Telegram-herald., 1890-06-06

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HatlslA- Pro1lsaa' = becomes HsosssAfy
q stars t1s grscLsG- Il dolug ia q
~l4 bs fezRd - subeiF1s lsss-E l2ts
ss sFsrzl t4etcFs, sizt
J. 70 GIPross l4yigall0u
ie Pf-se-t --s-E 4et-S2 - rssGlAt-As "a
cOod 4-s0n-rse.
: u rec--lla -@as ssr As,ricsltzrs.
Ths D. 3 0essrnmsas. 1nasr TIE
clause q tLs Constitution rec 2irtng q
= rsgalzts commerce las !2rlsdletioa
over E4sig45ls rivers. a1d iu - e-oEts
- improve them nay s1scats woEks
Unieh sIll Indirectly zEset. bensnei.llE
- otherwise, The ether tso objects.
Ihe second falls ~ the lgr of ths
residents Ia tie several States OF com
tiss ordering Ga the river. who. shea
they ha1 their property And lives IL
daazsrsd. naturally erect b4rFleads 20
keep sat ths foods. In this wsy De-
tween hfty and sixty millions have
been expended IN building levees OF
whieh only 2bout - COO 90 have been
appropriated by Congress.
The third section Is incidental and
cannot nov be considered. The problem
as it relates 10 the GOyernment is,
therefore, practically restricted 20 the
question OF improving navigation, and,
since during high stages, there Is an
abundance OF water for this purpose, II
must oe limited 10 a method which will
spply 70 IAs low water stage without
injury under other conditions
As stated, the lsyse system 10 the
outgrowth OF the instinct for self
protection. It has grown up spon-
taueously wherever large rivers flow
over allUVisl plains and there Is, there
fore, natural and deeply rooted con
victlon shat 10 Is the proper remedy.
Bat, ct the same time, history furu-
ished numerous proofs that the beds of
streams SO confined are continually ris-
ing Witness the well-known instances
OF the Hoang Ho, Danube, Pc, Gangss,
Mississippi and many others, all of
which sre said 10 flow IN ridges Why
this should bs so will be better under
stood when 10 Is considered that tho
general operation of natural agencies Is
TO carry all mobile materials into the
valleys aud streams, and unless the
sediment elected from the mouth be
equal IN amount 10 that injected by the
aIiusnts there must be residual de-
posit IN the bed; otherwise all the
alluvion carried in must be transported
20 the gulf or be left stranded on tho
fats Ii the bed be unconhned by dikes
or levees, then most of this mud and
silt which is carried in AT food stages
Is spread over the swamps and banks
which are submerged at high water and
the bed receives a much smaller per-
centage Of deposit Aad consequently
rises more slowly.
But the elevation of the bed involves
q corresponding raising of the levees at
en- increased ratio of cost and with
greater risks from erevasses, which ul-
timately occur.
To understand the remedies to be ap-
piled 10 is necessary 20 consider the
phenomena attending the flow Of water
under the influence of gravity. A fluid
flowing down an inclined plane under a
constant force will move with acceler-
ated velocity. In the case of a river,
the velocity will soon become sufficient
20 move the soil OF its. bed, which II car
riss and rolls along until it has built
submerged dam, which checks the ve-
locity. In passing over the down stream
slopes of this bar the water acquires q
fresh impetus and the operation is re-
peated, thus the bed becomes a success
sion of shoals and pools. These are ag-
gravated and modified by variations in
width or area of cross-sectiOn, since the
velocity for agiven stage varies inverse
~ on the section, so that at low water the
lesser velocity is IN the wide sections,
causing deposits in the pools, and the
greater velocity at the narrow sections
causing scum. At high water this pro-
cess Is reversed-the pools at the bends
are deepened and the bars built mp,
hence il follows that treatment de-
signed for low water stage is not good
for high water and the building of lev
ees for rectiac Itions OF the high water
channel and for protection can have but
a secondary effect on the low water
channels.
1t is the low water stage that must be
improved for navigation, and since the
greatest injury is produced by differ
ences of velocity in successive sections
the object Of the improvement must be
to establish uniformity by equslizing
sections /. e.. when abnormally wide
the river should be contracted. This
was she we'll defined policy adopted by
the Commission of 1880 and under which
thesystematic improvement was started,
yet We hnd, a few years later, the policy
ot tho Commission had changed with
its personnel and the principal works
were directed towards increasing the
resistance OF the csving banks by cover
ing them with rsvetments But there
is not space 20 discuss the notifications
OF plans which are nevertheless Of
great i'm portance TO the success of the
works.
From what has been said 10 will sD-
pear that the best treatment IL one
which will provide equalization Of ve-
locitiss. which are dependent upon cross
section and volume and stage This in
wolves a reotiacatiou and canalizsti0n
of the low water channel. with provis-
ion for DETECTING some Of the tributar-
les az certain stages into lateral chan
nels and for permitting the rapid escape
BY weirs or outlets of she foods Ia
fsctit must provide q means OF restrain
ing the low water and facilitating the
escape of ths high water volumes.
Principles. generally recognized as
sound and as applicable 20 large - to
small rivers This object revetting
~i,l not accomplish. yst there srs local
iti-s where it may be- justified 70 pro-
tect property have thus endeavored
o. sketch the general features Of plan
Of Improvement applicable % this
great river problem Il viii be seen %
involve ths adaptation q diTerent
methods a. different places and under
variable conditions which eau only hs
aetern ned hv the engineers IN charg-
az the otaItr. WORKING under = gen
sra rar a1l fhaor~ ~ ir-u-1va--e er