Sedimentation in Three Small 

5 Forested Drainage Basins in 

the Alsea River Basin, Oregon

'I I

GEOLOGICAL SURVEY 

CIRCULAR 490

PREPARED IN COOPERATION WITH THE OREGON STATE BOARD OF HIGHER EDUCATION
Sedimentation in 

Three Small Forested Drainage Basins

in the Alsea River Basin, Oregon

By R. C. Williams

GEOLOGICAL SURVEY CIRCULAR 490

Prepared in cooperation with 

the Oregon State Board of Higher Education

Washington 1964
United States Department of the Interior

STEWART L. UDALL, SECRETARY

Geological Survey

THOMAS B. NOLAN, DIRECTOR

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

Page 

Ab str act ____________________________ 1

Introduction, ________________________ 1

Purpose and scope_________________ 1

General description of the drainage

basins.______________________ 2

Methods of measurement ___________ 4

Rainfall ________________________ 5

Water discharge.________________ 5

Water temperature ______________ 5

Suspended-sediment discharge ____ 5

Page 

Introduction Continued

Water and sediment data___________ 6

Fluvial sediment____________________ 6

Relations to rainfall and runoff _____ 6

A freshet period________________ 11

Flow and concentration

duration _____________________ 14

Water temperature._______________ 14

Summary __________________________ 16

Literature cited ____________________ 16

ILLUSTRATIONS

Figure 1. Map showing location of the study basins___________________________________

2. Profiles of stream channels ______________________________________________

3. Comparison by drainage basin of precipitation, runoff, and suspended-sediment 

yield for 1960 water year ______________________________________________

4. Distribution by month for precipitation, runoff, and suspended-sediment

load for 1960 water year _______________________________________________

5. Comparison of hydrologic factors for the Deer Creek basin for the period

January 7-13, 1959 ___________________________________________________

6. Streamflow and suspended-sediment concentration duration curves for

the strearns __________________________________________________________

Page

3

4

10

12

13

15

TABLES

Table 1. Monthly rainfall of basins.__________________________________

2. Monthly streamflow and runoff of basins_____________________.

3. Average monthly maximum and minimum water temperatures __

4. Monthly suspended-sediment load____________________________

5. Annual rainfall, runoff, and suspended-sediment.__ ____________

Page 

5

7

8

8

9

III
Sedimentation in Three Small Forested Drainage Basins 

in the Alsea River Basin, Oregon

By R. C. Williams

ABSTRACT

A multidiscipline investigation to determine the effects of 

logging on the ecology of three small forested tributary basins is a part of an overall study of the Alsea River basin in 

the Coast Range of Oregon. The investigation of these small 

basins will be to (1) establish pre-logging conditions, (2) determine the effects of different logging methods, and (3) study 

the rate of recovery after the timber harvest. This report 

presents results of sedimentation in the basins, Deer and 

Flynn Creeks and Needle Branch, for the first 2 years of 

study (1959 and 1960 water years).

Rainfall, runoff, and sediment discharge are seasonal for 

the Coast Range of western Oregon. About 95 percent of the 

rainfall and rnnoff occurs during the period October to May, 

but nearly 100 percent of the suspended-sediment discharge 

occurs during the same period. For Deer Creek, in the I960 

water year, 23 percent of the annual suspended-sediment 

lis charge occurred on 1 day, 58 percent during the 10 days 

of greatest discharge, and 78 percent during the 38 days of 

greatest discharge.

qual for all three of the basins. 

The runoff of the Deer and Flynn Creek basins is about

Rainfall is practically

equal, but that of the Needle Branch basin averaged 8 percent less.

Sediment yield varies considerably for the three basins. 

The suspended-sediment yield of the Deer Creek basin is almost twice that of the Needle Branch basin and almost 1% 

times that of the Flynn Creek basin.

Water temperature of the three streams varied only 22* F 

'' " ' fears. The greatest variation between

Water temperature of the three streams varied only 22 r 

during the 2 water years. The greatest variation between 

streams was 3°F in the minimums. Water temperature effect 

can be neglected in comparing the sediment yields of the 

basins.

The aquifers of the basins have low storage capacities as 

illustrated by the very low, late summer flow. A study of a 

midwinter freshet period for the Deer Creek basin showed 

that virtually all the rainfall left the basin as runoff within 

4 days; the period of significant sediment transport was 

thus very short.

INTRODUCTION

PURPOSE AND SCOPE

The purpose of the overall study is to determine the effects of man's use on the environment of forested drainage basins. The 

scope of this part of the study is to investigate the effects of environmental changes on

the sedimentation of forested drainage basins under natural conditions, under different 

timber harvesting methods, and during the 

recovery phase after the timber harvest. 

This report is the first in a series of data 

analyses which will follow the progress of 

the sedimentation investigation. It deals with 

the first 2 years of the prelogging phase 

which will last approximately 5 years. The 

study of all aspects of watershed ecology will 

span a period of 10 to 15 years.

