The morning news. [volume] (Savannah, Ga.) 1887-1900, 1890-05-25
TANNING THE MISSISSIPPI.
What a Government Engineer Has tc
Say About the Matter.

Say About the Matter.
NEW YoRR, May pa am asked to make
brief statement of the plans proposed, and
of the one adopted by the government, for
the control of the Mississippi river. It is
the main trunk of the river, below Cairo, to
which the at ention of the public has lately
bee drawn by the recent overflow. It is
TO that portion of the Mississippi, that a
statement, in order TO be brief, must be
limited.
The functions of the river are two-fold.
1t is primarily great drain provided by
nature to carry OFF to the sea the rainfall Of
half continent" Secondarily, it is a
great navigable waterway, which is utilized
Uy man as a highway of commerce. In its
average condition it serves both purposes
we'll. But it is subject tn extreme stages
of high and low water. On the one hand
the quantity of water is at times greater
than can be carried within its natural banks
and there is an overflow, or food, which
square miles - of extremely fertile
land, to the great injury of the
people occupying it, On the other hand, at
the lowest stages, the channel is obstructed
by bars, and the depth is not sufficient for
the most economical navigation. 1t is the
general experience with rivers that as their
valleys are brought under cultivation and
the rainfall Is more rapidly precipitated
into them through improved drainage. the
variation between their extreme stages is
increased. that is, that the high water be-
comes higher and the low water lower. The
Mississippi appears to be no exception in
this rule. 1t is probable that if left to itself
the overfiows will become more disastrous in
the future, and the low water navigation
worse.
Congress has re -ognizsd its responsible ty
Tor the o c>nditi of lie river as a body
of navigable wat r. but not as drail it
has appr, pr. a5ed La ge sums of money Tor
| ire improve men, nut witt TIE provi-o
That no portion of this appropri uion snsll
be expended to repair or bui levees
the purI oSe OF reclining land or prevent
l injury 10 lands or pri ate property by
overflow" The improvement of the low
water channel for pup se' of navi cation is
the sole and exclusive object of tia law
IT Levels can be shown 10 have a beneficial
effe t upon Q low water channel taey may
be used, o herwise not.
The bottom Ian Is Of the Mississippi below
Cairo constitute vast alluvial plain some
| nifty or sixty miles wide and nearly 800
miles long, made up of the spoils from high
ground which the river has been bringing
down for countless centuries. Through
this mass of debris the stream flows in tor
tuous course in channel of its own forma-
ton. The length of the valley is less than
600 miles; the length of the river is nearly
100 miles. The dimensions of the channel
are those which the river has habituallv
required at times when it is most
powerful and therefore best able to
excavate channel, that is, at
the higher stages. The difference in level
between the highest water recorded and
tue lowest is at Cairo, tifty-three feet
Lower down the difference is less, but still
very great. At high water the river is
moving ocean, carrying vast quantities of
silt and possessing great building as we'll as
| destructive power. At low water the bed
is monotonous waste of yellow sand bars
| through which the channel wanders tortu-
Gus. shallow and shifting, with course
different from that of the high water
annel and much less direct. 1t is evident
| that the higher stages exert a controlling
influence upon the shape of the bed, and
| consequently of the low water channel
The quantity Of water flowing at the low
est stage is sufficient to provide for all the
needs OF navigation, but at many places it
is In bad shape, being spread out in thin
sheets mile or two wide. Wherever the
surface width does not exceed 5000 feet,
t1e depth is sufficient and the navigation
is good. The plan of improvement adopted
by the government contemplates the con-
centration of all the water at low stage ia a
cha mel having surface width of about
5000 feet. In dong this the building power
of the river is utilized, new banks being
built up closer together by means
of cheap silt-catching devices, and
large areas being reclaimed from
the river bed. At the same time its scour-
ing power is utilized by concentrating its
flow over a moderate width. But as the
low water channel is often obliterated at
high water, and moreover, as the greatest
securing power upon which the deepening
of che channel depends is found at high
water. 1T is not sufficient to control the
river at low water only. The width at high
water also must be reduced and the general
location of the high and low water channel
must be made to more nearly coincide than
they do in nature.
The question of what stage should prop
erly be considered high water in this con-
nection has led to some differences of
opinion among the engineers. The ma
jority of the Mississippi river commission
hold that the highest stages ever reached by
the river must be included. A minority of
the commission hold that it is not necessary
to include the exceptional stages of flood,
but only the habitual stages of high ater,
such as are indicated by the general level of
the ordinary high water banks The ma
jority find that levees are necessary for the
Improvement of the low water channel;
the minority thinks that under the law as
it stands they have no right to build them
Butthey are all agreed that as a protection
from overflow the levees are necessary and
practicable, and, in fact, the only means of
redemption for an important and extensive
section of country. The experience this
year in the Mississippi valley has given
them greater confidence than ever in that
system. That in the extraordinary combi-
nation of furious gale and rainsto-m COM
ing at the very top Of the flood, which was
the highest on record below Red river there
should have Teen breaks, is not surprising.
But the facts exist that out of about / 100
miles of levees there were only about
four miles of breaks Chat is, if the length
of all the breaks be added together
the aggregate will be only four
miles, and that whereas in 1SS2-the last
great fiood-all but about 10 per cent of the
cultivated ground of the valley was sub
merged. This year fully rs per cent. OF it
was protected. furthermore, this year the
discharge past New Orleans was nearly so
per cent greater than in 1882, while the
/ water surface was only sixteen inches higher
there this year than in 1882, showing the
fallacy of the objection raised by some to
| levees, that their nights must be inordl-
nately great. The levees, as constructed.
are far from perfect They are the result of
local efforts supplemented by national aid.
? They have been laid out and constructed
under a variety of systems More perfect
| construction and more powerful control in