risk At Risk 2.5 0.2 SS 15.1 18.5 2.3 38 30 5.7 >50.0 >50.0 1.8 1.6 At Risk At Risk 4.0 0.3 SS 15.1 18.5 2.3 38 39 5.4 >50.0 >50.0 1.4 1.2 At Risk At Risk 3.1 0.3 SS 15.1 18.5 2.3 38 30 6.3 >50.0 >50.0 1.9 1.6 At Risk At Risk 4.0 0.3 

Big Blue River Basin--Continued
Table 5 89

Table 5. Number and percent of bank sections for each method of analysis by stability category and soil group[Percent values are in bold font; because of rounding, the individual values may not add up to 100 for a given method or condition]

Soil 

group

Number 

of bank 

sections

Culmann

Without tension cracks With tension cracks ARS Method Indi

Unstable At Risk Stable Unstable At Risk Stable Unstable At Risk Stable Unstable At Ri

1 72 0 5 67 0 6 66 0 5 67 0 6 

0 7 93 0 8 92 0 7 93 0 8 

2 724 6 248 470 10 312 402 0 253 471 22 247 

1 34 65 1 43 56 0 35 65 3 34 

3-4 112 1 37 74 3 49 60 0 38 74 6 33 

1 33 66 3 44 54 0 34 66 5 29 

All 908 7 290 611 13 367 528 0 296 612 28 286 

1 32 67 1 40 58 0 33 67 3 31 
90 Stream Bank Stability in Eastern Nebraska

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°

Ambient Soil Unit Weight = 12.0 kilonewton per cubic meter

0 10 1 0.7 0.3 0.2 0.2 0.2

0 10 3 0.7 0.3 0.2 0.1 0.1

0 10 6 0.7 0.3 0.2 0.1 0.1

0 10 12 0.7 0.3 0.2 0.1 0.1

0 25 1 1.8 0.8 0.5 0.5 0.6

0 25 3 1.8 0.9 0.5 0.3 0.2

0 25 6 1.8 0.9 0.5 0.3 0.1

0 25 12 1.8 0.9 0.5 0.3 0.2

0 40 1 3.2 1.5 0.9 0.9 1.0

0 40 3 3.2 1.5 0.8 0.5 0.4

0 40 6 3.2 1.6 0.8 0.5 0.2

0 40 12 3.2 1.6 0.9 0.5 0.3

1 10 1 1.4 1.0 0.8 0.7 0.5

1 10 3 0.9 0.6 0.4 0.3 0.2

1 10 6 0.8 0.5 0.3 0.2 0.1

1 10 12 0.7 0.4 0.3 0.2 0.1

1 25 1 2.5 1.8 1.2 1.0 0.9

1 25 3 2.1 1.2 0.8 0.5 0.3

1 25 6 1.9 1.1 0.6 0.4 0.2

1 25 12 1.8 1.0 0.6 0.3 0.1

1 40 1 4.0 2.6 1.8 1.4 1.3

1 40 3 3.5 2.0 1.2 0.8 0.5

1 40 6 3.3 1.8 1.0 0.6 0.3

1 40 12 3.3 1.7 1.0 0.6 0.4

8 10 1 5.0 4.4 4.2 3.6 2.8

8 10 3 2.3 1.9 1.5 1.2 0.9

8 10 6 1.6 1.2 0.9 0.7 0.5

8 10 12 1.2 0.8 0.6 0.4 0.3

8 25 1 6.5 5.4 4.6 4.1 3.2

8 25 3 3.6 2.7 2.1 1.5 1.1

8 25 6 2.8 2.0 1.4 1.0 0.7

8 25 12 2.3 1.5 1.0 0.7 0.4

8 40 1 8.3 6.6 5.3 4.5 3.6

8 40 3 5.1 3.7 2.6 1.9 1.4

8 40 6 4.3 2.8 1.9 1.3 0.8

8 40 12 3.8 2.3 1.4 1.0 0.5

15 10 18.6 7.7 7.1 6.5 5.1

15 10 33.5 3.0 2.6 2.1 1.7

15 10 62.2 1.8 1.5 1.2 0.9

15 10 12 1.5 1.2 0.9 0.7 0.5

15 25 1 10.1 8.7 8.2 7.0 5.4

15 25 34.9 4.0 3.2 2.5 1.9

15 25 63.5 2.6 2.0 1.5 1.1

