An Interim Report 

EFFECT ON 

STREAMFLOW fl 

FOUR FOREST PMCTICES 

in the Mountains of West Virginia 

U. S, FOREST SERVICE RESEARCH PAPER NE-I 

8 963 

NORTHEASTERN FOREST EXPERIM ENT STATION, UPPER DARBY, PA. 

FOREST SERVICE, U. S. DEPARTMENT OF AGRICULTURE 

RALPH W. MARQUIS, DIRECTOR 
EFFECT 0 STREAMFLOW 

FOUR FOREST PRACTICES 

in the Mountains of West Virginia 

Page 

INmODBTCTION ........................ 1 

THE STUDY WAZRSHEDS .............. 2 

IENSTRUMENTATl[ON AND 

MEASrnEMENT ....................... 8 

CALIBRATION AND ANALYSIS .......... 10 + 

WATERSHED TREATMENT .............. n a 

TREATMENT EFFECTS .................. 20 

Egects on water ........................ 20 

Water quality ........................ 20 

"Fcptal discharge ....................... 25 

Low flow ............................ 28 

High flow (or storm flow) .............. 29 

Flow duration ................... .. ... 31 

RunoM as a percent of precipitadon ....... 34 

EnFfects orn timber production ............... 35 

DISCUSSION OF RESULTS ................ 36 

Water quality .......................... 37 

Water supply ........................... 38 

Flood Wows ............................ 40 

Timber valtzes .......................... 41 

Forest gan~e ............................ 43 

Future research ......................... 44 

SUMMARY ............................ 45 

EITEIWAWRIE REFERENCES .............. 47 

APPENDIX ............................. 49 

I . Climatic data ....................... 49 

11% Instrumentation and measurement ...... 49 

%XI . Calibratim and analysis .............. 54 

%'Be7 . Treatment egects .................... 56 

V . Discussion of results ................. 72 
series of resedf.ch pzlbliccltio?~~ by the Nol?beclsten 

efzt Strrfion. In this ~eul series, which ha bee?? ddop 

for dll the Forest dnd Rmge Experimenk Stdtio~zs o 

re~t Serzjice, the symbol ME wiEI desiandte publicdtio 1 the Northeastern Station. ' 

This +vew sefdies repldces the Noriihedstenz Xtdtio~z's series former 

k;tzown as Sfdtiolz P@erxS BE like mafzner, the ~eries of Fore 

Research Notes previously pzlblished by the Northeastern Station 

wig be designated from now on ds U. S. FOREST SERVICE 

RESEARCH NOTES, dnd wili be ideatiflied by the symbol P\IE 

and a n~mber, 

The AutBL980n~"sKENNETH G. REINHART, d forester-hydrologist, received his 

Bachelor's and Master's degrees ctt. Yale University. Vith the 

exception of 4 years during World Wdr 11, he has served with 

the U.S. Forest Service since 1939, i?z 60th administration and 

~e~arch, and since 1949 has aathored a number of pgblications 

deding with8 soil-moistzlre problems and measwewzents. A member 

of the reseurch staff of the Northeastern Forest Experiment Station 

since 1955, he is now a project leader in watershed-managem& 

research, sfdtioned at Pdrsons, Vest Virginia. 

GEORGE R. TRIMBLE JR., ~esedrch forester, &tended the University of Idaho and the University o Addine, where he received 

his Bachelor's degree in forestry, dnd b ds dlso done gradgate wovk 

at I2~uk.e University, i~z forest soils, We joined the U.S. Forest 

Service in 1932, grid the ivorthea~tern Forest Experimenf Station in 

1939. He has served in flood-control sgrveys, and in reseurcb on 

management of ?zorthern hardwoods in New Hampshire. At present he is project leader in forest-manugement research, stationed at 

Elkins, West Vi~ginia, where he has directed resedrcb in timber 

and wdtershed management and logging of mozlntain forests. 

ARTHUR R. ESCHNBR, research forester, received his Bachelor's 

degree from the New York State University College of Forestry 

dt Syracuse, received his Master's degree af Iowa St& College in 

1952, and joined the U.S. Forest Service in 1953, He has served 

in the Central States Forest Experiment Station and the Northeastern Forest Experiment Stdtion at Kingston, ,Pennsylvania, and 

Parsons, West Vi~ginnia. At present he is stationed at Syracgse, 

New York, where he is engaged if2 cooperative watershed-managemend research projects of the Northedstenz Station alzd the New 

Yovk Sfnte Universitj~ College of Forest~~y. 
Glossary of Term Used 

c,f .s. ---cubic feet per second. 

c.s,m. --cubic feee per second per square 

mile. 

area-inch -1 inch depth of water over the area 

considered. 

p.p.m. -parts per miflioa; for example, 

parts of soil per million parts of 

water. 

d.$,h, / -diameter breast high (4% feet 

above the ground surface). 

M b.m. -thousand feet board measure. 

basal area -the area in square feet of the cross 

section at breast height of all the 

trees in a stand. 

cul% ---unmerchantable tree. 

water-year -May I to April 30. 

growing season -Mzy 1 to Oceober 3 1. 

dormane. season -November 1 to April 30. 
Introduction 

F OR a Long time we have known that the type of forest 

management practiced on a watershed may affect the 

amount and distribution of streamflow and the quality of 

the water produced. Studies have shown that this reladonship 

between wagershed $reatmen$ and water is not a simple one. I 

A number of factors affect it, including soils, geology, topography, and climate. Though we know the general nature 

of forest treatment effects on water, we have not learned 

nearly enough to prescribe a specific treatment to give a 

specific result. We do not yet understand how to manipulate 

vegetation to increase or reduce water flow by specific 

amounts. Though we are better able to recommend practical measures to reduce erosion and sedimentation, we lack 

detailed knowledge of the fundamental relationships between 

land treatment and water pollution. 

A necessary complication in managing xnost areas for 

water is that other uses must be considered also, Our mushrooming population forces us to examine means of integrating various land uses. Compromises thac best serve the needs 

of society must be sought in the majoriry of cases. This is 

pointed up by the recent increasing emphasis on multiple 

use as a guiding principle of forest management in legislation, discussion, and practice. 

Research, now under way in many areas, is delving into 

forest treatment effects on water in an effort to provide 

guides for such watershed objectives as flood control, increased streamflay 2nd clear usable water. 

This report describes firsr results of forest watershed management research on the Fernow Experimental Forest in 

Tucker County, West Virginia. 

Streamflow measurement was begun on five small watersheds in May 19 1 1. For 6 years, records were gathered on rainfall, runoff, and water quality under undisturbed conditions. 

This was the calibration period when the natural behavior 

of the watersheds was measured as a yardstick to judge future runoff and water quality after the different treatments 

were applied. Timber was inventoried before and after 

treatment. 

The watersheds were treated in May 1957 to February 

19 f9. Effects of treattnellt are given for the 3-year period 
from the start of treatment through April 1960; limited 

data are also given for the 1960 growing season. 

The study is being continued to determine changes in 

streamflow resulting from regrowth in the watersheds after 

the initial cutting and to learn the effects of future cuttings. 

Concurrently, foresr growth and other data are being coilected to measure the long-range returns from these methods 

of managing the timber resource. The effects of these forest 

practices on deer habitatband on the qualities of streamflow 

related to trout management2 are also under study. 

The Study Watersheds 

The Fernow Experimental Forest is located in northern 

West Virginia (fig. 1) in mountainous country west of 

the main ridge of the Alleghenies. Drainage is via the Monongahela River to the Ohio at Pittsburgh. The five study watersheds, which range from 3 8 to 96 acres in area, are contiguous 

or nearly so. The topography, geology, soils and forest cover 

(fig. 2) are generally representative of this part of the 

Appalachians. 

'Cooperative study with Division of Game and Fish, West Virginia Department 

of Natural Resources. 

'Cooperative study with the Bureau of Sport Fish and Wildlife, 1Ji.S. Department of the Interior. 

Figure I .-Location of 

the Fessow Experimental 

Po1:est in the moustains 

of West Virgiaish. 
Figure 2.--Typical rerrain of the Fernow Expetimental Forest. 

Elevation and topography.--The study area ranges in elevation from about 2100 feet above sea level to about 2810 

feet. Slopes are generally steep (table I), and logging is difficult. 

Geology and soils.--The Experimental Forest lies in the 

Allegheny Mountain section of the Appalachian Plateau, 

as described by Fenneman ( 193 8 ) . The watersheds are underlain by rock strata composed primarily of fractured 

hard sandstone and softer shale. There is apparently little 

storage of water in the bedrock. 

Most of the soil in the watersheds is silt loam with considerable stone content. Infiltration and permeability of the 

undisturbed soils are high. Soil depth to bedrock ranges for 

the most part from 3 to feet. Humus depth averages 

about 234" inches; over most of the area the humus is classified as a naedium mull. 

3 
Table I,.---Watershed areas, and percentage of area 

in digerefit slope classes 

Slope class, in percent Vatershed No. 

and treatment 

Percent of area 

1. Commercial clearcut 74 5 -- 20 75 

2. Diameter limit 38 45 5 50 -- 

5. Extensive selection 90 5 40 40 15 

3. Intensive selectron 85 70 15 15 -- 4. Control 96 40 30 30 -- 

All watersheds 383 30 20 30 20 

Table 2.-Period of logging and gross timber volumes, 

ilrr! thousands of board feet per acre 

Gross timber volumes 

Watershed No. Period of 

and treatment 

Commercial clearcut May 1957-June 1958 9.9 8.5 1.4 

June 1958-Aug. 1958 7.1 4.2 2.9 

Extensive selection AU~. 1958-Nov, 1958 12.0 3.7 8.3 

Intensive selection Oct. 1958-Feb. 1959 8.3 1.7 6.6 

Not logged 10.6 0 10,6 

I In the Commercial clearcut, skidroads were bulldozed during the operation; in the 

other three watersheds, skidroads were constructed in October 1957. 

'~ross board-foot volumes to 8-inch top, including volumes in cull trees. 

"ull trees, 

Forest cover.-The area had been heavily cut over between 

190 5 and 19 10. Prior to the study, the forest was essentially 

uneven-aged, consisting of 50-year-old second growth, residuals from early cuttings, and pale-sized trees that came in 

after death of the chestnut about 30 years before. The major 

species present were: oaks (red, chestnut, and white), sugar 

maple, yellow-poplar, black cherry, and beech. 

At the time of treatment all watersheds were complete1 

forested, supporting stands averaging 7,000 to 12,000 boar 

feet per acre (table 2). No fires or grazing by domesti 

animals had disturbed these stands for at least 35 years. 
Climate and stream@owru.--The climatic conditions under 

which this research was conducted and those to which its 

results are likely to apply are described by the following mean 

values determined from 9 years of record on the Fernow 

Forest : 

Mean annual precipitation 58 inches 

Melean daily temperature 48" IF". 

Mean daily maximum temperature $7" F. 

Mean daily minimum temperature 38" F. 

Average date of first frost in fall Sept. 30 

Average date of last frost in spring May 7 

Average length of frost-free season 145 days 

Precipitadon is well distributed through the year (fig. 3 ) . Because of fairly shallow soils, steep slopes, and relatively 

little groundwater storage, Row is high during periods with 

considerable precipitation and falls off quickly during periods 

with little or no precipitation. 

Annual runoff from the Conrrol Watershed during the 

study period (191 1-60) averaged about 24 inches, of which 

7 inches came during the growing season and 17 inches in 

the dormant season. Four of the 9 years of record had one 

or more months with no flow; 9 of the 108 months had no 

MAY JUN JUL BUG SEP OCT NOV DEC JAN FEE MAR APR 

Figure 3,-Mean monthly 

precipitadon and stream 

flow of the Control WaPRECIPI TATIOIV~ STREAMFLOW tershed dg~ing the g-year 

study perizd,: 
streamflow. Flow in March was the highest, with an average 

of 4.06 inches; September was lowest, with 0.05 inch. 

On the average, 42 percent of the annual precipitation 

left the Control Watershed as screamflow. In the growing season, runoff was 23 percent of precipitation; in the dormant 

season it was 60 percent. Run08 as a percent of precipitation 

ranged from a high of 96 percent in March to a low of 2 

percent in September. More detailed information on precipitation, temperature, and streamflow of the watersheds 

is given in the Appendix. 

Infiltration rates are high and there is no surface runoff 

from these forest areas when undisturbed. Much of the precipitation from large storms reaches the stream as subsurface 

flow: the water passes through the soil to a less permeable 

layer or to bed rock; then it moves laterally downslope to 

the stream. It does not percolate further to groundwater. 

Evapobranspira#ion.-AnnuaI evapotranspiration may be 

estimared by subtracting annual runoff from annual preTable 3.-Mean monthly precipitation and runo%d of 

Control during 8-year study period - 

percentage of 

precipitation 

Hov 3,35 0.57 2.78 17 

Dec 4,98 2,54 2,44 5 1 

Jan 5,81 3,77 2.04 65 

Feb 4.82 3,36 1.46 70 

Pdw 5-31 4.06 1.25 76 

Apr 4,65 3.17 1.48 68 

' As soil-moisture storage is fairly uniform at the beginning and end 

of the water-year this value is taken as an approximation of evapotranspiration or consumptive use, This may be an overestimate because 

there may be some deep seepage from the watershed. 
cipitation (table 3). For the Control Watershed (IU~. 4) 

annual evapotranspiration was estimated at 34 inches in the 

9-year study period. The estimates varied considerably by 

watershed. The following tabulation shows mean values in 

area-inches for the 6-year calibration period: 

P~ecjfii- Preci$itatio~$ 

Wa tershgd Lation Runof minus rzlnoff 

1, Commercial Clearcue 60 23 37 

2, Diameter Limit 59 26 33 

3. Intensive Selection 59 25 34 

4, Control 59 2 5 34 

$ , Extensise Selection 5 8 30 28 

As can be seen, precipitation measured on the five watersheds was rather uniform; runoff less so. Further study of 

the watersheds must be made to determine whethr these 

differences resulted from digerent amounts of deep seepage 

or from other causes. 

In estimating evapotranspirarion from records of precipitation and streamflow, changes in storage of water in the 

watershed must be considered. The water-year used in the 

above calculations starts and ends on May I, when storage is 

generally near the maximum; and there should be little 

difference from year to year. For that reason, making the 

estimates without correction for storage should not greatly 

agect the result, 

Potential evapotranspiration has not been calculated for 

these watersheds. Such investigation is planned. Indications 

are that actual evapotranspiration is not far below the 

potential. 
and M 

The collection of data in this type of experimentation 

requires careful measurements over many years. Lack of 

measurement accuracy would easily mask significant diff erences, 

Stream discharge.--On the watersheds, 1 20-degree Vnotch weirs were used to measure stream discharge (fig. 4). 

Contkuous records of water level were obtained on drum 

charts by FW- I water-level recorders installed in concreteblock gage houses. A rating table was developed for each weir 

to show the relationship between gage height and discharge. 

From the chart record and rating table, tabulations were 

prepared of mean flow in c.s.m. by days. The flow was then 

tabulated in area-inches by month, season, and year. As 

needed, special tabulations of storm flow were prepared. 

Precipitation.-Precipitation was measured by a network 

of three recording gages and nine standard gages located over 

Tfigul~e 4.-A stream-gaging station oo one of the 

experime~t~-al watersheds, 
Pigere 5.-Recordisag and saanda~d gages insgalled 

in a clieariag to merasere p~ecipiitaticsn. 

the five watersheds (fig. 7). Trees were removed from the 

im~nediate vicinity of the gages to get a measure of precipitation in the open rather than under a canopy. 

Air temperadare and hamidity.--Air temperature and relative humidity were measured at one station on the Experimental Forest area. 

Vater 

from the 

the well-s, 

gzlality.-Wa ter-quali t y sampies were collected 

streams at sampl;ng points a short distance above 

Routine samples were taken according to schedule; 

special samples were obtained during storm periods. Samples 

were tested for tbghidity and certain chemical characteristics. 

In the calibration period, wager temperature was measured 

at the tilne water-quality samples were taken. Starting in 

May 19 5 8, maximum-minimum thermometers were placed 

in the streams and read and reset generally at weekly 

intervals. 
ibration and Ana 

During the calibration period, climatic and streamflow 

data were gathered as a basis upon which to predict water- ec shed behavior after treatment. In other words, normal" 

behavior pattern was established. 

