*f.?.r

Soil Conservation and the Reduction of 

Erosion and Sedimentation in the 

Coon Creek Basin, Wisconsin

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1284
Soil Conservation and the Reduction of 

Erosion and Sedimentation in the 

Coon Creek Basin, Wisconsin

By STANLEY W. TRIMBLE and STEVEN W. LUND

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1234

A study of changes in erosion and 

sedimentation after the introduction of 

soil-conservation measures

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON:1982
UNITED STATES DEPARTMENT OF THE INTERIOR 

JAMES G. WATT, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Library of Congress Cataloging in Publication Data

Trimble, Stanley Wayne.

Soil conservation and the reduction of erosion and sedimentation in the Coon Creek Basin, Wisconsin.

(Geological Survey professional paper; 1234)

Bibliography: p.

1. Soil conservation Wisconsin Coon Creek watershed (Monroe County-Vernon County) 2. Soil erosion WisconsinCoon Creek watershed (Monroe County-Vernon County) 3. Reservoir sedimentation Wisconsin Coon Creek watershed 

(Monroe County-Vernon County) 4. Coon Creek watershed (Monroe County-Vernon County, Wis.)

I. Lund, Steven W. II. United States. Geological Survey. III. Title. IV. Series.

S624.W5T74 631.4'5'0977554 81-607057

AACR2

For sale by the Distribution Branch, U.S. Geological Survey, 

604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Abstract 

Introduction 

The problem and research plan 

Sheet and rill erosion 

Page

1

1

2

6

7

Page

Application of the USLE -

Results 10

Sedimentation 11

Sediment yields in small reservoirs, 1962-75 11

Sediment delivery ratios, 1962-75 11

Sediment yields in small reservoirs, about 1936-45 13

Sediment delivery ratios, about 1936-1945 14

Sedimentation Continued

Sediment deposition rates in the main valley, 1853-1976 17 

Relation of erosion and sedimentation to land use and manageClimate as a variable 25

The Coon Creek area 25

The entire Driftless Area, 1867-1974 27

Is Coon Creek representative? 29

Conservation practices 29

Conclusions 30

Appendices 33

ILLUSTRATIONS

Page

FIGURE 1. Location map showing the Coon Creek basin, subbasins, debris basins, valley cross sections, and other research locations

2. Photographs of Coon Creek basin landscape, 1934 and 1967 

3. Map showing changes of cropping patterns on the Stromstad farm, before and after conservation management 

4. Diagram showing decrease of drainage density between 1934 and 1967 

5. Diagram showing land use in the Coon Creek area, 1850-1975 

6. Schematic diagram showing sediment movement '

7. Diagram showing changes of land use and management in 10 sample basins, Coon Creek, Wis., 1934 and 1967 9

8. Map showing subbasin41 12

9. Map and diagram showing sediment accumulation in the Johnson Civilian Conservation Corps dam reservoir 15

10. Diagram showing sediment deposition rates at selected valley sites in Coon Creek basin, 1853-1977 16

11. Composite curve of sediment deposition for the main valley of Coon Creek basin, 1853-1975 18

12. Diagram showing sediment accumulation in small reservoirs of the Driftless Area, about 1936-45 and 1962-75 

13. Photographs showing bank and channel erosion of perennial tributaries 

14. Graph showing erosion, sedimentation, and erosive land use, 1853-1975 

15. Diagram showing the relation of erosion and sedimentation to erosive land use, 1853-1975 

16. Photographs showing formation and healing of hillside gullies, 1905-78 -

19

20

21

22

23

17. Graph showing number of grazing animals, 1850-1975, and grazed forest, 1925-70, Vernon County, Wis. 24

18. Photographs showing deterioration of flood-plain pasture from accelerated sedimentation 25

19. Graphs showing precipitation trends in the Coon Creek area, 1927-73 26

20. Graphs showing precipitation trends in the Driftless Area, 1867-1974 28

21. Graphs showing precipitation trends at 15 selected stations in the Driftless Area, 1931-73 29

22. Spread of contour-strip farming from the Coon Creek Conservation Demonstration Area, Wis., 1939-67 30

TABLES

Page

TABLE 1. Examples of morphologic and process factors that affect rate of sediment delivery 

2. Land use in sample basins, 1934 and 1975 

ill
iv CONTENTS

Page

TABLE 3. Assumptions made concerning land management and "C" factors 10

4. Average annual upland sheet and rill erosion rates for the study area, 1934 and 1975, as calculated by the universal soil

loss equation 11

5. Sediment-survey data, Coon Creek basin, 1962-75; sediment accumulated in 10 flood-retarding reservoirs constructed

under Public Law 566 12

6. Accumulation of sediment in five small reservoirs, 1936-45 13

7. Management weighting factors to estimate erosive land use, 1853-1974 21

APPENDICES

Page

Appendix I. Cropping plan for the Stromstad farm, 1939-44 33

II. Assumptions made concerning land management and "C" factors 34

III. Average slope lengths and gradients for soils of the study area 35

Metric Conversion Table

Metric units of length, area, volume, flow rate, and mass used in this report can be converted into inch-pound units as follows: 

To convert from To Multiply by

kilometer2 (km2 ) mile2 (mi2) .386

meter3 (m3) foot3 (ft3) 35.31

meterVsecond (ms/s) foots/second (fts/s) 35.31

megagram(Mg) ton 1.102

megagram/kilometer2 (Mg/km2) ton/mile2 (tons/mi2) 2.862
SOIL CONSERVATION AND THE REDUCTION OF EROSION AND 

SEDIMENTATION IN THE COON CREEK BASIN, WISCONSIN

By STANLEY W. TRiMBLE1 and STEVEN W. LUNDZ

ABSTRACT

The Coon Creek Basin in Wisconsin, like most of the Driftless 

Area, has been strikingly transformed by soil conservation measures 

since the 1930's. Greatly improved management measures, which include contour plowing, contour stripcropping, long rotations, crop 

residue management, cover crops, and controlled grazing, have been 

used. As a result, erosion and sedimentation have been greatly 

reduced.

Sheet and rill erosion in 1934 and 1975 were compared by use of 

the universal soil loss equation. Analysis of 10 subbasins comprising 

9 percent of the study area indicated that the annual erosion rate in 

1975 on upland fields (Jc = 720 megagrams per square kilometer) was 

only about one-fourth that of the 1930's (£" = 3,000 megagrams per 

square kilometer).

Sedimentation rates were studied by two methods: (a) accumulation rates in small reservoirs and (b) deposition rates in the main 

valley. The sediment contents of 10 small reservoirs were surveyed 

for the period 1962-75, and 5 for various periods between 1936 and 

1945. The average measured annual accumulation declined from 

about 4,800 megagrams per square kilometer (1936-45) to 63 

megagrams per square kilometer (1962-75), but uncertainties concerning measurements for the early period make comparison difficult; the disparity may well be greater.

For deposition rates in tributary valleys, the total amount of sediment stored in these valleys was estimated by detailed measurements, and this amount was differentially budgeted over time on the 

basis of deposition rates in the main valley. This analysis indicated 

that net annual deposition rates had declined from about 3,700 

megagrams per square kilometer in the 1930's to about 35 to 70 

megagrams per square kilometer in recent years. Determination of a 

more exact rate for the present must await a sediment resurvey. By 

both the reservoir and valley sedimentation measures, present sedimentation rates are estimated to be only about 1 to 2 percent of the 

earlier rates.

These reductions in erosion and sedimentation have been caused 

principally by improvements in land management and, to a lesser 

degree, by changes of land use. For example, the area planted in 

crops did not change greatly, but the conservation management practices on that cropland were greatly improved. Erosion and sedimentation were functions of the erosive potential of land use (erosive 

land use), but both erosion and sedimentation demonstrated a time 

lag in their relationship to erosive land use. This lag increases with 

distance downstream and is caused mainly by (1) delayed changes of 

soil infiltration capacities, (2) delay in formation and growth of adequate upland and tributary channels to conduct increasing storm

1 Department of Geography, University of California at Los 

Angeles, and U.S. Geological Survey.

2 U.S. Army Corps of Engineers, Wilmington, N.C.

runoff peak and additional sediment, and (3) the time required for 

sediment to be transported downstream. Climatic changes may have 

imposed minor perturbations on the observed trends in erosion and 

sedimentation, but they do not seem to have been an important 

causal factor.

INTRODUCTION

How efficient has the soil conservation program 

been in the United States? Over 40 years of effort and 

many millions of dollars have been expended. Many 

valuable experimental data have been obtained, but 

there has been little information about effects of the 

conservation effort on the American landscape. This 

lack of applied information was lamented by Held and 

Clawson (1965, p. 232):

***As we review the bits and pieces of evidence on 

the progress of soil conservation which we have put 

together***it is difficult to avoid a feeling of frustration. There are simply no clear-cut, welldesigned data, especially on a historical scale, 

which are adequate to answer the critical questions 

about soil conservation achievement over the past 

30 years or so.***

Accelerated soil erosion has been widespread in the 

humid regions of the United States since European settlement (Butzer, 1975), and its anthropogenic causes 

are more readily documented than are those in arid 

regions (with respect to which there is still considerable controversy). For example, Trimble (1974) documented the rise and fall of accelerated erosion on the 

southern Piedmont, where erosion became serious 

after European settlement, about 1700, and was not 

brought under control generally until after 1940, but 

the data used in that study were largely qualitative. 

Moreover, the decline of erosion in that area was more 

the result of changes in land use, with reversion of 

cropland to forests and pasture, than of changes in 

land-management practices, whereas, for much of the 

United States, land that was used for crops in the 

1930's has continued to be so used.

A better opportunity to document the effectiveness 

of soil conservation efforts is provided by data
SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

available for the Coon Creek basin (fig. 1) in the 

Driftless Area of Wisconsin, a submaturely dissected 

plateau with local relief of about 135 meters, steep 

valley sides, and narrow valleys. The Driftless Area 

derives its name from the absence of deposits from continental glaciers that surrounded the area during the 

Pleistocene. The rock in the study area is sedimentary, 

with coherent to very friable sandstones and fractured 

shales overlain by a relatively resistant dolomite that 

underlies the rolling upland surface of the plateau. 

These uplands and milder slopes are capped with 

Pleistocene loess, and the alluviated valleys are partly 

filled with a series of alluvial terraces, probably of 

Pleistocene age (McKelvey, 1939, p. 13). At the time of 

European settlement, hillside swales and draws were 

partly filled with debris from former erosional 

episodes. This debris ranged in size from sand to 

dolomitic boulders. Although apparently stable at the 

time of European settlement, many were later cut by 

gullies and provided much sediment.

This severely eroded Coon Creek basin was designated the Nation's first conservation demonstration 

area. When the conservation efforts were started in 

1933, the area showed the effects of 80 years of poor 

land management: soils had been both depleted and 

eroded. Sediment from sheet, rill, and channel erosion 

was more than the streams could transport, and the 

main valleys were rapidly filling; as much as 2 meters 

of vertical accretion had occurred in 10 years 

(McKelvey, 1939). Part of the basin in early 1934 is 

shown in figure 2A; figure 3A shows cropping patterns 

on the farm outlined at the right side of figure 2A. The 

area was characterized in 1934 by rectangular fields on 

rolling to steep slopes (figs. 2, 3), poor crop rotations, 

removal of crop residues, insufficient manuring, nutrient depletion, lack of cover crops, and very active erosion. Pastures and woodland were overgrazed, compacted, and eroding in many places. The high drainage 

density, composed of eroded rills and gullies, provides 

evidence of extensive erosion caused by high rates of 

overland flow (fig. 4A). Many gullies, supplied with 

overland flow mainly from cropped areas of the rolling 

uplands, extended downslope through steep wooded 

areas. These woodland gullies were especially serious 

because they dissected old hillside sediment deposits. 

This coarser sediment was easily transportable down 

the steep slopes onto flood plains and into stream channels. Additionally, the channels of small stream 

tributaries were usually trenched from the high runoff 

peaks, thereby furnishing additional sediment 

downstream.

By contrast, present-day land management features contour plowing and contour stripcropping (figs. 

2B and 3fi). Management practices include long rotations, incorporation of crop residues into the soil, 

manuring, and cover crops (Appendix I). Figures 2 and 

3 show that land use has changed little, except on very 

steep areas, and the major change has been improved 

land management. The overall trend in land use since 

European settlement (about 1850) may be summarized 

as follows: the area of cultivated land generally expanded until about 1900 and has declined slightly but 

continually since that time (fig. 5). Although obvious 

effects of erosion (rills and gullies) on present cropland 

still occasionally exist, they are uncommon. Pastures 

are well managed with good cover, whereas woodlands 

are generally less grazed or ungrazed and therefore 

more dense. The rills and gullies have mostly disappeared (fig. 4). It is reasonable to assume that improved land-management practices have increased infiltration. Thus, an increasing proportion of the runoff 

from upland slopes has been changed from overland 

flow, which characterizes bare, disturbed areas, to subsurface flow, which had probably characterized the 

primeval landscape of prairie upland and forested 

slopes.