This investigation is concerned with the 

sedimentation in three small drainage basins 

in the Alsea River basin in Oregon. The first 

phase will be a definition of the undisturbed 

conditions in each of the three small basins. 

The second phase will measure the changes 

in sediment yield as logging progresses in 

the Deer Creek and Needle Branch basins. 

The Needle Branch basin will be clear-cut 

of all timber, whereas the Deer Creek basin 

will be logged in a staggered cutting pattern. 

The third phase will cover the rate and extent of recovery of the basins. Sediment 

yield from these two basins will be compared with that of the Flynn Creek basin, 

which will remain undistrubed for the entire 

study as the control or calibration basin. 

The area studied comprises only a small 

part of the Alsea River basin, but the findings 

should have application in other parts of this 

basin and some application to other forested 

drainage basins.

Runoff, suspended-sediment discharge, and 

water temperature are readily measured and 

provide good indices of drainage-basin environment. This report summarizes the hydrologic data collected during the first 2 

years of the study and points out some of the 

relationships between basin environment and 

climate.
SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

The overall study in the Alsea River basin 

is a multidiscipline examination of drainage 

basin ecology. The major parts of this comprehensive study are: (1) a soil-vegetation 

survey designed to inventory the soils and 

vegetation of the entire Alsea River basin and 

to provide a base for research in drainagebasin management, (2) a water resource survey of the major tributaries of the Alsea 

River designed to provide abase for research 

in drainage-basin management and water use, 

(3) a study of the effect of lagging upon the 

physical and biotic resources of small 

streams, and (4) the study of the migration 

and production of salmonoid fish in selected 

streams of the basin. The overall study is 

coordinated by the Oregon Agricultural Experiment Station under the Oregon State 

Board of Higher Education. The participants 

in this study include the U.S. Geological Survey, U.S. Forest Service, Bureau of Land 

Management, Soil Conservation Service, the 

Soils Department and School of Forestry of 

Oregon State University, Georgia-Pacific 

Corp., and the Oregon State Game Commission.

GENERAL DESCRIPTION OF THE DRAINAGE BASINS

The Alsea River rises on Marys Peak 

(elev. 4,097 feet) and drains about 473 square 

miles of the timber-covered Coast Range of 

Oregon before emptying into the Pacific 

Ocean at Waldport. The drainage basins being used for the sedimentation study comprise a very small part of the Alsea River 

basin. Deer Creek has a drainage area of 

1.20 square miles; Flynn Creek has a drainage area of 0.84 square mile; Needle Branch, 

the smallest of the three streams, has a 

drainage area of only 0.32 square mile. (See 

fig. 1.)

The altitude of these three small basins 

ranges from about 1,600 feet at the highest 

point of the Deer Creek hydrographic divide 

to about 430 feet at the Needle Branch confluence with Drift Creek. The drainage valleys are V-shaped and have moderate to steep 

side slopes. A canopy of Douglas fir intermixed with alder covers almost all of the 

area and intercepts much of the rainfall. A 

very heavy growth of under story vegetation 

covers virtually all of the drainage basins, 

giving good natural protection against erosion 

of the fine-grained surface soils. Much timber debris in the valley bottoms forms natural settling basins in places where it retards

the flow of the streams. Little meandering 

occurs, and the streambeds are generally 

well armored with fine to coarse gravel.

The area is underlain by the Burpee Formation of middle Eocene age, which may be 

contemporary with the Tyee Formation to the 

south (Yokes and others, 1949). The Burpee 

Formation consists of a thick sequence of 

micaceous sandstones interbedded with mudstones and siltstones. It is characterized in 

the study area by moderate dip slopes and 

heavy soil mantle, and by steep slopes and a 

shallow, sandy, soil cover where beds of 

sandstone are exposed. The variability of 

the slopes and soils causes much of the variability in the sediment yield from these basins.

The mild humid climate of the area is typical of the coastal region of western Oregon. 

About 90 inches of rainfall is recorded annually, and most of it occurs during the 

months from October to May. Temperatures 

generally range between 20°F and 90°F, with 

a mean of about 51°F.

The environments of the three basins appear to be very similar because all three are 

characterized by dense, virgin forest. The 

communities formed by the principal understory vegetation such as sword ferns, salmonberry, and vine maple vary greatly from 

place to place, but the density of growth 

varies little from basin to basin. However, 

the proportions of the Douglas fir and alder 

overstory vary appreciably. About 60 percent of the overstory in the Deer and Flynn 

Creek basins is alder, whereas the overstory 

of the Needle Branch basin is only about 20 

percent alder.

There are some differences in the geomorphology of the three basins. Surveys made by 

Oregon Agricultural Experiment Station personnel using an altimeter show that the basins have dissimilar gradients. The data 

from these surveys are plotted in figure 2.

Deer Creek basin has drainage slopes 

averaging about 40 percent and characteristically thinner mantles of sandy soil (C. T. 