15 25 12 2.7 1.9 1.3 1.0 0.6

15 40 1 12.1 10.1 8.6 7.6 6.0

15 40 36.6 5.0 3.8 2.9 2.1

15 40 65.0 3.6 2.5 1.9 1.3

15 40 12 4.2 2.8 1.8 1.3 0.8

30 10 116.2 14.7 13.6 12.7 10.0

30 10 36.1 5.4 4.9 4.1 3.3

30 10 63.5 3.0 2.6 2.1 1.6

30 10 12 2.2 1.8 1.5 1.2 0.8

30 25 117.8 15.8 14.5 13.2 10.3

30 25 37.6 6.5 5.4 4.4 3.4

30 25 64.9 4.0 3.2 2.5 1.8

30 25 12 3.5 2.6 2.0 1.5 1.0

30 40 119.8 17.2 16.3 13.8 10.7

30 40 39.4 7.6 6.2 4.9 3.7

30 40 66.6 5.0 3.8 2.9 2.1

30 40 12 5.0 3.6 2.6 1.9 1.3
Table 6 91

Ambient Soil Unit Weight = 15.0 kilonewton per cubic meter

0 10 1 0.7 0.3 0.2 0.2 0.2

0 10 3 0.7 0.3 0.2 0.1 0.1

0 10 6 0.7 0.3 0.2 0.1 0.1

0 10 12 0.7 0.3 0.2 0.1 0.1

0 25 1 1.8 0.8 0.5 0.5 0.6

0 25 3 1.8 0.9 0.5 0.3 0.2

0 25 6 1.8 0.9 0.5 0.3 0.1

0 25 12 1.8 0.9 0.5 0.3 0.2

0 40 1 3.2 1.5 0.9 0.9 1.0

0 40 3 3.2 1.5 0.8 0.5 0.4

0 40 6 3.2 1.6 0.8 0.5 0.2

0 40 12 3.2 1.6 0.9 0.5 0.3

1 10 1 1.2 0.9 0.7 0.6 0.5

1 10 3 0.9 0.6 0.4 0.3 0.2

1 10 6 0.8 0.5 0.3 0.2 0.1

1 10 12 0.7 0.4 0.3 0.2 0.1

1 25 1 2.4 1.6 1.1 0.9 0.8

1 25 3 2.0 1.2 0.7 0.5 0.3

1 25 6 1.9 1.1 0.6 0.4 0.2

1 25 12 1.9 1.0 0.6 0.3 0.2

1 40 1 3.9 2.4 1.7 1.3 1.3

1 40 3 3.5 1.9 1.1 0.7 0.5

1 40 6 3.3 1.8 1.0 0.6 0.3

1 40 12 3.3 1.7 1.0 0.6 0.4

8 10 1 4.2 3.7 3.5 2.9 2.3

8 10 3 2.0 1.6 1.3 1.0 0.7

8 10 6 1.4 1.1 0.8 0.6 0.4

8 10 12 1.1 0.8 0.5 0.4 0.3

8 25 1 5.7 4.7 3.9 3.3 2.7

8 25 3 3.3 2.4 1.8 1.3 1.0

8 25 6 2.6 1.8 1.2 0.9 0.6

8 25 12 2.3 1.4 0.9 0.6 0.4

8 40 1 7.5 5.8 4.8 4.0 3.1

8 40 3 4.9 3.4 2.4 1.7 1.2

8 40 6 4.1 2.6 1.7 1.2 0.7

8 40 12 3.7 2.2 1.3 0.9 0.5

15 10 17.1 6.3 5.8 5.3 4.1

15 10 33.0 2.6 2.2 1.7 1.4

15 10 62.0 1.6 1.2 1.0 0.7

15 10 12 1.4 1.0 0.8 0.6 0.4

15 25 18.7 7.4 6.5 5.7 4.4

15 25 34.4 3.5 2.7 2.1 1.5

15 25 63.2 2.4 1.7 1.3 0.9

15 25 12 2.6 1.8 1.2 0.9 0.6

15 40 1 10.5 8.7 7.2 6.2 5.0

15 40 36.1 4.5 3.3 2.5 1.8

15 40 64.8 3.3 2.3 1.6 1.1

15 40 12 4.1 2.6 1.7 1.2 0.7

30 10 113.2 11.9 11.0 10.3 8.0

30 10 35.1 4.4 4.0 3.3 2.6

30 10 63.0 2.6 2.2 1.7 1.3

30 10 12 2.0 1.6 1.2 1.0 0.7

30 25 114.8 13.0 11.8 10.7 8.4

30 25 36.6 5.5 4.5 3.7 2.8

30 25 64.4 3.5 2.7 2.1 1.5

30 25 12 3.2 2.4 1.7 1.3 0.9

30 40 116.8 14.4 12.9 11.3 8.8

30 40 38.4 6.6 5.3 4.1 3.0

30 40 66.1 4.5 3.3 2.5 1.8

30 40 12 4.8 3.3 2.3 1.6 1.1

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°
92 Stream Bank Stability in Eastern Nebraska