Acknowledgments. The authors of this report wish 

to thank several government groups, institutions, and 

individuals for their help in the successful completion 

of this project. The U.S. Geological Survey; the U.S. 

Soil Conservation Service; the Wisconsin Department 

of Natural Resources; the Wisconsin Department of 

Transportation, Division of Highway; and the University of California provided financial and logistical support. S. C. Happ, who designed a long-range sediment 

study for the valley in 1938, provided valuable field 

assistance and advice. Many students from the University of California at Los Angeles and the University of 

Wisconsin at Milwaukee assisted with both field work 

and office work. Area residents, who allowed access to 

their property for data collection, were extremely 

cooperative and helpful. Technical and administrative 

individuals too numerous to mention are also gratefully acknowledged.

THE PROBLEM AND RESEARCH PLAN

Demonstration of the effectiveness of soil conservation measures required ascertaining the quantitative 

changes of erosion and sedimentation between the 

mid-1930's and the present time and determining the 

relation between any such changes and improved conservation measures. On the basis of the qualitative 

evidence available, we believed that both erosion and 

sedimentation have been reduced significantly. On 

both procedural and conceptual grounds, it seemed 

best to separate the examination of erosion from that of
43°50'

9H5' 10' 5' 91°00' 55' 50' 90°45'

45°-

45'

Cashton

40'-

Middle , 

X Ridge I EXPLANATION

Stream-gaging station

Elevation at a point

Transverse valley profile. Surveyed 1938-39,

resurveyed 1974-78 

Public Law 566 subbasin, 1962-75 

Small reservoirs, 1936-1945

X

\>0 Portland LOCATION DIAGRAM

'"" >^VV 1356/C® YWISCONSIN... " ILLINOIS

LA CROSSE COUNTY

VERNON COUNTY

To Genoa

To Viroqua

HYDROLOGIC DATA 

Coon Valley, 1934-1940, USGS, 77.2 mi2

0 5 MIIES

i r

43°35'

I I l 

012345 KILOMETERS 

NATIONAL GEODETIC VERTICAL DATUM OF 1929

Mean discharge:

Maximum (daily):

Minimum (daily):

Mean base flows (July-August):

Average sediment yield:

I______ ___ I

0.530 (ft3/s)/mi2 

15.70 (ft3/s)/mi2 

0.268 (ft3/s)/mi2 

0.41 (ft3/s)/mi2 

856.00 (ton/mi2)/yr

FIGURE 1. Location map showing the Coon Creek basin, subbasins, debris basins, valley cross sections, and other research locations

mentioned in this study.

8

O ffi
SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS

FIGURE 2. Coon Creek basin landscape, 1934 and 1967. Location shown in figure 1; details shown in figure 3. A, Early 1934. Note rectangular 

fields and gully systems extending into the upland cultivated fields. B, 1967. Note contoured and stripcropped fields. Photographs by U.S. 

Department of Agriculture.
A. BEFORE PROGRAM 

1933

B. AFTER PROGRAM 

c. 1940

ACREAGES-1933 

Cropland

Corn

Alfalfa

Clover and timothy

Grain

Miscellaneous 

Pasture

Open

Wooded 

Farmstead, etc. 

Total

EXPLANATION

 X Fence

 Field boundary

 ~- * Waterway

Terrace outlet 

 Terraces

Woods ; 

Diversion dike 

H Permanent hayland 

P Pasture : 1, 4b Field numbers. See appendix I

300 METERS

Data from Coon 

vation Service 

Wisconsin

FIGURE 3. Map showing changes of cropping patterns on the Stromstad farm, before and after conservation managemen

Location shown in figure 1.
SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

A. 1934

Area of figure 3

B. 1967

FIGURE 4. Decrease of drainage density between 1934 and 1967. 

Shown are channels detectable on open land from airphotos (fig. 

2). Outlined area is that of figure 3. Location is shown in figure 1.

sedimentation, with the sedimentation analysis designed as general field corroboration of the erosion 

data.

Stream-sediment yields have long been used as the 

indicator of upland erosional processes. A steady state, 

or balance between material transported by the stream 

and that produced on the slopes, has been assumed to 

exist. Now we know that this concept of steady state is 

an oversimplification because much of the sediment 

flux is interrupted by periods of sediment storage between the upland slopes and the downstream point 

where sediment yield is measured. Unless these 

storage fluxes are accounted for, there can be little 

meaningful analysis of erosional phenomena and their 

causal factors (Trimble, 1975, 1977, in press).

A schematic chart (fig. 6) of sediment flux within a 

basin shows that material eroded from the upland

slopes has three immediate routes: it can be deposited 

within the basin either as colluvium or as alluvium, or 

it can be transported directly out of the basin to provide immediate sediment yield. Material deposited as 

colluvium can later be dissected and then redeposited 

as colluvium or alluvium, or it can be moved out of 

the basin. Alluvium can be eroded from the channel or 

flood plain and then transported from the basin, or it 

too can be redeposited farther downstream as alluvium. 

Some factors controlling sediment delivery are 

listed in table 1. Together, these factors act as a 

"screen" permitting more or less of the eroded material to leave as sediment yield. Table 1 covers a relatively short period (up to a few decades).

TABLE I. Examples of morphologic and process factors that affect 

rates of sediment delivery

Factors

Range in rate

Low High

-Gentle Steep.

-Coarse Fine.

-Small, Large,

discontinuous. continuous.

-Wide Narrow.

Morphologic:

Slope 

Sediment texture 

Areas of erosion 

Flood-plain width - 

Hydraulic roughness, 

channel and flood-plain 

Process:

Type of erosion Sheet Channel. 

Stream regime Equitable Flashy.

-High -Low.

Steady state or equilibrium is a useful concept in 

the analysis of the sediment budgets of stream basins. 

Under this concept, eroded material equals sediment 

yield, or, expressed another way, the net sediment 

storage flux is zero. However, such an ideal condition 

rarely exists in nature, if ever, and it is necessary to 

speak of disequilibria. If the gain of storage during a 

given period is greater than the loss of storage, then a 

positive disequilibrium exists, characterized by net 

storage gain and consequent aggradation of slopes and 

(or) channels and (or) flood plains. This condition has 

characterized many disturbed basins in the past (Trimble, 1975a, 1977, in press). If storage loss is greater 

than storage gain, then a negative disequilibrium exists whereby erosion of sediment deposits, especially 

channels and flood plains, is dominant and a consequent net sediment loss occurs.

SHEET AND RILL EROSION

Upland sheet and rill erosion in the Coon Creek 

basin was evaluated by use of the universal soil loss
SHEET AND RILL EROSION

Rural land not in farms 

(forest and prairie)

Unimproved" (Abandoned and brush)

1860 188°

1900 192°

1940

1960 1967

YEARS

Coon Creek area, 1850-1975.

SOURCE

Eroded 

(detached) 

material

(|n sjnks or transient storage)

EFFLUX I coverage for both 1934 and

1 sample basins to^^^^Hrf^ecialland 

landscape for the 1930 s,^ these baslns

treatment related to ruouc land manpossibly have somewhat better than avegbasing ^

edlmen, agement at P.^^ke* l«al relief is general- 

, | Jc-^^T^S. rdirf for the entire Coon 

Creek basin.

APPLICATION OF THE USLE

ic diagram showing sediment movement. F.OUHE 6,-Schematic

-"-"^SHEKrars

^SSSSSSi,

of the
SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

Soil Conservation Service (1975). More specialized information concerning the equation factors came from 

the Soil Conservation Service (1973a) and from addenda from the Soil Conservation Service office in Madison, Wis.

The 10 subbasins (fig. 1) were outlined on soil maps 

of the U.S. Department of Agriculture, and soilmapping units were then delineated. Data on land use 

were taken from U.S. Department of Agriculture airphotos for 1934 and 1974. This procedure divided the 

landscape into parcels on the basis of soil, slope, previous erosion, and land use. Land-use acreages for both 

periods are given in table 2 and figure 7. Data on present land management were obtained from individual 

farm-conservation plans and from Soil Conservation 

Service personnel. Predominant land-management 

methods of the early 1930's were provided by landinventory surveys (Wisconsin Department of Agriculture, undated) and from Soil Conservation Service personnel and others familiar with conditions of that time. 

The percentage of area controlled by Soil Conservation 

Service cooperators, persons who usually conform to 

prescribed soil management practices, is shown in 

figure 7A. At present, noncooperators usually emulate 

their neighbors to various degrees so that much land 

not under a formal agreement is still given moderate to 

good management. In contrast, in 1934, practically no 

one practiced good soil-conservation practices in the 

Coon Creek basin. A few did try to contour and to use 

stripcropping, but their methods were often crude and 

ineffective.

Figure IB shows the changes in land management 

on selected uses. As mentioned, some contouring and 

stripcropping were initiated in the Coon Creek basin 

by 1934, but the 1934 airphotos show none in the 

sampled subbasins. The fact that 38 percent of present 

cropland is neither contoured nor stripcropped (fig. 75) 

is compatible with acceptable management practices 

because most of the nontreated land is on the more gentle slopes of the rolling upland.

Crop rotations are also greatly improved (fig. 75), 

with longer periods in grass cover which not only offers 

more soil protection but also increases the soil's 

resistance to erosion during periods when it is under

TABLE 2. Land use in 10 subbasins, 1934 and 1975. Locations of 

subbasins shown in figure 1; data compiled from Lund, 1976, table 8

1934 1975 Change, 

1934-75

Hectares Acres Percent Hectares Acres Percent Percent

Cropland 

Pasture 

Woodland 

Farmyards 

Roads and buildings 

Total 

2,055

553

474

70

29

3,181 7,951

5,138 64.6

1,383 17.4

1,184 14.9

174 2.2

72 .9

100

1,937

622

522

68

32

3,181

4,842 60.9 - 5.8 

1,556 19.6 +12.5 

1,304 16.4 +10.1 

2.1 - 2.3 

1.0 + 9.7 

100

170

79

7,951

row crops. For example, 80 percent of all cropland is 

now in a rotation of 1 year of row crops, 1 year of oats, 

and 3 years of hay (RO3H, fig. 75). Besides immediately reducing erosion, the long periods of grass cover between row crops are important in replacing organic 

material, improving soil structure, increasing infiltration, and increasing fertility, factors which eventually 

further reduce erosion. All these effects are greatly 

reinforced by the prevalent good crop-residue management. At present (1975), only 1 percent of cropland has 

no rotation. We do not have a comparable figure for 

1934, but we assume that lack of crop rotation was 

more prevalent than it is at present. Even though crop 

rotations were common in 1934, the grass cover was 

usually not maintained sufficiently long to allow the 

soil to recover from the depleting effects of row crops 

and small grains.

Most woodland in the Coon Creek basin was heavily grazed in 1934 (fig. 7). Most of the forest understory 

was removed, and the soil was heavily compacted and 

disturbed. Grazing was commonly severe enough to 

kill trees (Soil Conservation Service, undated, p. 18). 

Grazed woodland areas were eroding seriously, and the 

resultant runoff damaged downslope fields. At present 

only 22 percent of woodland is grazed, and this grazing 

is usually light and not as destructive as that of the 

1930's.

Despite our efforts to determine precisely the landmanagement portion of the cropping management factor C, the exact condition of every land parcel in 1934 

could not be established. Therefore, application of the 

USLE required some uniform assumptions (table 3), 

which do not apply to every site, although they are 

believed to be correct as the general rule.

The rainfall factor, R, is a numerical measure of 

the annual erosivity. It is obtained by summing the 

products of total kinetic energy and maximum 

30-minute intensity (El) for each storm during the year 

(Wischmeier and Smith, 1965). The R value used in the 

USLE for both 1934 and 1975 is the average annual El 

value for long-term weather records. The Soil Conservation Service has computed average R values for 

counties of Wisconsin, that of Vernon County being 

150.

The soil erodibility factor, K, reflects the fact that 

some soils are eroded more readily than others, even 

where slope, rainfall, cover, and management are the 

same. K factors have been determined through field experimentation by the U.S. Department of Agriculture 

for all of Wisconsin. The most erodible soils in the 

study area are about one-third more erodible than the 

least erodible soils.

