The Colorado statesman., 1912-10-26
MAY STOP FLOODS
Regulation Of Streams by Forests
Is Solved.
Overflow Prevention Said to Have
Been Worked Out by United
States Geological Survey
Means Purchase of Land
Under Weeks Act.

Washington.-Tha the forest Gov
er of mountains and hills has an ap-
preciable and measurable effect on
navigation streams and that the re-
moval of the forest growth from the
lands tends to produce floods is the
conclusion reached by the United
States Geological Survey announced
as the result of a 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 problem long
a source of strenuous contention
among scientists. While the investi-
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 a
scientific method of preventing floods
generally.
In conducting its experiments, the
Geological Survey selected two small,
almost exactly similar drainage basins
OF about five 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-off
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-ofr of
the stream in the deforested area was
a comparative flood, practically dSu-
BILE that of the stream flowing through
the forested area.
On both streams photographic sta
tions were established and the stream
flow determined with a high degree
OF accuracy. The survey report shows
that the maximum flood flow from the
forested basin was only 67 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 1t tends-at least during the
spring months-to promote a steady
how of water in the master stream OF
which 1t is tributary.
Such an actual demonstration and
quantitative 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 at 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, so 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"