Changes due to treatment were determined by maintaining one of the five watersheds undisturbed as a control (Reinhart, 19 $8). Runog in terms of annual, seasonal, and monthly flows and other runoff characteristics of each of the other 

watersheds was compared to the control during a 6-year 

calibration period. And mathematical equations were developed so that the runoff of each watershed could be predicted 

from the runoff of the control. These prediction equations 

were tested for validity and accuracy and were found to be 

statistically sound. 

To illustrate simply: suppose we wish to predict annual 

flow of Watershed 1 (Y), or the expected discharge if there 

were no treatment eeect, from measured annual flow of the 

Control Watershed (X). A linear regression equation, developed from data in the calibration period, is used. This 

equation is of the type: Y = a + bX. For this- example 

the actual equation developed is U = -0.82 + 0.967x, 

in which Y and X are in area-inches, 

1 COMMERCIAL CLEARCUT - 74 ACRES -- WATERSHED BOUNDARY 

2 9IAMETER LIMIT - 38 ACRES m WEIR 

3 INTENSIVE SELECTION - 85 ACRES - --, sr*enM 

4 CONTROL WATERSHED -96 ACRES 

5 EXTENSIVE SELECTION - 90 ACRES 

Figure 6.-Relative locatiora and size of the 

five gaged watersheds 

on the Fernow Experimentali Forest. 
Now suppose we wish to tesc the effect of treatmen% on 

the annual flow of the Commercial Clearcut Watershed. 

The above equation gives a predicted or expected value. A 

measured value is obtained from the gaging station record. 

The difference between the two indicates the effect of treatment; the magni~ude of this digerence is then tested by 

routine statistical methods (Snedecor, 19 16, pp. 137-1 3 8) to 

determine whether it is large enough to be significant. 

Egects of treatment on other chzracteristics, say flow by 

season and by month, low flow, or high flow, are measured 

and tested in much the same way. Additional detail on calibration and analysis is given in the Appendix. 

Watershed Treat 

After completion of the 6- year calibration period, timber 

was harvested on four of the five watersheds, each by a different forestry treatment (fig. 6) . One watershed (No. 4) 

was left uncut to serve as a control for comparisoil. The four 

cutting practices ranged from a liquidation cutting-without conceria for %he future value of the property-to a conservative selection system cutting (table 4). Specifications 

for the four cutting practices applied were as follows: 

Commercial Clearcurbing.--This is the typical liquidation 

cutting only too commonly practiced throughout the mountain hardwood country. Everything merchantable is taken, 

including sawtimber and other products such as pulpwood 

and mine timbers in trees down to about 6 inches d.b.h. (fig. 

7). All cull trees are left; no cultural work of any kind is 

done. Skidroads are laid out on a logger's choice basis; generally they are steep. Water values are not considered; skidroads may run up and down the stream channels, and any 

type of strealn crossing is permissible (fig. 8 ) . No afterlogging care is practiced on the roads. 

Diame~er Linjii ratting.--This type of cutting may be 

considered a crude forest managemer~t program, Every merchantable tree of long-lived species above 17.0 inches d.b.h. 

is cut. Every tree of short-lived species (such as black locust, 

sassafras, and mountain magnolia) larger than 7.0 inches is 

cut. The only cultural measure employed is deadening culls 

larger than 17.0 inches. Plans are to cut agnin i1-3 20 years. 
Skidroads are logger's choice, similar to those in the 

mercial Clearcutting. Only one practice is used in con 

tion of road values: after logging, water bars for road 

age are installed at intervals of about 2 chains (I c 

-- 66 feet). 
Extensive Selection nranagement.--This is a selection management program in which harvesting and the killing of 

culls is limited to marked trees in the sawlog portion of the 

stand--trees larger than II.~ inches d.b.h. All trees to be 

harvested, or deadened as culls, are marked. The only cultural 

measure is cull deadening and cutting of grapevines that 

are damaging potential crop trees. Cutting cycle is 10 years. 

No skidding is done in stream channels; bulldozed skidroads 

are limited to about a 20-percent grade except where conditions dictate a somewhat steeper grade for short stretches. 

Water bars are established immediately after logging wherever they appear to be needed. 

lnrensive Selection managemenL.--This is n selection management program in which cutting and cultural work are 

done throughout the range of d.b.h.'s above j.0 inches (fig. 

9). All trees to be harvested, or killed as culls, are marked. 

Gutting cycle is F years. Bulldozed skidroads are limited to 

about I 0-percent grade except where conditions dictate a 

somewhat steeper grade for short stretches. Skidroads (fig. 

10) are located away from stream channels. The rule of 

thumb reported by Trimble and Sartz (1957) is used as a 

guide: distance between road and stream channel should not 

be less than 25 feet plus 2 feet for each percent slope of the 

land between road and stream No skidding is done in stream 

channels; stream crossings, if necessary, are by carefully 

planned bridges to protect the stream. After logging, water 

bars are established in skidroads as necessary; and potential 

sediment sources, if any, are seeded to grass. 

Treatment was begun on May 13, 19 57; and logging on 

the last watershed was virtually completed on December 10, 

19 18. A few logs were removed from the Intensive Selection 

Watershed in February 19F9. Data on the original stand, 

the amount cut, and the amount left were compiled 

(table 2). 

In the Intensive Selection Watershed, the original volume 

of the stand and condition of the timber made it necessary 

to make a very light cutting so that su6cient volume would 

be available for another cut in 5 years, as scheduled under 

this practice. Water values were given special consideration: 

no logging was done in wet weather. Where necessary to 

insure soil stabilimtion, short stretches of skidroad were 

seeded to grass immediately after logging (fig. 1 1 ) . Also, 

an old truck road built into the upper portion of this water- 
Figure "S-The Commercial Clearcrat Watershed after logging. 

Figure 8.-Tractor skidroad in the Commercial Clearcut 

Watershed, The road is almost in the streambed, and 

logging debris obstructs the channel, 
Figure 9.-The Intensive Selectow Watershed after Hogging. 

Figure 80.-lkr;lactor skidroad in the Intensive Selection 

Watershed just before logging. Note the gentle grade and 

the dip for drainage. 
Pipre 11,-This short stretch of skidroad in the Intelrnsive 

Selection Watershed was limed, fertilized, and seeded to 

grass as soon as the logging operation was completed, 

shed and the Extensive Selection Watershed made it ~ossible 

to remove a large part of the volume from above. 

In all watersheds, logging was done with a TD-9 tractor 

with rubber-tired sulky (fig. 1.2) . Generally, the tractor 

remained on the skidroad and tree lengths were winched 

to it. During the course of logging no truclr roads were constructed in the watersheds--only tractor skidroads. 

Skidroads for the Dizmeter Limn% Watershed and the two 

Selection Watersheds were constructed in October 19 57, 

about a year before logging, to allow settling time before 

use and to allow a measure of the efiect on streamflow of 
,. r, -u--- - . 

shortly niter dozing of roads. In the Commercial Clearcut 

Wntcrslied, skidro~lds were constructed as needed during the 

logging job. 

Most main skidroads were bulldozed; though where slopes 

were gentle, it was sometimes feasible to operate without 

'dozing. Also, some spur roads were located on relatively 

steep terrain and operated without 'dozing when only a few 

grips were scheduled to pass over them. The disturbance 

caused by 3 few trips, even on a steep gradient, has proved 

to be less than would result from 'dozing a road on the 

gade prescribed for the treatment. 

Figure 12.-Tractor with sulky skiddi~g logs. Tree lengths 

were usually winched in to the skidroad, 
Tgble 5.-Percentage of arefa and grade of skidmads 

in the four logged wacepslaeds 

Percent age of 

watershed area 

Watershed No. 

and treatment 

1. Commercial clearcut 

2. Diameter limit 

5. Extensive select ion 

3. Intensive select ion 

Detailed data were compiled separately for 'dozed and 

non-'dozed roads (table 5) because the amount of disturbance and impact on the watershed were much greater for 

the 'dozed roads. The unplanned skidroads of the Commercial 

Clearcur occupied the most area (7 percent of the watershed for both 'dozed and non-'dozed) and the carefully 

planned roads of the Intensive Selection Watershed occupied 

Figure 13.--Reovery of vegetation after logging was good. 

Left, the Commercial Clearat Watershed after logging was 

compleged, Right, the same area 15 months %ares. 
Figure 14.--Rooting depths of new and old vegetation. 

Left, the roots of jewel weed and nettle that came in after 

logging on &e Commerdal Clearcut Warershed. Right, 

roots of a large beech tree cut ar edge of main skidroad in 

the same watershed. One-foot rule shows scale in both 

photos. 

the leist (2 percent). If the cut in the Intensive Selection 

Watershed had been heavier, the percent of area in skidroads 

would probably have been only slightly higher. 

One significant feature of all treatments was the egect 

of logging on the forest floor. Except for the skidroad areas, 

the forest floor was subjected to only minor disturbance. 

The recovery of the area is being watched. The forest 

practices used were all one-shot treatments, which will be 

repeated at intervals; and after each phase of the harvesting 

operations there is a period of recovery. Periodic inventories 

of trees more than 5 inches d.b.h. and periodic reproduction 

counts will provide a measure of the rate of recovery. Successive photographs from established photo points will provide a photo record of the changes. 

Recovery was most noticeable on the Commercial Clearcut 

Watershed, which had the most drastic treatment (fig. 13 ) . Shortly after logging, a good growth of new vegetation appeared, composed mostly of herbaceous plants and tree 

sprouts, with some admixture of tree seedlings and grass. 

Depth of rooting of the new herbaceous growth was much 

less than that of the older growth (fig. 14). 
Treatment Effects 

ON WATER 

This study showed two things primarily: ( 1 ) that cutting 

of forest vegetation increases streamflow, and (2) that much 

of the damage to water quality due to poor skidroad practices can be avoided by proper planning of skidroads and 

reasonable care during logging. 

The results of treatment were analyzed as to their effect 

on the following facets of streamflow: water quality, total 

discharge by year, season, and month; low flow; high flow; 

flow duration; and runoff as a percent of precipitation. 

Water Qaality 

Careless logging resulted in very turbid water. This was 

certainly not unexpected. Maximum turbidities measured, 

ranging from 56,000 p.p.m. on the Clearcut to 15 on the 

Control (table 6 and fig. 1 5 ) illustrate the striking results 

of the different logging practices. Serious stream pollution 

was encountered on the two watersheds with unplanned 

skidroads-Clearcut (fig. 16) and Diameter Limit. On the 

Extensive Selection Watershed the effect of logging on water 

quality was not serious, and pollution subsided almost imTable 6.-Maximum turbidity measured, and frequency 

distribution of samples for the five watersheds, 

December 1957 to April 1960 

*~ou~hl~ parts of soil per million parts of water. 

Watershed No. 

and treatment 

** Not included in frequency distribution. This sample was taken at a tlme when the other 

watersheds were not sampled. 

1 U 1 

units Number of samples 

1. Commercial clearcut 56,000 126 40 24 13 203 

2. Diameter limit 5,200 171 17 8 7 203 

5. Extensive selection 210** 195 8 0 0 203 

3. Intensive selection 25 201 2 0 0 203 

4. Control 15 202 1 0 0 203 

Maximum 

turbidity 

measured 

Total 

No. of 

samples 

Frequency distribution of samples, 

by turbidity unit* classes-- 

0-10 11-99 100-999 

- 

1,000+ 
Figure lS.-Water samples showirng maximum turMdities 

measured on each of the five gaged wate~sheds, Bgerences 

are due largely to digerences in skidroad layout and construction. 

Figure 16.-----A steep, gullied skidroad in the Commercial 

Clearme W'ate~shed soogl aker ccsn~pletioa of the logging 

operadon. 
~a~le /,-~verage turDtatey oa routa%ae samples from 

Commercial Clearcut and Diameter 

Limit watersheds 

(Special storm-period samples not included) 

Period 

Commercial clearcut 

During logging operation 

First year after logging 

Second year after logging 

Diameter limit 

Before logging (after roadbuildingf 2 0 - 68 

During logging operation 897 0 - 5000 

Flrst year after logging 6 0 - 88 

Second year after logglng 0 0 

mediately after logging ceased. The egf'ect on water quality 

of logging the Intensive Selection Watershed was negligible: 

the water was clear, or almost clear, all of the the. 

The impact on water quality was greatest during and 

immediately after the logging operation (table 7 and fig. 17). 

Repeated disturbance during logging continually brought 

to the road surface a new supply of fine soil particles. Erosion 

decreased rapidly after logging, due first to the development 

on our soils of a partial erosion pavement (a surface cover 

of small stones) and later to vegetation growth on the 

roads. Frost heaving brought a temporary setback to this 

process. 

Eeects of the Commercial Clearcut treatment on water 

temperature were noteworthy. Analysis of current temperatures in the calibration period (when extremes were not 

measured) indicated that there was lietle difference in the 

temperature regimes between this watershed and the Control, 

Thus differences during the treatment period are considered 

results of treatment, 

Cutting in the Commercial Clearcut Watershed, as might 

be expected, accentuated the extremes. Growing-season maximums in 19 18 and 19 $9 were increased on the average by 

8" IF. The dormant-season minimums were reduced on the 

average by 3y2'. A slight effect in the same direction was 

apparent on the Diameter Limit Watershed; and no appreciable egects were evident sn the two Selection? Watersheds. 

22 
Figure 17,-A, sediment deposit at edge of main skidroad, 

Commercial Clearcut Watershed, one month after conspletion 06 logging operation. B, the sansne location 1 year 

later. 
Table 8.-IE@ecr of greatmeats on annual discharge 

I I I Discharge for year, / 

in area-inches 

Treatment 

195~-58~ 19 .O 2.2* 0,02 

Commercial clearcut 1958-59 26,5 .5.1* .0Ol 

1959-60 21.5 3.4% .003 

Diameter limit 

1956-59 35-3 1.0 Extensive selection 1959-60 29.3 .7 

1958-59 28.3 -.I Intensive selection 1959-60 23.2 .3 

"he probability that an increase of the magnitude measured could have occurred by chance alone. 

Treatment in effect only part of time or on only part of the area during 

year. * Statistically significant at 5-percent level, 

TaMe 9.----B@ect of treatments on dischgrge, by seasons 

Treatment 

' The probability that an increase of the magnitude measured could have occurred by chance alone. 

2Year of treatment (treatment in effect only part of time or on only part of mea). 

Negative value denotes a decrease, * 

Statistically significant at 5-percent level, 
Slight chemical changes were noted as a result of clearcutting: pII increased from a mean of about 6.1 to 6.4 and 

methyl orange alkalinity rose about 2 p.p.m. No appreciable 

changes in chemical characteristics resulted from the other 

three greatments, 

Total Discharge 

By year.--Using the equations developed from the calibration data, it was possible to predict (from the Control) 

the annual Gow Prom each treated watershed if it had not 

been treated. When this was compared to measured flow, 

certain significant changes were noted (table 8). 

There were large and statistically significant increases in 

streamflow from the Commercial Clearcut Watershed begbning the year of treatment, 19 57- 5 8. The greatest increase, 

I. I area-inches or 19 percent of the expected annual discharge, occurred the year after logging. In 1919-60, the 

increase was 16 percent. This drop may have been due both 

to increased use of water by plants as a result of vegetation 

regrowth and a combination of weather factors. men an 

alter-trend has been established over a period of several years 

it should be possible to estimate the effect of vegetation 

regrowth. 

The eaects of treatment on the Diameter Limit Watershed, 

cut in mid and late summer of 19Y8, were not so great. 

In 1959-60, the first full year after logging, there was an 

increase of 2, 5 area-inches or 10 percent. 

While the record of the Selection Watersheds indicates 

slight increases in annual flows for the first full year after 

logging (1959-60) the increases were too small to be statistically significant. 

Skidroads were constructed in the Diameter Limit and 

Selection Watersheds in October 19 5 7. Predicted discharges 

and changes in flow were computed for the I 917-1 8 wateryear; these analyses indicated that construction of skidroads, 

in the absence of logging, had no appreciable discharge 

egect on these three watersheds, 

By season.-The water-year has been divided for compilation and analysis purposes illto the growing season (May 

chrough October) and the dormant season (November 

through April) . Comparisons between predicted and measured flows in these two seasons were made and tested for 

statistical significance (table 9). 
For the first growing season after completion of logging, 

significant increases occurred on all but the Intensive Selection Watershed. On the Commercial Glearcut Watershed, 

increases were significant for all four growing seasons measured; and, as expected, the largest increase followed the 

completion of logging. 