The slope length factor, L, is the distance from the 

point of origin of overland flow to either the point
SHEET AND RILL EROSION

6000

5000

4000

C/3 

LU

3000

2000

1000

Cropland 

5138

4842

38

3012

1934 1975

A. Land use (shaded area controlled by Soil Conservation 

Service cooperators), 1934 and 1975 (compiled in part from 

Lund, 1976, tables 8 and 12)

EXPLANATION 

R03H Crop rotation. Number indicates years

R Row crops

0 Oats or other small grain

H Hay 

5138 Area in acres

38 Percent of total acreage

EXAMPLE: 2R03H is 2 years row crops, 1 year oats, 

and 3 years hay

Pasture

1556 

1383

Woodland

1304 

1184 ~22~

1934 1975 1934 1975 

YEAR

Farmyard 

Road and 

Building

246 249 ?Q

 2000

 1000

1934 1975

6000

5000 

4000 

3000 

2000 

1000 

( 

con

Cropland Cropland 

:ontouring and Crop rotation 

tour strip farming practices

03

C 

0

>/yvv

39

03

C 

0

; 51 '.

I

; w :

n

0) o

£

D 

0

C

O

0)

c

'i o

~ '*/**

° is -

^5s^

: j//<4/^

: mill 

: 80

>( 11

^ M^ig

S B. Land in various conservation practices, 

§ 1934 and 1967 (compiled in part from 

/ Lund, tables 8 and 9)

\ 

O

QC __

1. 

CO

O

DC

Woodland 

Grazed and Ungrazed

03 \VsXX "o N VsNNN: -jn ,- 03 

£ \\\\^ 72.5 N

§ ° Hi i

- 1 *^p'

1934 1975 1934 1975 1934 1975 

YEAR

 2000

 1000

FIGURE 7. Diagram showing changes of land use and management in 10 sample basins, Coon Creek, Wis., 1934 and 1974.
10 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

TABLE 3. Sample soil-loss computations for part of the individual soil mapping units in subbasin 15 using the universal soil loss equation,

A = RKLSCP

[A is computed to give an annual rate in tons per acre. The component variables R, K, L, S, C, and P are dimensionless. A, amount of soil loss; R, rainfall factor; K, soil erodibility factor; 

L, slope length factor; S, slope gradient factor; C, cropping management factor; P, erosion control practice factor]

Annual Rates

Soil Unit Land Use Area (acres) R K L S LS C P (Tons/acre) O^g/km")

1934

ArA

/-( TD

DsD2

DsE

DvE

0 1

7 *\

2 4

ft 4

110

crop 10.2

A n

A n

FvD2 crop 2.0

150 

150 

150 

150 

150 

150 

150 

150 

150

0.28 

.32 

.32 

.37 

.37 

.37 

.37 

.37 

.37

400 

200 

200 

350 

350 

250 

200 

200 

300

1 

4 

4 

16 

16 

25 

25 

25 

16

0.27 

.58 

.58 

5.37 

5.37 

8.50 

8.50 

8.50 

4.97

0.04 

.10 

.04 

.04 

.10 

.04 

.04 

.03 

.10

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0

0.45 

2.28 

1.1 

11.9 

29.8 

18.9 

18.9 

14.2 

27.6

102 

632 

252 

2,710 

6,870 

4,290 

4,290 

3,220 

6,270

1975

ArA

/-( TD

DsD2

DsE

DvE

FvD2

r\a 0+ 11 TV*

0 1

7 ^

8 8

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1 K Q

9 A

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9 n

150 

150 

150 

150 

150 

150 

150 

150

0.28 

.32 

.37 

.37 

.37 

.37 

.37 

.37

400 

200 

350 

350 

350 

250 

200 

300

1 

4 

16 

16 

16 

25 

25 

16

0.27 

.58 

5.37 

5.37 

5.37 

8.50 

8.50 

4.97

0.011 

.011 

.03 

.011 

.055 

.011 

.001 

.001

1.0 

1.0 

1.0 

1.0 

.9 

1.0 

1.0 

1.0

0.1 

.3 

8.9 

3.3 

14.8 

5.2 

.5 

.3

627 

70 

2,030 

746 

3,350 

1,180 

167 

61

where deposition begins as the slope decreases or the 

point where runoff enters a well-defined channel that 

may be part of a natural drainage network or a constructed channel such as a waterway or diversion. 

Average slope lengths for the soil mapping units of the 

study area were used in the computations (Appendix 

3). These average slope lengths, supplied by the State 

Office of the Soil Conservation Service in Madison, are 

based on actual field measurements in the region of the 

study area. Average slope lengths were used because 

the areal extent of the study area prohibited making 

direct measurements for each field and because the 

large local relief of the area made it difficult to obtain 

accurate measurements from aerial photographs. Also, 

the point of origin of overland flow or the point of 

deposition of colluvium cannot always be determined 

from aerial photos. Average slope lengths are used by 

Soil Conservation Service personnel in watershed and 

soil-conservation planning, and we desired to follow 

standard Soil Conservation Service procedures as 

closely as possible in soil loss computations so that our 

study could be duplicated.

The slope gradient factor, S, expresses the effect of 

the inclination of the land surface. The average slope 

for each class was used for calculations. For field application, slope length and slope gradient are combined 

into a single topographic factor, LS, to adjust the soilloss estimate for effects of length, steepness, and shape 

of the slope. This conversion is done by use of a slopeeffect chart (Soil Conservation Service, 1973a).

Examples of soil-loss computations by soil mapping 

units are given in table 3. These comprise about a 

quarter of the computations required for subbasin 15 

alone.

RESULTS

Calculated annual erosion rates from the 10 subbasins in 1934 ranged from 1,900 to 3,900 Mg/km2 with 

an area-weighted average of 3,000 Mg/km2 (table 4). In 

1975, the values ranged from 420 to 1,100 Mg/km2 , 

with an annual area-weighted average of 720 Mg/km2 . 

Thus, the present annual rate of upland erosion is calculated to be less than one-fourth that of 1934. We 

place more importance on the relative rates than on 

the absolute soil-loss values.

These data should be used only with at least two 

stipulations or warnings. First, we have calculated 

only upland sheet and rill erosion on fields; these 

figures are not equivalent to sediment yields downstream. Gully erosion, although not a significant sediment source at the present time, was significant in 

1934 (figs. 2 and 4). Running water confined to channels normally cuts much faster than thin sheet and rill 

flow, which encounters far more frictional resistance.
SEDIMENTATION 11

TABLE 4. Average annual rates of upland sheet and rill erosion for 

the study area, 1934 and 1975, as calculated with the universal 

soil loss equation. Locations of subbasins shown in figure 1.

_____________ 1934 ____________ 1975 1975/1934 

Subbasin (Mg/km2) (Tons/mi2) (Mg/km2) (Tons/mi2) (percent)

14

15

16

17

41

23

24

25

33

53

3,700

3,000

2,800

2,600

2,800

1,900

3,300

3,900

3,300

3,500

10,600

8,600

8,000

7,400

8,000

5,400

9,400

11,100

9,400

10,000

690

650

870

580

860

420

1,100

610

670

730

2,000

1,900

2,500

1,700

2,500

1,200

3,100

1,700

1,900

2,100

19

22

31

22

31

22

33

16

20

21

Area-weighted 

Average 3,000 8,600 720 2,100 24

Second, the index of soil erodibility for the USLE, the 

K factor, is based simply on soil series and takes no 

cognizance of specific soil conditions. That is, by 1934 

most soils in the study area had been abused for about 

80 years, and, given the lack of management practices, 

it appears reasonable to assume that these soils had 

undergone cumulative deterioration and were in poor 

hydrologic condition; that is, with little organic 

material, few roots and root channels, depleted nutrients, and a high degree of compaction. Erosion from 

these soils further aggravated the condition because 

most subsoils (B horizon) are more credible. For example, the subsoils of two regionally dominant soils, the 

Fayette and Palsgrove series are about 16 percent 

more credible than their topsoils (Soil Conservation 

Service, Madison, Wis., unpublished mimeographed 

data, February 1977). The management practices of 

the past 30 years, such as residue management and the 

maintenance of grass cover for longer periods, could 

only improve soil conditions. Because the 1934 rates 

were possibly higher than our calculations indicate, 

the 1934-75 disparity may be greater than our 4-to-l 

figure. Thus, we consider our calculations as a minimum change in rate.

Experiments in the Driftless Area near Coon Creek 

gave results similar to our estimated erosion rates. 

They indicated that 2 years of grass cover in a rotation 

was essential for minimum conservation on steeper 

slopes and that 3 years was even more beneficial (Hays 

and others, 1949). Under otherwise identical conditions, when rotation with only 1 year of grass cover lost 

an annual average of 2,200 Mg/km2 , rotation with 2 

years of grass cover lost only 1,300 Mg/km2 per year, 

rotation with 3 years of grass cover lost 800 Mg/km2 , 

and rotation with 4 years of grass cover lost only 700 

Mg/km2 . Additionally, the change from contour plowing to contour stripcropping reduced soil losses by 50 

percent.

SEDIMENTATION

We have attempted to measure sedimentation in 

two environments for both time periods. The environments are (1) total sediment yield in small tributary 

reservoirs or flood-retention structures with high sediment trap efficiencies and (2) deposition rates for 

modern alluvium in the main valley, storage of which 

accounts for much of the fluvial sediment generated 

since European settlement.

SEDIMENT YIELDS IN SMALL RESERVOIRS, 1962-75

Each of the 10 subbasins (fig. 1) was selected 

primarily because it was tributary to a flood-retention 

reservoir which acts as an efficient sediment trap. 

These reservoirs, built during 1960-63 (one built in 

1963) had collected most of the sediment delivered 

from their tributaries' basins when the sediment surveys were made in 1975. These surveys were done 

according to Soil Conservation Service standards using 

cross-sectional profiles or ranges and borings through 

the sediment accumulation (Soil Conservation Service, 

1971). Figure 8 shows one subbasin and its reservoir 

with the sediment survey profiles. Characteristics of 

the reservoirs and the sediment measurements are 

given in table 5. Annual sediment yields ranged from 8 

to 131 Mg/km2 with an areally weighted average of 56 

Mg/km2 .

All 10 basins had relict gullies that had probably 

been active in the 1930's. The presence of rank vegetation on previously unstable areas suggests that the 

gullies have been relatively inactive during recent 

years. Further, sediment accumulation in the reservoirs tended to be silty, which suggests an origin from 

upland loessial soils.

SEDIMENT DELIVERY RATIOS, 1962-75

The ratios between measured sediment yields and 

computed upland erosion suggest that sediment 

delivery ratios (SDK) range from about 2 to 18 percent 

with an average of about 8 percent (table 5). That is, 

only about 8 percent of material calculated to have 

been eroded since 1962 has been transported to the 

sediment-storage areas provided by the reservoirs. 

Much of the eroded material was deposited as colluvium in grass and weeds at the lower end of fields 

and in grassed waterways. Also, steep slopes between 

most fields and stream channels are heavily wooded. 

Sediment-laden overland flow which infrequently 

flows into these forests is usually rapidly infiltrated,
12 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS. 

SEDIMENT POOL 

REM Range end marker 

Observed pool 

elevation 1068 feet 

100 

I 

I 

200 FEET 

I 

100 METERS 

Viroqua I :62. 500. 1965 

0 

I 

SUBBASIN 41 (PUBLIC LAW 566) 

I MI LE 

I 

FIGURE 8.-Map showing subbasin 41. 

TABLE 5.-Sediment-survey data, Coon Creek basin, 1962-75: sediment accumulated in 10 flood-retarding reservoirs constructed under 

Public Law 566 (compiled from Lund, 1976). Locations of reservoirs shown in figure 1. 

Length Trap Drainage area Total Annual sediment yield Calculated annual erosion rate Sediment 

Subbasin of record effic iency' (km') (mi') sediment y ield for 1975 (table 6) delivery rate 

(years) (percent) (Mg) (Tons) (Mg!km') (Ton.slmi') (Mg!km') (Tonslmi') (percent) 

14 13 92 1.74 0.67 761 839 34 97 690 2,000 4.9 

15 13 92 3.07 1.19 1,240 1,370 31 88 650 1,900 4.8 

16 13 93 .86 .33 1,260 1,390 113 322 870 2,500 13.0 

17 13 92 2.95 1.14 600 661 16 46 580 1,700 2.8 

41 13 93 6.07 2.34 4,090 4,510 52 148 860 2,500 6.0 

23 14 91 3.64 1.41 430 474 8 23 420 1,200 1.9 

24 12 91 2.21 .85 1,230 1,360 46 131 1,100 3,100 4.2 

25 14 93 3.58 1.38 3,770 4,160 72 214 610 1,700 12.3 

33 15 93 4.99 1.93 3,790 4,180 51 146 670 1,900 7.6 

53 12 93 2.66 1.03 4,180 4,610 131 374 730 2,100 17.9 

Area-weighted average --- -------- - - - ----------------------- 56 160 720 2,100 7.8 

1 Tr-ap effic iency is the estimated percentage of total sediment y ield that is caught yields at these sites are adjusted with the appropriate trap efficiency supplied by the Soil 

behind the dam structure, the rest going through the spillway and downstream. Sediment Conservation Service, Madison, Wis. 
SEDIMENTATION 13 

leaving the sediment as colluvium. Such deposits are 

extensive in Driftless Area forests (R. S. Sartz, oral 

communication, 1974). 

