Progress in the Application

of Landform Analysis 

in Studies of Semiarid Erosion

GEOLOGICAL SURVEY 

CIRCULAR 437
Progress in the Application of 

Landform Analysis in Studies 

of Semiarid Erosion

By S. A. Schumm and R. F. Hadley

GEOLOGICAL SURVEY CIRCULAR 437

Washington 1961
United States Department of the Interior

STEWART L. UDALL, Secretary

Geological Survey

William T. Pecora, Director

First printing 1961 

Second printing 1 967

Free on application to the U.S. Geological Survey, Washington, D.C. 20242
CONTENTS

Page Page

Abstract _____________________________ 1 Drainage -basin components-Continued

Introduction__________________________ 1 Hill slopes-Continued

The drainage basin as a unit ________ 2 'Form__ __________.-__----__ - 7

Relative relief and sediment yield ____ 2 Aspect--________-_---------__-__ 7

Drainage density and mean annual Stream channels ___________________ 8

runoff __________________ _______ 2 Discontinuous gullies_____________ 8

Drainage area and sediment yield ____ 3 Aggradation _____________________ 12

Drainage-basin components____________ 7 Channel shape ___________________ 12

Hill slopes_________________________ 7 References__-_-_____-_ ____________ 13

ILLUSTRATIONS

Page 

Figure 1. Relation of mean annual sediment yield to relief ratio_--_-_____--_--------___- 3

2. Relation of mean annual sediment yield to relief ratio for 14 small drainage

basins __________________________________________________________________ 4

3. Relation of mean annual runoff to drainage density.___________________________ 5

4. Relation of mean annual sediment yield to drainage area ______________________ 6

5.. Diagram of typical seepage step ________-__________-___-_-_-_---------_-.---- 8

6. Rose diagram showing relation of slope aspect to steepness of slope ____________ 9

7. Drainage nets of six selected basins ________________-_________-----_-------- 10

8. Profiles of discontinuous gullies______________________________-__-___--__-_- 11

9. Relation of width-depth ratios to weighted mean percent silt-clay in alluvium

of bed and banks _____ _________________________-_-__-__-_-------_------ 13

in
Progress in the Application of Landform Analysis 

in Studies of Semiarid Erosion1

By S. A. Schumm and R. F. Hadley

ABSTRACT

The analysis of topographic and hydrologic data gathered 

during studies of erosion in semiarid areas of Western United 

States show the following relation: (a) Mean annual sediment 

yield from small drainage basins is related to a ratio of basin 

relief to length; (b) mean annual runoff from small drainage 

basins is related to drainage density; (c) mean annual sediment yield per unit area decreases with increase in drainage 

area; (d) the form of some convex hill slopes is related to 

surficial creep; (e) asymmetry of drainage basins, including 

differences in hill-slope erosion and drainage density, is 

related to microclimatic variations on slopes of diverse exposure; (0 the cutting of discontinuous gullies is closely 

related to steepening by deposition of the semiarid valley 

floor, (g) aggradation in ephemeral streams seems to be most 

prevalent in reaches where the ratio of contributing drainage 

area to channel length is relatively small; and (h) streamchannel shape, expressed as a width-depth ratio, is related 

to the percentage of silt-clay in bed and bank alluvium.

The above relations cannot be detected without measurement of terrain characteristics. They further indicate the 

imoortance of quantitative terrain analysis in studies of 

erosion.

INTRODUCTION

The impetus given to quantitative geomorphology by Strahler (1957) has led to several 

recent publications on the techniques of landform analysis. This report reviews the results obtained by applying some of these 

techniques to studies of the geomorphic and 

hydrologic characteristics of small drainage 

basins on the semiarid public lands of Western United States. These studies by the 

authors are part of the soil and moisture 

program of the Department of the Interior 

carried out by the Geological Survey.

This brief review of work completed and in 

progress demonstrates some relations among 

topographic and hydrologic characteristics of 

small drainage basins. There is no attempt 

in this report to offer detailed physical explanations for the existence of the relations

presented. Such explanations are attempted 

in the reports listed as references; the purpose here is simply to indicate the application 

of quantitative landform analysis to studies 

dealing with the hydrology and erosional characteristics of semiarid drainage basins.