Ambient Soil Unit Weight = 18.0 kilonewton per cubic meter

0 10 1 0.7 0.3 0.2 0.2 0.2

0 10 3 0.7 0.3 0.2 0.1 0.1

0 10 6 0.7 0.3 0.2 0.1 0.1

0 10 12 0.7 0.3 0.2 0.1 0.1

0 25 1 1.8 0.8 0.5 0.5 0.6

0 25 3 1.8 0.9 0.5 0.3 0.2

0 25 6 1.8 0.9 0.5 0.3 0.1

0 25 12 1.8 0.9 0.5 0.3 0.2

0 40 1 3.2 1.5 0.9 0.9 1.0

0 40 3 3.2 1.5 0.8 0.5 0.4

0 40 6 3.2 1.6 0.8 0.5 0.2

0 40 12 3.2 1.6 0.9 0.5 0.3

1 10 1 1.2 0.9 0.6 0.5 0.4

1 10 3 0.9 0.6 0.4 0.3 0.2

1 10 6 0.8 0.5 0.3 0.2 0.1

1 10 12 0.7 0.4 0.2 0.2 0.1

1 25 1 2.4 1.5 1.1 0.8 0.8

1 25 3 2.0 1.2 0.7 0.4 0.3

1 25 6 1.9 1.0 0.6 0.4 0.2

1 25 12 1.9 1.0 0.6 0.3 0.2

1 40 1 3.8 2.3 1.6 1.2 1.2

1 40 3 3.5 1.9 1.1 0.7 0.5

1 40 6 3.4 1.8 1.0 0.6 0.3

1 40 12 3.3 1.7 1.0 0.6 0.4

8 10 1 3.7 3.2 2.8 2.5 1.9

8 10 3 1.8 1.5 1.1 0.9 0.7

8 10 6 1.3 1.0 0.7 0.5 0.4

8 10 12 1.0 0.7 0.5 0.4 0.2

8 25 1 5.2 4.2 3.4 2.9 2.3

8 25 3 3.1 2.2 1.6 1.2 0.8

8 25 6 2.5 1.7 1.1 0.8 0.5

8 25 12 2.2 1.3 0.9 0.6 0.3

8 40 1 6.9 5.2 4.1 3.5 2.8

8 40 3 4.7 3.1 2.1 1.6 1.1

8 40 6 4.0 2.5 1.6 1.1 0.7

8 40 12 3.6 2.1 1.3 0.8 0.5

15 10 16.1 5.4 4.9 4.4 3.5

15 10 32.7 2.2 1.9 1.5 1.1

15 10 61.8 1.4 1.1 0.8 0.6

15 10 12 1.3 0.9 0.7 0.5 0.3

15 25 17.7 6.4 5.6 4.9 3.9

15 25 34.1 3.1 2.4 1.8 1.3

15 25 63.0 2.2 1.6 1.1 0.8

15 25 12 2.5 1.6 1.1 0.8 0.5

15 40 19.5 7.7 6.2 5.4 4.3

15 40 35.7 4.1 3.0 2.2 1.6

15 40 64.6 3.1 2.1 1.5 1.0

15 40 12 4.0 2.5 1.6 1.1 0.6

30 10 1 11.2 10.1 9.3 8.6 6.7

30 10 34.4 3.8 3.4 2.8 2.2

30 10 62.7 2.2 1.9 1.5 1.1

30 10 12 1.8 1.4 1.1 0.8 0.6

30 25 1 12.8 11.2 10.6 9.1 7.1

30 25 35.9 4.8 3.9 3.1 2.4

30 25 64.1 3.1 2.4 1.8 1.3

30 25 12 3.0 2.2 1.6 1.1 0.8

30 40 1 14.9 12.5 11.0 9.7 7.6

30 40 37.7 6.0 4.6 3.6 2.6

30 40 65.7 4.1 3.0 2.2 1.6

30 40 12 4.6 3.1 2.1 1.5 1.0

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°
Table 6 93