Dyrness, U.S. Forest Service, written communication, 1962). The drainage pattern of 

this basin is more fully developed than that 

for the other two basins; thus the runoff collects more rapidly and creates a greater 

sediment erosion potential in Deer Creek
INTRODUCTION

Waldpo;

9 10 ^ 20 30 MILES

2 MILES 

I

Figure 1. Map showing location of the study basins in the Alsea River basin, Oregon.
SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

140

120

£ 100

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1000 2000 3000 4000 5000 6000 

DISTANCE UPSTREAM FROM STREAM-GAGING STATION, IN FEET

Figure 2. Profile of stream channels. Q, sediment sampling site.

7000

basin. Some of the tributary channels in the 

basin show signs of active erosion; probably 

much of the sediment yield of the basin is 

derived from these tributaries.

The drainage slopes of Flynn Creek basin 

average about 34 percent. Much of the basin 

is on a moderate dip slope of the Burpee 

sandstone beds where there is generally a 

thick layer of fine soil. Water is temporarily 

stored in surface depressions and as soil 

moisture on the relatively flat dip slopes 

during freshet periods. The drainage pattern 

is not well defined, and the moderate runoff 

from these areas lacks the energy for largescale erosion of the tributary channels.

The Needle Branch basin has drainage 

slopes averaging about 37 percent. The heavy 

Douglas fir canopy and the relatively flat 

stream gradient combine to limit the runoff 

and sediment yield from the watershed. 

Thirty-two acres in the headwaters were 

logged off 7 to 10 years ago. The understory 

vegetation, however, has regrown to the extent that prelogging conditions seem to prevail as indicated by runoff and sediment yield.

*

The environment of the basins to date (1961) 

has been altered only by the structures and 

trails made for this study. Minor adjustments in the stream gradient in the vicinity 

of the concrete control weirs and fish traps 

will continue for sometime, but these changes 

are local in nature and should have little effect on the overall environment.

The various environmental factors affecting sediment yield are complicated and inseparable. A change in one will produce a 

change in the others. When logging or other 

uses of these basins begins, the Needle Branch 

basin could have a higher sediment yield than 

the Deer Creek basin.

METHODS OF MEASUREMENT

Often long-term sediment data must be obtained or a statistical approach must be used 

to establish relationships of sediment yield
INTRODUCTION

to the other hydrologic and environmental 

parameters. It is intended, during this study, 

to collect and use comprehensive hydrologic 

data to analyze these relationships. The material presented in this preliminary report is 

based on water and suspended-sediment data 

collected during the 1959 and 1960 water 

years. Terms used herein are those used by 

the U.S. Geological Survey in the annual series of Water-Supply Papers "Quality of Surface Waters of the United States."

Field surveys of the sediment deposits behind the concrete control weirs have been 

made to determine the amount and character 

of these sediments. The results of the surveys and particle-size analyses are incomplete at this time; they will be included in 

subsequent reports.

RAINFALL

Continuous records of rainfall are available for sites just downstream from the gaging stations in each of the three basins by the 

Oregon Agricultural Experiment Station at 

Oregon State University. The gages, USWB 

8-inch recording types, are so located as to 

be affected as little as possible by wind currents and vegetal cover. A summary of 

monthly rainfall for the period January 1959 

to September 1960 for these three sites is 

given in table 1. The records for these and 

other sites in the Alsea River basin have been 

published by Chapman and others (1961).

WATER DISCHARGE

Stream-gaging stations near the mouth of 

the streams are used to determine water discharge from the basins. These stations consist of a conventional gage house and well that 

are equipped with continuous water-stage 

recorders. Controls for stabilizing ratings 

of water discharge to gage height are provided by a concrete weir at each station.

WATER TEMPERATURES

A continuous record of water temperature 

for each stream is obtained by an attachment 

on the water-stage recorders. The sensing 

element is located at the end of the gagehouse well intake pipe in the pool behind the 

weir. Daily maximum and minimum temperatures are determined from these records*,

SUSPENDED-SEDIMENT DISCHARGE

During the period of record included in this 

report, the suspended-sediment load was 

measured at sites just upstream from the 

stream-gaging stations.