Landform analysis may range from field 

measurements of gross drainage-basin characteristics to the preparation and analysis of 

detailed topographic maps. Generally, the 

work reported herein was of a reconnaissance 

nature because of the lack of good topographic 

maps and aerial photographs for the areas investigated. Therefore, landform analysis may 

be little more than the surveying of a hillslope profile; however, measurement rather 

than qualitative description characterized the 

approach.

Comparisons of sediment yields,from small 

drainage basins in diverse climatic regions, 

show that mean annual rates of erosion are 

greatest in semiarid regions, excluding the 

effects of cultivation on highly erosive soils 

in some humid regions. Maximum sediment 

yields, in areas where the mean temperature 

is about 50°F, occur where the annual precipitation is between 10 and 15 inches (Langbein 

and Schumm, 1958). Sediment yields decrease 

sharply on both sides of this maximum, owing 

in one instance to a deficiency of runoff and 

in the other to increased density of vegetation. 

Average precipitation in the areas discussed 

here is less than zQ inches, and density of 

vegetation is low, generally less than 30 percent. These studies, therefore, were made in 

areas of high sediment yield. Such areas are 

ideal for the study of erosive processes and

'Presented at American Association for the Advancement of 

Science Symposium on Quantitative terrain studies, Chicago, 111., 

Dec. 27, 1959.
THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

the effects of landforms and erosion on each 

other.

Although rates of sediment yield are generally high in semiarid regions,the annual 

rates are variable. Consequently, it is necessary to collect records for long periods to 

obtain a dependable relation between the hydrologic and geomorphic characteristics of a 

drainage basin. However, if records longer 

than 5 years were required, little hydrologic 

data would be available for most semiarid regions. Therefore, 5 years of hydrologic record was accepted as the minimum required 

for correlation with basin charateristics.

The work to be described was grouped into 

two sections. The first includes small drainage basins that were studied as units, that is, 

the general topographic characteristics of the 

drainage basin were related to the hydrologic 

characteristics. In the second section only 

components of the drainage basin were considered, that is, hill slopes and selected 

reaches of stream channels.

THE DRAINAGE BASIN AS A UNIT

RELATIVE RELIEF AND SEDIMENT YIELD

Mean annual sediment yield was calculated 

from measurements of sediment deposited in 

stock-water reservoirs in Wyoming,Colorado, 

Utah, New Mexico, and Arizona. The 59 drainage basins studied ranged in size from 0.1 to 

18.2 square miles. The relative relief of these 

drainage basins is expressed as a relief ratio, 

which is the relief of the drainage basin divided by basin length measured in a straight 

line approximately parallel to the major drainage channel. Basin relief was measured from 

the spillway elevation of the reservoir to the 

maximum elevation on the divide. However, 

in basins where isolated high points on the 

divide tend to give undue weight to basin height, 

relief was measured to an average divide elevation. It is felt that this modification is justified because isolated high points commonly 

have a small area and have little effect on 

rates of sediment yield. Relief ratio has been 

related to other drainage-basin characteristics, for example, channel gradient and mean 

maximum slope angles (Schumm, 1956a).

The mean annual sediment yields from the 

59 drainage basins were averaged by rock type 

and plotted against the relief ratio in figure 1.

As shown on this figure, the points for drainage areas underlain by sandstone and conglomerate plot close to the lower end of the 

regression line as both relative relief and 

sediment yields are low. The shale areas are 

characterized by greater relative relief and 

higher sediment yields; the seemingly anomalous high relative relief in some shale areas 

may be attributed to recent gullying and badland development. The relation between sediment yield and relief ratio for 14 small 

drainage basins, underlain by rocks of the 

Fort Union formation and located in the Cheyenne River basin of eastern Wyoming, is 

shown on figure 2 (Hadley and Schumm, 1961).

Studies in Texas by Maner (1958) have shown 

a correlation between relief ratio and sediment yield. ^Recently in Illinois no meaningful 

correlation was found owing perhaps to the 

effects of cultivation within the drainage basins 

(Stall and Bartelli, 1959).

