The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1910-01-30
FLOODS INCREASE
IN MANY RIVERS
Government Gathers Data on
Important Subject.
DUE TO CUTTING AWAY TREES
On Potomac Number of foundations
Seven Greater In Last Nine Years.
Compared with Similar Previous
PeriOd-surface Conditions on the
watershed Change, Hence Floods.


watershed Change, Hence Floods.
Popular opinion for years has been
that floods are increasing IN frequency
and duration In many rivers OF the United
States. Until within a year, however
there had been no careful examination
OF records to see whether the popular
opinion is based upon fact. The scientific
bureaus of the government which are
directly interested in the matter had
assumed that records had not been kept
long enough on any river to show
change In the conditions Of flow.
About year ago il was thought worth
while to look into the records to see
whether any changes were dlscernible.
The results were surprising. 1t was
found that IN many OF the streams which
take their rise in the Appalachian
mountains there has been a steady in
crease IN the number and duration OF
foods during the past twenty or thirty
years
Following this discovery, a general
study was made OF the change which
has come about In the flow OF number
Of important rivers during the time for
which records have been kept Both tho
Geological Survey and the Forest Service
have secured data on this subject, ana
the results warrant the statement that,
Enthusiastically. floods are steadily on the
Increase in some OF our most important
rivers. Particularly is this true OF the
rivers which rise in the eastern noun
tains. The increases seem to be greater
on those watersheds where the condition
Of the surface has been the most changed
They are greatest in such streams as
the Ohio, Cumberland. Wateree, and
Santee. where the most forest has been
destroyed and least on the streams
where forest conditions have been least
changed
Opposite Tendency Observed.
II IS true that IN certain rivers an
opposite tendency IS 20 be seen. Floods
have decreased and low waters have
markedly improved But a full inquiry
into the conditions on these rivers, also,
as will be shown. seems TO prove the rule
that there is the closest kind Of relation
ship between the surface conditions Of a
watershed and the flow Of water through
the stream which drains II.
Accompanying an official report on the
subject IS a table giving all available
data regarding the streams studied:
on the Potomac River, for which meas
! uremeuts are given for eighteen years.
/ the number Of floods during the first
half OF the period was %; during the
| second half, q: while the number Of days
Of food in the FIRST half was %, and in
tho second half, 8.
l On the Allegheny River measurements
are given for thirty-four years. During
the first half Of the period there were SO
| foods; during the second half, 63. The
number Of days OF food during the first
/ half was 90: during the second half, 131.
Coming TO the causes for Increased
foods the report says:
Undoubtedly II is the clearing away OF
| the forest on the mountainous water
sheds OF the streams that has caused
| the great increase in frequency and du-
ration Of foods.
| Il IS a known fact that the forests on
these several watersheds have been cut
away with great rapidly during the past
+ thirty years. European conditions prob
ably offer no parallel 20 the rate al
which these watersheds have been cleared
/ 20 make way for the rapid advance OF
/ agriculture and 10 supply the great
manufacturing industries with the wood
which they require.
Worst Conditions Prevail.
Forest lands. which offer the best pos
sible conditions for soil absorption and
underground storage, those great regu-
lators Of stream flow, have been changed
( to poorly titled agricultural lands, which
are not so good. Then these agricultural
/ lands after few years have been ex-
/ hausted and their soil eroded into deer
/ gullies. Finally. many OF them have
/ been turned into pasture or even entirely
I abandoned because they reached q condi-
/ ton where they could not support even
/ a growth of grass and weeds. The best
condition has been changed TO the very
/ worst condition.
/ Again. repeated burning Of forest lands
/ has tended to reduce the thickness and
value Of the ground cover and 10 lessen
/ the power Of the soil to absorb and tc
store water. The extent OF damage from
/ fire, so far as water storage IS concerned
! is generally vastly underestimate.
! forest fire strikes both above and below
the surface It INJURIES or kills the trees
| destroys the underground and brush, and
consumes the great forest sponge-tht
/ ground cover and the humus.
| The extent Of the injury is. Of course
not always the same. 1t is sometimes
! slight; sometimes very great. Repeated
/ fires tend to every kind OF injury that
can possibly be inflicted upon a forest
soil, completely destroying the cover
down to the mineral substances, and
thus rendering It defenseless against the
attacks Of erosion. When that stage IS
reached, II may be depended upon that
the run-off Of the watershed has beer
profoundly affected and the regimen OF
the stream materially changed.