The streambed at the Deer Creek sampling 

site consists of angular rock fragments, 

whereas the beds at the Flynn Creek and 

Needle Branch sites consist of sand and fine 

gravel. Higher velocities at the Deer Creek 

site cause greater turbulence which probably 

results in a larger load of suspended sand

Table 1. Monthly rainfall of basins, in inches by water year

Month

October. ______ __ ___ ______ _ ____

November _______________________________

December _________ _ ___ _ _______________

January ____ _ ___ _ _ __ _ ___ ___

February ____ _____ _ ___ _ ___

March _ ______ _ ___

April _ _________________________________

May _ _ _ _

June. ____ ___ _ __ _____

July. _ __ _ _ __. . . _________ __ _

August. _________________________________

September ___________________________ _ _

Total _ _ _ _ __ _ _____

Deer Creek

1959

23.00 

12.00 

10.47 

4.83 

5.70 

3.62 

.65 

.60 

11.49

72.36

1960

8.73 

6.59 

9.26 

9.81 

18.16 

12.77 

9.04 

10.53 

1.20 

.03 

2.37 

.36

88.85

Flynn Creek

1959

21.27 

10.46 

9.82 

4.70 

5.22 

3.37 

.69 

.56 

11.26

67..S5

1960

7.77

5.95

8.16

10.29 

18.16 

12.77 

8.32 

9.84 

1.08 

.00 

2.14 

.29

84.77

Needle Branch

1959

25.19 

12.17 

11.33 

4.95 

6.30 

3.90 

.78 

.52 

13.12

78.26

1960

9.43 

6.96 

8.95 

11.00 

17.71 

13.65 

9.24 

9.19 

.95 

.00 

2.21 

.41

89.70
SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE RASINS IN THE ALSEA RIVER RASIN, OREGON

than that carried by the other two streams. 

Some sand and gravel move past the sampling 

sites as bedload. A major part of the bedload and some of the suspended sediment 

have been deposited in the backwater pools 

of the concrete control weirs. The rate of 

deposition gradually diminished until the end 

of the 1960 water year when the amount of 

sediment being retained in the pools behind 

the weirs was only a small part of the total 

sediment load. All the sampling sites were 

subsequently moved to the control weirs 

where virtually the total sediment load can 

be sampled and the yield of the basins can be 

compared more accurately.

Surveys were made at selected transects 

of the channel upstream from the weirs to 

determine the volume of the deposits. Random core samples were obtained to determine the specific weight and the particle-size 

distribution of the material in the deposits. 

This procedure will be repeated yearly to 

evaluate the amount and character of this 

part of the sediment load. These values will 

then be reported in yearly increments to 

permit the determination of the annual total 

load.

The suspended-sediment samples were collected at midstream with DH-48 depth-integrating samplers at time intervals ranging 

from one or two times a week during periods 

of low flow to as often as four times a day 

during periods of high flow. These midstream samples were considered to be representative of stream concentration because 

of the narrow, turbulent nature of the streams.

For some periods when no samples were 

collected, daily loads of suspended sediment 

were estimated on the basis of water discharge, sediment concentrations observed 

immediately preceding and following the periods, and suspended-sediment loads for 

other periods of similar discharge. Sediment loads from one or both of the other two 

stations and weather conditions were used to 

make these estimates.

WATER AND SEDIMENT DATA

Complete tables of water and sediment data 

summarized for this report are published in 

U.S. Geological Survey Water-Supply Papers. 

These reports also contain discussions of 

'standard methods and terms used but not 

fully defined in this report. Daily streamflow data for the period covered have been 

published in Water-Supply Papers 1638 and 

1718* These data are summarized in table 

2. Data on daily extremes of water temperature, daily suspended-sediment loads, and 

sediment particle-size analyses will be published in Water-Supply Papers 1745 and 

1815. Monthly averages of the daily water 

temperature extremes are summarized in 

table 3. A summary of monthly suspendedsediment loads is given in table 4.

FLUVIAL SEDIMENT

RELATIONS TO RAINFALL AND RUNOFF

Data on rainfall, runoff, and suspendedsediment transport collected during the 1959 

and 1960 water years are summarized in 

table 5. The recorded rainfall data are for 

the period January 1, 1959, to September 30, 

1960. All other data are for November 20, 

1958, to September 30, 1960. The data were 

tabulated in this form to compare individual 

items for corresponding periods of time. 

The true relation of the rainfall to runoff 

may not actually be so close as the table indicates because rainfall was recorded at only 

one point near the mouths of the streams. 

The relation might be different if rainfall 

had also been recorded at upstream sites.

Table 5 suggests that the rainfall for the 

Needle Branch drainage basin is greater than 

that for Deer and Flynn Creek basins. Shortterm precipitation records may be misleading, however, because studies have shown 

that considerable differences are sometimes 

recorded even by adjacent gages (Court, 1960; 

Mead, 1950). No significant difference in the 

average annual rainfall of the three basins is 

expected because of the close proximity of 

the basins, their alinement, and their similar 

altitudes. During the short period of record 

no large differences have occurred in the 

amount and distribution of the rainfall at the 

three rain gages used during this study.