SEDIMENT YIELDS IN SMALL RESERVOIRS, ABOUT 1936-45 

Unlike the situation in the present period, there 

are not good records of sediment yields from small 

watersheds for the 1930's and early 1940's. Although 

many small reservoirs, detention structures, and 

debris dams were built in that period, we found no 

recorded surveys of original capacity that would have 

given us baseline data for computing sedimentation 

rates from later resurveys. Hence, we had to reconstruct original reservoir capacities. This was done by 

stratigraphy from borings and dug pits, dendrochronology, photogrammetry, and detailed topographic surveys. The possibility of reconstructing the original 

capacities was the first criterion for selection of sites. 

Other criteria were (1) the ability to date the accumulation so as to establish rates and (2) a ratio of capacity to 

drainage area large enough to trap a major portion of 

the sediment delivered to the reservoir. Five reservoirs 

met these criteria and were included in the study (fig. 

1, table 6). Two of the basins (sites 1 and 4) are located 

in the Coon Creek basin; three (sites 2, 3, and 5) are outside the basin in the Driftless Area. 

Whereas the 1962-75 reservoir data are probably 

accurate within 10 percent, the older records are probably not as accurate for reasons which include very different environmental conditions among sites, very uncertain trap efficiencies, and our ignorance of volume 

of above-spillway sediment deposited after the reservoir filled to spillway level, bulk density of deposits, 

the exact original reservoir configuration, and the ex· 

act time required for filling. 

The different environmental conditions among 

basins include greatly different basin sizes, basin 

slopes (expressed as relief-length ratios, table 6), and 

types of erosion. All sites except site 4 include significant gully erosion, and gully erosion appears to have 

been most important at sites 2, 3, and 5. 

Trap efficiency is the greatest uncertainty. 

Although trap efficiency at all sites except No. 5 was 

high at first [perhaps as high as 60-80 percent according to the Brune (1953) method], the values declined as 

the pools filled. Because we did not know the trap efficiencies, we could not correct for them, as we did for the 

period 1962-75, and our rates may be underestimated. 

Even after the pools were completely filled to 

spillway level, coarser sediment was still deposited 

above the spillway level on the lessened slopes of the 

filled ponds. That is, even though a reservoir may have 

been reported to have been filled to spillway level by a 

certain date, above-spillway deposits continued to accumulate slowly for some time thereafter. These 

deposits are present at all sites, but we were able to adjust for this effect at sites 1 and 4 by dendrochronology 

and eyewitness accounts. At sites 2, 3, and 5, the 

above-spillway deposits are included in the rates, and 

thus the rates partially reflect accretion above the 

spillways. However, the above-spillway deposits probably do not completely offset the underestimate caused 

by unknown trap efficiencies. 

The reservoir deposits (except those at site 4) were 

poorly sorted. The sediment at site 4 is loessial silt, 

compacted by grazing, and we measured its bulk 

specific gravity as 1.4. At the other sites, dug pits 

TABLE 6.-Accumulation of sediment in fi ve small reservoirs, about 1936-45 (locations shown in fig. 1), given in order of decreasing 

dependability of data. 

Site Site Period Drainage area Relief· Annual sediment yield 

No. of (km') (mi') length name (Mg!km') (Tonslmi'l accumulation ratio 

1. Clement SCS Dam---------· 1936-42 5.45 2.10 0.040 4,400 13,000 

(6 yr). 

2. Upper Michell Dam-------- · 1941-45 .23 .09 .126 5,400 15,000 

(4 yr). 

3. Bischel! Debris Dam--- - --- - 1937-39 .28 .11 .189 14,000 40,000 

(2 yr). 

4. Johnson CCC Dam --------- 1936-77 .28 .11 .034 1,100 3,000 

(41 yr). 

1936-62 .28 .11 .034 1,600 4,600 

(26 yr calc). 

1936-40 .28 .11 .034 2,500 7,000 

(4 yr ca lc). 

5. Middle Michell Debris Dam-- 1941-43 .08 .03 .205 2,500 7,000 

(2 yr). 

Area-weightedaverage ----------------------------------------------------------- ---------- 4,800 14,000 
14 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

revealed large boulders (up to 80 cm mean diameter) in 

matrices composed of particles ranging from clay to 

small boulders. There is little pronounced stratification, but the general trend in eight dug pits, ranging in 

depth from 2 to 4 m, is for increasingly fine material 

toward the surface. Boulders (30-60 cm mean diameter) 

were found in the lower half whereas the surface 0.3- 

0.5 m was mostly silt and fine sand. We interpreted this 

as reflecting the decrease with time of extremely high 

runoff peaks and concomitant reduction of erosion and 

sediment load. Except at site 4, there was a decrease of 

particle size towards the dam. As a result, it was difficult to determine bulk specific gravities of these 

heterogeneous mixtures. On the basis of samples of the 

finer materials, we estimate a bulk specific gravity of 

about 1.4 for all sites except 5. Site 5 had more large 

rocks than the others, so we estimated a bulk specific 

gravity of 1.9.

The final uncertainty is the exact time required to 

fill the reservoirs. Because the times were short (about 

2 years at sites 3 and 5), a small error in time could be 

critical. For inclusion of a site, we required at least one 

reliable witness and we tried to obtain corroboration. 

For example, this was done by dendrochronology at 

site 1, where an age-dated willow tree near the dam at 

spillway level verified the information given by a local 

witness, a 92-year-old man, to the exact year.

At site 4, we measured the entire deposition from 

1936 to 1977 and budgeted that over time to get 

shorter-term rates (fig. 9). Site 4 is important because 

the erosional debris, all fine textured, came primarily 

from sheet and rill erosion on upland slopes, mostly 

cultivated land, whereas the other four sites had considerable gully erosion in addition to upland sheet and 

rill erosion. The total sediment deposited since 1936 at 

site 4 was about 12,300 Mg (13,600 tons), giving an 

overall 1936-77 annual rate of 1,100 Mg/km2 (fig. 9). 

However, annual sediment yields from upland erosion 

for the period 1962-75, as measured in our 10 basins, 

ranged from 8 to 131 Mg/km2. If we apply the maximum 

annual value obtained from those basins (131 Mg/km2) 

to site 4 for the same period, we can then rebudget the 

remainder of the sediment for the period 1936-62 giving an adjusted rate for that period of 1,600 Mg/km2 . We then smooth the curve to give continuity and insure that the mass volumes are equal (that is, area 

[volume] A = area [vol.] A' and 5 = 50. The shape of 

the curve is thus determined by the number of constraints imposed. There are three lines of evidence 

which support continuous sedimentation and justify a 

smooth curve. The first is historical: the rapid sedimentation rates of the 1920's and 1930's are within the 

memory of many area farmers. Average vertical accretion rates of that period were about 15 cm per year, and

this was usually from several events. Although a 

single event could bring enough sediment to bury the 

grass cover of the flood plain, aggradation was usually 

more insidious so that fence posts seemed to shrink in 

height over a period of time. Second, detailed precipitation data from the Coon Creek basin for the years 

1934-40, when sedimentation rates were at the highest, 

show no extreme daily events (Soil Conservation Service, 1942). However, extreme events (>20 cm/d) did occur in 1951 and 1978 without the high sedimentation 

rates which occurred in the 1920's and 1930's. Third, 

superimposition of six continuous sedimentation 

graphs (figs. 10, 11) indicates that the curves are 

remarkably similar (these data will be developed later 

in this study). Because the times of observation are different in each of the six graphs, the similarity would be 

highly improbable unless the rates were generally continuous. The curves should be considered as trend lines 

and may not be correct for any given year. The curves 

can be integrated to yield composite curves (fig. 11).

Figure 9 indicates that annual sediment yield rates 

from upland erosion alone during the period 1936-40 

may have been well over 2,400 Mg/km2 . This figure 

compares well with that obtained by the USLE for 

1934 of about 3,000 Mg/km2 and probably reflects the 

more efficient offsite transport of sediment through the 

rills and upland gullies of that period. If sediment 

yields from upland sheet and rill erosion were as high 

as indicated at site 4, then overall annual sedimentation rates, including valley trenching, of 4,000-5,000 

Mg/km2 (as found, for example, at site 1, fig. 12) appear 

to be reasonable.

The small reservoir sites for the period 1936-45 are 

subjectively ranked in order of data dependability (1-5, 

table 6). Given the trap efficiency problem, the estimated sedimentation rates are probably low. We have 

no way of testing the values statistically, but we 

believe that they are all correct within the bounds of 

-25 percent and +50 percent. Despite the uncertainties, the sediment yields for the period are remarkably 

consistent with a maximum/minimum range of 5.5 

times, while the ostensibly better 1962-75 data have a 

variation of 15 times. Although the value for any one 

site may be imprecise, the errors may well be partially 

compensating. We believe the overall annual areally 

weighted average of 4,800 Mg/km2 is a reasonable 

value for Coon Creek basin and for much of the Driftless Area during the 1936-45 period.

SEDIMENT DELIVERY RATIOS, ABOUT 1936-45

The weighted yield of 4,800 (Mg/km2)/yr (table 6, fig. 

12) was about 60 percent greater than the average upland erosion calculated for the 10 subbasins in 1934 

and about 30 percent greater than the highest value.
SEDIMENTATION 15

/Profile number 1

.Profile number 2

/Profile number 3

<,2

EXPLANATION

1853-1936 1936-1977 

Assumed datum in feet ® Stations

0 100 200 300 400 500 FEET

'Profile number 4

PLAN VIEW

/Fenceline

50 75 100 METERS

SEDIMENT ACCUMULATION 1936-1977 

8527 M3@1440 Mg/M3= 12,325 Mg

1070jyis/km?/yr

Approximate head

Profile number 4

PROFILE VIEWS

Profile number 3

Profile number 2 

Station 2

120-

115- Profile number 1

Top of 

110- north

0 5 10 15 20 25 FEET i i I i 

012345 METERS

Gully

below 

95 - dam

I___1

1853-1936 1936-1977

FIGURE 9. Map and diagram showing sediment accumulation in the Johnson Civilian Conservation Corps dam reservoir.

Detailed location in figure 1.
16 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

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DEPOSITION, YEAR MENT INEGAGRAMS KILOMETER PER SQUARE 

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am showing sediment deposition rates at selected valley sites in Coon Creek basin, 1853-1977.
SEDIMENTATION 17

QUANTITY OF MODERN OVERBANK SEDIMENT c. 1853-1938 r,

i 

Distribution shown by width proportional to cross-section area ^J

of sediment deposits

SQUARE FEET

10,000 (930 SQUARE METERS)

5000

0 /LA CROSSE/COUNTY

N-_ -* / s x--

4 MILES

012345 KILOMETERS

FIGURE 10. Continued

Given the low SDK's of the present, the observation 

that sediment yields for small basins in the 1930's 

were apparently greater than upland sheet erosion 

rates is somewhat surprising. However, at least three 

phenomena appear to explain this disparity. First, the 

upland was locally riddled with gullies, many of which 

extended down through the woods to the stream channel (figs. 2 and 3). Not only would these gullies have 

greatly increased erosional debris, but the possibility 

of colluvial deposition was greatly diminished, thus 

permitting much of the erosional debris from upland 

fields to reach the stream channel. Second, tributary 

stream channels were themselves rapidly becoming 

trenched in the late 1930's (McKelvey, 1939, p. 41-43; 

Happ and others, 1940, p. 52). Third, a sandy high terrace in the lower ends of some valleys tributary to the 

lower half of the Coon Creek basin was being rapidly 

eroded at that time (as at site 1, for example; such erosion no doubt made a significant contribution to the 

observed rate of sediment accumulation in the lower 

valley).

SEDIMENT DEPOSITION RATES IN THE MAIN VALLEY,

1853-1976

The Coon Creek basin was selected for this study in 

part because an earlier study of valley morphology had

been done in 1938-39 (McKelvey, 1939). Detailed surveys were made of sediment accumulation on the flood 

plains and the values were recomputed in 1975 (Trimble, 1976a). In the mainstream valley, most of this 

material was deposited by vertical accretion, but in the 

tributaries, lateral accretion was almost as important. 

Of the total volume of modern sediment measured in 

the Coon Creek basin, vertical accretion accounted for 

93 percent and lateral accretion was only 7 percent. 

