Evening star., 1902-04-12
Improvements Made Dimin-
ish River zRisings.
FUTURE OVERFLOWs s
CHANNELS AND DRAINAGE MAY
ENTIRELY PREVENT THEM.
Devastation Of Forest Lands is Cause
but Recent Methods Snow
the Cure.

One-thlrd of the total area of the United
States is brought at periods of unusual at
mospheric conditions, such as excessive
rainfall or drought under a stress either
OF flood or water famine. OF the two con-
ditions, the flood causes by far the greater
loss of life and property.
During the spring season, occasionally be-
ginning early as January, and terminal
ing as late as July, the industries located
over this extensive area are confronted at
one point another with an impending
danger of flood that partly or wholly dew
astates the country for miles, and renders
homeless thousands of families, if not caus-
ing loss of life, to say nothing of the enor-
nous financial loss
For many years there was a firm opinion
held by the most eminent of scientific men
that the melting SHOWS throughout the ba-
sins. mountainous districts and the head
waters of the tributaries to the great riv-
ers were the direct cause of freshets and
floods. .t:
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 food seasons and the volume of
water pTOuuCeu thereby moving INTO the
tributaries of the rivers 1t has only been
during the past fifteen or twenty years
that reliable data on this point has been
obtainable Even today it is difficult to
convince some minds that melting snow is
not the cause of floods.
| One foot in depth of ordinary moist snow
| over 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 fails during the winter
months melts or evaporates within a very
short time, 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 fnches!" During February
the depth constantly ditninishes, and with
the rising temperature of March the snow
in most sections disappears. Snow, then, is
not the principal factor In causing floods
nor is it's influence lin producing or aggra-
waiting flood conditions to be considered,
| when the records show. the snow
throughout the headwaters Of the Missis-
| sippi and Missouri Trirers disappears fully
one month before the rivers are open In
those districts.
The question then arises. What is the
cause of floods 2sr, >,
a1ter the winter SOlSt1ce tne low
! pressure storms which pass in from the
| North Pacific or find a birthplace in the
northwest travel eastward over the north
crn states and out the st. Lawrence valley.
| They are preceded and attended by unsea-
soHably high temperatures and excessive
| rainfall. The ground fstff1 being frozen ut
| tie or none of this heavy rainfall percola tes
| the soil. but flows off 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, Ten
! nessee 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 the ground softens sufficient
| for the heavy spring rains to percolate to
| any depth the floods in the ountainous
districts begin TO diminish. In advanced
| seasons the floods come earlier and in de-
| lay ed seasons later. .'
Are Floods Diminishing.
! Heavy spring rains probably not di-
| 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
py keSpliS lic oNet VI water
| within it's channels. This is what we have
| done by our system of levees along the
| Mississippi.
| 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. it 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
| menced with the founding of New Orleans
| In 111S. This levee was J,4GO feet long when
! completed. In 1T2S levees extended twelve
| miles above and thirty-five miles below
! New Orleans. Even these were found in
| sufficient to restrain the flood waves pass
! ing down the lower Mississippi, and in 1884
| orders were issued to property holders
| along the river to build levees under penal
| ty of confiscation.
The extension Of the levee system con-
| tinued by private and state appropriate
| until the national government found 1t i'm
! perative to give aid to control the father
| Of waters and placed the solving of this
| great problem in the hands Of commits
| sion. This was done in 1879.
| D. The Mississippi today is confined to It's
| channel by massive embankments, which.
In some places, are reinforced b va second
or emergency embankment. The latter
! forms an excellent protection In case of a
break or small crevice. The water Is then
| held in check and seldom finds its way
| through the second embankment. These
| leFeeS extend from the mouth OF the Mis-
| sfssippi to Cairo; the rivers above the latter
point seldom overflow their banks. The up
per Missouri and Mississippi occasionally
have ice gorges. which frnpound the water.
and when the break comes freshets over a
limited section of COUNTRY occur. The great
est Inconvenience In the Northern region of
| the great rivers is drought instead of flood.
| Great uneasiness has recently been felt
| throughout the headwaters of the Missis-
sippi because it was thought the tributaries
to that river were running dry There
need be no serious apprehension, however,
for there has been NO change in the geo.
| graphical conditions Of that country to
| bring about a diminutfoh OF the water sup
| ply. et'.-ls <
The cutting away of trees and shrubbery
in mountainous country renders the val
| leys more liable td food. This does not,
| however. apply to- the open watersheds,
where there is an abundance of earth and
channels and reservoirs, prepared for the
In the mountainous, districts 1t will be
found more difficult to Iestrain the flood
| wave than in the open country: relief. how
ever. may be afforded by building dams
| and impounding a portion Of the surplus
| water; such a restraining effort may ma
terially modify an otherwise disastrous re-