Increases as a percentage of expected discharge ranged up 

a;o P P B percent, which occurred on the Clearcut Watershed in 

19F9. The increase in 1958 was larger, 4.4 inches compared 

to 3.0 inches; but in the summer of 19 $8 precipitation and 

streamflow were high, which resulted in a lower percentage 

increase over the expected value. 

Though the increase on the Intensive Selection Watershed 

in 19 59 was not statistically significant, it amounted to 0.3 

area-inch or 9 percent of the expected value and fell into a 

logical pattern when considered with results from the other 

watersheds. This 0.3 area-inch is equivalent to more than 

8 thousand gallons per acre. 

The effect of treatment was less in the 1960 growing season; however, increases for both the Clearcut and Diameter 

Limit Watersheds were still significant. In 1959 and 1960, 

Diame~er Limit increases were ;about half those on the Clearcut Watershed, 

Figure 1 @.--Increase in 

flow related to volume 

cut and culled, 1359 

growing season. 

0 2 4 6 8 10 

VOLUME CUT AND CULLED IN THOUSAND BOARD-FEET PER ACRE 
Table 10,-Increase in flow, by months, in area-inches1 

(Increase shown only if statistically significant at 5-percent level) 

' Records of runoff ava3.lable for only f isst 6 months of water-year 1960-61. 

A definite relationship appears to exist between the severity 

of the cut and the increase in discharge. A graph showing this 

relationship for the 1959 growing season, with volumes 

expressed in board feet, is presented in figure 18. During the 

dormant seasons insignificant increases were recorded in 

streamflow for the two most heavily cut watersheds. 

Analyses were made of seasonal discharges between dozing 

of roads and logging on the Diameter Limit and Selection 

Watersheds. No significant effect of this phase of the treatment was demonstrated. 

By month.-Similar ~nal~ses were made of discharges by 

month after start of treatment in each watershed. Table 10 

presents in an abbreviated form the results of this analysis. 

Increases are sho.rrn only when statistically significant. 

Increases in flow on the Clearcut Watershed were consideiable, ranging up to 1.6 area-inches in July 19 $8, a month 

of heavy precipitation just after completion of logging. Increases in some of the drier months were small in actual 

amount but were large compared to expected flow; for example, in October 1917 on the Clearcut Watershed the 

increase was only 0.6 area-inch but measured flow was more 

than 10 times the expected flow. 
increases in flow on the Diameter Limit Watershed; however, 

increases were smaller than on the Commercial Clearcut. The 

two Selection Watersheds had much smaller and for the most 

part statistically insignificant increases in the growing-season 

months; however, in October 1 9 r 9 both watersheds showed 

increases significant at the 5 -0ercen t level, 

Months of the dormant season generally did not show large 

increases in. .$%ow, November hcreases were sipaBiicant on the 

Commercial Clearcut and Diameter Limit Watersheds, Decreases that occurred in certain dormant -season months mav 

be associated with the eifect of treatment on snowmelt rat& 

and will be discussed later. 

Low Flow 

An analysis was made to determine the treatment effect on 

the number of days in the year that stream discharge was 

below certain rates of flow. Three levels were considered: 

0.05, 0.075, and 0.10 c.s.m., approximating $0, 75, and 100 

gallons per acre per day. Table 11 gives the results for YO 

gallons per acre per day; the other analyses are reported in the 

Appendix. 

For example, it was predicted (from the relationship of the 

Table II.-E@ect of treatmeats an nmber of days of 

low ~BW (less ehan 50 gallons per acre per day) 

Nwnber of days of low flow 

Treatment 

Commercial cleareut 1958 38 38% 

1959 99 6 3" 

1960 46 3 9" 

1958 22 22" 

Diameter limit 1959 7'4 4 7* 

1960 29 2 7* 

Extensive selection 1959 58 21" 

1960 1'7 14* 

Intensive selection 1959 6 5 

1960 20 

' Decrease in number of days of low flow results from aa increase In streamflow, * 

statistically significant at 5-percent level. 
CBearcu~ and Control Watersheds before treatment and the 

of the Control in 1959) that the Glearcut Watershed would discharge less than 50 gallons per acre per day 

on 99 different days in 1959. Actually, streamflow was below 

this rate csaa only 36 days. 

The analysis shows that treatment had a strong effect on 

low flows: the heavier the cut, the greater the effect. In 1959 

and 1960 together, days of low flow on the Clearcut were 

reduced from 145 to 43 ; on the Diameter Eimit from 103 

to 29; on the Extensive Selection from 75 to 40 ; and on the 

Intensive Selec tion f rom 8 5 to 67, 

Nigh Flow (or Storm Flow) 

Analyses of high flows were difficult, largely because the 

effect of treatment on these flows was variable. Depending 

on conditions at the time of a storm, the efiect might be an 

increase, little change, or even a decrease. High flows occurred 

too infrequently to group by classes based on antecedent precipitation or other factors affecting rreatment results. More 

extensive analyses of high flows were made lor the Commercial Clearcut Watershed than for the partially cut watersheds because the effects of treatment were obviously greater, 

ns expected, on the Clearcut than on the others. Under some 

conditions, storm flow from the Clearcut Watershed was 

several times that from the Control. 

Figure 19 shows sample hydrographs of these watersheds 

before and after treatment. Before treatment, the hydrographs of the two watersheds were close together. Number 

4, the Control, was slightly above Number I, the Clearcut. 

The rounded peaks on both hydrographs indicated undisturbed forested watersheds with negligible overland flow. 

The hydrographs after treatment represent a i-day period 

shortly after completion of logging on the Clearcut at the 

height of the growing, or evapotranspiration, period. The 

flow of the Clearcut Watershed was higher at the start; this 

was the normal relationship of these watersheds in the growing season after treatment. The sharp peaks on the Clearcut 

were probably caused by quick overland flow from skidroads. 

The storm flow is far greater than that from the Control. 

Runoff for the 3-day period, July 1 1 to 13, was 0. r 2 area-inch 

on the Glearcut Watershed, almost 9 times the discharge of 

0.06 area-inch on the Control. 
skbew~hr~ &*a owanl&. ybs.dw~8e WJ. nxx~xb Ibw IVV Vv LkL BILkMbIIL UILllLlblXb 

from the instance described above. For example, in late 

March 1960 a 2-foot snow cover melted away over a 14-day 

period in which some additional precipitation occurred. The 

following tabulation shows streamflow in area-inches of the 

Clearcut and Control Watersheds and the precipitation 

record :: 

Discharge ill 

Precipitation area-inches from-- 

March- Snow Rain Ckvearcat Conf rokv 

14-day 

sum 1.04 -69 4.01 4,3 8 

For the 14-day period, flow of the Clearcut was 92 percent 

of that of the Control. In the first I I davs, flow of the Clearcut exceeded that of the Control. This was more than 

compensated for by lower flow of the Clearcut in the last 

3 days: on the day of highest flow, March 10, flow of the 

Clearcut was only 71 percent of that of the Control. The 

maximum instantaneous peak on the Clearcut (38 c.s.m.) 

was only 75 percent of the corresponding peak ( 5 I c.s.m.) 

on the Control, Observations on the watersheds indicated that 

snow cover disappeared near the end of the period and that 

it was gone sooner on the Glearcut than on ;he Control. In 

this instance, exposure of the snow cover apparently resulted 

in a much lower ~eak flow. d 

To define the effects of heavy cutting on storm flow, four 

different types of analyses were made on data of the Clearcut 

Watershed. One analysis, ulldertaken on datn of all lour 
BEFORE CUTTING 

CONTROL 

Figure 19.-Sample storm 

hydrographs of Clearcult 1200 2400 1200 2400 1200 and Control watersheds JULY 9, 1955 1 JULYIO ( JULY II 

before and after treatment. 

JULY I!, 1958 1 JULY 12 1 JULY 13 

treated watersheds to determine effects sf all cuts, showed 

that effects of treatment were decisive on the Clearcut Watershed but not on the partially cut watersheds. 

Instantaneous peaks on the Clearcut Watershed in the 

growing season were increased on the average by 2 1 percent; 

in the dormant season they were reduced by 4 percent. 

Considering yearly quantity of discharge above 10 c.s.m. 

on the Clearcut Watershed, there was an average increase of 

11 percent in the 3 years after logging. The increase was 42 

percent in the three growing seasons. And analysis indicated 

a decrease of 1 percent in the three dormant seasons. 

The following pattern of treatment effects was evident: 

in general, heavy cutting augmented high flows in the growing season and resulted in either increases or decreases in the 

dormant season. The decreases usually occurred when snow 

melt was involved: 

Flow Dzllrdtion 

The flow-duration curve of a stream, showing the percentage of time that specified discharges are equaled or exceeded, is a useful tool in studying effects of treatment 

(Searcy, 19 19) . Many flow-duration curves were prepared 

in this study; all were based on mean daily flow in c.s.m. 
Figure 20,--Flow-duratP 

don cumes for Clearcut 

Watershed in the four 

growiag seasons after 

start of logging, 

PERCENTAGE OF TIME FLOW IS EQUALED OR EXCEEDED 

Average curves for the Clearcut Watershed in the growing seasons of the treatment period show that the treatment 

effect was greatest on low flows (fig. 20). Curves based on 

both predicted and measured values are shown; these represent flow in the 736 days of the 1957-60 growing seasons. As 

can be seen, the "measured" curve is far to the right of or 

above the "predicted" curve; this difference is a measure of 

the treatment eeect. 

The following tabulation indicates how the curves may be 

used and the magnitude of the treatment effect. For example, 

based on pre-treatment relationships, it was estimated that 

2 5 percent of the time after treatment Wow would be $60 

gallons per acre per day or greater if treatment had no egect. 

Actually, measured flow for 2 1 percent of the time was 4 ,800 

gallons per day or greater. 

Flow that is er/z~aled or exceeded, 

Perce~ztage of ti~lze ijz gallolls per acre da3~ -- 

P~frdisfed Measzsvcd 
Another practical way of using these curves is indicated by 

an example. Assume that a certain industry or water user 

needs a discharge of 100 gallons per acre per day to operate 

at full capacity and has no facilities for impoundment. This 

user would have been able to operate fully only about 50 

percent of the time during the growing seasons indicated if 

the watershed had remained in its pre-treatment condition. 

As a result of the clearcant treatment, it would have been able 

to operate fully 76 percent of the time. This advantage will 

diminish year by year as regrowth occurs. 

The general increase in flow, the considerable augmentation 

of low flow, the relatively smaller increase in high flow, and 

the relation of a;hese egects to severity of greatmeat are all 

readily apparent in the flow-duration curves of the four 

treated watersheds for two growit~g seasons, 1959 and 1960 

(fig. 2 1 ) . These were the two growing seasons immediately 

Figure 2 1.---Growing season ifflow-duration cumes 

for the fou aeated WBtersheds in 1959 and 1960, 

PERGEMTAGE OF TIME FLOW IS EQUALED OR EXCEEDED 

- MEWSURED ---- PREDICTED 
of precipirarion on the Clearcut watersha 

3-season mean 

3-year mean 

*statistically signif icant at 5-percent level. 

after completion of logging for all watersheds except the 

Commercial Clearcut; for the three watersheds, these are 

probably the years of maximum effect. 

Run08 as a Percent of Precipitation 

One interesting and often computed characteristic of a 

watershed is runoff as a percent of precipitation. Because the 

Clearcut treatment had considerable effect on stream discharge, it is not surprising that runoff as a percent of precipitation also changed. An analysis made on this characteristic 

showed, as expected, that the growing season changes were 

considerably larger than changes for the year as a whole 

(table 12). 

As for effects of the other treatments on runoff as a percent 

of precipitation, fbr the water-year the only change measured 

as a result of partial cutting was an increase from 43 to 47 

percent on the Diameter Limit Watershed. In the growing 

season, increases from 41 to 42 percent and from 12 to 18 

percent were measured in 19 5 8 and 19 5 9, respectively. The 

Extensive Selection Watershed showed an increase from I 5 to 

20 percent in 1919. No change was noted on the Intensive 

Selection Watershed, 
WOJJ parpnls sr Ouasan~~y pue %ur~2n~ $0 spoqlaur ure2Ja3 

yl!h 3uaura8eukur jo a663 uahrz -i Y~TYM U! sluau~aiuiue~~e 
1 11e LIlllltilCb -3LskbdU usg ksg \wil% &g1186&~ 1~ Gaauwaa v wakbaalba ,/ 

show a partial picture of operations to date (table 13 ) . These 

data alone are not sufficient for evaluating the different treatments because the study has not been under way long enough. 

Fortunately records are available from treatment replicates 

on the ocher areas, some of which were placed under management more than 10 years ago. A few involve not only the 

first cutting in unmanaged stands but a second cutting as 

well. A synthesis of the watershed data and the results from 

other compartments, along with available information on 

timber growth and quality from study plots, provides a basis 

for comparing the four treatments. 

For the first cutting, the Clearcut generally showed the 

greatest net return per acre because of heavy removal; and 

the Diameter Limit cut showed the greatest net return per 

M b.m. removed. This last was followed closely, and occasionally preceded, by the Extensive Selection cutting, depending 

on the nature of the stand. These latter two programs were 

concerned only with sawlogs; trees too small to produce 

sawlogs were ignored. The ~Atensive Selection program generalily returned the least net income per acre and per M b.me 

on the first cutting because of the concentrated effort to 

remove Door trees above 5-0 inches d.b,h, Also, more monev A 

was expended on cultural work and after-logging care. 

In general, from all replications, the first cutting in all 

practices paid the logging costs and some stumpage. This was 

not true for the Intensive Selection Watershed, Here the verv 

light cutting did not compensate for the road and bridge 

costs. These were first-cutting comparisons only and did not 

reflect returns from long- term management. 

Discussion sf Resu 

Results of this study add to the slowly accumulating fund 

of knowledge about the forest's influence on streamflow. For 

years Psrested watersheds, much like those of the Fernow, 

have been studied in several Eastern States and many Western 

States. The first study in the United States, at Wagon Wheel 

Gap, Colorado, dates back to 191 0. In the East, the center of 

research has been the Coweeta Watersheds in western North 

Cardina, which have been studied since 1934. In all, about 

60 experimental watersheds in the East, and around the same 
number in the West, currently are being studied by U.S. 

Forest Smvice Experiment Stations* 

To this research must be added a growing list of soilmoisture studies in which water use by forest trees is calculated by periodic soil-moisture and rainfall measurements. 

We would like to relate the Fernow results to previous 

research. However, most of the published findings suggest 

that climatic, edaphic, and topographic conditions of other 

studies are quite different from those on the Fernow. Nor are 

surlicient data published to permit quantitative evaluation 

of these difierences; accordingly, the Fernow findings cannot 

be correlated with those from other experimental watersheds. 

About all that can be said here is to point out possible reasons 

for bro;ed agreements or differences, 

~oweverrthe Fernow research cannot be dissociated from 

watershed research done or being done in other places. For 

that reason, some of the other watershed research is reviewed 

briefly in the Appendix. 

Water Qzlality 

The fact that poorly planned logging operations play havoc 

with water quality has been well demonstrated. This study 

has shown that, at least on areas comparable to the Fernow, 

care in logging can prevent most of the turbidity that results 

from logging. This fact has also been demonstrated on the 

Fraser Experimental Forest in Colorado. In most cases, a 

planned road system for timber harvest and methods of 

operation that protect the water resource will not cause 

appreciable increases in logging costs. Fernow records show 

chat costs can often be reduced with these timber practices 

as compared with those of an unplanned "logger's choice" 

operation (Hutnik and Weitzman, 19 $7). In many locations, 

the greatest need is for an education and extension program 

to show operators how they can log more eaciently and at 

the same time conduct an operation that will conserve the 

water resource. 

On the Fernow "logger's choice" watershed, erosion and 

stream turbidity rapidly diminished after logging was completed. This points up the fact that, for water-quality, afterlogging care cannot be substituted for proper location of 

roads and good road drainage during the operation itself. 

The importance of the research results on the other waterquality characteristics studied--pH, alkalinity, temperature 
bekore any recommendations tor application can be made. 