Even in tributaries, vertical accretion was more important than lateral accretion (Trimble, 1976a, p. 103, 

107). During the period 1853-1938, sediment deposition was 19.5 x 10" m8 from an area of 365 km2 (Trimble, 1976a, p. 103). This is a net total value; that is, the 

estimated volume of material eroded from tributary 

channels has been subtracted. At an assumed average 

bulk specific gravity of 1.4, the overall annual rate of 

deposition averaged about 920 Mg/km2 between 1853, 

the time of European settlement, and 1938. From 1938 

to 1975 the annual rate of deposition was about 40 percent of the earlier rate, or about 370 Mg/km2 . This 

valley sediment may represent more than 80 percent of 

all eroded material reaching the streams, only a small 

proportion being transported out of the basin by the 

stream as basin efflux or sediment yield (Trimble, 

1976b, in press).
18

14

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LU

DC 12 

LU

SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

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YEARS

FIGURE 11. Composite curve of sediment deposition for the main 

valley of Coon Creek basin, 1853-1975.

Of the fluvial sediment stored in the Coon Creek 

basin from 1853 to 1938, about 75 percent was in the 

main valley. Although deposition rates in tributaries 

may have been somewhat different than in the main 

valley, for the purpose of budgeting sediment deposition we have assumed them to be about the same; error 

introduced by this assumption is probably minor at the 

basinwide scale. We established differential rates of 

deposition through time (fig. 10) by using buried cultural features such as roads, bridges, fences, and buildings, all of which could be dated.

The profile at range CV30, located in the lower 

main valley of Coon Creek, serves as a good example

(fig. 10B). The 1853 (presettlement) flood plain was 

located in 1938 by borings to the old alluvial soil, a 

dark, organic, texturally homogeneous (probably 

Mollic) soil. The approximate elevation of the 1904 

flood plain, about 0.75 m above that of 1853, shows a 

rate of only 0.015 m per year of vertical accretion during the first 51 years of settlement. The 1904 elevation 

was approximated by finding the compacted flood plain 

surface behind a railroad embankment which had acted 

as a dike, allowing flood-plain aggradation on the 

stream side but eventually creating a lake between the 

dike and the adjacent hillside. The elevation thus approximated is probably a maximum value. By 1930, the 

flood plain had aggraded by another 1.5 m (or 0.06 m 

per year), a remarkable increase over the previous 

rate. The 1930 flood-plain elevation was established 

by locating and boring to an old gravel road which 

crossed the stream at a local bridge, the abutments of 

which have been completely buried. The existence of 

the road, the year of abandonment (1930), and the fact 

that the road was at the level of the flood plain were 

disclosed by elderly local residents. Of interest is the 

fact that within 3Vfe years of abandonment, the road 

was completely covered by sediment and not detectable 

on an aerial photograph made in early 1934. The 1938 

profile was a surveyed line. In the 8 years following 

1930, the flood plain aggraded almost 1.2 m (or 0.15 m 

per year), indicating the massive sedimentation occurring during the 1930's. Then, in the 38 years between 

1938 and 1976, there was only 0.6 m (0.016 m per year) 

of aggradation, a greatly reduced rate.

The deposition rates for the discrete periods above 

were established from the area (and hence relative 

volume) of accretion shown in the cross-sectional profile (fig. 10B). There is enough information here to 

draw a smoothed line describing the differential rates 

of sediment deposition through time, but the line can 

be improved with more definite end values derived as 

follows.

We know that erosion and sediment deposition 

rates were low at the time of European settlement from 

the following evidence:

(1) Minimal upland erosion. We infer that the 

deep, well-structured forest and prairie soils probably 

had enough infiltration capacity for all but the 

greatest precipitation intensities and amounts. Thus, 

most stormflow would have been subsurface flow 

(largely throughflow) (Ward, 1975, p. 247) with surface 

stormflow generally restricted to channel areas. 

Research in the region has shown that relatively 

undisturbed forest and grasslands generally have little 

surface stormflow and practically no erosion. Sartz 

(1976, p. 130) estimates a 13-year sediment yield of
SEDIMENTATION 19

15,000

10,000

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DRAINAGE AREA, IN SQUARE MILES

10

FIGURE 12. Diagram showing sediment accumulation in small reservoirs of the Driftless Area, about 1936-45 and 1962-75.

0.02 Mg/km2 annually from a wooded area which 

formerly had been affected by grazing. Many tributary 

watersheds of over 1 km2 (0.39 mi2) had no stream 

channels at the time of European settlement, indicating the low surface runoff at that time. Concerning 

channel erosion in perennial streams, early literature 

indicates stable stream banks (for example, Owen, 

1847, p. 35, 37, 58) and photographs indicate that these 

channels were stable in some areas until after 1900 

(fig. 13).

(2) Small stream-sediment loads. Early explorers 

of the region, including scientists, uniformly praised 

the clarity of the streams. One report even described

the stream bottom as seen several feet beneath the surface (Owen, 1847, p. 35, 37, 58). Streams were inhabited 

by brook trout, which are very intolerant of suspended 

sediment (Trowbridge, undated, p. 19). Early Army 

Engineer reports indicate that the upper Mississippi 

River was clear enough in the 1860's so that stream 

bottom dune formations and vegetation could be easily 

observed (U.S. House of Representatives, 1867, p. 11, 

17, 59, 61). In 1867, about 15 years after settlement, a 

flood of 3-year frequency on the Mississippi River 

downstream at Keokuk, Iowa, had a sediment concentration of only 100 parts per million (U.S. Army Corps 

of Engineers, 1867, p. 321). These observations suggest
20 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

that stream sediment loads were quite low by present 

standards.

(3) Flood-plain soils. As already noted, the presettlement flood plains were generally covered with a 

dark, well-developed Mollisol of fairly uniform, loamy 

texture. The widespread presence of this soil indicates 

stable conditions for a long period preceding European 

settlement and seems to preclude rapid vertical accretion and bank cutting and accompanying lateral 

accretion.

(4) Carbon-14 dates in older alluvium. In the 

Kickapoo River, adjacent to Coon Creek, Johnson 

(1976, p. 132; written communication, 1976) has established a date of about 2445 ±60 years before present at 

0.75 m below the surface of the old flood-plain soil. 

Other carbon-14 dates obtained by Johnson gave 

similar rates of vertical accretion. If we transfer the 

above value to Coon Creek using the cross-sectional 

profile at range CV30 (fig. 10B), the annual rate of 

deposition would have been approximately 10 Mg/km2 

of material from the total drainage area. The exact 

value is not as important as the fact that the value is 

extremely low relative to the rates after agricultural 

activity.

The rate of deposition for recent years can be 

definitely ascertained only after a few more years 

when resurveys can be made of the profiles. Deposition 

on flood plains has been slow in recent years, as shown 

by such evidence as lack of aggradation around fence 

posts and root crowns of trees, but these observations 

do not yet give good quantitative data. However, surveys of the reservoirs constructed under Public Law 

566 give us a reasonable estimate of eroded material 

delivered downstream to tributary flood plains where

the dams are located: this material is the maximum 

net amount from upland sources available for deposition on the flood plains in valleys not controlled by 

Public Law 566 reservoirs. Of this material, which 

amounts to 56 Mg/km2 annually (table 5), an unknown 

proportion is deposited on downstream flood plains 

during the now-infrequent floods, and the remainder is 

transported out of the system by the stream as sediment discharge. The determination of the proportion 

transported from the basin is complicated by the channel erosion occurring in tributaries and in the upper 

main valley. Of course, channel erosion is primarily a 

reworking of existing sediment deposits, and any material later deposited downstream in the channel or on 

the flood plain cannot be considered a net addition. 

However, assuming that the annual rate of delivery of 

sediment (56 Mg/km2) to the 10 small reservoirs is 

representative of the basin as a whole places an upper 

limit on net addition to sediment storage.

Using the beginning and end points derived above, 

we can now draw smoothed curves indicating differential deposition rates through time (fig. 10).

The sediment accumulation rate at each of the six 

main valley sites is used to budget all sediment identified in the Coon Creek basin, and the areal base is the 

entire basin, not just the upstream tributary area. This 

uniform areal base allows integration of the values 

from various locations so that composite curves can be 

drawn. The indicated peaks, all in the 1930's and early 

1940's, range from 3,500 Mg/km2 at range CV24 to 

4,700 Mg/km2 at range CV19. Because so many uncertainties exist in reconstructing such rates, the variation among sites is probably insignificant and only a 

mean or composite value is useful. The individual rates

FIGURE 13. Photographs showing bank and channel erosion of perennial tributaries. A, Near Fairwater, Minn., on the North Fork of the 

Whitewater River, a Driftless Area stream similar to Coon Creek, about 1905. Note vegetation growing close to water's edge on apparently stable banks of relatively narrow stream. B, 1940, Note that stream has widened by a factor of several times and now has a braided configuration. Photographs by USDA Soil Conservation Service.
RELATION OF EROSION AND SEDIMENTATION TO LAND USE AND MANAGEMENT 21

have been superimposed and a composite drawn (fig. 

11). Given the difficulties and uncertainties of reconstructing such rates, there is remarkable coincidence 

of the six graphs. The composites indicate that the 

highest rates existed between 1920 and 1945; the rates 

peaked in the decade of the 1930's. Composite B is the 

most meaningful because the sediment estimated to 

have come from tributary channel erosion (Trimble, 

1976a) has been excluded from the budget. This peak of 

about 3,700 Mg/km2 is relatively similar to the 

weighted values of 4,800 Mg/km2 measured in reservoirs during about the same period (table 6, fig. 12). We 

therefore conclude that the average annual net rate of 

sedimentation on the flood plains was over 3,500 

Mg/km2 in the 1930's, while the rate for recent years 

appears to be on the order of 35-70 Mg/km2 . This 

means that the current net sedimentation rate is on 

the order of about 1 or 2 percent of that existing in the 

1930's.

RELATION OF EROSION AND SEDIMENTATION 

TO LAND USE AND MANAGEMENT

An objective of this study is to relate erosion and 

sedimentation to land use. A major problem is that 

while we have reconstructed a continuous record of 

sedimentation in the main valley, we do not have a 

similar record for erosion on upland agricultural fields.

We have reconstructed erosive land use (the erosive 

potential of land use) from the graph of historical land 

use (fig. 5). To do this, each type of land use was 

weighted by an erosive factor proportional to the management involved (Trimble, 1974, p. 6-8). These factors 

are a combination of the vegetative cover (O and management practices (P) factors of the USLE discussed 

previously, and they change over time (table 7). We 

have assumed that management changed little from 

the time of settlement to the 1930's, when modern conservation measures were introduced.

These management-cover factors are clearly estimates, and changes in them would change our estimate of erosive land use (fig. 14). The values given are

TABLE 7 . Management-weighting factors used to estimate erosive 

land use, 1853-1974

Land use

Hay and pasture 

Farmstead and roads 

Abandoned 

Urban 

1853- 

1930

0.45 

.20 

.04 

.20 

.05 

.03 

.002 

.05

1940

0.32 

.15 

.022 

.15 

.045 

.025 

.002 

.05

1950

0.26 

.13 

.014 

.13 

.043 

.023 

.002 

.05

1960- 

present

0.20 

.10 

.005 

.10 

.04 

.02 

.002 

.05

FIGURE 14. Graph showing erosion, sedimentation, and erosive land 

use, 1853-1975.

composite values: the percentage of land area in each 

land use was multiplied by the appropriate factor, the 

weighted values for each land use were summed for 

that year, and the sum was multiplied by 100 to give a 

whole number which is the composite value for the 

entire area. The decrease of the factors since the 1930's 

reflects both improvement of individual management 

practices and the spread of their use.

Erosive land use and main-valley sedimentation 

rates are graphed as a function of time in figure 14. Additionally, a graph of upland erosion has been sketched 

based on the data points shown plus the logical deduction that upland erosion was very low before European 

settlement. All three rates are correlated in a general 

way, but our analysis suggests a time lag, or hysteresis, in the relationship of erosion and sedimentation 

to erosive land use. That is, a change in erosive land 

use did not immediately cause downstream changes of 

sediment yields, but there appears to have been a lag 

in the response of erosion and perhaps an even greater
22 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

lag in downstream sedimentation, the latter being 

related to travel time and temporary storage of sediment en route. Such a lag has long been suspected 

(Happ, 1944, p. 62-63; Trimble, 1976c; Knox, 1977), 

but it has not yet been documented.

The data in figure 14 have been transformed to a 

format which shows erosion and sedimentation as functions of erosive land use (fig. 15). The erratic fluctuations in the graph between 1880 and 1925 are probably 

due to poor data and their significance is dubious. As 

would be expected from earlier discussion, erosion and 

sedimentation behave somewhat differently in response 

to erosive land use.

In the first three decades of settlement, erosive 

land use expanded rapidly, causing erosion to increase 

(probably at a rate that was initially low but exponentially increasing). This was caused in part by (1) expansion of agriculture on increasingly steeper slopes 

(Trowbridge, undated, p. 19, 51) and (2) gradually increasing depletion, compaction, and degeneration of 

soil which was originally well structured, high in organic material, and uncompacted and had a high infiltration capacity.