More refined drainage-basin parameters 

can be used where topographic maps are 

available. For areas where there are none or 

only aerial photographs of poor quality, simple measures such as relief ratio are readily 

obtained. Basin length can be measured on 

the poorest aerial photograph, and relief can 

be obtained readily with an altimeter in the 

field.

Figures 1 and 2 indicate that with uniform 

climate, sediment yield from small drainage 

basins depends on geomorphic characteristics. The good correlation between mean annual sediment yield and relief ratio suggests 

that a practical approach to an erosion classification of semiarid lands may be through a 

quantitative analysis of the geomorphic characteristics of a region.

DRAINAGE DENSITY AND MEAN ANNUAL RUNOFF

Another important hydrologic variable is 

mean annual runoff. Runoff data were obtained by measuring inflow of water to small 

reservoirs in the Cheyenne River basin from 

April through October, 1951-54 (Culler, 1961). 

In spite of the short record a correlation exists 

(fig. 3) when drainage density, the total length 

of channels per square mile of drainage area, 

is plotted against mean annual runoff for 13 

small drainage basins ranging in size from 

0.1 to 3.0 square miles (Hadley and Schumm, 

1961"). The relation shown in this figure
THE DRAINAGE EASIN AS A UNIT

100

-Id

O _j

UJ

UJ

o:

£o 1 co 

0 o:

^UJ

CO Q_

S i»J

^UJ 2 U.

a:

Z S 

< <

UJ

]

New J

Mexic 

Arizon 

4*

. 'r

»

:o- ,'

n Q < i "^ i A

' Utah 

T New

.» 

Wye

 Wyi 

Wyomi

/

f

/

7 Wye

,6 New

Mexicc 

>ming

Colorado T I0

jming 

 9

ifl/

V- ±i2 "

1C. \A

*Utah

>ming- 

 Mexic

>-Ariz

o-Arij

sna 

/

/r

\

Jtah

:ona

/

/

/

/

' 1

«

:

i

 (

.

 1

/

F

. Cone 

2. Fria 

3. Sha 

\. Con 

5. Shir 

5. Mes 

7. Lan 

3. For

A

f

/

X PL 

Li Is-, r 

ble ss. 

le 

g., ss. 

lammf 

averd 

ce san 

t Unic

/

*IO W]/ominc

A NAT ION 

esistant ss.

> cong 

e ss. 

dy she 

>n ss.

.

IAItJ

and sh

9. Pierre shale

1

1

1

I

0. White River she 

1. Wasatch ss. 

2. Mancos shale

lie

)

ale 

0-02 0.04 0.06

MEAN RELIEF

0.08 

RATIO ( h/,)

0.10 0.12

Figure 1. Relation of mean annual sediment yield to mean relief ratio for 59 small drainage basins in Wyoming, Colorado, Utah, New

Mexico, and Arizona.

suggests that drainage density, if not dependent simply on runoff, is at least dependent on 

the same variables that influence runoff. The 

importance of this relation to the hydrologist 

is that annual discharge may be predicted for 

ungaged drainage basins when the geomorphic 

characteristics are expressed in quantitative 

terms.

DRAINAGE AREA AND SEDIMENT YIELD

The decrease in unit rate of sediment yield 

with increasing size of drainage basin has 

been noted in many studies of sediment yield

(Glymph, 1954; Hadley and Schumm, 1961). 

The relation between sediment yield and size 

of contributing drainage area for 73 small 

drainage basins in the Cheyenne River basin 

shows such a decrease (fig. 4). The gentler 

stream gradients and slope angles near the 

mouth of a drainage basirywhen compared with 

the generally snore rugged topography near 

drainage divides^may explain the decrease in 

sediment yield with increased drainage area. 

In addition, water.losses in sandy ephemeralstream channels (Schumm and Hadley, 1957) 

may promote deposition and hinder sediment 

movement out of the larger drainage basins. 

One other factor may be important; that is,
THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

10.0

UJ

>- 

iUJ

LU

^ 1.0

o

(/)

 UJ 

Q QL 

UJ (/) ILU

0.1

0.(

0 0.02 0.04 0.06 0.08 

RELIEF RATIO ( h/.)

