Iowa state bystander. [volume] (Des Moines, Iowa) 1894-1916, 1912-10-25
!, MAY sI0P FLOODS
Regulation Of Streams by Forests
10 Solved.
Overflow Prevention Said to Have
Seen Worked Out by United
States Geological Survey
Means Purchase Of Land
Under Weeks Act

washington. the Forest Gov
Or of mountains and hills has an ap-
preciable and measurable effect ON
Aavigation streams and that the re-
moval of the forest growth from the
lands tends to produce foods is the
conclusion reached by the United
States Geological Survey announced
a the result Of . series Of scientific
experiments in the White mountains
Of New England. The report carries
with 1t the statement Of the survey
that the removal of the forests tends
to produce floods. The Investigations
are believed to solve a problem long
source of strenuous contention
among scientists. While the inv6sti.
cations have direct reference to the
White mountain area only. they estab-
lish a principle Of far wider applica-
ton and indicate that there may be .
scientific method of preventing foods
generally.
In conducting It's experiments, the
Geological Survey selected two small,
almost exactly similar drainage basins
Of about Ave square miles each on the
east branch OF Pemigewassett river.
one largely clothed with virgin timber
and the other deforested and burned.
Careful measurements of precipita-
ton over the areas and Of the run-o6
Of the respective streams show that
not only was the snow held better in
the forested area, but that during a
period Of II days in April, including
three extended storms, the run-oR OF
the stream in the deforested area was
. comparative food, practically dou-
bic that of the stream flowing through
the forested area.
On both streams photographic sta
tons were established and the stream
dow determined with q high degree
Of accuracy. The survey report shows
that the maximum food flow from the
forested basin was only 81 per cent.
Of that from the deforested basin
The Survey says:
The stream of the forested basin
Is observed to be the steadier Of the
two and in proportion to its drainage
area it tends-at least during the
spring months-to promote steady
flow of water in the master stream OF
which it is tributary.
Such an actual demonstration and
cumulative measure Of the perform.
ance OF different areas, some forested
and others deforested, has never been
attempted in trying to determine the
effect Of forest cover on stream flow.
Efforts to arrive ut definite conclu-
sions have always been based on a
study of longtime records OF precipi.
tation and stream discharge; but ow.
ing to the many qualifying factors
such efforts have simply resulted in
divergent opinions and inconclusive
controversies.
THE results of the present actual
measurements In these mimic drain
age basins, 80 accurate and refined in
method as to approach laboratory ex
periments, where exact results may be
expected, leave no doubt as to the con
clusion. Forest cover and the re-
sulting forest mat in the White noun
tain granite area does to a consid
cradle and measurable degree steady
and regulate stream flow, and there
fore must be stated as an important
factor in maintaining the navigability
Of streams whose headwaters lie In
such areas"