However, it can be stated that under some conditions a clearcutting practice may result in increases in maximum water 

temperatures detrimental to trout. 

Water Sapply 

OP-a tlke Fernow, forest cutting resulted in an increase in 

streamflow; the increase was more or less in proportion to the 

severity of the cutting. The amount of the increase was considerable, ranging up to 5 inches on the Clearcut Watershed 

the first year after completion of the logging operation. 

First -year increases obtained f rom other heavily cut-over 

watersheds ranged from 17 and 15 inches at owee eta to 4.2 

and 1.4 inches at Fraser and Wagon Wheel Gap, Colorado, 

and 3.j inches at Kamabuti, Japan. 

Usually the results of treatment are more pronounced in 

well-watered areas, such as the Fernow, ~oweGa Hydrologic 

Laboratory in North Carolina, and Kamabuti, Japan. Areas 

of low precipitation are likely to show less effect, such as 

Wagon Wheel Gap in Colorado and Sierra Ancha Experimental Forest in Arizona, Treatment efiects of considerable 

magnitude at Fraser and on the White River Watershed, 

Colorado, where most of the precipitation comes as snow, may 

likely be due to a combination of reduced interception and 

transpiration following killing of the conifers. 

The concept of potential evapotranspiration (Thornthwaite and Mather, 191 y) helps to explain these results. 

Potelltial evapotranspiration is the amount of water that is 

evaporated and transpired under a given set of climatic conditions when the moisture supply is unlimited. When potential evapotranspiration far exceeds the water supply available 

from precipitation and soil-moisture storage, a partial reduction in evapotranspiration by removal of vegetation cannot 

be expected to have lgluch eeect on streamflow, When the 

supply exceeds potential evapotranspiration and a water 

surplus is available for streamflow, any reduction in the 

amount of evapotranspiration should increase the surplus. 

On the Fernow, most of the increase came in the May-toOctober period; effects of treatment were not regularly 

shown in May and June but were generally strong in the 

July-to-October period: The July - to-Sep tember increases 

can be explained as the direct result of decreased transpiration 
in those months. The October increases are associated with 

the effect of treatment on soil-moisture recharge: this can 

be considered a delayed eiTect of decreased transpiration in 

the preceding growing season. Increases in streamflow as a 

result of lower requirements for soil-moisture recharge often 

occurred in November and sometimes in December, 

The timing of increases resulting f ram vegetation changes 

is not the same in all areas. In areas where the greatest effect 

is upon snow storage and melt, such as at Fraser, the increases 

will be expected to show in the spring melt period. Growing 

season increases are usually signiffcarat only in regions haying 

considerable growing season precipitation, such as the 

Fernow, Coweeta, and Kamabuti. Often, much of the effect 

is shown in the soil-moisture recharge period. Depending on 

climate, soil depth, and other factors, there are often extreme 

differences in the time of year that recharge starts and in the 

duration of the period. 

On the Fernow, with about 60 inches annual precipitation, 

recharge is apparently accomplished earlier than at Coshocton, Ohio, less than 1 TO miles away, with about 40 inches 

of precipitation. Streamnow changes at Coshocton were 

much lager in the year than those on the Fernow. Maximum 

increases on some of the Coweeta watersheds were in the 

November- to-February period. This fact calls for an explanation that a detailed study of the soil-moisture regime and 

precipitation record might supply. 

In areas with relatively low growing-season precipi~ation 

and cold winters, differences in fall soil-moisture storage due 

to differences in growing-season transpiration may not affect 

streamflow until the following spring-melt period. As evidence of this, m index of antecedent soil-moisture is often 

used to improve water-yield predictions based on snow 

surveys. Thus part of the Fraser streamflow increases, though - 

registered in the spring, may in some years be due to reduction 

of transpiration the previous summer. Certainly in areas of 

very low growing-season rainfall, manipulating vegetation 

cannot be expected to provide much in the way of growingseason ~acreases. 

On the Fernow and many of the other study areas discussed, it should be stressed that the forest floor was to a large 

extent maintained intact* In treatments where the forest door 

is severely disturbed, results are likely to be much different, 

e.g., heavy surface runoff during storm periods and a decrease 

rather than an increase in discharge in low-flow periods. 
cutting will result in an increase in streamflow, watershed 

foresters may wish to put these results into practice. However, knowledge is still too meager to prescribe a specific 

treatment for a watershed area and to confidently predict - - 

the amount and timing of the increase. 

One reason for this is the wide variety of conditions on 

different watersheds that affect the results of treatment, 

These include amount and time distribution of precipitation, 

temperature, soil depths, soil-moisture storage capacities, 

vegetation, and the like. Also, even on the same watershed, 

weather varies from year to year and this has a bearing on any 

treatment effect obtained. 

Another question with respect to putting results into practice is the more or less transitory effect of forest cutting. The 

Fernow studies are not far enough along to determine much 

about the duration of stareamflow increases obtained; some of 

the Goweeta studies show more in this respect (Kovner, 

19 5 6) . The shallow rooting of the volunteer herbaceous vegetation on the Fernow Clearcut Watershed helps to explain 

why increased streamflow is still measured after an almost 

complete vegetative cover has been reestablished. 

Even with the present limited knowledge, however, the 

wateqshed forester should be able to recommend a treatment 

to influence water yields in many areas. And he should be able 

to predict the direction and general magnitude of resulting 

changes in streamflow. For a more or less permanent increase 

in now, the recommended practice would probably be one of 

heavy cutting on relatively small portions of the watershed 

in successive increments spread over a number of years. A 

hypothetical example of such a treatment is given in the 

Appendix. Other possibilities include the conversion from 

forest to grass or other vegetation types. 

Flood Flows 

On the Fernow, rhe effect of heavy forest cutting on high 

flows was variable, depending upon presence or absence of 

snow, antecedent soil-moisture, and probably other factors. 

It is clear, however, taking the Fernow results and reviewing other research, that building up or preserving fullystocked stands will generally be a benefit to flood control in 

the growing season and in the fall recharge period. 

In the dormant season, after completion of the fall re- 
charge period, the eifect is not usually very great. Under 

certain conditions heavy cutting may result in decreased 

flows, as has been described. Somewhat the same results were 

noted in the investigations at Fraser and in the Harz Mountains in Germany, 

In the region where the Fernow Experimental Forest is 

located, flood occurrence is greater in the dormant season than 

in the growing season. At the gaging station on the Cheat 

River near Parsons, West Virginia, 4 miles from the Fernow 

Experimental watersheds, there have been 13 5 occurrences 

of discharge above a base of about 10,000 c.f.s. (14 c.s.m) 

skce a9 a 3. Of these, 4 02 occurred il.9 the dormant season and 

only 3 3 in the growing season.:' 

Again, it must be pointed out that none of the Fernow 

treatments resulted in serious disturbance of the forest jtlloor 

except on limited areas of skidroads. If the forest floor had 

been severely disturbed much greater changes in high Bows 

could have been expected. 

Timber Values 

In the management of forest lands, many uses must be 

considered. In research on the Fernow, water and timber are 

the two main uses being studied. In recommending treatments to be applied to watershed lands, the impact upon 

values from timber growth and harvest cannot be ignored. 

Generally, heavy cuttings and low stand densities, while prescribed to obtain increases in water yield, might result in a 

decrease in timber growth and yields. And high stand densities, while prescribed for reduction of summer flood flows, 

probably would result in greater growth rates. However, to 

utilize this growth and at the same time maintain dense stands 

for maximum flood protection would necessitate light and 

frequent harvests. Such management is generally not very 

profitable under present cost -and-re turn conditions. Economic evaluations must be made for individual areas in the 

light of specific physical and economic conditions prevailing 

there, 

When we look to the future aid examine the four treatments in terms of returns from continued management, we 

envision a financial situation dieerent from the one defined 

by cost-and-return data from the first cutting. To do this, 

"ata supplied by U.S. Geological Survey, Cllarleston, West Virginia. 
we IlIlUSL UPaW UpVIP UUJ. fiIHUWlCU&G WL 4t8lBU U&YGAUYlbl&llAL Ill 

relation to the management goals defined for. each of the 

treatments, 

We can expect the net return from the Extensive Selection 

Watersbed to increase for several cuttings. Roads have been 

constructed and the most costly cultural work has been done. 

Considering the productivity of the sites in this watershed, 

the 10-year cutting should finally level off at an estimated 

4 M b.m. per acre with a high proportion of the volume in 

desirable species and good quality logs. 

Estimating future returns from the Diameter Limit Watershed is more of a problem. Growth of lnerchantable trees in 

this watershed is expected to be less than for Extensive Selection because mortality is higher with the 20-year cutting 

cycle and the lower level of cultural treatments leaves many 

small culls to occupy growing space. Also, the designation of 

a diameter limit for cutting allows no leeway to cut low-vigor 

trees below this limit or to leave high vigor ones above it. We 

can expect less consist en^ volumes in succeeding cuttings 

because the method used will not exercise control over spacing 

and size-distribution of the trees. The unit value of products 

from this watershed will probably be less than for the Extensive Selection Watershed because there is no opportunity, 

without marking of individual trees for cutting, to up-grade 

the stand by favoring trees of desirable species and high 

quality potential. As compared to Extensive Selection, forestry costs for cultural treatment and marking of trees, etc., 

will be lower. All things considered, it is likely that this practice will be financially feasible. 

The Intensive Selection Watershed will show a future increase in volume harvested and a big increase in product value. 

However, costs of marking, cultural treatment, and probably 

logging will be higher than for the other areas. The higher 

cost of logging will be due to the following factors: the special care 'taken to protect water quality; the small volume 

cut per acre because of the short cutting cycle; and the higher 

cost per thousand of removing some trees below sawlog size. 

The 5-year cutting should eventually build up to about 2 

M b.m. per acre which would make this a marginal operation 

under present market conditions when both forestry costs 

and logging costs are considered. Generally, returns are not 

likely to balance costs on many intensively-managed areas cut 

every I years unless the stands are very easily accessible and 

on very productive sites. There is little question tha-t this 
management practice would be profitable if the cutting cycle 

were lengthened. 

The Glearcut Watershed will not produce another cutting 

equal in value to the one just made for another 60 to 80 years. 

It is even doubtful if a small-products operation for materials 

such as pulpwood can be made on a break-even basis in less 

than 2 5 years. 

In discussing the relative prohtability of the different treatments, the assumption was made that site productivity, or site 

quality, is about the same on all the watersheds. Though not 

strictly true, they are close enough to make this generalization. In addition, the assumption was made that all areas are 

easily and equally accessible. Actually, the Clearcut Watershed is less accessible than the others. 

Forest Gafr~e 

Deer browse and dea use have been measured for 10 years 

on compartments managed like the watersheds.7We no 

firm comparisons can as yet be made between management 

programs in respect to these factors, a tentative pattern is 

emerging. 

After cutting, all four practices produce browse and kover. 

The Clearcut produces more of each for about 10 to 15 years. 

After this period, both browse and cover become progressively 

more scarce on clearcut areas. As far as deer are concerned, 

the developing even-aged, large-sapling, and pole stands provide neither su6cient cover nor browse. 

The Intensive Selection program, with the short cutting 

cycle, probably provides the most constant supply of deer 

browse and desirable cover, In the Diameter Limit the 20- 

year cycle between cuttings is so long that the young vegetation that follows treatment grows beyond the deer-utilization 

stage before the next cutting. 

No studies have as yet been made on the Fernow on the 

effect of the management programs on other game. However, 

continuing discussions of game habitat with game technicians 

and knowledge of forestry environment developing under 

these programs enable us to make a surmise on the subject. 

The Clear cutting eliminates such mast as acorns, hickory 

~~uts, and beech nuts for a long time. Squirrels are practically 

Cooperative study with the Division of Game ancI Fish, West Virginia Department of Natural Resources. 
  

up to large sapling size, they provide cover for grouse. New 

clearcuts also provide berries as well as weed and shrub seeds, 

which grouse feed on. Apparently grouse, like deer, prefer 

new clearcuts but later on find them unattractive, 

Both selection programs provide for maintaining a large 

part of their canopy in big vigorous trees. As a consequence, 

they further the production of large mast crops, which favor 

such mast-eating game as squirrel, turkeys, and bear, and to a 

lesser extent deer and grouse, 

The current studies on the Fernow Experimental Forest 

will be continued to: ( 1 ) measure changes in vegetation f ollowing the treatments, (2) measure the trend of treatment 

effects on streamnow quantity and quality, and (3) measure 

the effects of successive cuttings on the partially cut watersheds, 

A large mass of data has been accumulated in this investigation. This report shows how that data was analyzed and 

interpreted. Much more knowledge about forest watershed 

hydrology doubtlessly can be gained from this data, and 

further opportunities for fruitful analysis of the data already 

collected will be explored. 

In this experiment, and in other research, much has been 

learned about the effect of digerent forest treatments 01131 

streamflow, Much more research is needed to broaden our 

present knowledge and to improve management on watersheds where physical conditions vary widely and where objectives of management difier. 

More basic research is needed to relate results to primary 

causes. To a considerable extent, results of this type of 

research are generally applicable and not limited to the region 

or locality in which the studies are conducted. 

Much could be gained from a comprehensive study of 

the many investigations already completed in many regions 

of the United States and in other countries. Many data have 

been collected which should be subjected to intensive analysis. 

Correlation of various types of sgudies in various places should 

reveal the underlying reasons for differences in water quality 

resulu, differences in quantity and timing of water yield, and 

SO on* 

Fuller attainment of benefits from research already done 

and new research, both basic and applied, may be expected 
to greatly advance forest watershed management in the next 

decade or two. The forest manager should then be able to 

prescribe sound forest watershed management practices and 

predict results in quantitative as well as qualitative terms. 

After a (;-year calibration, four watersheds on the Fernow 

Experimental Forest were logged in 19 5 7- 1 8. Treatments 

ranged from a commercial clearcutting with unplanned logger's choice skidroads to a fight selection cutting with planned 

skidroads on moderate grades. For the most part, the treatments did not seriously disturb the forest floor. 

Treatments resulted in an increase in annual flow, ranging 

up to I area-inches on the Clearcut Watershed the year after 

treatment. Flow increases fell into a logical pattern in relation 

to volume cut, Most of the flow increase cme into the growing season. In the 6-month period from May to October 19 I 9, 

for example, increases were 3.0, 1.8, 1.4, and 0.3 area-inches 

for per-acre cuttings of 8.5, 4.2, 3.7, and 1.7 M b.m., respectivel ye 

Low flows were augmented, especially for the two heavilycut watersheds. Effect on high flows was variable. On the 

Clearcut Watershed some storm-period discharges in the 

growing season were more than doubled as a result of treatment and some snowmelt flows were reduced* 

Care in the logging operation was clearly reflected in water 

quality. Maximum turbidities ranged from 5 6,000 p.p.m. on 

the watershed with unplanned and undrained skidroads to 25 

on the watershed with carefully planned skidroads. Even on 

the two watersheds with unplanned skidroads, turbidities were 

high only during and immediately after the logging operation. 

Egects of treatment are diminishing with time. Measurements on the watersheds are continuing in an effort to determine the duration of changes due to treatment and the eIfect 

of succeeding harvests on the partially cut watersheds. 

Literature References 

Bates, C. G., and Henry, A. J. 

1928. FOREST AND STREAMFLOW EXPERIMENT AT WAGON WHEEL GAP, 

COLO. U.S. Weather Bur. Monthly 

Weather Rev. Sup. 30. 79 pp., illus. 

Biswell, H. H., and Schultz, A. M. 

1958. EFFECTS OF VEGETATION REMOVAL ON SPRING FLOW. Calif. Fish 

and Game 44 (3) : 211-230, illus. 

Burger, Hans. 

1943. [THE WATER ECONOMY IN THE 

SPERBEL AND RAPPEN WATERSHEDS 

FROM 1927-28 to 1941-42.) Mitt. 

Schweiz. Anstalt f. Florstl. Versuchsw. 

23 (1). [In German. U.S. Forest Serv. 

Div. Forest Influences Translation 368. 

39 pp. June 1945.) 

Delfs, J., and others. 

1958. [THE INFLUENCE OF FORESTS 

AND CLEAR FELLINGS ON RUNOFF, THE 

WATER ECONOMY AND SOIL EROSION.] 

Aus dem Walde, Hannover, No. 3. 