Ambient Soil Unit Weight = 20.0 kilonewton per cubic meter

0 10 1 0.7 0.3 0.2 0.2 0.2

0 10 3 0.7 0.3 0.2 0.1 0.1

0 10 6 0.7 0.3 0.2 0.1 0.1

0 10 12 0.7 0.3 0.2 0.1 0.1

0 25 1 1.8 0.8 0.5 0.5 0.6

0 25 3 1.8 0.9 0.5 0.3 0.2

0 25 6 1.8 0.9 0.5 0.3 0.1

0 25 12 1.8 0.9 0.5 0.3 0.2

0 40 1 3.2 1.5 0.9 0.9 1.0

0 40 3 3.2 1.5 0.8 0.5 0.4

0 40 6 3.2 1.6 0.8 0.5 0.2

0 40 12 3.2 1.6 0.9 0.5 0.3

1 10 1 1.1 0.9 0.6 0.5 0.4

1 10 3 0.8 0.5 0.3 0.2 0.2

1 10 6 0.8 0.5 0.3 0.2 0.1

1 10 12 0.7 0.4 0.2 0.1 0.1

1 25 1 2.3 1.5 1.0 0.8 0.8

1 25 3 11.6 1.1 0.7 0.4 0.3

1 25 6 1.9 1.0 0.6 0.4 0.2

1 25 12 1.8 1.0 0.6 0.3 0.2

1 40 1 3.7 2.2 1.5 1.2 1.2

1 40 3 3.4 1.8 1.1 0.7 0.5

1 40 6 3.3 1.8 1.0 0.6 0.3

1 40 12 3.2 1.7 1.0 0.5 0.4

8 10 1 3.4 2.9 2.6 2.3 1.8

8 10 3 1.7 1.3 1.1 0.8 0.6

8 10 6 1.2 0.9 0.7 0.5 0.3

8 10 12 1.0 0.7 0.5 0.3 0.2

8 25 1 4.8 3.9 3.1 2.6 2.1

8 25 3 2.9 2.1 1.5 1.1 0.8

8 25 6 2.4 1.6 1.1 0.8 0.5

8 25 12 2.1 1.3 0.8 0.6 0.3

8 40 1 6.4 4.9 3.8 3.3 2.6

8 40 3 4.4 3.0 2.1 1.5 1.0

8 40 6 3.9 2.4 1.5 1.0 0.6

8 40 12 3.5 2.1 1.2 0.8 0.4

15 10 15.5 4.9 4.3 4.0 3.1

15 10 32.5 2.1 1.7 1.3 1.0

15 10 61.6 1.3 1.0 0.8 0.5

15 10 12 1.2 0.9 0.7 0.5 0.3

15 25 17.0 5.9 5.1 4.5 3.5

15 25 33.8 2.9 2.2 1.7 1.2

15 25 62.9 2.1 1.5 1.1 0.7

15 25 12 2.4 1.6 1.1 0.7 0.5

15 40 18.8 7.1 5.8 4.9 4.0

15 40 35.4 3.9 2.8 2.1 1.5

15 40 64.4 2.9 2.0 1.4 0.9

15 40 12 3.8 2.4 1.5 1.0 0.6

30 10 1 10.1 9.1 8.2 7.8 6.1

30 10 34.0 3.5 3.0 2.4 1.8

30 10 62.5 2.1 1.7 1.3 0.9

30 10 12 1.6 1.3 1.0 0.8 0.5

30 25 1 11.7 10.2 9.7 8.2 6.4

30 25 35.5 4.5 3.6 2.8 2.0

30 25 63.8 2.9 2.2 1.6 1.1

30 25 12 2.9 2.1 1.5 1.1 0.7

30 40 1 13.6 11.5 10.1 8.8 7.0

30 40 37.2 5.6 4.3 3.3 2.4

30 40 65.4 3.9 2.8 2.0 1.4

30 40 12 4.4 2.9 2.0 1.4 0.9

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°
94 Stream Bank Stability in Eastern Nebraska

