Brownsville herald. [volume] (Brownsville, Tex.) 1910-current, 1928-11-15
Nv CHARLES p. STEWART

nv 4
WASHINGTON. Nov. 10.-About a
third too much moisture has to flow
down the Mississippi valley in flood
time for the main channel Of the
Father Of Waters 10 hold-even
banked up. on either side. into the
highest. strongest levees which can
be built. with a reasonable pros
pect Of maintaining them.
This figure-one-third furnished
BY Colonel Ernest Graves. OF the
war departments rivers and harbors
board. is a great deal more than a
mere estimate. IL is based on care
full measurements. covering many
years.
The colonel. retired from the army
engineers. but still active in the
rivers and harbors service. is re-
garded BY the war department rs
its last word on all questions relat-
ing TO the country's w~atercourses,
natural and artificial.
His verdict is that the problem
Of Mississippi flood control--to
which Major General Edgar Jadwin.
chief OF army engineers; Colonel
Charles l.. Potter, president Of the
+lANsANriHVA IlNtE NUiifuASSiON anu
Carleton W. Sturtevant. civilian ex-
pert. have been delegated By recent
act OF congress 10 find an answer
u not impossible. within certain
limitations.
That is 10 say. Colonel Graves
does not argue that the floods can
be dried IN. He does contend that
they can be kept to areas where
they will do a minimum OF damage.
"lf." said the colonel, "the Missis-
sippi flowed through a groove in
the bottom Of a valley and tended
to overflow that groove. there would
be no way Of controlling ii: but by
confirming the groove between two
l~evees. as in Diagram l."
tThe colonel sketched it.l
"And il those levees.' he con
tinued. could not be made high and
strong enough to prevent the stream
from overlapping or breaking
through them-why. levees would be
mo- answer 70 the flood problem.
But in fact" explained the river
veteran. "the Mississippi flows
through a groove in a ridge at the
bottom of the valley. so that the
main valley consists Of two valleys.
as in Fig. ?. The river channel
traverses the height-of-land which
divides them.
"If a levee breaks. that valley is
flooded I'm marking il A in Fig.
3.
most or this area Is good land.
but there j. ant to be a strip where
- - l1u~auH sLus - ,ra.mI- Ill
a secondary river bed.
Let US have a map-Fig. l-in-
stead OF a cross-section Of the coun-
try. The streams main channel Is
between the parallel. winding lines.
The shaded portions are marsh
land.
I'VE have a snillway IN the main
levee at b Fearful Of A break
elsewhere. unless he relieves the
pressure on the embankment. the
engineer in charge opens the b
spillway. and r third Of the stream
pours out into the marsh. which is
no great loss-it j. only marsh land.
anyway.
but the marsh is diked. too. so
II does not spread. IL simply fol-
lows the low strips direction. be-
tween the walls Of the emergency
levee. and returns 70 the main
stream at C. to be passed out again
at the - spillway. maybe.
Suppose. however. there had
been no n spillway. and the Ieyec
had broken AZ 'E-the river would
have flowed out. an over the land.
as far ut any time liable to he trans
formed into a river bed. at certain
seasons"
But could not the main channel
be sufficiently protected 70 avoid
even the necessity for these ocea-
sional diversions OF a third. per-
haps. OF its volumer
Hardly" opined the colonel.
Such levees would have 10 be too
high 10 he dependable. Besides.
even though as the marsh. and
across the marsh. and still farther.
until rising ground stopped il.
Fig : illustrates how the system
should work. "F' is the secondary
channel-the relief channel. There
would not always be water in il. of
course-only at high stages Of the
river. IL might be farmed a little.
but IL must be recognized that II il
was they held. here would be dan
ger Of enfiltration through the soil
under the tremendous pressure. with
the constant risk that the water
would burst out. say al c. in Fig. 5
possibly far. far back from the
~levee."
"To speak Of A strip Of land on
either side Of the river a. being
rescued from the flood peril IS
hardly exact supplemented the
old officer. because il is not a con
tinuous strip. In one place there
may be an area on one side. in an
other place on the other side. de-
pending on the topography.
Roughly. to call II a strip. Il
would average 30 miles wide by 1000
miles long-enourh to be we'll worth
saving
IL is predicted that in 10 years
there will be one automobile in Ed