Much of the early (to about 1890) erosion was probably characterized mostly by sheet and rill erosion, 

usually on discontinuous areas of the few steeper 

slopes then in cultivation. In many areas, soil was 

transported no farther than the base of slopes or the 

lower edge of fields, where vegetation trapped the 

sediment and allowed much of the water to infiltrate. 

Additionally, most smaller basins of as much as 1 km2 

(0.39 mi2) had nearly level valleys that were concave 

upwards with no channels and supported vegetation 

which acted as an efficient sediment trap. Thus, much 

sediment was stored on the slopes and in the shallow 

draws of the upland.

The progressive erosion of loamy topsoil decreased 

infiltration, thus further increasing surface runoff. In 

experimental studies, for example, Borst and others 

(1945) found that as continuing cultivation had removed 15 cm (6 in) of soil, the organic content (a determinant of soil structure and infiltration capacity) 

decreased from over 2.0 percent to less than 0.5 percent. After some period of time, perhaps one to four 

decades, the combined effects of increasing cultivated 

area, steeper slopes, soil degeneration, and soil erosion

34567 

EROSIVE LAND USE (ELU), CP FACTOR *100

FIGURE 15. Diagram showing the relation of erosion and sedimentation to erosive land use, 1853-1975.
RELATION OF EROSION AND SEDIMENTATION TO LAND USE AND MANAGEMENT 23

increased, causing overland flow to be of sufficient 

magnitude to flow uninterrupted across one or more 

fields, effectively transporting most of the eroded material to preexisting drainageways or channels. This 

movement of water created a drainage network of rills 

and gullies across fields that, in turn, increased the 

magnitude and velocity of surface flow (figs. 2 and 4). 

In particularly severe cases, the channelized flow sufficiently exceeded the infiltration capacities and erosional thresholds of vegetated strips, meadows, and 

forest below cultivated fields so that these areas were 

cut by gullies (Trowbridge, undated, p. 53), many of 

which dissected previously stored sediment (fig. 16A 

and B\ By the 1930's Trowbridge (p. 30) could state 

that "field gullies are common and a whole series from 

6 inches to 3 feet deep can form in a field as the result 

of one hard rain if it occurs in a large field that is 

devoid of vegetation or in a clean-tilled crop." The 

gullying not only meant greatly increased sediment 

loads but allowed delivery of the sediment farther 

downslope and downstream where much was deposited 

as storage on the relatively gentle slopes of tributary 

flood plains and even farther down valley. As storm 

runoff peaks continued to increase, some upper tributary valleys, including modern sediment deposits, were 

eroded (trenched), and sediment was transported farther downstream, rapidly aggrading the main valley. 

This problem was further exacerbated by increased 

grazing of upland pasture and forest as more cattle had 

to be accommodated (fig. 17). Perhaps more importantly, the flood-plain pastures, upon which farmers had so 

long depended, were being frequently flooded by about 

1920. The flood danger to the animals plus the deterioration of flood-plain pasture by sediment deposits (fig. 

18) forced some farmers to greatly increase upland 

grazing densities. In Winona County, Minn., a region 

similar to the Coon Creek basin, about one-fourth of 

the flood-plain area had been damaged by sediment 

deposition, primarily sandy material, and had become 

idle (Brown and Nygard, 1941, p. 15, 18). The grazing 

of forests decreased infiltration and caused overland 

flow, damaging the land downslope (Soil Conservation 

Service, undated, p. 32). For example, Hays and others 

(1949, p. 36-37) found that ungrazed forests of the

FIGURE 16. Photographs showing formation and healing of hillside 

gullies, 1905-78. A, Elba, Minn., a part of the Driftless Area 

similar to Coon Creek, about 1905. Note forested slopes above 

town. B, 1940. Note cleared and gullied hillside. Primary source 

of gullying appears to be the upland field, but the large channel 

to the left apparently originates on the cleared slope. C, 1978. 

Photograph made 4 weeks after rainstorm which exceeded the 

100-year return frequency (24 hr). Note generally good forested 

condition and complete lack of gullies. A and B by USDA Soil 

Conservation Service. C by authors.
24 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

Driftless Area had negligible runoff while grazed 

forests had about four times that of open pasture and 

about one-sixteenth that of cultivated land. By the 

1930's, forest was being cleared for pasture on such 

steep slopes that dislodged boulders actually rolled 

down the slopes in some cases (Trowbridge, undated, p. 

33). In general, open pasture was depleted of nutrients, 

giving poor vegetative cover, and was overgrazed and 

compacted. The droughts of the early 1930's exacerbated the problem by further weakening the vegetation (Soil Conservation Service, undated, p. 19). The 

additional runoff peaks from open and wooded pasture 

caused hillside gullies and increased downstream 

valley trenching which, by 1920-25, caused sedimentation rates to exceed the estimated rates of sheet and rill 

erosion on upland agricultural fields (fig. 14).

If no changes had occurred on the agricultural landscape, erosion and sedimentation would have continued 

and would have declined only as land became too eroded 

to cultivate, was abandoned, and slowly reverted to 

scrub and eventually to forest. However, great improvements in land use were initiated in 1934, consisting of better management and some decreases in area 

cultivated, especially steep, critical areas (figs. 2-5, 7).

Although erosive land use was greatly decreased between 1930 and 1940, a commensurate decrease of erosion did not occur. That is, there was a lag between the 

implementation of soil conservation measures and a 

significant decrease of erosion and sedimentation. The 

reasons are a general reversal of those previously 

given for a deteriorating watershed. Improvements in 

soil management may give limited immediate soil improvement. While changes such as terracing, cover 

crops, and contour plowing may give rapid results, 

many years of replenishing organic material, implementing good crop rotations, growing cover crops, and 

restoring fertility are required to improve soil structure and decrease bulk density to the point that infiltration and water-transmission capacity are significantly improved (Borst and others; 1945; Harold and 

others, 1962; Hendrickson and others, 1963). Such improvement is especially slow when crop demands from 

the soil remain heavy as they have in the Coon Creek 

area. This slow decrease of overland flow may allow 

the maintenance or even growth of drainageways and 

gully systems developed in the earlier regime. In 

severe cases, such drainage systems may take years to 

heal unless extensive measures are taken to speed

120

1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 

FIGURE 17. Graph showing number of grazing animals, 1850-1975, and grazed forest, 1925-70, Vernon County, Wis.
RELATION OF EROSION AND SEDIMENTATION TO LAND USE AND MANAGEMENT 25

stabilization. Additionally, the cure for erosion on an 

upland field may not solve downstream problems, at 

least immediately. The purpose of some terrace systems, for example, is to efficiently route the water from 

the fields and into drainageways. Such systems may 

greatly decrease upland erosion but have much less effect on downstream storm runoff and channel erosion. 

A similar situation exists where soils with decreased 

infiltration capacities are given a thick vegetative 

cover which greatly limits erosion but has an initially 

limited effect on storm runoff. The effect in both cases 

is to release relatively clear storm runoff, which has 

the ability to erode tributary channels and to carry 

increased amounts of sediment downstream.

As a result, the initial decrease of erosive land use 

did not bring an immediate commensurate decrease of 

channel erosion and downstream sedimentation (see 

decade 1930-40, fig. 15). After a decade or so of mutually reinforcing improvements in land management, 

however, sedimentation rates began to decrease significantly, and this trend has continued. As fields were reshaped (fig. 3) and channel systems were removed or 

were healed (fig. 4), the off-field and downstream 

transportation of erosional debris was decreased. This 

change, along with the downstream results of reduced 

flood peaks, has decreased main valley sedimentation 

to a present rate considerably lower than that of upland sheet and rill erosion, a feature discussed earlier 

in the section on sediment delivery ratios, for the 

period 1962-75.

The decrease in overland flow is best shown by the 

healing of hillside gullies which had been active in the 

1930's (fig. 16Q. A quantitative approximation of the 

improvement is obtained by estimating the peak discharge from a 25-year, 24-hour rainfall, assuming 

medium antecedent moisture conditions in this case. 

The basin selected for analysis is watershed 33 (table 

5), a basin of 499 ha, and the method is that of the Soil 

Conservation Service (1973b). Rainfall of more than 

100 mm would, by this estimate, have produced a peak 

of about 39 m3/s in 1934 but should now produce 

22 m3/s, a 45-percent reduction.

CLIMATE AS A VARIABLE

Climatic change, especially through changes in frequency and magnitude of precipitation, is often invoked 

as a hypothesis to account for geomorphic changes 

similar to the ones examined here (Knox and others, 

1975). Has the climate changed since the 1930's? More 

particularly, are the decreases in erosion and sedimentation due to a decrease in rainfall or to a moderation 

of storm intensities? The ideal time-trend analysis of 

the precipitation as it relates to erosion would be the

7IT77T if

FIGURE 18. Photographs showing deterioration of flood-plain fields 

and pasture from accelerated sedimentation during the period 

1936-38. This damage increased the pressure on upland areas. 

Photographs by USDA Soil Conservation Service.

computation of erosive index (El) values for succeeding 

years (Wischmeier and Smith, 1965). However, El computations require the maximum 30-minute intensity 

and the total rainfall of each storm, while Weather 

Bureau records give only daily amounts up to 1962, 

with hourly amounts for some stations thereafter.

THE COON CREEK AREA, 1927-73

We first analyzed precipitation in the area surrounding Coon Creek for the period 1927-73 (fig. 19). 

Two stations were in operation in 1927 (the closest being at La Crosse, Wis.), but the number had increased 

to 4 by 1932 and to 10 by 1944.

Our approach was to first analyze time trends of 

total annual precipitation. Figure 19A shows the 

deviation (in number of standard deviations) of each 

year's total rainfall from the 1927-73 mean of all stations. No overall time trend is discernible. However,
26 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

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FIGURE 19. Graphs showing precipitation trends in the Coon Creek area, 1927-73.

only 2 years between 1929 and 1940 inclusive were appreciably wet (0.5 standard deviation above the mean). 

For the period 1962-73 inclusive, 4 years were appreciably above the mean.

We then attempted to damp the annual oscillation 

by computing a 3-year moving average (fig. 19B). This 

indicated 3- to 7-year cycles, but no overall pattern. 

The first half of the 1930's was rather dry, and the sec-
CLIMATE AS A VARIABLE 27

ond half was only slightly drier than normal. The first 

half of the 1960's was very dry; the second half and the 

early 1970's were wet.

Annual precipitation figures do not in themselves 

tell much about runoff and erosive effects. For example, did 32 inches of precipitation come in many 

moderate showers, or did most of the annual amount 

come in a few intense storms of several inches each? To 

examine this question we plotted intense 24-hour 

storms against the annual precipitation for the year of 

the storm (fig. 19C). For the purpose of this discussion, 

a large storm is taken as one of 2.5 inches of rainfall or 

more, 2.5 inches being the 24-hour rainfall magnitude 

of 1-year frequency. Figure 19 C suggests an association between wet years and intense storms. No year of 

less than mean precipitation has a storm greater than 

3.5 inches in 24 hours, whereas wet years had storms 

as great as 8 inches. Expressed another way, only 

about 20 percent of all large storms occurred in dry 

years, and these storms were among the smaller of the 

large storms. We may say that the more intense storms 

are associated with the wetter years indicated in 

figures 19A and 195. The data suggest that the rainfall of the 1930's was no more erosive than that of the 

1960's and early 1970's and may well have been somewhat less. Thus, we cannot attribute the decrease of 

erosion and sedimentation to amelioration of climatic 

conditions.

THE ENTIRE DRIFTLESS AREA, 1867-1974

In our earlier discussion we presented evidence 

that erosion and sedimentation increased by approximately three orders of magnitude within 75-80 years 

after European settlement. We then presented further 

evidence thfet erosion and sedimentation have been 

drastically reduced, perhaps by as much as two orders 

of magnitude, within the past 40 years. Based on our 

observations and studies over much of the Driftless 

Area and drawing from the available literature 

(Adams, 1940, 1942; Happ, 1944; Knox, 1977; Kunsman, 1944), we think it likely that much of the Driftless Area has undergone a history similar to that of the 

Coon Creek basin. It is important to know if climatic 

change has played a role in these remarkably rapid 

landscape changes. Thus, we attempt to analyze rainfall variation, as it affects soil erosion, for the entire 

Driftless Area during the period 1867-1974. We proceed 

as before, but time and space are greatly expanded. 

Only 2 stations were available in 1867, but this 

number had increased to 22 by 1895 and to 43 by 1954. 

We presume the weather stations give a representative 

sample, but the limited number in the earlier period 

make that assumption uncertain. However, we can be 

more definite about the period since 1900.