Saturated Soil Unit Weight = 15.0 kilonewton per cubic meter

0 10 1 0.2 0.1 0.1 0.1 0.1

0 10 3 0.2 0.1 0.1 0.1 0.1

0 10 6 0.2 0.1 0.1 0.1 0.1

0 10 12 0.2 0.1 0.1 0.1 0.1

0 25 1 0.6 0.2 0.1 0.1 0.1

0 25 3 0.6 0.2 0.1 0.1 0.1

0 25 6 0.6 0.2 0.1 0.1 0.1

0 25 12 0.6 0.2 0.1 0.1 0.1

0 40 1 1.1 0.3 0.1 0.1 0.1

0 40 3 1.2 0.3 0.1 0.1 0.1

0 40 6 1.2 0.3 0.1 0.1 0.1

0 40 12 1.1 0.3 0.1 0.1 0.1

1 10 1 0.8 0.6 0.4 0.3 0.2

1 10 3 0.5 0.3 0.1 0.1 0.1

1 10 6 0.4 0.2 0.1 0.1 0.1

1 10 12 0.3 0.1 0.1 0.1 0.1

1 25 1 1.3 0.8 0.4 0.3 0.2

1 25 3 0.9 0.4 0.1 0.1 0.1

1 25 6 0.8 0.3 0.1 0.1 0.1

1 25 12 0.7 0.3 0.1 0.1 0.1

1 40 1 2.0 1.0 0.5 0.3 0.2

1 40 3 1.5 0.6 0.1 0.1 0.1

1 40 6 1.3 0.5 0.1 0.1 0.1

1 40 12 1.2 0.4 0.1 0.1 0.1

8 10 1 3.6 3.1 2.7 2.3 2.0

8 10 3 1.5 1.2 0.9 0.7 0.5

8 10 6 1.0 0.7 0.5 0.3 0.1

8 10 12 0.7 0.4 0.3 0.1 0.1

8 25 1 4.4 3.6 3.0 2.5 2.0

8 25 3 2.2 1.5 1.0 0.6 0.2

8 25 6 1.5 1.0 0.6 0.2 0.1

8 25 12 1.2 0.6 0.3 0.1 0.1

8 40 1 5.3 4.0 3.1 2.6 1.9

8 40 3 2.9 1.8 1.1 0.5 0.1

8 40 6 2.2 1.2 0.6 0.1 0.1

8 40 12 1.7 0.8 0.3 0.1 0.1

15 10 16.2 5.6 5.1 4.6 3.7

15 10 32.4 2.1 1.7 1.4 1.0

15 10 61.4 1.2 0.9 0.7 0.4

15 10 12 0.9 0.7 0.5 0.3 0.1

15 25 17.1 6.1 5.2 4.6 3.7

15 25 33.2 2.4 1.8 1.3 0.8

15 25 62.1 1.4 1.0 0.6 0.1

15 25 12 1.5 0.9 0.5 0.2 0.1

15 40 18.1 6.7 5.5 4.7 3.7

15 40 34.0 2.8 2.0 1.2 0.3

15 40 62.8 1.7 1.1 0.5 0.1

15 40 12 2.1 1.2 0.6 0.1 0.1

30 10 1 11.7 10.7 10.1 9.1 7.4

30 10 34.3 3.8 3.4 2.8 2.2

30 10 62.4 2.1 1.7 1.4 1.0

30 10 12 1.4 1.2 0.9 0.7 0.4

30 25 1 12.7 11.4 10.3 9.1 7.4

30 25 35.2 4.3 3.5 2.8 1.9

30 25 63.2 2.4 1.8 1.3 0.7

30 25 12 2.1 1.4 1.0 0.6 0.1

30 40 1 13.9 12.1 10.4 9.2 7.4

30 40 36.1 4.8 3.6 2.7 1.6

30 40 64.0 2.8 1.9 1.2 0.1

30 40 12 2.8 1.7 1.1 0.5 0.1

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°
Table 6 95