As table 5 shows, the runoff for Deer and 

Flynn Creek basins was nearly equal for 

each of the 2 years of study, but that for 

Needle Branch basin averaged only 92 percent of the average for the other two. Part 

of the difference can probably be explained 

by the difference in the overstory vegetation 

of the basins. As pointed out earlier, the 

Needle Branch basin has about 80 percent 

Douglas fir in the overstory compared to
FLUVIAL SEDIMENT

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SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON 

Table 3. Average monthly maximum and minimum water temperatures, in degrees Fahrenheit by water year

Month

October ________________

November ______________

December ______ _ ______

January ________ _ ____ _

February ____ _ _ ____ _

March.. _ ____ _ _ _ _ _ _

April _ __ _ _ __ _ __ _ _

May. _ __ ___ _ __ __ __

June_____ ______ _ _ _ _ _

July_____ _ _

August. _ __ _ _ _ _ ____

September ___ _ _ ______

Average _ ___________

Deer Creek

1959

Max.

54 

49 

48 

47 

47 

48 

50 

49 

51 

55 

55 

52

50

Min.

52 

48 

47 

46 

46 

47 

48 

48 

50 

54 

54 

51

49

1960

Max.

50 

46 

46 

43 

46 

46 

49 

49 

53 

56 

56 

54

50

Min.

49 

45 

46 

43 

45 

45 

47 

48 

50 

52 

54 

52

48

Flynn Creek

1959

Max.1

52 

49 

48 

47 

47 

48 

49 

50 

52 

56 

55 

52

50

Min.

51 

48 

48 

47 

46 

47 

47 

48 

51 

54 

53 

51

49

1960

Max.

51 

48 

48 

46 

47 

48 

49 

50 

53 

55 

56 

54

50

Min.

50 

47 

47 

45 

47 

46 

48 

49 

51 

52 

53 

52

49

Needle Branch

1959

Max.

53 

49 

48 

47 

47 

46 

49 

49 

51 

55 

55 

54

50

Min.

52 

48 

47 

46 

46 

46 

47 

48 

50 

54 

54 

53

49

1960

Max.

51 

48 

46 

44 

46 

47 

49 

49 

53 

56 

57 

56

50

Min.

51 

46 

45 

43 

46 

46 

48 

49 

51 

54 

55 

54

49

Table 4. Monthly suspended-sediment loads, in tons

Month

October_______

November _____

December......

January. ______

February _____

March.. _ .___

April _ _ _____

May _ _.__.__.

June.. ________

July ... _

August. _ _ _ _.

September _ __

Total ____ _

]

Deer Creek

ltl.l

5.2

62.0

7.1

2.8

1.5

1.7

.8

.3

.1

1.1

3 89.7

L959 Water y

Flynn Creek

*2.4

3.2

39.1

4.3

1.4

1.1

.8

.2

i9\ v-t

r9\

.6

3 53.1

ear

Needle Branch

*1.4

.9

10.3

1.3

.7

.2

.3

ty\

fy\ \^l

f9\

.4

3 15.5

Deer Creek

1.7

4.9

5.6

7.0

53.3

6.6

7.3

3.3

.4

(2)

t9\ C^ 

(2)

90.1

1960 Water ye

Flynn Creek

0.7

.9

1.2

3.3

27.0

2.9

2.3

.3

/9\ ^)

(2)

(2) 

C2)

38.7

;ar

Needle Branch

0.2

.3

.2

.5

8.1

.6

.4

.3

*9\

W

W

t<y\ \*l

C2)

10.6

 " Does not include sediment load for Nov. 1 19.

2Less than 0.050 ton.

3 Does not include sediment load for October 1 to November 19, 1958.
FLUVIAL SEDIMENT

9

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C & oi a CU ^

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73 73

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about 40 percent in the other two basins (C. 

T,. Etyrness, U.S. Forest Service, written communication, 1961). The fir intercepts more 

of the water during the heavy rainfall period 

because the alder has no leaves then. Another possible explanation of the difference 

could be the loss due to subsurface flow from 

the basin, either through the tilted sandstone 

beds or through the alluvium of the valley 

mouth.

The suspended-sediment loads of the three 

streams for November 1958 to September 

1960 vary considerably, as would be expected from the relative size of their drainage basins. The drainage area of Deer Creek 

is 3.8 times that of Needle Branch, but the 

sediment load was 6.9 times as large. Flynn 

Creek has 2.6 times the drainage area, but 

transported 3.5 times more sediment than 

Needle Branch.

A better comparison of the three basins 

canbe made by dividing the annual suspendedsediment load of each stream by the area of 

the drainage basin to obtain the suspendedsediment yield. These unit area values (table 

5) show that the suspended-sediment yield 

for the Deer Creek basin for November 1958 

to September 1960 was 1.4 times that for the 

Flynn Creek basin and 1.9 times that for the 

Needle Branch basin.

The 1960 water year was the only full year 

for which records of rainfall, runoff, and 

suspended-sediment yield were available. 

The bar graph presented in figure 3 compares 

the relationships between precipitation, runoff, and suspended-sediment yield for 1960. 