The time-trend of average annual precipitation is 

shown in figure 20A. The overall trend is a decrease of 

annual precipitation, but that is greatly influenced by 

the wet years of the early period. Of greater import to 

this study is the concave-upward nature of the trend 

with wetter years early and late during the period and 

drier years during the middle of the period. This is conveniently demonstrated by arbitrarily dividing the 

record into two periods. For 1867-1920, the trend is 

negative, whereas for 1920-74, the trend is positive. 

As before, larger storms were associated with wetter 

years (fig. 20B). This concave-upward trend (fig. 20A) 

approximates the annual flood series for the region 

recorded on the Mississippi River at Keokuk, Iowa 

(Knox and others, 1975, front cover). Flood flows there 

were higher up to about 1895 and after 1960, and lower 

during the intervening period. Thus, from a climatic 

standpoint alone, one would expect greater potential 

for soil erosion during the early and late periods. Such 

a trend, however, is negatively correlated with our 

findings (figs. 10,11,12,13, and 14); that is, the wetter 

years, with greater storms and higher runoff, were 

coincident with the clear streams of the presettlement 

and early settlement period and with the present 

(1962-75), while the drier years tend to coincide with 

the intervening period of extreme erosion and sedimentation demonstrated in this study.

A 3-year moving average (fig. 20D) indicates that 

the wet years of the early period were followed by a 

deep and prolonged dry period in the 1880's. Since that 

time there have been lesser wet and dry cycles of 3-7 

years, but none of these cycles can be related to any 

major erosional cycle that we have identified.

Perhaps the best analysis of precipitation change 

in the Driftless Area is a chronological array (fig. 21). 

Stations were selected on the basis of continuous operation and complete published data. The period begins 

with 1931 because by that time the optimum number 

of stations had become available. Major features of the 

array are (1) few intense rainstorms during the 1930's 

and (2) periods of many large rainstorms in the early 

1940's, early 1950's, and early 1960's. The late 1960's 

and early 1970's were wet, but large storms were not 

concentrated as they were in the three earlier periods. 

There is no correlation of this chronological pattern 

with that of erosion or sedimentation (fig. 14).

Finally, the consistency of our data argues against 

a significant cyclic climatic variable. For example, the 

rates of sedimentation at different sites are remarkably similar (figs. 11 and 13). Given the spread of dates 

at the six sites, one should expect at least one out-ofphase, or even bimodal, curve in the group if precipitation trends had exerted a significant effect. Although 

we acknowledge that the 5- and 10-year precipitation
THREE-YEAR MOVING 

AVERAGE ANNUAL 

PRECIPITATION, IN 

INCHES

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AVERAGE ANNUAL 

PRECIPITATION, 

IN INCHES

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5

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ciT

24-HOUR PRECIPITATION, IN INCHES

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i

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00 

CO

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S" co & <±>

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3

en

CO

O

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CO

Ol

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CO

- J

o
IS COON CREEK REPRESENTATIVE? 29

X + 2oX + oX

X-oX-2oz- 8.0 

o 7.0

< 6.0 t oo

E:^ 5.0 

£| 4.0

^z 3.0 cc =

g 2.0

5 1-0

0

A. PRECIPITATION TREND

B. STORMS EXCEEDING 2.5 INCHES IN 24 HOURS

n i rri r

o

43.4 < 

38.0 ^ 

32.7 ^ 

27.3 ^ 

22.0 ^

C. IND^X MAF1 I

r

jfk-Minneapolis

WISCONSIN 

MINNEX* 

SOTA« ^ . 

 -Tf Madisoi

YEARS

Average annual precipitation

3-year running average annual precipitation

Weather station

FIGURE 21. Graphs showing precipitation trends at 15 selected stations in the Driftless Area, 1931-73.

cycles would have some effect on erosion and sedimentation rates in a basin that had already been disturbed, 

the traces of this effect were subsumed in the general 

trend which is best correlated with erosive land use 

(figs. 14 and 15).

Overall, we see no relation of rates of erosion and 

sedimentation to precipitation. We believe that the 

role of climatic cycles has been to superimpose perturbations on the overall trends caused by land use and 

land management.

figure 5. The three-county area has more nonagricultural land than does the Coon Creek basin (as characterized by the 10 sample basins examined in this study) 

and thus has a smaller percentage of the area in 

cropland and a larger percentage in forest. However, 

the changes in land use since 1934 have been proportionally similar between the three-county area and the 

Coon Creek basin. For example, cropland decreased by

IS COON CREEK REPRESENTATIVE?

Given that significant reduction of erosion and 

sedimentation have occurred in the Coon Creek basin, 

is our sample representative of the surrounding area in 

the Driftless Area? We shall look at both land use and 

conservation practices.

The changes in land use for the three-county area 

surrounding the Coon Creek basin area are shown in

6 percent in the larger area over the period 1934-67 

and by 6 percent in the Coon Creek basin. At the same 

time the increases in pasture were 8 percent and 13 

percent for the two areas, respectively, while forest increased 9 percent in the large area and 10 percent in 

the Coon Creek basin. Thus, the trend in both areas 

since 1934 has been a comparable slight increase in 

forest and pasture at the expense of cropland.

CONSERVATION PRACTICES

The Coon Creek basin was established as a soil conservation demonstration area in the 1930's to set an 

example from which, it was hoped, proper conservation 

practices would diffuse into the surrounding area. That 

this succeeded can now be seen on the landscape, 

whether from an aircraft or auto or on aerial 

photographs: contouring and contour-strip farming 

are widespread phenomena on the Driftless Area 

landscape.

The diffusion of contour-strip farming southward into neighboring counties will serve as an example (fig. 

22). In 1939, most of the farms that had adopted 

contour-strip farming were in or very near the Coon 

Creek watershed. By 1949 the practice had spread 

greatly, but the major concentration was still near the 

area initially treated. By 1955, the number of adopters 

was still increasing and the distribution was becoming
30 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

Coon Creek 

Basin

One dot=one adopter

i i I 

0 10 20 30 KILOMETERS

1955 (3128 ADOPTERS) 1961 (5286 ADOPTERS) 1967 (6402 ADOPTERS)

FIGURE 22. Spread of contour-strip farming from the Coon Creek Conservation Demonstration Area, Wisconsin, 1939-67.

One dot = one adopter. Source: H. E. Johansen, 1969.

more equalized. By 1967, the number of adopters had 

more than doubled since 1955 and no concentration 

was evident. The areas of lower density are on flatter 

areas and in the Wisconsin River valley where 

conservation measures against erosion are less 

necessary than they are in the steeper parts of the 

area. Based on these data, it appears that the practice 

of contour-strip cropping had become widespread 

across this portion of the Driftless Area by 1967. If 

other land-management practices have increased 

everywhere in proportion to increases in contour stripcropping (a reasonable assumption based on our observations), then there should be little difference in total 

land management. Indeed, 7 years of observation 

across the Driftless Area strongly indicate to us that 

the changes in land use and erosion found in the Coon 

Creek basin are typical of the region.

CONCLUSIONS

We conclude that erosion and sedimentation have 

been dramatically reduced in the Coon Creek basin 

and in most of the Driftless Area. These reductions 

have been caused principally by improvements in land

management and, to a lesser degree, by changes in 

land use. Climatic changes may have imposed minor 

perturbations on the observed trends in erosion and 

sedimentation, but they do not seem to have been an 

important causal factor.

In the decade or more since 1965 when Held and 

Clawson made their lament, the fervor of the environmental crusade has often overshadowed the considerable conservation accomplishments of the past. Indeed, 

we have often been given to understand that environmental degradation is a recent phenomenon. This 

study of the Coon Creek basin shows that constructive 

efforts have been made to overcome such degradation 

and that these efforts have been largely successful in 

this case.

REFERENCES

Adams, Clifford, 1940, Modern sedimentation in the Galena River 

Valley, Illinois and Wisconsin: Iowa City, University of Iowa, unpublished M.S. thesis, 72 p.

 1942, Accelerated sedimentation in the Galena River Valley, 

Illinois and Wisconsin: Iowa City, University of Iowa, unpublished Ph.D. dissertation, 67 p.
REFERENCES 31

Borst, H. L., McCall, A. G., and Bell, F. G., 1945, Investigations in 

erosion control and the reclamation of eroded land at the Northwest Appalachian Conservation Experiment Station, Zanesville, 

Ohio, 1934-42: U.S. Department of Agriculture Technical 

Bulletin 888, 95 p.

Brown, M. H., and Nygard, I. J., 1941, Erosion and related land use 

conditions in Winona County, Minnesota: U.S. Department of 

Agriculture, Soil Conservation Service Erosion Survey 17, 33 p.

Brune, G. M., 1953, Trap efficiency of reservoirs: American Geophysical Union Transactions, v. 34, p. 407-418.

Butzer, K. W., 1975, Soil erosion: a problem in man-land relationships, in Manners, I. and Mikesell, M., eds. Perspectives on Environment: Washington, D.C., Association of American 

Geographers, p. 57-78.

Happ, S. C., 1944, Effect of sedimentation on floods in the Kickapoo 

Valley, Wisconsin: Journal of Geology, v. 52, p. 53-68.

Happ, S. C., Rittenhouse, G., and Dobson, G. C., 1940, Some principles of accelerated stream and valley sedimentation: U.S. Department of Agriculture Technical Bulletin 695, 133 p.

Harold, L. L., Brakensiek, D. L., McGuinness, J. L., Amerman, C. R., 

and Dreibelbis, F. R., 1962, Influence of land use and treatment 

on the hydrology of small watersheds at Coshocton, Ohio, 1938- 

1957: U.S. Department of Agriculture Technical Bulletin 1256, 

194 p.

Hays, O. E., McCall, A. G., and Bell, F. G., 1949, Investigations in 

erosion control and the reclamation of eroded land at the Upper 

Mississippi Valley Conservation Experiment Station near 

LaCrosse, Wisconsin, 1933-43: U.S. Department of Agriculture 

Technical Bulletin 973, 87 p.

Held, R. B., and Clawson, Marion, 1965, Soil conservation in perspective: Baltimore, Johns Hopkins Press, 344 p.

Hendrickson, B. D., Barnett, A. P., Carreker, J. R., and Adams, W. E., 

1963, Runoff and erosion control studies on Cecil soils on the 

southern piedmont: U.S. Department of Agriculture Technical 

Bulletin 1281, 33 p.

Johansen, H. E., 1969, Spatial diffusion of contour strip cropping in 

Wisconsin: Madison, University of Wisconsin, unpublished M.S. 

thesis, 66 p.

Johnson, W. C., 1976, The impact of environmental change of fluvial 

systems: Kickapoo River, Wisconsin: Madison, University of 

Wisconsin, unpublished Ph.D. dissertation, 294 p.

Keyes, D. M., and Anderson, H. O., 1939, Description of the Coon 

Valley Soil Conservation Demonstration Area: Unpublished 

study on file at office of State Conservationist, Soil Conservation 

Service, Madison, Wis., 38 p.

Knox, J. C., 1977, Human impacts on Wisconsin stream channels: 

Annals, Association of American Geographers, v. 67, p. 323-342.

Knox, J. C., Bartlein, P. J., Hirschboek, K. K., and Muckenhirn, R. J., 

1975, The response of floods and sediment fields to climatic variation and land use in the Upper Mississippi Valley: University of 

Wisconsin-Madison, Institute for Environmental Studies Report 

52, 76 p.

Kunsman, H. S., 1944, Stream and valley sedimentation in Beaver 

Creek Valley, Wisconsin: Madison, University of Wisconsin, unpublished Ph.D. thesis, 134 p.

Lund, S. W., 1976, Conservation and soil lost through fluvial processes, Coon Creek Watershed, Wisconsin, 1934 to 1975: 

Milwaukee, University of Wisconsin, unpublished M.S. thesis.

McKelvey, V. E., 1939, Stream and valley sedimentation in the Coon 

Creek Drainage Basin, Wisconsin: Madison, University of Wisconsin, unpublished M.A. thesis, 122 p.

Owen, D. D., 1847, Report of geological reconnaissance of the Chippewa Land District of Wisconsin: U.S. 30th Congress, 1st. session, U.S. Senate Executive Document 57, 134 p.

 1852, Report of a geological survey of Wisconsin, Iowa and 

Minnesota: Philadelphia, Lippincott, Grambo and Co., 63 p.

Sartz, R. S., 1976, Sediment yield from steep lands in the Driftless 

area, in Proceedings of the Third Federal Inter-Agency Sedimentation Conference, Denver, Water Resources Council, Section 1: 

p. 123-131.

Soil Conservation Service, U.S. Department of Agriculture, undated, 

Farming against erosion: the experiences and recommendations 

resulting from five years of efforts to check erosion in the Coon 

Creek area at Coon Valley, Wisconsin: Madison, Soil Conservation Office, unpublished manuscript, 107 p.