0.10 0.12

Figure 2. Relation of mean annual sediment yield to relief ratio for 14 small drainage basins underlain by the Fort Union formation

in eastern Wyoming.
THE DRAINAGE BASIN AS A UNIT

30

Lul

iu20 

or

Z)

o

(D

<T 

UJ 

CL

E2 15

H

W

^

Q

UJ

QC 

Q

/

0 10 20 30 40 50 60 

MEAN ANNUAL RUNOFF, IN ACRE-FEET PER SQUARE MILE

70

Figure 3. Relation of mean annual runoff to drainage density for 13 small drainage basins in eastern Wyoming.
THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

en

UJ

UJ 

£T 

<

0

cn

<

UJ 

CC

UJ 

O

01

 . Q

o

4

o

d.O

311IAI 3dVnOS d3d 133d-3dOV Nl 'Q13IA 1N31MIQ3S IVPINNV
DRAINAGE-BASIN COMPONENTS

the formation of bottomlands or flood plains 

bordering the stream channel.

To determine the relation between bottomland formation and drainage area, data from 

76 small drainage basins in the Cheyenne 

River basin were used. The area of bottomland in each drainage basin was measured 

from aerial photographs. Bottomland begins 

to form in drainage basins larger than 0.1 

square mile. The ratio of the area of bottomland to upland reaches a maximum in basins of 

about 2.5 square miles and remains nearly 

uniform for all larger basins. In the drainage 

basins with areas larger than 0.1 square mile, 

the increase in area of bottomland with increased drainage area will hinder sediment 

movement from hill slopes to the adjacent 

stream channels and will afford sites for sediment deposition during floods, thereby decreasing sediment yields.

DRAINAGE-BASIN COMPONENTS

In addition to relief ratio, which is a parameter characteristic of the drainage basin as a 

unit, many components of a drainage basin, 

when expressed quantitatively, can be related 

to erosion processes or to variables influencing erosion rates and processes. For example, the inclination and aspect of hill slopes 

markedly affect the rates and mechanics of 

runoff and erosion. Therefore, it is desirable 

to attempt to relate such characteristics of 

drainage-basin components to the existing 

data concerning erosion processes.

HILL SLOPES

FORM

Investigations of hill-slope erosion by the 

Soil Conservation Service have shown that both 

slope length and slope inclination are important factors determining erosion rates on a 

hill slope (Smith and Wischmeier, 19S7); further, the shape of a hill slope may be related 

to the dominant erosive process operative on 

the slope (Schumm, 1956b). For example, in 

Western United States many straight steep 

slopes, which retreat at a constant inclination, 

form under the action of rainwash. Convex 

slopes, on the other hand, apparently form 

under the action of creep, owing to alternate 

swelling and compaction of lithosols high in

montmorillonite. The recognition of this process through its effect on slope-profile form 

may be important with regard to attempts to 

improve grazing conditions over large areas 

of Western United States, for on slopes where 

such swelling and creeping of the surficial 

material occurs only the <most hardy range 

plants grow. Perhaps the degree of curvature 

of a hill-slope profile may indicate the relative importance of rainwash or creep.

An additional example of the dependence of 

hill slope form on erosional processes has 

b.een reported by Hadley and Rolfe (1955). 

Many hill slopes in eastern Wyoming and 

western South Dakota and Nebraska are broken 

by erosional scarplets less than 2 feet high 

(fig. 5). These features are roughly parallel 

to adjacent stream channels and in some 

cases follow a slope nearly on contour for as 

much as a quarter of a mile. The scarplets 

are developed in a surficial mantle of relatively high permeability which overlies a finegrained less permeable weathered shale. Flow 

of water along the contact between the mantle 

and underlying weathered shale causes a basal 

sapping of the scarplet and subsequent migration upslope. The scarplets are termed seepage steps after the process which is responsible for their maintanence. The initial seepage step is probably the result of channel 

cutting in the valley floor.

ASPECT

Within any one area microclimatic variations.dependent on the direction of slope exposure or aspect.affect hill-slope and drainagebasin development. Studies now being made by 

Hadley show that hill slopes of different aspect 

have marked contrasts in morphology, hydrology, and vegetal cover. These contrasts have 

been observed and reported from several localities and may be common at all latitudes. 

