Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1882-03-04
LETTERS FROM THE PEOPLE.
Phenomena of Floods.

10 the Editors OF the Appeal:
The phenomena of floods are so mysteri-
GUS, and opinion on the subject so varied,
that it has become allowable for any one
who has opinion of his own to express it,
Not claiming to be river man, nor indeed
at all scientific, / will venture an opinion as
to practical means Of preventing an over
flow of the Mississippi river. l will premise
that levees cannot be relied on to prevent an
overflow. First, because over a stretch of
thousand miles-through forests and over
trescherous beds-a continuous levee cannot
be kept intact; it will break or be broken
somewhere. Secondly, even if kept intact,
the river confined within its banks, and fol-
lowing the tortuous windings of the river
bed, will rise above any levee of practicable
hight Then the outlet system, though theo-
retically and scientifically considered very
plausible one, would be likely TO fail in
practice for the want of momentum OF
velocity, which can only be obtained
through channels in direct line OF
the river currents, and over beds of con-
siderably greater descending grades than can
be maze in the level and fiat country through
which the outlet channels would necess arily
pass. The conditions OF velocity of current
are depth and gravitation to lower levels
Both these conditions are wanting in any
proposed or practicable system OF outlets
through the fiat regions that intervene be-
any practicable or proposed initial point for
such a system. In practice it would be found
that a canal, say twenty feet deep, 200 feet
wide, and 100 miles long, with a continuous
fall of one inch 10 the mile, would carry off
the water at velocity so low that the volume
thus diverted from the channel OF the Mis-
sippi river would afford no appreciable check
to its rise. So it Is but a reasonable conclu-
sion that neither system, the levee or the out
let, or indeed both combined, can be relied
on az a preventive of overhows. But there
is yet another plan, which has some support
in the known effect OF the ietty system. and
that il TO straighten and deepen the river by
cut-UGa @nd n continuous system of ietties
The solution OF The Whole problem Is at
tanned the moment you find a system that
will increase the velocity OF the river cur
rent to such degree that the river bed will
afford channel for that volume OF water
that now leaves it and overhows its
shores. Reducing the problem to fig
ures and facts, for illustration: Sup
pose that by Strengthening and deepen
ing, or by either, the velocity of the river
current is increased so that it will move five
miles further in day than now at high tide;
then the increased volume of water kept
within river banks over the amount which
would otherwise move in the channel, would
more than equal all that now passes into the
region of overflow. Let US try the figures:
Five square miles Of water, one mile wide
and an average of sixty feet deep, would
cover $500 square miles one inch deep. Now
suppose that the area overhowed from Cairo |
to the gulf to be l0S00 square miles, then
the increase in the carrying capacity OF the
river channel would relieve the overflow of
one inch depth OF water over the whole area
of overflow in less than three days; or it
would control and keep within its channel
volume of water which otherwise, or as
now, would cover an area OF $500 square |
miles per day, or 10,SO0 square miles, the
full area Of the present overflow; IN three
days. Such a volume of water daily pass
ing into the overflow would produce and
maintain the greatest food ever known in
the valley. So l venture to suggest that the
thing to be attempted is, not TO meet and
keep back rise, but to prerent a rise of the
water level. The elements that enter into
the problem of prevention are depth and
velocity, and the factors would be ietties and
cut-offs, so adjusted and combined, that
while jetties would deepen, they would also
in their relation to cu;-offs, perfect a system |
of Strengthening, deepening and shortening
the river channel, with the natural and |
necessary result OF increased velocity and
increased capacity.