 1942, Hydrologic studies at the Coon Creek Demonstration 

Project, Soil Conservation Service-Wisconsin-1, Coon Valley, 

Wisconsin: Technical Pamphlet 46, 4 p., appendices.

 1960-1963, As built plans (design data of Coon Creek flood 

retention structures): on file at Soil Conservation Service district 

field offices, Sparta and Viroqua, Wisconsin.

 1971, Sedimentation: National Engineering Handbook, Section 3: Washington, D.C., U.S. Government Printing Office.

 1973a, Estimating soil loss resulting from water and wind erosion in the Midwest: Lincoln, Nebraska.

 1973b, A method for estimating volume and rate of runoff in 

small watersheds: Technical Publication 149, 19 p., appendix.

 1975, Procedure for computing sheet and rill erosion in project 

areas: Soil Conservation Service Technical Release 51, 16 p.

 1976, Wisconsin technical guide notice: CONS-WI-16: Madison, Wisconsin.

Trimble, S. W., 1974, Man-induced soil erosion on the Southern Piedmont, 1700-1970: Ankeny, Iowa, Soil Conservation Society of 

America, 180 p.

 1975, Denudation studies: can we assume stream steady 

state?: Science, v. 188, p. 1207-1208.

 1976a, Sedimentation in Coon Creek Valley, Wisconsin, in 

Proceedings of the Third Federal Inter-Agency Sedimentation 

Conference, Denver, Water Resources Council, section 5, p. 

100-112.

 1976b, Unsteady state denudation: Science, v. 191, p. 871.

 1976c, Sedimentation rates in Coon Creek Valley, Wisconsin: 

oral presentation at the Inter-Agency Sedimentation Conference, 

Denver, Colorado, March 1976.

 1977, The fallacy of stream equilibrium in contemporary denudation studies: American Journal of Science, v. 277, p. 876-887.

 in press, Changes in sediment storage in the Coon Creek basin 

Driftless Area, Wisconsin, 1853-1975: p. 13, 17, 46.

Trowbridge, A. L., undated, Conservation survey report of Coon 

Creek Watershed, Coon Valley, Wisconsin: Section of Conservation Surveys, Soil Conservation Service, unpublished study on 

file at office of State Conservationist, Soil Conservation Service, 

Madison, Wisconsin, 95 p.

U.S. Army Corps of Engineers, 1867, Annual Report: Washington, 

U.S. Government Printing Office.

U.S. House of Representatives, 1867, Survey of Upper Mississippi 

River: Executive Document 58, 39th Congress, 2nd Session, 116 p.

Ward, R. C., 1975, Principles of Hydrology, 2nd ed.: Maidenhead, 

McGraw-Hill, 367 p.

Wischmeier, W. H., and Smith, D. D., 1965, Predicting rainfall erosion losses from cropland east of the Rocky Mountains: U.S. 

Department of Agriculture, Agriculture Research Service Agriculture Handbook 282, Washington.

Wisconsin State Department of Agriculture, undated, Wisconsin 

Land Inventory: Land Economic Inventory and Land Use Section, Madison, Wisconsin.

APPENDICES 33 

APPENDICES

APPENDIX 1. Cropping plan for the Stromstad Farm, 1939-44. (Refer to figs. 2, 3, and 4) 

[Data from Soil Conservation Service, Madison, Wise. Alf and Tim, alfalfa and timothy; Cl and Tim, clover and timothy]

Field

1

2

3a

3b

3c

3d

3e

4a

4b

4c

5

6

7a

7b

7c

7d

7e

7f

7g

8a

8b

8c

9a

9b

9c

9d

9e

9f

10

Acres

41.5

1.3

2.8

2.7

2.5

1.9

2.8

1.1

1.3

1.2

0.8

2.0

1.8

1.9

2.1

2.1

1.8

1.8

1.9

0.9

1.0

0.8

1.1

4.0

2.8

2.8

2.0

2.0

6.5

1939 1940 1941

Ungrazed Wood

Corn

Alfalfa and Bluegrass

Corn

(Cl and Tim)

Cl and Tim

Tobacco

Corn

Tobacco

Ter

Corn

Alfalfa and Bluegrass

Grain

(Alf and Tim)

Alfalfa and Bluegrass

Corn

Alfalfa and Bluegrass

1.0 Alf and Tim

0.9 Grain (Alf and Tim)

Grain

(Alf and Tim)

Cl and Tim

Grain

(Cl and Tim)

Grain

(Cl and Tim)

Corn

Grain

(Sw. Cl)

Cl and Alf

Tim

Alfalfa and Bluegrass

Corn

P a s t u r

Corn

Grain

(Cl and Tim)

Grain

(Alf and Tim)

Timothy

Corn

Grain

(Cl and Tim)

Grain

(Cl and Tim)

Tobacco

race OutletPa s t u r

Grain

(Alf and Tim)

Emerging Hay

Alf and Tim

Corn

Grain

(Cl and Tim)

Corn

Alf and Tim

Alf and Tim

Tobacco

Cl and Tim

Cl and Tim

Grain

(Cl and Tim)

Corn

Alf and Tim

Emerging Hay

Grain

(Alf and Tim)

e managed

Grain

(Alf and Tim)

Corn

Alf and Tim

Corn

Grain

(Cl and Tim)

Cl and Tim

Cl and Tim

Tobacco

1942

land

grazing

Alf and Tim

Cl and Tim

Alf and Tim

Grain

(Alf and Tim)

Cl and Tim

Corn

Tobbaco

Grain

(Alf and Tim)

-Pasture Regulated

e managed

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Cl and Tim

Grain

(Alf and Tim)

Corn

Alf and Tim

Tobacco

Cl and Tim

(Reseed)

Corn

Cl and Tim

Grain

(Alf and Tim)

Alf and Tim

Corn

Alf and Tim

Pasture managed

grazing

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Tobacco

Cl and Tim

Grain

(Cl and Tim)

Corn

Alf and Tim

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

grazing

1943

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Alf and Tim

Corn

Tobacco

Tobacco

Alf and Tim

Grazing

Alf and Tim

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Alf and Tim

Corn

Grain

(Alf and Tim)

Corn

Cl and Tim

Grain

(Alf and Tim)

Alf and Tim

Corn

Alf and Tim

Alf and Tim

1944

Alf and Tim

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Tobacco

Grain

(Alf and Tim)

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Alf and Tim

Corn

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Tobacco

Corn

Alf and Tim

Alf and Tim

Grain

(Alf and Tim)

Alf and Tim

Corn

14.5 Open pasture
34 SOIL CONSERVATION, EROSION AND SEDIMENTATION, COON CREEK BASIN, WIS.

APPENDIX I (Continued)

Field

APPENDIX I. Cropping plan for the Stromstad Farm, 1939-44. (Refer to figs. 2, 3, and 4) 

[Data from Soil Conservation Service, Madison, Wise. Alf and Tim, alfalfa and timothy; Cl and Tim, clover and timothy]

Acres 1939 1940 1941 1942 1943 1944

11

12

13

14

15

16

17 

Total

18.5

2.4 

3.2

7.0

1.0 

1.8

Grain 

(Cl and Tim)

0.4 Potatoes

4.5 Farmstead

138.0 acres

4.5 Wooded pasture managed grazing

Ungrazed woodland 

Ungrazed woodland

3.1 Open pasture 

3.9 Wooded pasture managed grazing

Grain

Cl and Tim Corn (Alf and Tim) Alf and Tim 

H a y 1 a n d 

Grain 

Corn (Alf and Tim) Alf and Tim Alf and Tim

Alf and Tim

Alf and Tim

APPENDIX II. Assumptions made concerning land management and 

"C" factors (from Lund, 1976, appendix II). "C" factors interpolated from Soil Conservation Service, 1976

I. 1934

A. Medium stocked stand, unmanaged (grazed and burned), 40 to 

70 percent tree canopy, 70 percent ground cover, C = 0.30.

B. Pasture

Overgrazed bluegrass, no appreciable canopy, 60 percent 

ground cover, C = 0.04.

C. Farmyard

Grass, no appreciable canopy, 50 percent ground cover, C = 

0.07.

D. Cropland

Uniform 3-year rotation of 1 year row crop, 1 year small 

grain, and 1 year hay-meadow (ROM), fall plowed, conventional tillage, residues removed, C = 0.10.

II. 1975

A. Woodland

1. Grazed, medium stocked stand, 40 to 70 percent tree 

canopy, 70 percent litter cover, C = 0.03

2. Ungrazed, well stocked stand, 75 to 100 percent tree

canopy, 90 to 100 percent litter cover, C = 0.001. 

B. Pasture

Bluegrass, no appreciable canopy, 85 percent ground cover,

C = 0.011. 

C. Farmyard

Grass, no appreciable canopy, 50 percent ground cover,

C = 0.07. 

D. Cropland

1. Continuous tobacco, spring plowed, conventional tillage, 

residues removed from field, C = 0.45.

2. Six-year rotation of 2 years row crop, 1 year small grain, 

and 3 years hay-meadow (2RO3M), conventional tillage, 50 

percent fall plowed - 50 percent spring plowed, 33 percent 

of residues left - 67 percent removed, interpolated 

C = 0.105.

3. Six-year rotation of 2 years row crop, 1 year small grain, 

and 3 years hay-meadow (2RO3M), strip tillage, 4,000-6,000 

pounds per acre of corn residue left, C = 0.05.

4. Three-year rotation of 1 year row crop, 1 year small grain, 

and 1 year hay-meadow (ROM), conventional tillage, 50 

percent fall plowed - 50 percent spring plowed, 33 percent 

of residues left - 67 percent removed, interpolated 

C = 0.085.

5. Four-year rotation of 1 year row crop, 1 year small grain, 

and 2 years hay-meadow (RO2M), strip tillage, 3000-4000 

pounds per acre of corn residue left. C = 0.025.

6. Four-year rotation of 1 year row crop, 1 year small grain, 

and 2 years hay-meadow (RO2M), conventional tillage, 50 

percent fall plowed - 50 percent spring plowed, 33 percent 

of residues left - 67 percent removed, interpolated 

C = 0.07.

7. Five-year rotation of 1 year row crop, 1 year small grain, 

and 3 years hay-meadow (RO3M), conventional tillage, 50 

percent fall plowed - 50 percent spring plowed, 33 percent 

of residues left - 67 percent removed, interpolated 

C = 0.055.

8. Five-year rotation of 1 year row crop, 1 year small grain, 

and 3 years hay-meadow (RO3M), strip tillage, 

3,000-4,000 pounds per acre of corn residue left, C = 0.02.

9. Six-year rotation of 1 year row crop, 1 year small grain, 

and 4 years hay-meadow (RO4M), strip tillage, 

3,000-4,000 pounds per acre of corn residue left, 

C = 0.015.
APPENDICES 35

APPENDIX 111. Average slope lengths ana gradients for soils of the 

study area 

[Data from A. J. Klingelhoets, Soil Conservation Service, Madison, 

written commun., 1976]

Soil 

series

Alluvial land 

Alluvial land, wet 

XXI AfPTiTvill CllZJV lilt? r»OUt cn1i~ 1UCL1X.1 InniM " "~" ~~

Chaseburg silt loam 

Downs-Tama silt loams 

T^nViiimio ciili* Irtim

Dunbarton-Sogn Stony soils 

Fayette silt loam, uplands 

Fayette silt loam, valleys 

Gale silt loam 

Map 

symbol

Ad

Al

x\rr\ ArA

ArB

CaA

CaB

DmA

DsB

DsC

DsD

DsE

DvD

DvE

FuB

 p.,P ruo

FuD

FvD

FvF

GaB

GaC

GaE

Slope 

gradient 

(percent)

1 

1 

1

2

4

2

4

9

16

25

16

25

3

16

16

35

4

8

25

Slope 

length 

(feet)

200 

150 

400

onn /UU

150

200

450

450

400

350

250

250

200

350

qnn oUU

250

300

250

300

250

200

Soil 

series

Hixton loam 

Kickapoo fine sandy loam 

Norden loam 

Norwalk silt loam 

Orion silt loam 

Oshkosh silt loam 

Palsgrove silt loam _ 

xvozetta silt loam 

Stony colluvial land 

Stony rock land 

Stronghurst silt loam 

Map 

symbol

HID 

HIE 

KpA

KpB

N1F 

NwB

NwC

OrA

OsB

OsC

OsD

PaA

PaB

PaC

PaD

PaE

RoA

RoB

RoC

ScA

ScB

SkE

SkF

StB

Slope 

gradient 

(percent)

16 

25 

1

2 

35 

3

8

1

3

9

16

1

4

9

16

25

1

3

8

2

4

25

35

3

Slope 

length 

(feet)

250 

200 

200

150 

200 

250

200

350

300

200

150

300

450

400

300

250

qnn OUU

250

200

150

100

350

350

300

* U.S. GOVERNMENT PRINTING OFFICE: 1982-361-614/115