North-facing slopes in semiarid regions of 

Western United States are steeper, less dissected, and support a more luxurious growth 

of vegetation than slopes in the same drainage basin-facing southward, which are often 

deeply rilled and nearly barren.

Six small drainage basins were selected 

for an intensive study of the effects of slope 

aspect. Between 30 and 50 measurements of 

slope inclination were made in each of the
THE APPLICATION OF IANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

TREAD

SEEPAGE FACE

RECONSTRUCTED SLOPE

ZONE OF RELATIVELY LOW PERMEABILITY, 

USUALLYWEATHERED BEQROCK

5 Feet

Figure 5. Diagram of typical seepage step showing integral parts.

six basins, on slopes facing nearly every compass direction. When the data from one of the 

basins are plotted on polar coordinate paper 

(fig. 6), the steepest slopes are found to be 

facing north and northeast. This is because 

the smaller amount of solar radiation received on these slopes tends to inhibit the loss 

of soil moisture, resulting in additional moisture which in turn supports more vegetation 

capable of retarding erosion. In contrast, the 

south-facing slopes lose soil moisture rapidly 

with consequent poorer vegetative cover and 

more erosion.

Measurements of drainage density show 

that the number of channels on the southfacing or northern side of a drainage basin is 

more than twice that found on the southern 

side of the drainage basin (fig. 7). The average drainage density, as measured in the 

study areas, is 11.3 miles per square mile 

on the northern side and only 5.2 miles per 

square mile on the southern side of the drainage basins.

Because of these differences in hill-slope 

erosion there is a tendency for the main 

stream channel in an east-west-trending drainage system to be shifted to the south by the 

eroded material derived from the south-facing 

slopes. This channel migration has caused 

asymmetrical development of drainage basins

in several widely separated localities of dissimilar geology and climate. An index of 

symmetry is used to describe the effects of 

channel shifting on basin shape. The index is 

the ratio of the distances from the main 

drainage channel to the northern and to the 

southern drainage divide. An index of 1.0 

describes a symmetrical drainage basin. 

Each of the basins selected for study (fig. 7) 

has an index greater than 1.0 indicating an 

asymmetry caused by shifting of the main 

drainage channel to the south.

STREAM CHANNELS

DISCONTINUOUS GULLIES

An important problem in semiarid areas 

is the downcutting of ephemeral-stream channels to form gullies. In many semiarid valleys 

downcutting is not continuous throughout the 

valley, but instead trenched reaches are separated by uncut reaches of the valley floor. 

Trenched reaches are known as discontinuous 

gullies. The formation of continuous and discontinuous gullies may be attributed to climate 

change or overgrazing, but whatever the ultimate cause of the trenching, until the mechanics of aggradation and degradation are 

known, little can be attempted in the way of 

conservation measures aimed at the prevention of gully cutting. Surveys (Schumm and
DRAINAGE-BASIN COMPONENTS

W.270°h H90°E.

00°

Figure 6. Rose diagram showing relation of slope aspect and steepness of slope.

Hadley, 1957) of the longitudinal profiles of 

channels in Wyoming and New Mexico indicated that the points of initial trenching could 

be identified.

The trenching of the alluvial fill in each of 

the valleys surveyed was associated with a 

steepening of the gradient on the valley fill 

(fig. 8). The cutting seems mostly to have 

originated on these steeper reaches, and the

channel has eroded up the valley with only minor extension of the trench down the valley. The 

larger valleys studied range in drainage area 

from 0.6 to 19 square miles; in these, cutting 

begins on si opes of from 1.5 to 2.5 percent. The 

smaller valleys range in drainage area from 

0.05 to 0.5 square mile; here the cutting begins on slopes of from 2.5 to 5.4 percent. The 

higher gradients required for trenching on 

smaller drainage basins suggests an inverse
10 THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

S=l.22

S=l.75

5=1.48

5 = 1.50

M

5=1.52

5= Index of symmetry

Figure 7. Drainage nets of six selected basins in Niobrara County, Wyo., showing asymmetrical basin development and differences in

drainage density owing to exposure.
DRAINAGE-BASIN COMPONENTS 11

40'r

HARNEY CREEK DRAW

JOE WARREN DRAW

400'

MANNING DRAW

Figure 8. Profiles of discontinuous gullies in Niobrara County, Wyo. Figures are gradient for each section of the profile in feet per foot.
12 THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

relation between discharge and the angle at 

which the fill will be trenched; that is, for a 

given storm, discharge will be less from the 

small drainage systems and cutting will not 

occur on a slope as gentle as in a neighboring larger basin with greater discharge.

