The Jersey City news. (Jersey City [N.J.]) 1889-1906, 1895-09-25
JERSEY WATERSHEDS.
Interesting Scientific Report
Giving Effect Of Natural
Causes and De-
forestation.

Mass, was that of Mr.. c.. c.. Vermeuiel
consulting engineer of the Geological
Survey of New Jersey, says Garden
and Forest and it related to his in
v~estigations of the water supply re-
sources of that State, an important
matter, since considerably more than
a hundred million gallons of water are
every day consumed by about a million
inhabitants. Mr.. Vermeule made a per
sonal study of certain watersheds in
New Jersey for four years, and, in adj
dition to his own data, he used for COM
parison a long series of measurements
of streams in New England and the
Middle States. Taking evaporation to
mean the difference between the total
rainfall and the total runoff of the
streams, his conclusions. briefly stated,
are that the amount of rain evaporated
was not proportional to the total rain
fall. as is often assumed to be the
case. Evaporation increased slightly
with increased rainfall, but very rapidly
with increased temperature of the at
mosphere-
The stream-fiow was found to depend
upon the rainfall in connection with the
temperature, and little effect upon the
run-off was traceable to forest, to other
vegetation or to topography. Examples
IN three river basins, one of which con
tanned ID per cent. of forest. another 80
per cent, and a third A per cent, all
showed the same total fiow-off for a CIV
en- annual rainfall. the varying forest
areas seeming to have no effect upon
evaporation. The Connecticut showed
much less evaporation than the Potomac,
with abOut tho co NJ prnnorfiop IF fnraSf
but with a temperature of 2.7 degrees
lower, and generally evaporation was
found to vary with the mean tempera-
ture without regard to the amount of
forest. a great number of observations
seemed to s-ubstantiate his theory, and
the conclusions were that in New Eng
land and the Middle States the effect of
forests upon the total fiow-off of the
streams is not important enough to be
shown in the measurements. The in
1uence of the temperature of the air
upon evaporation will be appreciated
when it is understood that the moisture
which is held in the air is doubled for
each increase of 20 per cent. in tenn
p~erature.
EFFECT OF FORESTS UPON FLOW
OF STREAMS.
In studying the effect of forests upon
the greatest and least flow of streams
no effect due to the forests was discov-
cred. The heaviest feshet usually occurs
when the ground is frozen and warm rain
comes on a heavy covering of snow, or
else in summer when a heavy rain falls
upon the ground already saturated. The
rate of how-offs is hen determined
mainly by topography. The lowest flow
occurs when the stream has for a long
time been drawing upon the stored
ground water, and mas drained it to q
point below Wnifh It caa ar De a+ inf ~ Gow
is then mostly affected by the capacity
of the earth for holding water and It's
rate of Yielding i up, This n s, is not ga a
ology, and for this reason it is thought
the forests have. little effect upon. the
greatest or least rate of the flow OF the
These results, it ought to be said, were
questioned by some of the experts pres
ent, especially. because there are no IN
measurements. They. are altogether
negative, however, and they do not i'm
ply that a covering of forest exercises
no beneficial effect upon the water sup
ply. Mr.. Vermeule explained that his
studies make it clear that streams are
often supplied for many months entirely
from mn water ip Il fhe in ps the gr9 Rdyar W WraI
CAdIilPlS, III DOL Lax
supplied for eight months in this way;
With only rain enough to make good
evaporation. land in New Jersey VIII
spring water equal to from 2,29 to 7.5s
inches. of rainfall. Small barren red
stone catchments yield the least water,
and the sand and gravel Of the tertiia y
uniformly. from two to two and a half
inches a month may be taken into the
ground n discharged thence into the
"a :, Usbo = aptiraE roinfoh nf q N aXT6r-
age year, less the evaporation, could be
thus taken into the earth and none need
flow over the surface into the streams.
STREAMS OF SOUTH JERSEY.
Anything. therefore, which affects the
capacity Of the earth to take up water
and to control its rate of discharge into
making it more or less uniform through
out the year. And here the generally re-
cognized good effects of a forest
e earth can "a 4 take i up are seen. The basins ms
which lave the largest proportion of for
est invariably showed the best sustained
nov r. Vas a ary no se aseafteS si' TbeE str ri q 500 Of
Southern New Jersey which nave the
most forests are remarkably steady, the
dry season flow averaging twice as much
as that of the northern rivers. This is
due. undoubtedly. in large part to the abb
sorpent power OF the sandy soil; but a
rivers shows that the cedar swamps con-
tribute largely to the result. Should these
be all cut Off the streams would certain
ly suffer and become more unreliable.
The conclusion of Mr.. Vermuele's inter-
esting paper is as follows
CATCHMENTS DISCUSSED.
1t will be seen that as to cultivated and
forested attachments our ~gaugings indi-
cate the same total run-off for a given
rainfall, but a much more uniform dis
charge, fewer floods and shorter dry
periods on the forested areas. Forest
streams are consequently more valuable
and reliable for power, and for water
supply they require less storage capacity
to provide for a given daily diaught
The waters are also much less likely to
become muddy or otherwise contamina-
ted. The worst condition of all for a
catchment is barrenrsess. Barren earth
is a non-absorbent. The water soon fails
to penetrate 1t and oxidizes its fertilizing
constituents. Heavy rains run over the
surface, wash off all the loose materials,
and barren conditions once begun per-
petuate themselves. There is always dam
ger of such conditions when slopes or
other areas unfit for cultivation are de-
forested. and there is special danger
where forest fires are prevalent. There
are a few small red sandstone areas in
New Jersey now in this condition, where
the streams dry up for weeks In success,
sion to become torrents when the rain
fals in considerable quantity. Compared
with barrenness, cultivation is harmless
to the stream. Our end, therefore, should
be to keep all ground unfit for cultivation
clad with forest.