Saturated Soil Unit Weight = 18.0 kilonewton per cubic meter

0 10 1 0.3 0.1 0.1 0.1 0.1

0 10 3 0.3 0.1 0.1 0.1 0.1

0 10 6 0.3 0.1 0.1 0.1 0.1

0 10 12 0.3 0.1 0.1 0.1 0.1

0 25 1 0.8 0.2 0.1 0.1 0.1

0 25 3 0.8 0.2 0.1 0.1 0.1

0 25 6 0.8 0.3 0.1 0.1 0.1

0 25 12 0.8 0.3 0.1 0.1 0.1

0 40 1 1.4 0.4 0.1 0.1 0.1

0 40 3 1.4 0.4 0.1 0.1 0.1

0 40 6 1.4 0.5 0.1 0.1 0.1

0 40 12 1.3 0.5 0.1 0.1 0.1

1 10 1 0.8 0.6 0.4 0.3 0.2

1 10 3 0.5 0.3 0.2 0.1 0.1

1 10 6 0.4 0.2 0.1 0.1 0.1

1 10 12 0.4 0.2 0.1 0.1 0.1

1 25 1 1.4 0.8 0.5 0.4 0.3

1 25 3 1.1 0.5 0.2 0.1 0.1

1 25 6 0.9 0.4 0.1 0.1 0.1

1 25 12 0.9 0.3 0.1 0.1 0.1

1 40 1 2.1 1.1 0.6 0.4 0.3

1 40 3 1.7 0.7 0.2 0.1 0.1

1 40 6 1.6 0.6 0.1 0.1 0.1

1 40 12 1.5 0.6 0.1 0.1 0.1

8 10 1 3.3 2.9 2.4 2.1 1.8

8 10 3 1.5 1.2 0.9 0.6 0.4

8 10 6 1.0 0.7 0.5 0.3 0.1

8 10 12 0.7 0.4 0.3 0.1 0.1

8 25 1 4.3 3.4 2.7 2.3 1.8

8 25 3 2.2 1.5 1.0 0.6 0.2

8 25 6 1.6 1.0 0.6 0.2 0.1

8 25 12 1.3 0.7 0.3 0.1 0.1

8 40 1 5.3 3.9 2.9 2.5 1.8

8 40 3 3.0 1.9 1.1 0.5 0.1

8 40 6 2.3 1.3 0.6 0.1 0.1

8 40 12 1.9 0.9 0.3 0.1 0.1

15 10 15.6 5.1 4.6 4.1 3.3

15 10 32.3 1.9 1.6 1.3 0.9

15 10 61.4 1.1 0.8 0.6 0.4

15 10 12 0.9 0.7 0.5 0.3 0.1

15 25 16.7 5.7 4.7 4.2 3.3

15 25 33.1 2.3 1.7 1.2 0.7

15 25 62.1 1.4 1.0 0.6 0.1

15 25 12 1.6 0.9 0.5 0.2 0.1

15 40 17.8 6.3 5.1 4.3 3.4

15 40 34.0 2.8 1.9 1.2 0.4

15 40 62.9 1.8 1.1 0.5 0.1

15 40 12 2.3 1.2 0.6 0.1 0.1

30 10 1 10.6 9.7 9.1 8.1 6.6

30 10 34.0 3.5 3.1 2.5 2.0

30 10 62.3 1.9 1.6 1.2 0.9

30 10 12 1.4 1.1 0.8 0.6 0.3

30 25 1 11.7 10.4 9.2 8.2 6.7

30 25 35.0 4.1 3.2 2.5 1.8

30 25 63.1 2.3 1.7 1.2 0.7

30 25 12 2.1 1.4 1.0 0.6 0.1

30 40 1 13.1 11.2 9.5 8.3 6.7

30 40 36.0 4.6 3.4 2.5 1.5

30 40 64.0 2.8 1.9 1.2 0.1

30 40 12 2.9 1.8 1.1 0.5 0.1

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°
96 Stream Bank Stability in Eastern Nebraska