For almost equal values of recorded rainfall, 

the runoff values for Deer and Flynn Creek 

basins were almost equal, but the runoff for 

the Needle Branch basin was only 88 percent 

of the average of the other two. The ratios of 

runoff to rainfall are 0.74, 0.79, and 0.65, 

respectively, for the Deer Creek, Flynn Creek, 

and Needle Branch basins. Sediment yields 

for the 1-year period reflect differences almost the same as those for the November 

1958 to September 1960 period. Deer Creek 

basin has 1.6 times the yield of the Flynn 

Creek basin and 2.3 times that of Needle 

Branch basin.

Another comparison can be made of the 

sediment-transport characteristics of the 

three basins by using the weighted-mean 

concentration. Values of this index were
10 SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

I 

O

90

80

70

60

9 50

a:

Q

O

UJ

a: Q.

40

30

20

10

DEER CREEK

Precipitation

FLYNN CREEK

Runoff

NX 

XV

90

80

70

60

cr

LJQ.

50 P

40

30

20

10

Q

_J 

UJ

C/)

Q

UJ 

Q. 

C/)

NEEDLE BRANCH

Suspended-sediment yield

Figure 3. Comparison by drainage basin of precipitation, runoff, and suspended-sediment yield for 1960 water year.

computed (table 5) for the period November 

20, 1958, to September 30, 1959, for the 1960 

water year, and for November 20, 1958 to 

September 30, 1960. A comparison of these 

values for the three basins again emphasizes 

the greater amount of sediment transported 

by Deer Creek.

A small part of the differences in sedimenttransport rates may be due to differences in 

the turbulence at the individual sampling 

sites. As shown in figure 2, the gradient 

where samples were obtained on Deer Creek 

is steeper than the gradients where samples

were obtained for the other two streams. 

Total load computation to be presented in 

future reports will provide adequate data for 

study of this item.

The weighted-mean concentration is also 

useful for comparing the water dischargesediment load relationship for a period of 

years. Because the data for the missing period October 1 to November 19 of the 1959 

water year would have little effect on the 

weighted-mean concentration of the streams, 

values computed for the rest of the year can 

be compared with the 1960 values. This
FLUVIAL SEDIMENT 11

comparison shows that the sediment concentration of these streams was nearly the same 

for each of the 2 years of record. Little 

change can be expected as long as the streams 

remain under virgin-forest conditions, but 

changes in the environment of the basin will 

most likely be reflected by changes in the 

weighted-mean concentrations.

The time distribution of precipitation, runoff, and sediment load has vital importance in 

the study of the hydrologic environment of 

these drainage basins. The monthly distribution of precipitation, runoff, and suspendedsediment load is given for each drainage basin 

for the 1960 water year in figure 4. About 95 

precentof the precipitation and runoff occurs 

during the period October to May, but nearly 

100 percent of the sediment discharge occurs 

during the same period. During the 1960 water year, almost two-thirds of the total annual 

suspended-sediment discharge from the three 

drainage basins occurred during February. A 

further breakdown for Deer Creek the largest 

carrier shows that 23 percent of the annual 

suspended-sediment discharge occurred during 1 day, 58 percent during the 10 days of 

greatest discharge, and 78 percent during the 

38 days of greatest discharge. Thus almost 

all the sediment discharge of these undisturbed forested watersheds occurs during the 

relatively few days of freshet activity.

A FRESHET PERIOD

Because most of the sediment discharge 

occurs during freshet periods, it is appropriate to study one such interval. The absence of clear definition of the variations of 

sediment concentration for freshet periods 

precludes a comprehensive comparison of 

the drainage basins. The period January 7- 

13, 1959, was selected for a study of a freshet 

in the Deer Creek basin. Definition of the 

suspended-sediment concentration for the period was fair, and data on rainfall and runoff 

were available. Data on rainfall intensity, 

rate of runoff, suspended-sediment concentration, suspended-sediment discharge, and 

water discharge for the above period are 

presented in graphic form in figure 5. For 

general comparison with the hydrologic relationships of other freshet periods for all 

three basins, all quantities are plotted on a 

per unit area basis. Water discharge is 

plotted in cubic feet per second per square 

mile in the upper graph for better comparison with concentration and suspended-sediment discharge. The suspended-sediment

discharge peak closely coincides with the 

water-discharge peak. During the logging 

phase, the concentrations may be higher and 

may thereby have more influence on the 

shape of the suspended-sediment discharge 

graph.

Figure 5 shows that rainfall intensity has 

little effect on sediment discharge. In densely 

forested areas, such as these drainage basins, there is limited opportunity for the 

raindrops to reach the soil mantle and to 

loosen particles by impact. Sediment discharge is influenced by rainfall intensity in 

these small basins to the degree to which the 

rainfall determines the magnitude and duration of the runoff peak.

