Omaha daily bee., 1902-04-13
FLOOD DANCERSO THE WANE
Possibility Of Overflow in Great River
Valleys Considered Remote,
EFFECT OF RECENT IMPROVEMENTS
sixteen Thousand square Miles of
Flood Country safe
Farmer" Dunn's Cheer
ing observations,

Copyright, 1902, by e. B. Dunn.)
one-third Of the total area of the
United States is brought at periods Of
unusual atmospheric conditions. such as
excessive rainfall or drouth. under a stress
either Of flood or water famine. or the
two conditions the flood causes by far the
greater loss Of life and property.
During the spring season. occasionally
beginning as early as January and ter
minating as late as July, the Industries
located over this extensive area are con-
fronted at one point or another with an
impending danger Of food that partly or
wholly devastates the country for miles and
renders homeless thousands of families. II
not causing loss of life, to say nothing Of
the enormous financial loss.
For many years there was a firm opinion
held by the most eminent Of scientific men
that the melting SHOWS throughout the
basins, mountainous districts and the head
waters Of the tributaries to the great rivers
were the direct cause Of freshets and foods.
There must be some excuse offered for
this line Of reasoning, which was evidently
a conclusion drawn from insufficient or In
correct information regarding the depth
OF snow usually covering the ground at or
prior to the flood seasons and the volume
Of water produced thereby flowing into the
tributaries of the rivers. 1t has only been
during the last fifteen or twenty years that
reliable data on this point has been OBJ
tainable. Even today 1t is dificult to con-
vince some minds that melting snow is not
the cause of floods.
One foot in depth Of ordinary moist snow
over a foot square of surface, when melted,
equals about one inch of water, SO to create
floods from melting snow would require a
depth Of many feet on the ground at the
opening Of spring. The records show that
the snow that falls during the winter
months melts or evaporates within a very
short time, 30 that at the beginning Of
February, throughout the upper Mississippi
and Missouri valleys, there is. from actual
measurement on the ground. an average Of
about seven inches of snow, while in the
mountainous districts of the northeast the
average is less than half a foot. In the
New England districts this may be in
creased by three inches. During February
the depth constantly dlminishes, and with
the rising temperature of March the snow
in most sections disappears. Snow, then,
is not the principal factor in causing foods,
nor is its influence in producing or aggra-
waiting food conditions to be considered,
when, as the records show, the snow
throughout the headwaters of the Missis-
sippi and Missouri rivers disappears fully
one month before the rivers are open In
those districts.
The question then arises, What is the
cause of floods?
Course of Spring Storms.
Shortly after the winter s~olstice the low
pressure storms which pass in from the
North Pacific or find a birthplace in the
northwest travel eastward over the north
ern states and out the st. Lawrence valley.
They are preceded and attended by unsea>
sonably high temperatures and excessive
rainfall. The ground still being frozen,
little or none of this heavy rainfall perco-
lates the soil, but flows of the hard
surface over the drainage system into the
tributaries. The result of these early heavy
rains is most noticeable in mountainous
sections, and is evidenced by the February
rises In the Allegheny, Monongahela, Ohio.
Tennessee and Cumberland rivers. The
crest of the early flood wave does not
usually pass Cairo into the Mississippi
until some time In April, at which time the
high water from the Arkansas and Red
rivers empties into the lower Mississippi,
and the latter river usually reaches its
highest point.
AS soon as the ground softens sufficient
for the heavy spring rains to percolate to
any depth the floods in the mountainous
districts begin to diminish. In advanced
seasons the floods come earlier and in de-
layed seasons later.
Are Floods DiminishinRf
Heavy spring rains are probably not d.
minishing in frequency, and it is beyond
the power Of man to control the elements
or curtail the water supply from this cause,
but 1t comes within his province to modify
materially the disastrous effect Of floods by
keeping the o-ver-abundance Of water within
its channels. This is what we have done
by our system Of levees along the Missis-
sippi.
Andrew Elliott, surveyor general Of the
United States in 1903, in his report for that
year, speaks OF the recurring floods in the
Mississippi. river. From this 1t is evident
floods were more or less pronounced
throughout the valleys Of the great river
systems from the earliest periods.
The building of the first levee was COM
meneed with the founding Of New Orleans
in 1918, and was 5,400 feet long when COM
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