Memphis daily appeal. [volume] (Memphis, Tenn.) 1847-1886, 1882-03-29

generally does somewhere between extremes.
/ So it seems to be in hydraulics as applied
to the Mississippi river. Unfortunately
| there are levee men, outlet men, lefty and
cutoff men, each distinct school, and each
with large following. But few and l1ne
some are the eclectics in river matters. Yet it
seems to me that any perfect system would
naturally embrace a modicum OF each OF
these systems, and that such an adjustment
would be natural, consistent and practicable.
In former article | ventured to say that
the problem 10 be solved embraced two
things: 1) Prevention of a maximum rise
of water level; ~ protection against
much of a rise cannot be prevented.
took the position that the prime factor OF
prevention would be increased
VELOCITY;
that a probably effective adjunct OF a system
that primarily looked TO increased velocity
would be outlets, and that natural but sec
ondary adjunct would be private levees-iso-
lated acknowledgements and located
SO as to afford the required protection OF
particular exposed sections, and in some in
stances SO located as to facilitate the great
work intended to be accomplished by cutoffs.
II is a singular fact that wide and thorough
as the discussion has been, and diverse
al the conclusions, the very arguments
used 10 opposition to cutoffs have afforded 10
those who advocate outofls all the support OF
their theory that they desire. To illustrate
this singular fact, We, the cutoff men, say
that cutoffs will increase the velocity of the
river current 10 such degree that the water
which now goes into the overflow viii de-
scend within the river banks. The opponents
of cutoffs reply, that 10 straighen the river
by cutoffs will so increase the velocity az to
impede navigation, etc, thus admitting all
we imagined they considered doubtful, the
practicability OF Increasing velocity by cut
offs. Then. levee men claim for the levee
system that it would confne the river within
a narrow channel, and thus increase velocity,
admitting 8n important object TO be attained
by the levee system to be increased velocity.
Then outlet men protest that velocity is not
affected upfsvorably by outlets. So, sum-
ming up
THE ADMITTED TRUTHS,
we have from the opponents OF the cutoff
system much that is required in a demon
stration of its practicability; that is to say,
they admit that cutcGs will increase velocity
to degree far beyond any degree required,
and that velocity is an important factor in
any plan looking TO the lowering of the
water level. / have, through the courtesy OF
Major Benyaurd had access to official maps
which show on large scale the course of
the river from St. Louis to the gulf L have
counted the abrupt bends, measured the dis
tances across each, as shown on the map, and
have also consulted standard authorities as
to the depth and volume OF water, and its |
velocity at high tide. / therefore write now
with more confidence than formerly, and |
feel quite confirmed in the correctness of The |
opinion herein expressed. propose now to |
show two important facts:
Fiyt-That with very moderate increase in |
the velocity OF the river current, water that
now constitutes the overflow womb pass down |
within the river banks to a point which it might |
be necessary to use as GdJuncts, levees, or cutos,
second-Thst the cost of all cutofs necessary 10
affect this object would be far under that OF
complete system of leyees.
The average width of
THE RIVER, BETWEEN BANKS, |
from Cairo to the gulf is $500 feet; its aver
age depth at high tide is sixty feet; its veloc-
ity at high tide about four and a-half miles
per hour. The territory covered by over
flow is about 10000 square miles, or, say
width Of twenty miles on each side of the
river, and the river rises this area at
high tide at the rate of one inch in twenty
four hours. This item OF overlooked terri
tory is considered exaggerated, but | desire
to so state it, with view TO more certainty
in the conclusions arrived at. Now, sup
pose the river to be at high tide, and rising
over the OVERT Jwed area at the rate of one
inch in twenty-four hours; then, running a
distance OF 30 miles in twenty four hours,
it adds one inch depth to the water over an
area 120 miles in length by forty miles in
wiith--or 1900 square miles-in twenty-four
hours. Now, suppose that, by some means,
The current of the main stream isso aeceler sted
that it shall run l35 miles in twenty four
hours, or fifteen miles further than now;
then we have volume of water passing !
down within the banks fl teen miles long,
$500 f-et wide and sixty feet deep, which
now, and without such accelerated velocity, |
ioes not pass down, but does pass into the
1verfowed area. This volume of water |
would be about ten square miles, sixty feet !
ieep-or 700 square miles, one inch deep ]
y hich would cover 2l00 square miles more
han is now covered by daily rise OF one Z
nch. But if the rise should be greater the
7elocify might be greater also, and this, too, l
within limits that would not affect naviga-
ion For suppose the velocity should be
to six miles per hour, then {
THE DAILY DISPLACEMENT
lue to increased velocity would be of an :
mount of water that would cover an area of
bout 5000 square miles daily, which would :
over the whole overflowed surface within
ach days outflow at the rate of about four
inches per day; and still with this more than
equired increase of velocity, it is not likely
hat any one Will be found TO say that such
increased velocity would seriously impede
navigation. 1t would be Just here a peril
lent iuqllry Can the velocity be so gradu
ted by cutofis as to attain the desired rate
nd not produce such a wild and Tuinous &C '
tltTdllOn as 10 JHlptuS atlOhJ oDl | :
he banks and carry destruction in its track? )
[ can only be answered, that no cutoff made d
o this date has caused such results; and 1t +
Gems very reasonable that by careful pro /
ression and systematic use OF the means of
celebration, the required rate of current-how I
nay be accurately attained, for. beginning
With one cutoff, the number may be fixed,
xperimeu:ally, by continuing the system up
0 and not beyond the number found neces- @
airy to establish the velocity required. The
ffieisl map in the Office of b
MAJOR BENYAURD SHOWS
weniy three abrupt herds in the river from |
oint short distance above Cairo to the gulf.
o cut channel across each of these-an ag- !
regate of fifty miles-would make the river
ute direct in its flow from the point above
afro to the gulf, and this would shorten the
is, ance about 240 miles. | will suppose
hat to attain the required velocity it will be
to make, say one-half of these pos
ible cutofs. These would be an aggregate
sDgth OF twenty-five miles. Now, with these
alta, will compare the cost of the two
ystems, viz: All levees and no cutoffs, and
utoffs with leyees from point about, say
lightly miles above New Orleans to the gulf,
lakipg no estimate for outlets or jetties, but
onsidering them as possible and available
djuncls to the system, which is primarily
ne cutoff system. River men say that ordi-
arily a cutoff will carry the river through ii
properly located and cut through depth
thirty feet and width of $50 feet. Such
channel would contain about 100000 cubic
eet of earth to the mile. This, at thirty
ents per cubic foot, would cost $4,000 per
lille; or for twenty-five miles, the total length
cutofs required, the cost would be S., $780,
90. Now,
WE WILL SUPPOSE
nat the increased daily flow OF water due
accumulation would cause a rise Of the
ater-level for distance of $50 miles above
he gulf. Here we would begin to raise o,
wees TO prevent an overflow of the lowlands
that region. We estimate, then, for a "
wee on each bank from a point, say eighty 2
lilies above New Orleans 10 the gulf-esti- \
latirg for Ievees fifteen feet high, twelve
eel top width and ninety feet base-that the !.
,tal quantity would be 10000 Gu bic yards lie
er mile, or at thirty cents per cubic yard, 10
I5, GOO per mile; or for 300 miles, the total al
pgth, an aggregate cost of S13,000,O0O.
his amount for levees, added to the cost of OIL
.cA-. toll NJ / G