The foregoing indicates that knowledge of 

the geomorphic characteristics of ephemeral 

streams is necessary to an understanding of 

their past, present, or future activity. Also, 

geomorphic factors may possibly be predominant in determining when a valley will be 

trenched. That is, before change of climate 

or increased grazing can cause the trenching 

of a valley, sufficiently steep reaches of the 

channel or valley floor must have formed.

AGGRADATION

Trenching of stream channels in semiarid 

regions may begin on critical reaches of the 

channel, which can be identified by measurements of the valley profile. It may also be 

possible to identify the reaches of a stream 

most susceptible to aggradation by measurements of stream profiles. The reaches of a 

channel in which aggradation is most likely 

to occur are located where few tributaries 

enter; that is, in a reach of the channel in 

which the increment of contributing drainage 

area to the increment of channel length is 

relatively small (Schumm, 1961, in press). 

The reason for the aggradation is probably 

the loss of water by infiltration into the channel bed, which results in an increased sediment concentration in the remaining flow. 

Therefore, aggradation may occur in those 

reaches of the channel where little water is 

added to the existing flow.

Data presented in the accompanying table 

show the increase in drainage area with channel length along four aggrading streams. The 

ratio of these two values are given for both 

aggrading and stable reaches of the channels 

studied, and aggradation occurs consistently 

in a reach along which the increase of drainage area per mile of channel length is significantly less than that for the stable channel 

reaches. For example, in the Sage Creek area 

there is an average increase of 2 square miles 

of drainage area for each mile of channel 

length along the stable reach; whereas, this 

decreases to only 0.2 square mile per mile of 

channel length along the aggrading reach.

Ratio of drainage area to channel length

Study area

Sage Creek, S.Dak. 

Sand Creek, Nebr...

Arroyo de los Frij oles 

and Arroyo 

Calabasas, 

N. Mex. 

Bayou Gulch, Colo..

Nonaggrading 

reach 

(section 

lumbers)

1-6

2-6 

C-6

1-4

Aggrading 

reach 

(section 

numbers)

6-7

6-10

6-9

4-5

Drainage area ' 

(square 

- miles)

12.7 

.26 

6.4 

1.7 

19.4 

17.2

9.0 

.5

Channel 

length 

(miles)

5.7 

1.1 

3.6 

1.6 

3.2 

2.7

1.1 

.2

Arealength 

ratio

2.2 

.2 

1.8 

1.1 

6.0 

2.7

8.1 

2.5

^Adjusted for noncontributing area.

This suggests that if aggradation were to be 

induced in a stream channel as a conservation measure, the site of the structure should 

be selected at least partly on the basis of 

changes in the ratio of drainage area to channel length along the channel.

CHANNEL SHAPE

During the progress of the aggradation 

studies just mentioned, a great contrast in 

the characteristics of stream channels formed 

of either predominantly sandy or silty matetials was observed. The more sandy the 

channel the wider and shallower it appeared. 

Data on stream-channel dimensions and the 

size distribution of sediment forming the 

perimeter of the channel were collected at 

70 locations at which the channels were considered stable (Schumm, 1960). Channel 

shape expressed as a width-depth ratio is 

plotted against the weighted mean percent 

silt-clay forming the banks and bed of the 

channel (fig. 9). Silt-clay is defined as that 

sediment passing the 200-mesh sieve, or 

smaller than 0.074 mm. The weighted mean 

was calculated to give the bed and bank sediments a weight proportional to the length of 

channel perimeter composed of each type of 

material. The correlation shown in figure 9 

reveals that as the bed and bank materials 

contain progressively more silt-clay, the 

channels become relatively narrower and 

deeper. This is attributed to the greater cohesion and resistance to erosion of alluvium 

containing high percentages of silt-clay.