The disposition of the rainfall that leaves 

the basin as runoff can be studied by means 

of the graphs presented in figure 5. In the 

lower half of the figure, water discharge (in 

cubic feet per second) has been converted to 

rate of runoff (in inches per hour) for direct 

comparison with rainfall intensity. On the 

rate-of-runoff graph a smooth curve was used 

between the computed plots, but because of 

the necessity of computing numerous values 

for definition, a graph of average rainfall intensity was used. The rainfall intensities 

changed rather suddenly, and a good average 

value could be obtained between major breaks 

of the mass-rainfall curve. These average 

values were plotted as straight lines for the 

periods they represent. If a period of time 

is considered, rate of runoff and rainfall intensity become inches of depth on the drainage area, and therefore, the area under a 

segment of either graph represents a volume. 

Because both are plotted on the same scale, 

the runoff- storage budget can be approximated 

for any period of time by using the lower half 

of figure 5. The amount represented by the 

area between the two graphs above the rateof-runoff graph is stored or lost to the atmosphere, and the amount represented by the 

area between the two graphs below the rateof-runoff graphs is taken from storage. If a 

period is chosen between times when surface 

runoff is depleted, the amount of water contributed to or taken from storage can be approximated for a particular period of time. 

It must be assumed that recorded rainfall 

equals actual rainfall and that average rainfall intensities approximate instantaneous 

values. The daily rainfall for January 7 13 

was computed by accumulating the products 

of the average rainfall intensity and the
12 SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

25

20

15

10

UJ

X

o

z J

X^

^

Suspended-sediment load

DEER CREEK

i

,-n

R^L.

60

50

40

30

20

10

 ; 20

u_

O

o:

15

o

UJ _

a: 5

Q.

0

20

I^a_ I

^

S|

FLYNN CREEK

i ^

N*; 

^

I

40

30

20

10

40

15

10

30

20

10

NEEDLE BRANCH

X

A 

^^1

^ 

^

x \

X?3 X^

I 1

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

Figure 4. Distribution by month for precipitation, runoff, and suspended-sediment yield for 1960 water year.
RUNOFF, AND RAINFALL 

HOUR PER INCHES IN 

PER FEET CUBIC IN DISCHARGE, WATER 

MILE SQUARE PER SECOND 

i\j

8888

MILLION PER PARTS IN CONCENTRATION, 

8

IN) 

O1

8

DISCHARGE, SUSPENDED-SEDIMENT 

MILE SQUARE PER HOUR PER POUNDS IN 

TVIAIVH 1N3WKHS SI
14 SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

period of time in hours. The values obtained 

compared closely with values taken directly 

from the mass-rainfall graphs, and thus indicate that no great error was introduced. 

Losses by evaporation and transpiration can 

be neglected for the purposes of this study 

because these losses are small for freshet 

periods of short duration during the winter 

months.

Computation by the procedures described 

above shows that the total rainfall for the 

January 7 13 period was 10.46 inches; the 

runoff was 7.64 inches; and the remaining 

2.82 inches was stored in surface depressions or as soil moisture. Thus a volume of 

water equaling 73 percent of the rainfall ran 

off before midnight on January 13. At this 

time, almost 21 hours after the last shower 

of the freshet period, the discharge of Deer 

Creek was still 20.6 cfs (cubic feet per second). This discharge decreased at an almost 

constant rate to 13.1 cfs at 7:00 p.m. on January 15, when the next shower began. If the 

rate of decrease in discharge is assumed 

constant, after only about 3|- days after midnight on January 13, the discharge would fall 

to 5.8 cfs, the base-discharge at the beginning of the January 7 13 period. If all surface runoff had ceased by midnight January 

13, the 2.82 inches of water stored during the 

period would be depleted in less than 4 days 

even if evaporation and transpiration losses 

were ignored. The above analysis indicates 

that a volume of water equaling the rainfall 

for the period made its way to the surface 

water courses and left the basin in a short 

period of time; little was left to sustain flow 

during the late summer months. If the aquifer was not saturated before this freshet period, a low recharge rate and a low specific 

yield for the Burpee Formation in this vicinity are indicated.

The volume of water discharge (in cubic 

feet per second-hours per square mile) for 

any period of time (in hours) is represented 

by the area under the water-discharge graph 

in the upper half of figure 5. This amount of 

water was available for flu vial-sediment 

transport for that period. The area under 

the sediment discharge graph for the same 

period of time represents the suspendedsediment load (in pounds per square mile) 

that was transported during the period.

FLOW AND CONCENTRATION DURATION

For many water uses, it is desirable to 

know what percentage of time during a year 

various magnitudes of daily mean flow and 

suspended-sediment concentration will be exceeded. These values can be predicted with 

fair accuracy by the use of the frequency 

duration curves based on the data for the 

first 2 years of record (fig. 6). Inasmuch as 

long-term records at nearby Newport, Or eg., 

(12 miles northwest of the study area) indicate that rainfall during these years was 

slightly higher than normal, the rainfall in 

these basins was also probably higher than 

normal. Because the flows and concentrations are assumed to have been higher than 

normal also, the values predicted for a normal year by these curves should be slightly 

high. An example of a possible use of these 

curves would be to find what percentage of 

time the flow exceeds a known value at which 

salmon can move upstreamto spawning beds. 