223 pp. + 105-pp. sup., illus. [In 

German. English abstract in Forestry 

Abstracts 20 (2) : 181, 1959.3 

Dils, Robert E. 

1957. A GUIDE TO THE COWEETA HYDROLOGIC LABORATORY. U.S. Forest 

Serv. Southeast. Forest Expt. Sta. 40 

pp., illus. 

Ellis, M. M., Westfall, B. A., and Ellis, 

Marion D. 

1948. DETERMINATION OF WATER 

QUALITY, U.S. Fish and Wildlife Serv. 

Res. Rpt. 9. 122 pp., illus. 

Engler, Arnold. 

1919. [RESEARCHES UPON THE INFLUENCE OF THE FOREST UPON THE 

DISPOSITION OF TERRESTRIAL AND ATMOSPHERIC WATERS.) Mitt. Schweiz. 

Centralanst. f. forstl. Versuchsw. [In 

'German. U.S. Forest Serv. Div. Silvics 

Translation 100; 378 pp., illus.) 

Fenneman, N. M. 

1938. PHYSIOGRAPHY OF EASTERN 

UNITED STATES. 714 pp., illus. New 

York. 

Goodell, Bertram C. 

1958. A PRELIMINARY REPORT ON THE 

FIRST YEAR'S EFFECTS OF TIMBER HARVESTING ON WATER YIELD FROM A 

COLORADO WATERSHED. U.S. Forest 

Serv. Rocky Mt. Forest and Range 

Expt. Sta.. Sta. Paper 36. 12 pp., illus. 

Harrold, L. L., Brakensiek, D. L., McGuinness, J. L., and others. 

1962. INFLUENCE OF LAND USE AND 

TREATMENT ON THE HYDROLOGY OF 

SMALL WATERSHEDS AT COSHOCTON, 

OHIO, 1938-1957. U.S. Dept. Agr. 

Tech. Bul. 1256. 194 pp., illus. 

Hertzler, R. A. 

1938. DETERMINATION OF A FORMULA 

FOR THE 120-DEGREE V-NOTCH WEIR. 

Civil Engin. 8: 756-757, illus. 

Hutnik, Russell J., and Weitzman, 

Sidney. 

1957. GENTLE-GRADE ROADS MEAN 

FASTER SKIDDING. U.S. Forest Serv. 

Northeast. Forest Expt. Sta. Forest 

Res. Note 71. 3 pp. 

Koshi, Paul T. 

1959. SOIL-MOISTURE TRENDS UNDER 

VARYING DENSITIES OF OAK OVERSTORY. U.S. Forest Serv. South. Forest 

Expt. Sta. Occas. Paper 167. 12 pp., 

illus. 

Kovner, Jacob L. 

195 6. EVAPOTRANSPIRATION AND WATER YIELDS FOLLOWING FOREST CUTTING AND NATURAL REGROWTH. SOC. 

Amer. Foresters Proc. 1956: 106-110, 

illus. 

Linsley, Ray K. Jr., Kohler, Max A., 

and Paulhus, Joseph L. H. 

1949. APPLIED HYDROLOGY. 689 pp., 

illus. New York. 

Love, L. D. 

1955. THE EFFECT ON STREAMFLOW 

OF THE KILLING OF SPRUCE AND PINE 

BY THE ENGELMANN SPRUCE BEETLE. 

Trans. Amer. Geophys. Union 36: 

113-118, illus. 

Maruyama, I., and Inose, T. 

1952. EXPERIMENT OF FOREST INFLUENCES UPON STREAMFLOW AT KAMABUTI. Govt. Forest Expt. Sta. Bul. 53. 

44 pp. Meguro, Tokyo, Japan. 

Metz, Louis J., and Douglass, James E. 

1959. SOIL MOISTURE DEPLETION UNDER SEVERAL PIEDMONT COVER TYPES. 

U.S. Dept. Agr. Tech. Bul. 1207. 23 

pp., illus. 

Moyle, Ralph C., and Zahner, Robert. 

1954. SOIL MOISTURE AS AFFECTED BY 

STAND CONDITIONS. U.S. Forest Serv. 

South. Forest Expt. Sta. Occas. Paper 

137. 14 pp., illus. 
1960. METHODS FOR COLLECTION AND 

ANALYSIS OF WATER SAMPLES. U.S, 

Geol. Survey Water-Supply Paper 

1454. 301 pp., illus. 

Reinhart, K. G. 

1958. CALIBRATION OF FIVE SMALL 

FORESTED WATERSHEDS. Trans. Amer. 

Geophys. Union 38 : 933-936, illus. 

Rich, Lowell R. 

1959. WATERSHED MANAGEMENT RESEARCH IN THE MIXED CONIFER TYPE. 

In WATERSHED MANAGEMENT RESEARCH IN ARIZONA, PROGRESS REPORT 1959: 7-16, illus. U.S. Forest 

Serv. Rocky Mt. Forest and Range 

Expt. Sta. 

Rocky Mountain Forest and Range Experiment Station. 

1959. ANNUAL REPORT for 1958. 129 

pp., illus. U.S. Forest Serv. Rocky Mt. 

Forest and Range Expt. Sta. 

Rothacher, Jack S. 

1953. WHITE HOLLOW WATERSHED 

MANAGEMENT: 15 YEARS OF PROGRESS 

IN CHARACTER OF FOREST, RUNOFF, 

AND STREAMFLOW. Jour. Forestry 5 1 : 

731-738, illus. 

Searcy, James K. 

1959. FLOW-DURATION CURVES. U.5. 

Geol. Survey Water-Supply Paper 1542 

A. 33 pp., illus. 

1956. STATISTICAL METHODS. kd. 5, 

534 pp., illus. Ames, Iowa. 

Southeastern Forest Experiment Station. 

1961. ANNUAL REPORT for 1960. 74 

pp., illus. U.S. Forest Serv. Southeast. 

Forest Expt. Sta. 

Tennessee Valley Authority. 

1955. INFLUENCES OF REFORESTATION 

AND EROSION CONTROL UPON THE 

HYDROLOGY OF THE PINE TREE 

BRANCH WATERSHED, 1941 to 1950. 

Div. Water Control Planning, Hydraulic Data Branch, Tech. Monog. 

86. 95 pp., illus. 

Thornthwaite, C. W., and Mather, J. R. 

195 5. THE WATER BALANCE. Drexel 

Inst. Tech. Climatology Lab. Pub. 

Climatology VIII, No. 1. 104 pp., 

illus. 

Trimble, George R. Jr., and Sartz, 

Richard S. 

1957. HOW FAR FROM A STREAM 

SHOULD A LOGGING ROAD BE LOCATED ? 

Jour. Forestry 55 : 339-341, illus. 

Wilm, H. G., and Dunford, E. G. 

1948. EFFECT OF TIMBER CUTTING ON 

WATER AVAILABLE FOR STREAM FLOW 

FROM A LODGEPOLE PINE FOREST. U.S. 

Dept. Agr. Tech. Bul. 968. 43 pp., 

illus. 
Appendix 

I. CLIMATIC DATA 

Precipitation and temperature records for the experimental watersheds 

are shown in tables 14, 15, 16, by month, season, and year in the study 

period. Table 17 shows streamflow of the Control Watershed. 

11. INSTRUMENTATION AND MEASUREMENT 

Stream discharge.-The gaging stations on the five watersheds are 

120-degree V-notch weirs with FW-1 water level recorders installed in 

concrete-block gage houses. In construction of the concrete weir cutoff 

walls every effort was made to extend the wall down to bedrock or impervious subsoil so that all flow from the watershed would be over the weir 

blade. The weir blades are constructed of 3% x 3% inch angle iron and 

are bolted to the concrete wall. The upper edge of each blade is bevelled 

to a knife edge at a 45-degree angle. The notch is 2 feet deep. 

The recorder is attached by perforated tape to a float in the stilling well 

below the gage house. A pen arm is actuated by the tape and records a 

continuous tracing on a drum-chart driven by an 8-day clock. The pen arm 

shows height of water surface above the low point in the V-notch. 

A rating table, showing quantity of flow corresponding to any stated 

depth, was prepared for each weir. The rating was based upon the formula 

determined by Hertzler (1938) for the prototype of these weirs. 

The formula is: Q=4.43H2.449, in which Q is discharge in c.f.s. and 

H is head (or height of water above low point in notch) in feet. For low 

flows, the discharge was collected over a measured time period and weighed 

or measured volumetrically. Based on these measurements, the rating table 

determined from the above formula was adjusted for the individual weir 

as necessary. Adjustments were made up to heads of about 0.2 foot for 

three weirs; the rating table was applicable without adjustment for the 

other two weirs. 

From the charts and the rating tables, mean daily flow in c.s.m. was 

computed and tabulated. Then compilations were made of flows by month, 

season, and year in area inches. Other tabulations were made from the 

charts for special purposes, such as discharge during storm periods. 

Precipitation.-At the start of the study, 15 standard precipitation 

gages and 3 weighing-recording gages were installed on the 5 watersheds. 

These were distributed more or less uniformly over the area and located to 

sample various topographic positions. After several years of operation, 

analyses were made to determine whether some gages could be dropped 

without ap reciably affecting the amount of catch. As a result, the number 

of standar i' gages was reduced to nine. 

Amount of catch is determined by the standard gages. The record of 

the recording gages is used to break down amounts measured in the standard gages by storm, by day, or for studies involving intensities. 

Precipitation on each watershed was computed by storm or by month 

by weighting the catches in the individual gages by the Thiessen polygon 
Table 14.-Precipitation on the Fernow watersheds, by month, season, and year, in inches 

(~i~bres are averages for the five watersheds) 

Month 

May 5.40 6.00 6.54 3.61 3.31 8.91 3.81 5.45 4.98 5.33 

June 10.70 4.03 4.22 3.62 5.48 6.76 8.13 6.90 2.92 5.86 

July 3.18 3.73 6.63 6.28 4.65 7.48 3.80 11.96 7.10 6.09 

August 2.01 2.44 7.14 10.68 9.05 6.74 1.55 8.62 4.95 5.91 

September 3.09 3.63 1.72 2.34 1.69 3.98 2.54 3.02 1.40 2.60 

October 2.09 1.47 1.45 10.78 3.95 2.84 5.59 1.65 6.99 4.09 

May-Oct total 26.47 21.30 27.70 37.31 28.13 36.71 25.42 37.60 28.34 29.89 

November 4.93 2.90 2.08 2.74 3.65 2.70 2.28 3.58 5.33 3.35 

December 7.21 4.18 4.62 5.57 2.60 7.02 6.51 1.85 5.59 5.02 

January 8.85 6.68 5.29 4.04 5.32 6.72 4.70 6.18 5.69 5.94 

February 1.30 4.17 3.10 5.78 8.16 7.69 4.70 3.59 5.06 4.84 

March 4.76 6.13 6.55 7.34 7.35 3.04 4.54 4.55 4.04 5.37 

April 5.20 5.15 3.29 3.42 3.94 4.97 6.65 5.36 4.27 4.69 

Nov-Apr tot a1 32.25 29.21 24.93 28.89 31.02 32.14 29.38 25.11 29.98 29.21 

Total for year 58.72 50.51 52.63 66.20 59.15 68.85 54.80 62.71 58.32 59.10 

9-yea 

me an 

Water-year 

1951-52 1952-53 1953-54 1954-55 1955-56 1956-57 1957-58 1958-59 1959-60 
Table 15.-Mean air temperature on the Fernow Experimental Forest by month, season, and year, in OF. 

*~ean of 8 years of record. 

Month 

method (Linsley et al., 1949). Totals by season and year were then 

tabulated for each watershed. 

Air= temperature and humidity.-A weather shelter is maintained near 

the center of the experimental area. It houses a recording hygrothermograph 

and maximum and minimum thermometers. This installation was serviced 

weekly. Tabulations of maximum, minimum, and mean temperature were 

prepared by day, month, and year. 

May -- 55 61 51 59 57 58 56 6 1 57* 

June -- 6 7 65 63 59 62 6 5 60 63 63* -- July 68 66 65 69 64 64 67 68 66* 

August 64 65 6 3 64 67 62 62 63 70 64 

September 58 57 58 60 59 54 60 58 65 59 

October 53 45 5 3 50 48 53 45 48 53 50 

Growingseason -- 60 6 1 59 60 59 59 59 6 3 60* 

me an 

November 33 40 42 37 36 39 41 41 38 39 

December 33 32 32 27 24 40 34 25 33 31 

January 34 34 30 25 24 26 24 26 32 28 

February 34 33 34 3 1 34 36 20 32 27 31 

March 36 38 35 40 36 38 33 36 24 35 

April 47 45 54 53 45 52 48 50 53 50 

Dormant - season 36 37 38 36 33 38 33 35 34 36 

me an 

Waterye a- -- 48 49 47 47 49 46 47 49 48* 

me an 

Water qzcaZity.-Water samples were obtained by hand sampling. The 

sample bottle or glass was dipped into the stream at the designated sampling 

point a short distance upstream from the weir. As the stream gradients were 

high and flow usually turbulent, this simple method provided a representative sample. 

When the sample was clear (that is, 5 turbidity units or less), the record' 

was made on the basis of observation. For turbidities between 5 and 25, 

the determination was made by reference to a series of standard suspensions 

in Nessler tubes prepared by the chemist of the West Virginia State Water 

Resources Commission. Turbidities above 25 were measured with a Jackson 

turbidimeter (Rainwater and Thatcher, 1960) . For some very turbid samples this method will not work; for these the 

9-year 

Water-year 

1951 

-52 

1952 

-53 

1953 

-54 

1954 

-55 

1956 

-57 

1955 

-56 

1957 

-58 

1958 

-59 

1959 

-60 
Table 16.-Mean maximum and mean minimum air temperatures on the Fernow 

Experimental Forest by month, season, and year, in OF. 

-- -- 77 59 76 56 75 55 78 61 71 57 73 55 74 59 77 58 75* 58 

72 55 74 55 72 55 71 58 74 59 69 55 71 53 72 55 81 60 73 56 

68 46 69 48 68 52 67 50 62 46 68 53 66 49 78 51 68 49 

64 42 57 33 66 41 58 41 57 39 61 45 53 37 58 38 64 42 60 40 

-- -- 70 49 72 51 68 50 69 51 67 50 68 50 68 49 74 52 69* 50 

42 24 50 31 53 30 45 29 45 27 48 28 50 31 51 31 49 28 48 29 

42 24 38 25 40 23 34 20 33 15 47 32 42 25 34 16 41 25 39 23 

43 25 42 26 38 21 34 16 31 17 35 18 32 17 35 17 39 24 37 20 

42 25 42 24 44 24 41 21 43 26 44 28 28 13 42 22 36 18 40 22 

45 27 47 29 45 24 51 28 47 26 47 30 39 33 48 25 34 14 45 26 

57 37 55 35 67 41 65 40 56 34 64 40 59 36 62 38 66 39 61 38 

Dormant - season 45 27 46 28 48 27 45 26 42 24 48 29 42 26 45 25 44 25 45 26 

-- -- 58 39 60 39 56 38 56 38 57 40 55 38 57 37 59 38 57* 38 

*Wan of 8 years of record. 
solid matter in a sample of measured volunle was filtered out, dried, and 

weighed to obtain suspended solids in parts per million. 

For pH determination, the Hellige color comparator was used. With 

this instrument, indicator dyes are added to a sample of the water (Ellis 

et al., 1948) and the resulting color is compared to standard colors on 

labeled discs. This method is not the most accurate. However, it was considered adequate for the purposes of this study because the waters being 

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all being made from one day's o eration by one observer. In this way 

personnel differences were largely e p. ~minated. 

For phenolphthalein alkalinity (hydroxide and normal carbonate alkalinity), phenolphthalein indicator solution was added to the water samples 

(Ellis et al., 1948). With the Fernow samples, no color resulted in this 

test and phenolphthalein alkalinity was always recorded as zero. 

Methyl orange alkalinity, or total alkalinity, was determined by adding 

methyl orange indicator to the solution and then titrating with N/50 

sulfuric acid (Ellis et al., 1948). The alkalinity in p.p.m. was determined 

from the amount of acid added. 

The specific conductance of water is a measure of its ability to carry an 

electric current; hence it is an indication of the ionic strength of the solution and a measure of the amount of dissolved minerals in the water. It is 

determined with a meter using the principle of the Wheatstone bridge 

and is recorded in micromhos per square centimeter. 