Discharge apparently has a minor effect on 

channel shape, for the data (fig. 9) were obtained from channels characterized by a great 

range of mean annual discharge from about 

20 to 4,920 cfs. The drainage area above the
REFERENCES 13

1000

\

100

10

O.I 10 10 

WEIGHTED MEAN PERCENT SILT-CLAY (M)

100 1000

Figure 9. Relation of width-depth ratios to weighted mean percent silt-clay in alluvium of bed and banks at 70 channel cross sections.

cross sections sampled ranges from 1.7 

square miles for the smallest ephemeral 

stream to 56,700 square miles for the Kansas 

River at Topeka, Kans.

Data collected along individual streams 

show that changes in channel width and depth 

in a downstream directioruthat cannot be attributed to changes in discharge,, are related 

to downstream variations in the percent siltclay in the stream channel. In addition, the 

introduction of sediment from tributaries into 

the main channel may cause a change in the 

shape of the main channel. Stream-channel 

shape, therefore, depends largely on variations of the silt-clay content of channel banks 

and bed. The importance of this relation to 

other aspects of fluvial morphology and hydraulics has yet to be investigated.

REFERENCES

Culler, R. C., 1961, Hydrology of stock-water 

reservoirs in upper Cheyenne River basin: 

U. S. Geol. Survey Water-Supply Paper 

1531-A.

Glymph, L. M., Jr., 1954, Studies of sediment yields from watersheds: Association

internationale d Hydrologie Publication (Assemblee' generale de Rome), v. 1, p. 178-191.

Hadley, R. F., and Rolfe, B. N., 1955, Development and significance of seepage steps 

in slope erosion: Am. Geophys. Union 

Trans., v. 36, p. 792-804.

Hadley, R. F., and Schumm, S. A., 1961, Sediment sources and drainage-basin characteristics in upper Cheyenne River basin: 

U. S. Geol. Survey Water-Supply Paper 

1531-B.

Langbein, W. B., and Schumm, S. A., 1958, 

Yield of sediment in relation to mean annual precipitation: Am. Geophys. Union 

Trans., v. 39, p. 1076-1084.

Maner, S. B., 1958, Factors affecting sediment 

delivery rates in the Red Hills physiographic 

area: Am. Geophys. Union Trans., v. 39, 

p. 669-675.

Schumm, S. A., 1956a, Evolution of drainage 

systems and slopes in badlands at Perth 

Amboy, New Jersey: Geol. Soc. Am. Buli., 

v. 67, p. 597-646.

 I956b, The role of creep and rainwash 

on the retreat of badland slopes: Am. Jour. 

Sci., v. 254, p. 693-706.

-I960, The shape of alluvial channels

in relation to sediment type: U.S. Geol. 

Survey Prof. Paper 352-B, p. 17-30.
14 THE APPLICATION OF LANDFORM ANALYSIS IN STUDIES OF SEMIARID EROSION

Schumm, S. A., 1961, The effect of sediment 

characteristics on erosion and deposition 

in ephemeral-stream channels: U.S. Geol. 

Survey Prof. Paper 352-C, in press.

Schumm, S. A., and Hadley, R., F., 1957, Arroyos and the semiarid cycle of erosion: 

Am. Jour. Sci,, v. 255, p. 161J-174.

Smith, D. D., and Wischmeier, W. H., 1957, 

Factors affecting sheet and rill erosion:

Am Geophys. Union Trans., v. 38, p. 889- 

896.

Stall, J. B., and Bartelli, L. J., 1959, Correlation .of reservoir sedimentation and watershed factors, Springfield Plain, Illinois: Illinois State Water Survey Kept. Inv. 37, 21 p.

Strahler, A. N., 1957, Quantitative analysis of 

watershed geomorphology: Am. Geophys. 

Union Trans., v. 38, p. 913-920.

INT.DOT.,D.C.61-90 509

U.S. GOVERNMENT PRINTING OFFICE 1967 O 274-526