Saturated Soil Unit Weight = 20.0 kilonewton per cubic meter

0 10 1 0.3 0.1 0.1 0.1 0.1

0 10 3 0.3 0.1 0.1 0.1 0.1

0 10 6 0.3 0.1 0.1 0.1 0.1

0 10 12 0.3 0.1 0.1 0.1 0.1

0 25 1 0.9 0.3 0.1 0.1 0.1

0 25 3 0.9 0.3 0.1 0.1 0.1

0 25 6 0.9 0.3 0.1 0.1 0.1

0 25 12 0.9 0.3 0.1 0.1 0.1

0 40 1 1.5 0.6 0.2 0.1 0.2

0 40 3 1.6 0.6 0.1 0.1 0.1

0 40 6 1.6 0.5 0.1 0.1 0.1

0 40 12 1.5 0.6 0.1 0.1 0.1

1 10 1 0.8 0.6 0.4 0.3 0.2

1 10 3 0.5 0.3 0.2 0.1 0.1

1 10 6 0.5 0.2 0.1 0.1 0.1

1 10 12 0.4 0.2 0.1 0.1 0.1

1 25 1 1.5 0.9 0.5 0.4 0.3

1 25 3 1.1 0.5 0.2 0.1 0.1

1 25 6 1.0 0.5 0.1 0.1 0.1

1 25 12 1.0 0.4 0.1 0.1 0.1

1 40 1 2.3 1.2 0.6 0.3 0.4

1 40 3 1.9 0.8 0.2 0.1 0.1

1 40 6 1.7 0.7 0.1 0.1 0.1

1 40 12 1.6 0.7 0.1 0.1 0.1

8 10 1 3.1 2.7 2.2 1.9 1.6

8 10 3 1.4 1.1 0.8 0.6 0.4

8 10 6 1.0 0.7 0.5 0.3 0.1

8 10 12 0.7 0.4 0.3 0.1 0.1

8 25 1 4.1 3.2 2.5 2.2 1.7

8 25 3 2.2 1.5 1.0 0.6 0.2

8 25 6 1.7 1.0 0.6 0.3 0.1

8 25 12 1.3 0.7 0.3 0.1 0.1

8 40 1 5.2 3.7 2.7 2.4 1.7

8 40 3 3.1 1.9 1.1 0.5 0.1

8 40 6 2.5 1.3 0.7 0.1 0.1

8 40 12 2.1 1.0 0.4 0.1 0.1

15 10 1 5.2 4.7 4.2 3.7 3.0

15 10 3 2.2 1.8 1.5 1.2 0.8

15 10 6 1.4 1.0 0.8 0.6 0.3

15 10 12 0.9 0.6 0.4 0.3 0.1

15 25 1 6.4 5.3 4.4 3.8 3.1

15 25 3 3.1 2.3 1.7 1.2 0.7

15 25 6 2.2 1.4 0.9 0.6 0.1

15 25 12 1.6 1.0 0.6 0.2 0.1

15 40 1 7.7 5.9 4.7 4.0 3.1

15 40 3 4.1 2.7 1.9 1.2 0.5

15 40 6 3.0 1.8 1.1 0.5 0.1

15 40 12 2.4 1.3 0.6 0.1 0.1

30 10 1 9.7 8.8 8.2 7.3 6.0

30 10 3 3.7 3.3 2.8 2.3 1.8

30 10 6 2.2 1.8 1.5 1.1 0.8

30 10 12 1.4 1.0 0.8 0.6 0.3

30 25 1 11.0 9.6 8.7 7.5 6.0

30 25 3 4.8 3.8 3.0 2.3 1.6

30 25 6 3.1 2.3 1.6 1.2 0.6

30 25 12 2.2 1.4 0.9 0.6 0.1

30 40 1 12.4 10.4 8.7 7.6 6.1

30 40 3 5.9 4.4 3.2 2.3 1.4

30 40 6 4.1 2.7 1.8 1.2 0.1

30 40 12 3.0 1.8 1.1 0.5 0.1

Table 6. Factors of safety from Rotational Equilibrium Analysis of Multilayered Embankments (REAME) analysis of idealized

straight banks—Continued

[kPa, kilopascal; °, degrees; m, meter]

Cohesion

(kPa)

Friction angle

(°)

Bank height

(m)

Bank angle

15° 30° 50° 70° 90°