Assume that this value is 6.5 cfs for Flynn 

Creek. Use the flow duration curve for Flynn 

Creek to find where 6.5 cfs on the ordinate 

intersects the curve and, by vertical projection to the abscissa, read 22. This figure is 

the percentage of time that a daily mean flow 

of 6.5 cfs can be expected to be equalled or 

exceeded at the Flynn Creek gage. It might 

be desirable to know for hydrologic or aquatic 

studies what value of suspended-sediment 

concentration for Flynn Creek will be exceeded 50 percent of the time. To find this 

value, project the intersection of the 50-percent line with the concentration duration 

curve for Flynn Creek horizontally to the 

ordinate, and read 2+ ppm (parts per million) 

the daily mean concentration that will be 

equalled or exceeded 50 percent of the time. 

The relationships given by these curves 

should not change greatly until the parameters are changed when logging operations 

begin.

WATER TEMPERATURE

The variation between the maximum and 

minimum water temperatures for the three 

streams during the 1959 and 1960 water years 

was only 22°F, the maximum was 59°F, and 

the minimum was 37°F. The maximums for 

the three streams were identical at 59°F, and 

the minimums ranged from 37°F for Needle
FLUVIAL SEDIMENT 15

1000

100

L\

Vv

10

1.0

100

\

10

\

1.0 Nv

x

0.1

0.01 0.05 0.2 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99.5 99.9

PERCENT OF TIME STEAMFLOW OR CONCENTRATION WAS EQUAL TO 

OR GREATER THAN THE INDICATED VALUE

99.99

Figure 6. Streamflow (bottom) and suspended-sediment concentration duration (top) curves for the streams (based on records for 1959 and

1960 water years).
16 SEDIMENTATION IN THREE SMALL FORESTED DRAINAGE BASINS IN THE ALSEA RIVER BASIN, OREGON

Branch, the smallest stream, to 40°F for 

Deer Creek, the largest stream. These 

streams are the greatest distance apart and 

have the greatest difference in average altitude. Table 3 gives a summary of average 

monthly maximum and minimum water temperatures.

The differences given above for streams 

indicate that the water temperatures of these 

streams vary little from stream to stream 

and from time to time. The effect of water 

temperature therefore can be disregarded 

when comparing sediment yields from these 

small forested basins during the prelogging 

period because the small differences shown 

for the basins would have little effect on 

flu vial-sediment transport (U.S. Inter-Agency 

Committee on Water Resources, 1957). The 

turbulence in these streams is more than 

sufficient to hold in suspension silt and clay 

particles which would otherwise be most affected by temperature differences.

SUMMARY

The rainfall, runoff, and sediment yield of 

the three basins are seasonal. A large proportion of the rainfall and runoff occur during 

the freshets of the October to May period. 

Almost all of the sediment discharge occurs 

during the relatively few days of freshet activity. As much as one-fourth of the annual 

sediment load may occur in 1 day, and over 

one-half may occur in the 10 days of greatest 

discharge.

For the 2 years of record, the annual precipitation, runoff, and suspended-sediment 

yield for each of the three forested drainage 

basins did not vary greatly. However, the 

suspended-sediment yield of the Deer Creek 

basin was nearly 2 times that of the Needle

Branch basin and nearly lj times that of the 

Flynn Creek basin.

A study of the January 7-13, 1959, freshet 

period in the Deer Creek basin showed that 

probably only a small part of the precipitation during freshet periods is stored as 

ground water. The study showed that a volume of water equal to the rainfall for the period left the basin in less than 4 days.

Water temperature during the 1959 and 

1960 water years variedonly 22°F. The maximum variation between streams at any one 

time was only about 3°F.

On the basis of records for the first 2 

years of study, the Flynn Creek basin was a 

wise choice as the control or calibration basin. This drainage most nearly represents 

the average of the hydrologic conditions of 

the three study basins.

LITERATURE CITED

Chapman, D. W., Corliss, J. F., Phillips, R.W., 

and Demory, R. L., 1961, Alsea watershed 

study: Oregon Agr. Exp. Sta. Misc. Paper 

110, 52 p., Corvallis.

Court, Arnold, 1960, Reliability of hourly precipitation data: Jour. Geophys. Research, 

v. 65, no. 12, p. 4017-4024.

Mead, D. W., 1950, Hydrology: New York and 

London, McGraw-Hill Book Co. p. 195-208.

U.S. Inter-Agency Committee on Water Resources, Subcommittee on Sedimentation 

1957, Some fundamentals of particle size 

analysis: Rept. 12, p. 24.

Vokes, H. E., Norbisrath, H., and Snavely, P. 

D., Jr., 1949, Geology of the NewportWaldport area, Lincoln County, Oregon: 

U.S. Geol..Survey Oil and Gas Inv. Prelim. 

Map OM-88.

U. S. GOVERNMENT PRINTING OFFICE : 1964 O - 742-302