III. CALIBRATION AND ANALYSIS 

The control-watershed concept was used in this study to compensate as 

far as possible for climatic variation from year to year. One watershed 

(No. 4 in this instance) was used as a control for each of the other four 

watersheds. 

Prediction equations, computed from data of the 6 calibration years, 

are in the form of straight-line regressions; in most instances, very high 

correlation coefficients were obtained, indicating that the straight-line 

regressions are appropriate. For example, correlation coefficients for annual 

flow-of the watersheds to be treated and the Control were 0.996, 0.996, 

0.998, and 0.998 for Watersheds 1, 2, 3, and 5, respectively. 

In most analyses, the regressions were based on six observations (6 

years) ; put in another way, N equals 6. This was true even for the analyses 

of flow by months; there were, for example, six Julys in the 6-year calibration period. For high flows, some analyses considered the quantity of high 

flow in the year or season with an N of 6. Others treated individual storm 

flows as separate observations and the N's were larger; for example, 48 

calibration-period storms were used in several of the analyses. 

Analyses of water quality were handled somewhat differently. In the 

case of turbidity, the effects of treatment-and the differences between treatments-were of such magnitude that statistical tests of significance were 

considered unnecessary. For chemical tests and water temperature, comparison of paired observations by simple "t" tests was used. 

After treatment, the regression equations were used, along with measured 

values for the Control Watershed, to compute predicted values for the 

treated watershed. This prediction, of course, was the value that would be 

expected if the treatment were without effect. Measured and predicted 

values were then compared, the difference being an apparent treatment 

effect.. 

The difference between individual predicted and measured values was 

tested by computing the error of estimate for an individual value (Y) of 

the treated watershed (Snedecor, 1956). The example in table 18 shows 

how the prediction equation was computed and how an individual aftertreatment value was tested for significance. 
Table 18.-Sample computation: annual discharge-prediction equation for Clearcut Watershed 

and test for significance of increase in discharge in water-year 1958-59 

Reference: Snedecor, G. W. 1956. Statistical methods, 5th Ed., 534 pp. Iowa State College Press, Ames, Iowa. 

Calibration data 

Prediction equation 

(~traight~line rgression) 

A 

Y = 0.967X - 0.82 

A Y = Estimated flow of Clearcut 

Watershed, assuming no 

trea$ment. 

X = Measured flow of Control. 

n = 6 

- 

x = 24.52 

- 

y = 22.89 

Sx2 e 188.3947 

$ = 0.996 

s 2-0.398 

Y *X 

\ 

Water 

-year 

Test of significance 

- - x = X - x = 28.22 - 24.52 = 3.70 in which X is flow 

of Control in test year. 

x2 = (3.70)~ 13.6900 

2 2 

sy = SySx2 (1 + l/n + x /Sx2) = -398 (1 + l/n +[13.6900/188.3947] ) 

= 0,4935 

s - 0.4935 = 0.702 

- YA 

t = (Y-Y)/sy = 5.09/.702 = 7.25 

Detepmine probability by reference to graph of t over probability. 

Probability = 0.001 (The probability that an increase of this magnitude occurred by chance alone. This is a 

test for increase, and area under one end only 

of the probability curve is considered.) 

1951-52 25.95 24.40 

1952-53 18.02 

1953-54 17.93 ::::: 

1954-55 28.74 25.91 

1955-56 22.97 21.52 

1956-57 33.49 32.20 

Prediction for water-year 1958-59 

Measured flow of Control = 28.22 

area-inches . Measured flow of Clearcut = 31.56 

area-inches. 

Predicted flow of Clearcut = 

0.967 (28.22) - 0.82 = 26.47 

Increase in flow of Clearcut = 

31.56 - 26.47 = 5.09. 

Annual discharge, 

in area-inches 

Control 

Y 

Clearcut 

X 
ln ~rlr CX~LII~IC, LUC y~wvau~~l~y wa;r LUUA ~ULLU uo Y.VVL, L1l CLrlV "---. J 9 

the accepted level of significance was 0.05. Thus this analysis showed that 

there was a significant increase in annual flow in the 1958-59 water year 

on the Clearcut Watershed. 

Analysis of covariance has not been relied upon so far in this study even 

though it is often recommended in experiments of this type. In most cases, 

too few after-treatment observations were available for covariance analysis. 

In analyzing for treatment effects on individual storm flows, sufficient observations were available but variances in the calibration and treatment period 

were not homogeneous. Homogeneity of variance in both periods is a 

data were not analyzed by covariance. 

requisite for covariance analysis by usual methods; therefore the storm ire- ow 

The fact that variances before and after treatment are not homogeneous 

is not surprising: the watersheds were as near identical as could be when 

selected and as a result correlations in the calibration period were naturally 

high; treatment purposely resulted in differences between each treated 

watershed and the Control and resulted in poorer correlation in this period. 

When analyses were made at the close of the calibration period, it 

appeared that prediction equations for discharge by individual months were 

not precise enough to be used for deterniination of significance of treatment 

results. This was based upon an estimated 10 to 25 percent change in flow 

due to treatment. However, for many of the months after treatment, especially on the Commercial Clearcut Watershed, significant treatment effects 

were obtained. In many cases, the increase in flow resulting from treatment 

amounted to several hundred percent. 

IV. TREATMENT EFFECTS 

Water Qclality 

Tables 19 and 20 are given here as background information about the 

effects of treatment on certain chemical characteristics and on water temperature. The streams on the experimental watersheds are slightly acidic: 

Table 19.-Mean pH, alkalinity, and specific 

conductance of water. from experimental 

watershed, December 1957 to April 1960 

Specific conductance 

Watershed ~icromhos/cm2 

Commercial 

clearcut 6.4 9 38 

Diameter 6.1 6 25 limit 

Extensive 6.2 6 selection 24 

Intensive 6.1 6 16 selection 

Control 6.1 6 17 

pH 

Alkalinity 

(methyl orange) 

p.p.m. CaC03 
Table 20-Maximum, minimum, and mean 

water temperatures on the Control 

Watershed by month, in OF. 

'Averages for two years of record; May 

1958 through April 1960. 

Month 

watershed mean pH values ranged from 6.1 to 6.4. Alkalinities are very 

low; the water is essentially unbuffered. Specific conductances are also very 

low, indicating that there is little mineral matter dissolved in the water. 

As for water temperatures, maximums measured were not very high: mean 

maximum for July was only 63O F. The month with the lowest mean 

minimum temperature was March, with 35O F. (both of these means were 

based on only 2 years of record). 

Total Discharge 

May 54 47 50 

Jun 58 50 54 

Jul 63 54 58 

AUg 62 5 5 58 

S~P 64 52 58 

Oct 58 46 52 

Nov 50 42 46 

Dec 45 38 42 

Jan 44 3 8 41 

Feb 44 3 8 41 

Mar 44 35 40 

Apr 53 44 48 

Water-year 53 45 49 

Water temperature 

A graph was shown earlier to relate increase in flow, by seasons, to the 

amount of cut and cull in M b.m. per acre. Figure 22 shows a similar 

presentation based on basal area rather than M b.m. More complete tables 

showing effect of treatment on flow by individual months are presented 

here (tables 2 1 to 24). 

Maximum 

Low Flou! 

Results of an analysis of number of days of low flow below 0.05 c.s.m. 

(approximating 50 gallons per acre per day) were presented earlier. Table 

25 shows also the effect of treatment on number of days of flow below 

0.075 c.s.m. and 0.10 c.s.m. (75 and 100 gallons per acre per day). This 

table also shows the probabilities associated with the decreases. All changes 

are decreases in number of days of low flow (indicating an increase in 

quantity of flow due to treatment) and most are significant at the 5-percent level. 

Minimum Mean 
Table 21.-Increase in flow on Commercial Clearcut Watershed 

after start of logging, by month, in area-inches , 

*statistically significant at 5-percent level. 

' The probability that an increase of the magnitude given could have occurred by chance alone. 

Negative value indicates an apparent decrease. 

1957-58 

Month 

1958-59 

May 0.78 0.26 0.10 

Jun 1.37 -.02 -- 

Jul .18 .48* .01 

Aug .03 .03 .43 

Sep .oo .04 .15 

Oc t .06 .58* <.001 

Nov .13 .27* .01 

Dec 3.00 .54* .02 

Jan 1.98 .14 .22 

Fe b 1.83 .47* .O1 

Mar 4.10 .27 .10 

AP~ 5.46 -. 79 -- 

Probabil1ty1 

Probabillty 

1959-60 

Discharge Discharge 

May 3.00 0.09 0.30 

Jun 1.85 1.27* <.001 

Jul 3.99 1.60* .003 

Aug 3.83 1.141. .003 

Sep .09 .46* <.oo1 

Oc t .05 .16* .001 

Nov .56 .64* <.001 

De c 1.10 -.18 -- Jan 4.26 -. 11 - - 

Fe b 2.08 .22 .08 

Mar 2.78 .08 .35 

AP~ 2.78 -.17 -- 

1960-61 

pre - dlcted 

Pre - dicted 

ProbIn- ahllity 

crease 

Increase 

Discharge 

May 1.88 0.25 0.09 

Jun .32 .09 .31 

Jul .15 .58* .004 

Aug .14 .53* .02 

Sep .01 .16* .oo4 

Oc t .29 1.27* <.001 

Nov 1.51 .86* c.001 

De c 4.05 -.30 -- 

Jan 4.28 -.I6 -- 

Fe b 1.31 .20 .10 

Mar 4.24 .12 .27 

AP~ 3.36 -.I8 -- 

Probahil~ty 

Dlscharge 

Predicted 

May 3.10 0.00 -- Jun 1.05 .46* 0.02 

Jul .14 .22 .06 

Aug .34 .29 .08 

Se P .35 .?I* .oo1 

Oc t .08 .16* .002 

-- -- - - -- -- -- -- -- -- -- -- -- 

-- -- -- -- -- -- - - -- -- -- - - -- 

Predicted 

- 

Increase 

Increase 
Table 22.-Increase in flow on Diameter Limit Watershed 

after start of logging, by month, in area-inches 

* 

Statistically significant at 5-percent level. 

I ' The probability that an increase of the magnitude given could have occurred by chance alone. 

Negative value indicates an apparent decrease. 

1958-59 1960-61 

Month 

1959-60 

Month Month 

- - -- -- -- Jun 2.22 0.27* 0.04 

Jul 4.30 .24 .24 

AUg 4.21 .47* .01 

Sep .ll .28* <.001 

Oct .05 .12* .01 

Nov .58 .31* .03 

De c 1.09 -.03 - - Jan 4.95 -. 01 - - 

Fe b 2.47 .05 .35 

Mar 3.06 .OO - - 

AP~ 3.17 .02 .46 

May 3.72 0.17 0.10 

Jun 1.24 .17 .12 

Jul .17 .21 .07 

AUg .38 .07 .28 

Sep .39 .20* <.001 

Oct .08 .05 .08 

-- -- -- - - 

- - -- -- -- 

-- -- - - -- 

-- -- - - -- -- -- -- - - 

- - - - - - -- 

Probability 

May 2.41 0.42* 0.01 

Jun .34 .13 .18 

Jul .18 .44* .01 

AUg .17 .30* .02 

Se P .03 .lo* <.ool 

Oct .32 .40* <.001 

Nov 1.85 .52* .01 

Dec 4.65 -.38 - - 

Jan 4.98 -. 22 -- 

Fe b 1.62 .27 .052 

Mar 4.89 .37* .01 

AP~ 3.79 -. 20 - - 

Probability 

Discharge Discharge Prob - ability Predicted 

Discharge 

Increase Predicted Increase Predicted Increase 
Table 23.Increase in flow on Extensive Selection Watershed 

after start of logging, by month, in area-inches 

5.43 2 -0.37 .23 .21 .15 .50 .14 0.23 

-21 .06* 0.03 .05 .06* .70 .04 .28 

Oct .ll .02 .41 Oct .40 .58* .001 Oct .15 .04 .33 

Month 

Nov .91 .16 .18 

Dec 1.61 -.25 - - Jan 5.54 -.I8 - - 

* Increase is statistically significant at the 5-percent level. 

-- -- -- - - 

-- -- -- -- -- -- - - -- 

Discharge 

Fe b 2.85 .12 .31 

Mar 3.61 -.05 - - AP~ 3.73 .05 .34 

' The probability that an increase of the magnitude given could have occurred by chance alone. 

Probability 1 Predicted 

Nov 2.36 .50* .04 

Dec 5.35 -.57 -- Jan 5.56 -.27 - - 

Negative value indicates an apparent decrease. 

May 2.56 0.50 0.06 

Jun .50 . 00 -- Ju~ .37 .18 .16 

Increase 

-- -- -- -- -- - - -- -- - - - - -- - - 

Fe b 1.87 -.03 - - Mar 5.58 -.27 -- 

APr 4.44 -. 21 -- 

Month 

May 3.89 -0.04 -- Jun 1.45 -.I2 -- 

Jul .36 -.01 -- 

-- -- -- -- - - - - -- -- -- -- - - - - 

Discharge Probability Predicted Increase 

Month Probability 

Discharge 

Predicted Increase 
Table 24.Increase in flow on Intensive Selection Watershed 

after start of logging, by month, in area-inches 

* 

Statistically significant at 5-percent level. 

The probability that an increase of the magnitude given could qave occurred by chance alone. 

+ Negative value indicates an apparent decrease. 

1958-59 

Month 

1959-60 

-- -- -- -- -- -- -- -- -- - - -- - - 

-- - - -- -- -- -- -- -- 

Oct 0.06 0.03 0.051 

NOV .61 -. 07 - - De c 1.06 .10 .21 

Jan 4.37 . 00 -- 

Feb 2.31 .12 .25 

Mar 2.93 -. 06 - - AP~ 3.04 .03 .14 

Month 

1960-61 

Probability' Month 

Discharge 

May 2.32 0.06 0.36 

Jun -44 .01 .45 

Ju 1 .24 .03 .41 

AUg .18 .03 .41 

S~P .04 . 00 - - 

Oct .29 .07* .005 

Nov 1.79 -. 04 - - Dec 4.21 -.23 -- Jan 4.39 -.I1 - - 

Fe b 1.53 .09 .30 

Mar 4.40 .16 .08 

AP~ 3.59 -. 02 -- 

-- 

Predicted 

Probability 

May 3.45 0.15 .20 

Jun 1.27 .14* .049 

Ju 1 .23 .06 .32 

AUg .39 -.08 - - 

S~P .65 -.02 -- Oct .09 .06* .O1 

-- -- - - - - - - -- -- -- - - - - - - - - 

-- -- -- -- -- - - -- -- 

-- -- - - - - 

Increase 

Discharge Probability . 

Predicted 

Discharge 

Increase Predicted Increase 
mvm 

mmv 

* ~m mu3 d N 

am m~ bm mu, 

* * I Nbb 

NIN 

High Flow (or Stornl Flow) 

As already stated, analysis of high-flow data was more complicated than 

in the case of the other characteristics studied. Of the many analyses made 

on data for the Clearcut Watershed (the major analysis effort), four are 

presented here. Features common to all four analyses: 

1. Prediction equations (straight-line regressions) were developed based 

upon calibration-period data to relate high flow of the watershed to be 

clearcut (No. 1) to the Control (No. 4). 
2. Precipitation in the storms causing the high flow was analyzed. When 

weighted precipitation of No. 1 was more than 10 percent above or belo,w 

that for No. 4, the resulting high flow was not analyzed in either calibration 

or treatment periods. 

3. High flows measured after treatment were compared with predicted 

flows and the amount of change determined. The probability that a change 

of this magnitude could have occurred by chance alone was then computed. 

This was done by using Student's "t" test and took into account the area 

in both tails of the probability curve (a two-tailed test). 

Special features of each analysis : 

Andlysis I: Instantaneous peaks. The basic data in this analysis were 

the maximum instantaneous discharges in c.s.m.; flows were included when 

discharges on the Control Watershed exceeded 10 c.s.m. 

Analysis 11: Storm period discharge. The basic data in this analysis 

were the volumes of discharge in the period between the time runoff began 

(SRB) and the time when the hydrograph receded to a stage midway between that at SRB and the peak. This time interval was determined on the 

Control. Discharge was computed for the Clearcut Watershed for the same 

time period. 

