Sacramento daily record-union., 1881-02-15
rHs CARRYING CAPACITY OF RIVERS.

! bounds, and the Iact that the sacramento
has overhowed its banks for a number OF
years in seasons of exceptionally high water
appears to justify the "common- sense mo
ton. But ideas which are formed without
competent knowledge Of the natural laws
which govern the phenomena observed are
usually more apt to mislead than to bring
the observer to right conclusions. 1t Is
not until Science comes forward and ascer-
tains exactly how phenomena are pro-
duced, and the character and limits OF the
] laws which control them, that the truth is
arrived at. Mankind by the exercise OF
their unins.ructed vision reached the be-
| lief that the earth was fiat, that the sky
was dome resting on the edges of the
earth, and that the planets were insignifi-
cant specks fastened to the roof of the
dome much alter the fashion of broad
headed nails. Common sense, in fact, has
in all ages been the sponsor for great
many nonsensical beliefs, and therefore in
discussing question like the carrying ca
pacity of rivers it is necessary to put it
aside altogether, and to trust entirely to
the Investigations of Science.
Now Science teaches us that the carry
ing capacity of a water channel does not
depend upon its breadth, but primarily
upon the amount of force which is brought
to bear upon the water to be impelled
through it. The quantity of water that
can be carried in a given channel depends
upon the velocity impaired to the current,
and if the velocity can be indefinitely in
creased there is practically no limit to
the volume of water which can be
carried. To obtain a high velocity there
must be a sufficient surface slope to the
current, or in other words a sufficient fall
per mile and there must be minimum
of friction. Friction is produced by the
character of the channel, and by the sedi-
ment carried in suspension. The form of
channel which offers the least resistance
to the current is the semi-cylindrical
form. If then this form can be main
tanned if the channel can be straight
ened and if the current can be made to
deposit the heavier part of its sediment,
high velocity can be obtained, and a
larger volume can be carried.
1t is possible for river to double its
discharge capacity without materially rails
ing its surface level. In such case the
river is carrying twice its ordinary volume
of water, and it is doing this by doubling
its velocity. Increase the velocity still
further, and the same channel may be
made to carry three or four times its origi-
nal volume, and in fact there is no limit to
its carrying capacity but the several ele-
ments of friction, or resistance, already
spoken of. 1t has been asserted by the
engineers, and notably by Captain Eads,
that the Sacramento could be made to
carry five times its ordinary volume with
out difficulty, provided that the frictional
resistance is diminished by Strengthening
its course, aad holding back its sediment.
In fact, Captain Eads has given it as his
opinion that if the river channel is cor
rected in accordance with the plans already
drawn, it Will carry whatever volume
may at any time be poured into it, without
overtopping its banks.
When, however, the levees give way,
and the river flows out over the adjoining
country, the velocity Of the current is at
once checked, and it begins to deposit the
sediment which it previously carried with
ease, thus raising the bed and increasing
the general difficulty. The fact, already
demonstrated during the past high water,
that the highest stage occurs after the
occurrence of extensive breaks in the
levees, eonclusively proves the truth of
this. This dispersion of the river checks
the current, diminishes its power, and thus
back up the water which comes down sub
sequently. During the present floods it
has been remarked by steamboat men that
in several places, both above and below
Sacramento, the current Of the river has
been running upwards instead Of down,
and at one point this strange phenomenon
has been found to extend over distance
OF four miles. This proves that the cur
rent has been completely paralyzed by the
breaks in the levees. 1t is also we'll known
that the flood waters which flow down
through the tules, and strike the Monte
yuma hills, are detected there, and pass
across the current of the river at Grand
Island, arresting it and backing it up for a
long distance.
All these facts point to the same COZ.
clusion. In food times the carrying ca.
pacity of the river is enormously dimin-
isbed by the spreading of the waters. Con-
fine the channel by raising the banks
throughout it's course; straigthen the
crooked places in it; force the current
above to deposit the heaviest debris by
erecting brush dams and it will be possible
TO prevent foods in the future, and to re-
claim permanently the fertile lands which
have hitherto been exposed to continued
injury from inundation. These are the
methods which science points out, and they
are every one based upon comprehensive
study of natural laws. What is needed is
to increase the velocity of the Sacramento,
and if that is done, as it can be done, the
channel will prove entirely capable of car.
rying the greatest volume Of water that
can be poured into it. This is not "com.
mon sense view, but it is what is very
much more trustworthy, namely, scien-
tifc view.
TIE CONDITION OF LEGISLATION.
We publish catalogue of the bills