Analysis ZII: Volume of discharge above 10 c.s.m. by storms. For each 

period of high flow, the volume of discharge above 10 c.s.m. was determined. This is equivalent to drawing a horizontal line through the hydrograph at 10 c.s.m. and determining the discharge represented by the area 

above the line and below the hydrograph tracing. High flows were included 

when discharge on either or both the Clearcut and Control Watersheds 

exceeded 10 c.s.n~. 

BASAL AREA OF TIMBER 

Figure 22 .-Increase in 

flow related to basal area 

cut and culled, 1959 

CUT AND KILLED, SQUARE FEET growing season. 

63 
o,- -.-- 

 - ... -J ------- Y --

. 

This analysis was based upon tabulations of mean daily flow in c.s.m. For 

each day of flow above 10 c.s.m., the amount in excess of 10 c.s.m. was 

tabulated. Totals were computed for growing season, dormant season, and 

year; then they were converted to area-inches. Separate prediction equations 

were developed for the two seasons and for the year. Days of high flow 

were included when mean daily discharge of either or both the Clearcut 

and Control Watersheds exceeded 10 c.s.m. 

Comparison of the fozlr methods.-In considering high flows, use of 

instantaneous peaks (Analysis I) is the most logical and easiest to explain. 

However, correlation studies between watersheds are not too valuable because minor differences in intensity and timing of precipitation may cause 

sizable differences in peaks. Also, measurement of maximunl instantaneous 

flow is generally of little practical importance except at points of flood 

damage. 

Stonn period discharge (Analysis 1i) provides an arbitrary method of 

comparing high flows before and after treatment, with results that are 

suitable for statistical analysis. 

One shortcoming of both these analyses resulted from the poorer correlation of high flows on the treated watershed and the Control after treatment as compared to before treatment. High flows when discharge on the 

Control exceeded 10 c.s.m. but that on the treated watershed was less than 

10 c.s.m. were included in the analysis. When the reverse was true, data 

were excluded from analysis. This tended to underestimate any effect of 

treatment on increasing high flows. 

The analysis of discharge above 10 c.s.m. (Analyses I11 and IV) avoided 

this difficulty. Of these two analyses, Analysis I11 (by storms) had the 

advantage of a larger number of observations. Analysis IV (by season or 

year) had fewer observations. However, particular pains were taken with 

these observations to reduce the variability and to increase the scientific 

reliability. Analysis IV was also based upon tabulations of mean daily flow 

which had been previously prepared and were much easier to use than 

determination of volumes of flow from study of the hydrograph. 

Tables 26 to 29 give the results of these four analyses. They all show 

similar results. 

The following tabulation, prepared from season and year totals in tables 

26 to 29, shows the percent change in high flows resulting from the Clearcut treatment: 

IV 

111 Discha~~ge 

Discharge over 10 

I 5tosn.z- over 10 c.s.nz. (by 

I~tstdjzta~zeozl.r period r.s.nz. (by sedsotz 6 

Period peaks dischdlpge .rtortfz) yeara) 

Growing season -1- 21 + 24 

Dormant season - 4 +2 - 1 

+ 75 

0 

+ 42 

Year + 4 + 7 + 13 + 11 

In all analyses, there is a considerable increase for the growing season. 

The dormant season shows small changes, either increases or decreases. 

The annual changes are increases, but these are small when compared to 

those in the growing season. 
Table 26.-High-flow analysis I: effect of treatment 

on instantaneous peaks, Clearcut Watershed 

Date 

of 

storm 

Peak flow 

Predicted Change 

,in c.s.m. Probability in c.s.m. 

GROWING SEASON 

(7 storms) 

-- -- 

Growing-season total 176.6 +37.0 - - 21.0 

Growing-season mean 25.2 + 5.3 - - - - 

Dormant-season total 

~ormant-season mean 

Tot a1 

DORMANT SEASON 

(13 storms) 

* 

Significant at 5-percent level. Prediction Equation 

A Explanatory Notes Y = 1.220X - 2.34 

(X is peak flow of control in c.s.m.) Observations not included in analysis 

if measured precipitation on Watershed n = 48 

1 was 10 percent more or less than that - on No. 4 (Control) .' x = 24.30 

2 Sx = 18,600.78 
on storm-period discharge of Clearcut Watershed 

' One of storms in Analysis I was not used here in Analysis I1 because clock on 

Control recorder failed after the peak and part of hydrograph had to be estimated. 

Date 

of 

peak 

*significant at 5-percent level. 

Explanatory Notes Prediction Equation 

GROWING SEASON 

(6 storms)l 

5/5/58 1.26 +O. 10 0.34 -- 6/14/58 .66 + .46* <.001 -- 6/22/58 .58 + .07 .51 -- 8/1/58 .84 + .l6 .13 - - 8/4/58 .60 + .03 .78 - - 5/8/58 .80 + .30* .006 -- 

Growing-season total 4.74 +1.12 - - 23.6 

Growing-season mean .79 + .19 - - - - 

DORMANT SEASON 

(13 storms) 

12/7/57 1.15 +O .45* <0.001 -- 12/26/57 .70 + .02 .85 - - 

1/22/58 .50 + .06 .57 - - 4/28/58 1.56 - .Ol .93 -- 1/15/59 1.04 - .lo .34 -- 1/22/59 1.52 + .18 .10 -- 2/15/59 .78 + .02 .85 -- 11/28/59 .62 + .07 .50 -- 12/12/59 1.17 - .13 .22 -- 1/3/60 .68 + .03 .77 -- ?/15/60 1.17 + .03 .77 -- 3/30/60 3.86 - .21 .17 -- 4/4/60 1.03 - .Ol .92 - - 

Dormant -season total 15.78 + .40 -- 2.5 

Dormant-season mean 1.21 + .03 - - -- 

Tot a1 20.52 +1.52 - - 7.4 

Me an 1.08 + .08 -- -- 

A 

Basic data: For each storm when flow Y = 0.981X + 0.01 

Change as 

percent age 

of 

predicted 

Storm period discharge 

on Control exceeded 10 c.s.m., stormperiod discharge is the discharge be- (X is storm period discharge of the 

Control in area-inches) tween the time when storm runoff began 

Predicted 

A 

Y in areainches 

to the time when the stage receded-to 

a point midway between the peak stage 

and the stage when runoff began. 

Storms with non-uniform precipitation 

were excluded as in Analysis I. 

Change 

A 

- in 

area- inches Probability 
Table 28.-High-flow analysis 111: effect of treatment 

on storm-period discharge above 10 c.s.m. 

i I I 1 Date 

of 

GROWING SEASON 

(8 storms) 1 

inches I in areaGrowing-season total 1.304 + .982 -- 75.3 

Growing-season mean .163 + .I23 - - -- 

DORMANT SEASON 

(1.3 storms) 

Change zs 

percentage 

of 

Discharge above 10 c.s.m. 

Dormant-season total 6.266 - .014 -- -0.2 

Predicted 

predicted 

Y-Gin value 

area-inches 

Dormant -season mean .482 - .001 -- -- I 

Change 

Probability 

Tot a1 7.570 + .968 - - 12.8 

' One of storms in Analysis I excluded here for same reason as in Analysis 11. 

Two additional storms were used in this analysis (July 25, 1959 and Oct. 23, 

1959). In these storms, flow of 10 c.s.m. was exceeded on the Clearcut Watershed 

but not on the Control. This distinction was also followed in analysis of calibration data. 

Explanatory Notes 

Basic data: For each storm, the amount 

of discharge above 10 c.s.m. was computed. This is equivalent to drawing a 

line across the chart at 10 c.s.m. and 

determining the discharge represented 

by the area between this line and the 

hydrograph tracing when the latter is 

above the line. 

Storms with non-uniform precipitation 

were excluded as in Analysis I. 

Prediction Equation 

A 

Y = 0.991X = 0.01 

(X is discharge above 10 c.s.m. on 

the Control) 

n = 48 

x = 0.311 

2 Sx = 6.946460 

s =0.080 

Y-x 
 my • &A" v """A ]dAU I I . bllbLL UI LLLLILlllCllL 

by season and year on discharge above 

10 c.s.ni. on Clearcut Watershed 

Water 

Year 

I Discharge above 10 c.s.m. I Change as I 

percentage 

Change Predicted of 

Y in area- predicted 

Y-Yin 

inches value 

are a- inches Probability 

I GROWING SEASON I 

1957-58 0 0 -- -- 

1958-59 1.73 +0.51* 0.048 - - 1959-60 0 + -22 .23 -- 

Growing-season total 1.73 + .73 -- 42.2 

Growing-season mean .58 + .24 -- -- 

DORMANT SEASON 1 

1957-58 +O .47* 

1958-59 

1959-60 

:::: + .06 ::: 

1: 1 3.72 - .61* .01 -- 

Dormant -season total 5.88 - .08 -- -1.4 

Dormant-season mean 1.96 - .03 - - -- 

1957-58 1.09 +O. 54* <O. 01 -- 1958-59 2.64 + .66* <.01 -- 1959-60 3.74 - .41* .02 -- 

Total for year 7.47 + .79 -- +10.6 

Mean for year 2.49 + .26 -- -- 

' Values for seasons do not sum up exactly to values for year because different 

prediction equations were used. 

*significant at 5-percent level. 

Exalanatorv Notes 

Basic data: Using tabulations of mean daily flow, the amount of flow above 10 

c.s.m. was accumulated for each watershed (Clearcut and Control) by seasons and 

years. For each day of high flow, 10 c.s.m. was deducted from the mean daily 

value. Flows were converted to area-inches. 

Prediction Equations 

Growing season Dormant season - Year 

A A 

Y = 1.083X - 0.09 Y = 0.988X + 0.01 G = 1.019X - 0.086 

n=6 n = 6 n=6 - 

x = 0.62 area-inch x = 1.57 area-inch = 2.19 area-inch 

2 

sx2 = 1.4938 Sx = 8.0841 2 Sx = 11.0537 

s = 0.130 area-inch s z 0.099 area-inch Y.X s = 0.094 area-inch 

Y .x Y.X 
Due to the characteristic of the analysis, it is to be expected that percent 

change will be higher when the volume of discharge over 10 c.s.m. is 

analyzed instead of the whole storm-period flow. 

Inspection of data for individual storms shows that changes in the growing season are almost universally increases-some small and some large. 

Changes in the dormant season may be either increases or decreases. 

Discussion of dormant season variability.-General observation in the 

watersheds and a study of the records indicate that changes in dormantseason flow are largely the result of treatment effect on rate of snowmelt. 

The treatment resulted in increased insolation and more melt and streamflow on cool, sunny days. Thus less snow remained to contribute to streamflow during succeeding relatively warmer periods during which rain sometimes occurred. Snowmelt from insolation seldom results in extremely 

high flow. It is most effective for only a small part of the day and, because 

of varying aspects, on only part of the watershed area. On occasion, high 

flow from snowmelt occurred on the Control when a considerable portion 

of the Clearcut Watershed was bare of snow. 

Other treatments.-So far, effect of treatment on high flows has been 

given for the Clearcut Watershed only. Table 30 shows a comparison with 

the other three treatments for area-inch increase in volume of flow over 

10 c.s.m. The comparison is for the 1959-60 water-year, the only year when 

all four treatments were in effect. 

The considerable treatment effect on the two selection-cut watersheds as 

compared to the other two watersheds is surprising. One reason perhaps is 

that the Clearcut Watershed was logged more than a year before the others 

and regrowth had occurred. 

The 1959 growing season did not provide any large storms (flows over 

10 c.s.m.) on any of the five watersheds except the Clearcut. Hence, there 

was no good test of storm effects. All watersheds show decreases for the 

1959-60 water-year; if it had not been for the snowmelt runoff in the period 

March 19-29, 1960, the change for the year would have been an increase. 

Table 30.-High-flow analysis: effect of treatments 

by season and year on discharge above 

10 c.s.m. in water-year 1959-60 

1 Procedure of analysis same as in Analysis IV. * 

Significant at 5-percent level. 

Item 

Growing season +O .22 0 -0.32 0 

Dormant season - .61* - .81 - .68 -0.25* 

Year -0.41* -1. lo* -0.99* -0.30* 

Change in volume of discharge above 10 c.s.m., 

in area-inches ' 

Intensive 

selection 

Extensive 

selection 

Commercial 

clearcut 

Diameter 

limit 
flow characteristics. More study is needed-on these watersheds and otl 

other areas-to get a clearer picture. 

Flou~ Duration 

Figure 23 is the flow-duration curve for the Control Watershed for the 

3288 days in the study period (May 1, 1951 through April 30, 1960). It 

gives a general picture of streamflow on the undisturbed watersheds. 

To derive the flow-duration curves to show the effect of treatment on the 

Clearcut Watershed in the growing season, data on mean daily flows were 

first tabulated showing, for Watershed 4 (the Control) and for No. 1 

(Clearcut), the number of days in each growing season that flow exceeded 

0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 20, 30, 40, and 50 c.s.m., 

respectively. This was done by electronic computer. 

Using data for the six growing seasons in the calibration period, prediction equations (straight-line regressions) were computed for each of the 

rates of flow listed above. For each growing season in the treatment period, 

a prediction was made for the number of days each rate of flow would be 

equaled or exceeded. This was made using the equation and the measured 

number of days for the Control in each of the treatment years. For each 

rate of flow, the number of days was totaled for the four seasons in the 

treatment period and the appropriate percentage was determined by divid- 

-- PERCENTAGE OF TIME FLOW IS EQUALED OR EXCEEDED 

ti& curve of the Control 

Watershed in the 9 years 

of the study period. 
Figure 24.-Flow-duration curves for Clearcut 

Watershed for growing 

seasons in 1957 and 1958. 

0 20 40 60 80 100 0 20 40 60 80 100 

PERCENTAGE OF TIME FLOW IS EQUALED OR EXCEEDED 

- MEASURED ---- PREDICTED 

ing by 736, the total number of days in the four growing seasons. The 

resulting percentages were plotted on semi-log scale to form the predicted 

flow-duration curve. 

Based on streamflow measurements on the Clearcut Watershed in the 

four seasons of the treatment period, the number of days and corresponding 

percentages were computed and plotted on the same graph to form the 

~lzeasured flow-duration curve. 

The growing-season curves for the Clearcut Watershed showed the 

average effect on flow duration in the four seasons after start of treatment. 

It is of more than passing interest to examine the situation in a d~y year 

and in a wet year, especially since water-supply problems usually occur in 

abnormal years rather than in years having near-average conditions. 

In the 1957 growing season, there were 75 days on the Control Watershed when flow was below 5 gallons per acre per day. In 1958, there were 

only 3 such days. Figure 24 shows flow-duration curves of the Clearcut 

Watershed for these two growing seasons. The displacement to the right 

of both 1958 curves, when compared with those for 1957, reflects the 

difference in the weather of the two seasons. However, the treatment 

resulted in substantial augmentation of low flows in both the u1et and the 

dr')) year. 

Figure 25 shows the average effect of the Clearcut treatment on the flowduration curve for 3 water-years following the start of logging. In line 

with other analyses, the spread between the curve based on predicted flow 

and the one based on measured flow is not as pronounced as that for ihe 

growing-season curves; however, the difference between the two is readily 

apparent. 

Effects of treatment on discharge were not very large in the dormant 

season on any of the watersheds; therefore, flow-duration curves are not 

given for this season. 

An additional note should be added concerning this resentation of flowduration curves. These curves are not intended to esta 1 lish whether or not 

the treatments had a statistically significant effect upon discharge. As 

analyses by water-year, season, and month that have already been presented 
brwr* curvrci lul LlCillLUL 

Watershed in 3 wateryears after start of logging, May 1957 through 

April 1gG0. 

PERCENTAGE OF TIME FLOW IS EQUALED OR EXCEEDED 

showed such increases in many cases, the flow-duration curves have been 

presented to indicate the relationship between increase and rate of discharge. 

Runoff as a Percent of Precipitation 

Effect of treatment on runoff as a percentage of precipitation has already 

been given for the Commercial Clearcut Watershed. Table 31 gives the 

same type of information for all four watersheds and shows the probabilities associated with the increases. As might be expected, the results are 

similar to those obtained in the analyses of quantity of streamflow by 

season and year. The results are impressive: this type of analysis appears 

to be a sensitive and fruitful approach to the problem of determining 

treatment effects. 

V. DISCUSSION OF RESULTS 

Following is a hypothetical example of how the research results might 

be used to obtain an approximation of the effect of a treatment made to 

increase water yield. 
Assumptions: 

I. Watershed under consideration is similar to Fernow watersheds in 

climate, soil, geology, topography, etc. 

2. Effect of treatment will be the same as in Fernow experiments in 1959 

and 1960. 

Treatment.-Apply diameter-limit cutting practice5 to 5 percent of 

watershed each year but construct skidroads to standards of the intensiveselection program.' Insofar as practicable, choose each cutting area so that 

it includes a cross-section of aspects and slope positions. 

Expected increase in discharge.-Table 32 gives the expected increase 

in water yield for the growing season and for two late-summer months. 

Any gain in flow that might occur more than 2 years after cutting is not 

included in the computations; this might be considered a safety factor. 

Increases are given in area-inches, in gallons per acre, and in terms of 

number of people that could be supplied. 

' Treatment considered here is a diameter-limit cutting because of availability 

of research results; a different cutting practice might be more desirable ,for either 

water or timber production. 

Table, 31.-Effect of treatment on runoff as a percentage 

of precipitation on the four treated watersheds 

Diameter 

Extensive 

selection 

Intensive 

Diameter 

Extensive 

selection 

Intensive 

selection 

* 

Statistically significant at 5-percent level. 
Note: This example is presented as an illustration only; wide variations from watershed to 

watershed prevent precise quantitative estimates of practical application of these research 

results. 

Item 

VI. OTHER WATERSHED RESEARCH 

Many investigations have been made at various times and places in an 

effort to determine the effect of forest cutting on streamflow. The results 

obtained have differed greatly because of the wide variety of conditions 

under which the studies were made, the various treatments applied, and 

different study methods used. 

Increase on area treated 

in first year after treatment ......... area-inches .. 1.8 0.3 0.1 

Increase on area treated 

in second year after treatment ........ area-inches .. .7 -1 .2 

Mean increase on area treated ......... area-inches .. 1.25 .20 .15 

gallons/acre . . 33,942 5,431 4,073 

Average increase distributed 

over whole watershed ................. gallons/acre .. 3,394 543 407 

Days in perlod ............................. number .. 184 31 30 

Average increase for watershed ... gallons/acre/day .. 18 18 14 

Assumed per-capita consumption ........ gallons/day .. 50 50 50 

Watershed area needed to supply 

one additional person from 

increase in flow ............................ acres .. 3 3 4 

Forest Cntting on Watersheds Calibrated 

with a Coaztrol Watershed 

. 

Discharge period 

Wagon Wheel Gap, Colorado.-The historic forest and streamffow 

experiment at Wagon Wheel Gap, Colorado, is well known (Bates and 

Henry, 1928). In this experiment, started in 1910, two watersheds of about 

200 acres each were calibrated for 8 years. During the experiment, annual 

precipitation averaged 21 inches. After calibration, one of the watersheds 

was denuded by cutting, piling, and burning the vegetation of Douglas-fir, 

pine, spruce, and aspen. Within a year after cutting, a thin stand of aspen 

sprouts developed. Strcamflow measurements continued for 7 years after 

treatment. 

To facilitate comparison, the records of annual flow for the Wagon 

Wheel Gap Watersheds have been reanalyzed in the same way the Fernow 

Growing 

season August September 

- 
data were analyzed. The following tabulation shows the increases in annual 

flow on the treated watershed at Wagon Wheel Gap: 

As percetzt 

Area- of predicted 

Year inches flow Probability I 

Year of treatment 0.63* 8 0.018 

First year after 1.35" 19 < .OOl 

Second year after 1.86* 2 7 < .OOl 

Third year after 0.98* 16 .002 

Fourth year after .85* 12 .004 

Fifth year after .53* 12 .029 

Sixth year after .52* 12 ,031 

lThe probability that an increase of the magnitude given could have 

occurred by chance alone. 

*Statistically significant at the >-percent level. 

The pattern of seasonal increase is of interest: 80 percent of the increase 

in annual flow occurred during the spring melt period (March 1 to July 

lo). At Wagon Wheel Gap snowmelt provided most of the annual flow. 

Peak flow in the spring was increased about 50 percent as a result of 

treatment. 

Fraser Experimental Forest, Colorado.-After a lengthy calibration 

period, about half the merchantable timber on 714-acre Fool Creek Watershed was harvested by strip clear-cutting in the period from summer 1954 

to fall 1956 (Goodell, 1958). At Fraser, annual precipitation is about 30 

inches; about three-fourths of this falls as snow in the October to June 

period. This treatment resulted in a definite increase in annual streamflow; 

in 1956 the increase was 4.2 area-inches or 37 percent of the expected 

flow; in 1957, 3.4 area-inches or 17 percent. In 1958, the increase was 2.1 

inches (Rocky Mountain Forest and Range Experiment Station, 1959). 

The bulk of the increases occurred during spring freshets from snowmelt. 

However, streamflow was also slightly higher during summer and fall in 

1956 and 1957. 

The s ring flood peak was increased the first year after cutting and 

decrease a in comparison with the control in the second year. In 1958, the 

third year after cutting, peak flow was 30 percent higher than predicted. 

The interaction between spring weather and treatment seems to explain 

the difference in spring peaks. 

Sediment yields since cutting have been low due to the considerable 

care taken in the logging operation. For example, no timber was cut within 

90 feet of the main stream. 

Roads were constructed in the watershed well ahead of logging (in 1950 

and 1951). No effect on water yield could be detected as a result of the 

35 acres of roadway clearing. 

Coweeta Hydrologic Laboratory, North Carolina.-Because of similarities in climate, forest types, topography, and methods of study, research 

results from the Fernow Forest can perhaps be compared with those from 

Coweeta better than from anywhere else. Average annual precipitation at 

Coweeta is 80 inches, almost all of which occurs as rain (Dils, 1957). 
On Coweeta Watershed 17, all vegetatlon was cut ana lerr 011 Lllr 

ground; this was followed by an annual slashing of regrowth. Since no 

logging was done, there was little disturbance of the forest floor. Firstyear increase in streamflow was 17 area-inches. In the second year, after 

regrowth was cut for the first time, many herbaceous plants began to 

invade the area. Under this cover, the increase in water yield leveled off 

at about 11 area-inches from the third to the thirteenth year. D'ils states, 

"The maximum increases came in the November to February period, but 

significant increases also occurred in July, August, and September-the 

period when municipal and industrial water shortages are most likely. 

Maximum peak discharges during storm periods and the distribution of 

streamflow were not appreciably altered . . . There has been no measurable change in stream turbidity. Air temperatures near the forest floor have 

increased markedly." 

Coweeta Watershed 13 was treated in the same manner as No. 17 

except that forest growth was allowed to come back naturally. Streamflow 

increase in the first year was about 15 area-inches; the increase diminished 

with time but was still more than 4 inches 15 years after cutting. Here, 

also, the greater increase occurred in -the winter period. As in the case of 

Watershed 17, there were no measurable changes in storm peaks, volume 

of stormflow, or distribution of storm runoff. 

After a 6-year calibration period, 212-acre Coweeta Watershed 10 was 

logged: 50 percent of the basal area was removed over a +year period. 

Skidroads were "logger's choice" as on the Fernow Clearcut and Diameter 

Limit Watersheds; truck roads were also constructed in the watershed. 

Logging in this manner caused extensive erosion and consequently very 

high stream turbidities, even in small storms ; maximum turbidity measured 

was 5,700 p.p.m. Even after logging stopped, the exposed clay subsoil 

continued to move into streams after every storm, thus impairing the water 

quality. 

This study has been reported as a demonstration of effects of exploitive 

logging on water quality. Apparently the effects of treatment on quantity 

of discharge received little emphasis; a streamflow increase of 4.0 areainches was measured the first year after logging (Southeastern Forest 

Experiment Station, 1961). 

Other Coweeta experiments have been conducted and reported upon but 

do not compare so directly with the Fernow investigations as those listed 

above. Some additional watershed treatments at Coweeta, not yet fully 

reported in the literature, have resulted in streamflow increases that were 

small in relation to those described above. Watershed research must seek 

the causes for these differences in results that apparently are not explained 

by the amount cut nor proportion of the stand removed. 

Sierra Ancha Experimental Forest, Arizona.-Three watersheds in 

the Workman Creek drainage in central Arizona have been studied since 

1938. The forest stand is of the mixed conifer type (Rich, 1959). Average 

annual precipitation is 32 inches. A logging operation and timber-standimprovement measures in 1953, 1954, and 1955 reduced the basal area 

by 36 percent. No significant change in water yields had, as of 1959, 

resulted from this treatment. 

Kamabuti, Japan.--Many investigations of the effect of forest cover and 

forest cutting upon streamflow have been made in foreign countries. Unfortunately, many of these have not had adequate control, so definite 
conclusions cannot be drawn. One Japanese experiment is of particular 

interest (Maruyama and Inose, 1952). The control-watershed approyh 

was used with a calibration period of 8 years. This experiment also gives 

an idea of treatment effects in an area of high average precipitation (99 

inches annually) and high average streamflow (76 area-inches annually). 

After calibration, the mixed conifer-broadleaf stand was clearcut and the 

regrowth cut annually on the 6-acre treated watershed. Over a 3-year 

period, annual streamflow was increased by about 5 percent. Increases were 

significant in the summer season (June to November) but not in the 

winter season (December to May). Average peak runoff and increased 

runoff due to heavy rains for 6 examples rose more than 20 percent 

by cutting. 

Other investigations on Watersheds 

Relating Vegetation Differences to Streamfloul 

Sperbel. and Rappen, Switzerland.-An early Swiss study, repo,rted 

upon by Engler (1919) and Burger (1943) showed that streamflow from 

the fully forested Sperbel watershed was continuously less than streamflow 

from the lightly forested Rappen watershed. 

Flow of Springs, Calif ornia.-Biswell and Schultz ( 1958) report a 

prompt and measurable increase in flow of several springs in California 

following removal of vegetation by burning or cutting. 

White River, Colorado.-The killing of spruce and pine by an insect 

epidemic affected streamflow of the White River in Colorado as reported 

by Love (1955). Average annual precipitation at Meeker, Colorado, is 

about 16 inches. In the period 1941 to 1946, the beetle killed most of the 

trees on 226 square miles, or 30 percent of the 762-square-mile watershed. 

Analysis, using nearby Elk River as a control, showed that annual flow 

of the White River was increased by 2.3 inches (or 22 percent) in the 

1947 to 1951 period. Love estimates that an increased flow of 7.7 areainches came from the 226-square-mile area of beetle-killed timber. 

Harz Mountains, Germnu ?!.--A recent paper (Delfs et al., 1958), 

compared two watersheds, orle forested and one clearcut, in the Harz 

Mountains of Germany. Annual water yield was slightly higher from 

the clearcut watershed ; winter yield was slightly higher from the forested 

watershed. Flood peaks when rain followed a thaw were frequently 

higher from the forested area; during summer, peaks were generally higher 

from the clearcut area. Suspended sediment was higher from the clearcut 

area than the forested area. 

Ref orestation Experinrents 

This paper has dealt largely with effects of cutting, complete or partial, 

of the forest stand. Generally speaking, reforestation, afforestation, or 

the improvement of existing forest stands by protection fro111 fire or other 

forest-management measures should have a corresponding effect in the 

opposite direction. Many studies have been conducted to determine such 

effects. 
Coshocton, Ohio, in 1939 has resulted in a progressive decrease in annual 

streamflow of about 0.28 area-inch per year, amounting to about 5 inches 

by the 18th year of the plantation (Harrold et al., 1962). Average annual 

precipitation at Coshocton is about 38 inches. Decrease was divided between the growing and dormant seasons; about 70 percent of it occurred in 

the dormant season. This indicates that groundwater recharge has been 

affected to a considerable degree. 

White Hollow Watershed, Tennessee.-On White Hollow Watershed 

in Tennessee, 588 acres out of a total 1,715 acres were reforested and 

other conservation methods were applied (Rothacher, 1953). No effect on 

annual discharge was noted. Summer peak flows were reduced 73 to 92 

percent. Overland flow and soil erosion were practically eliminated. 

Pine Tree Branch, Tennessee.-The Tennessee Valley Authority also 

investigated the effect of reforestation and other erosion-control measures 

upon the hydrology of 88-acre Pine Tree Branch Watershed (Tennessee 

Valley Authority, 1955). Watershedetreatment was done largely in the 

period 1945 to 1948. Considering records to 1950, the report states, 

"There is some indication of a slow, progressive decrease in water yield, 

but whether or not this is significant remains to be determined by further 

measurements." Marked reductions in peak discharges and sediment production were measured; however, much of this is probably due to measures 

other than reforestation, such as contouring and check dams in stream 

channels and gullies. 

Plot Studies 

Many studies have been made of the effect of forest cutting upon soil 

moisture. It is logical to infer that under most conditions any treatment 

that results in maintaining a higher level of soil moisture will increase 

streamflow to some degree. Much of the information needed to corroborate 

and explain results determined on gaged watersheds will come from 

plot studies. Of the many experiments conducted, only a selected few will 

be lmentioned here. 

Crossett Experimental Forest, Arkansas.-Moyle and Zahner (1954) 

measured soil moisture on a number of plots at Crossett, Arkansas, during 

the summer of 1953. At Crossett, annual rainfall is about 50 inches and 

the normal for the May-September period is 18 inches. They found 

sizable soil-moisture differences related to stand conditions. For exam le, 

in August there was as much as 10 inches less water in the upper 4 P eet 

of soil under an all-aged cull-hardwood stand than under a similar stand 

in which all hardwoods over 4 inches d.b.h. had recently been poisoned. 

Their summary states in part: "Where pine or hardwood stands with a 

stocking of 70 to 100 square feet of basal area were undisturbed, water 

was removed from the ground rapidly with the onset of hot dry weather. 

On plots where large cull hardwoods were deadened, and where all living 

vegetation was removed, soil water remained relatively high throughout 

the summer." 

Frdser Experimental Forest, Colorado.-Wilm and Dunford ( 1948 ) 

reported on an intensive plot study conducted near Fraser, Colorado, to 
determine water available for strean~flow fro111 areas cut to varying 

residual volumes of timber. Approximating the amount of timber cut, the 

following tabulation shows the annual increase in water available for 

streamflow : 

Vol~mze of nzerchu~ztuble A vernge i~zn.euse nvailnble 

tim bey cut over 4-yen/. period 

M b.~. Perce~zt of Aren- Perce~zj of 

/dc?.e lotnl vol?cnze i1zct4e.r expec f ed vnl14e 

These increases are attributed largely to the effects of treatment on 

snow interception and evaporation. Autumn soil-moisture deficits (a measure of evapotranspiration during the summer) showed "only a weak 

average effect" of treatment. The authors point out that this effect was 

much stronger in the one treatment year when above-average precipitation 

(5.9 inches) occurred in the July to September period. In t at year the 

deficits were as much as 1.24 inches less on the treated plots. 

College Station, Texas.-Ko,shi ( 1959) studied soil-moisture trends 

under varying densities of oak overstory near College Station, Texas. 

Normal annual precipitation for College Station is about 39 inches. 

Throughout the period of observation, soils of clearcut plots had more 

moisture than those of undisturbed plots, while soils of thinned plots had 

an intermediate amount. Differences for the upper 24 inches of soil between clearcut and undisturbed plots ranged up to about 3.5 inches. Differences tended to be greatest in periods of high soil moisture and least 

at times of drought. After one prolonged drought, there was little difference in residual moisture among the three treatments. 

Calhoun Experimental Forest, South Carolina.-Metz and Douglass 

(1959) studied soil-moisture depletion under several cover types in the 

Piedmont of South Carolina. Average annual precipitation in the area is 

about 48 inches. For a drying period of 40 days, the authors report soilmoisture losses in a 60-inch soil layer of about 2.9, 4.0, and 5.8 inches 

from barren, broomsedge, and pine plots, respectively. 
Acknowledgment 

HE evalution of treament effects in investigations of this kind depends as t~auch upon the accuracy and dependability of daily measurements as 

upon the magnitude of the treatment effects themselves. For the decade of this study, Burley D. Fridley, forestry aide on the Fernow Experimental Forest, 

Parsons, West Virginia, maintained the instruments 

and installations and collected nlost of the basic 

records. Much of the success of this study can be 

attributed to his conscientious and efficient field work.