Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1881-01-31
THE RIVERS AND THE RAIN.

Gus. It has commonly been held that if
ever the Sacramento, American, 1uba,
Feather and Bear rivers should be full at
the same time, it would be impossible for
the Sacramento to carry its flood waters,
and that it would inevitably break out of
its banks, and cause an inundation perhaps
more disastrous than that of 1862. This
theory seemed to be strengthened by the
fact that in 1878 the highest water ever
known in the Sacramento at this city was
reached at time when the American,
Feather, Yuba and Bear rivers were COM
paratively low, and when there were many
extensive breaks in the levees and banks
both above and below Sacramento. twas
argued consequently that if so high
stage of water was possible under
these circumstances, the addition to
the volume of the Sacramento OF the
flood waters of the American and the other
rivers named would necessarily produce a
deluge against which no defense would be
of any USE But in the late storm all the
conditions supposed to imply great flood
were fulfilled together, and yet there has
been no flood, and none is threatened. The
Sacramento has actually fallen short by
several inches of the food hight of 1878,
and yet it is carrying the full volume of
all it's tributaries, and this without having
broken its banks to anything like the ex-
tent that it did in the previous year. 1t is
evident that popular apprehension has been
at fault, and in what direction was shown
by Captain Eads when he was here last
summer. The truth is that, paradoxical as
it may appear at first sight, the more water
there is in river channel the easier it will
be carried. The problem in fact is one of
velocities. When the Sacramento, in
1878, carrying little more than its own
flood waters, attained so great hight, it
was because of, and not in despite of, the
numerous breaks which were made in its
banks. These breaks permitted so much
water to flow off as to diminish the
velocity of the current, and conse-
quently the discharge capacity of the
stream, and through this paralysis
OF the current the water was enabled as it
were to pile up in the channel until it
reached an alarming height. But when,
as now, the full volume of the American,
the Feather, the Yuba and the Bear rivers,
are poured into the Sacramento, the result
is to increase the velocity of the current
proportionately, and to augment not only
the drainage capacity but the securing
capacity of the river. OF course there must
be limit to this process. If fresh floods
were poured down all the tributary
streams, point would be reached at which
the increase of velocity could not keep pace
with the addition to the volume, and then
the river would break its banks and spread
itself over the country. The determine
ton of this point must depend principally
upon the degree of sediment carried in
solution by the river, for this sediment pro-
duces friction which at certain stage
would limit the velocity of the current
There is very important lesson in this
experience, and it bears directly upon the
engineering works, the continuance of
which is now being debated by the Legs
lature. 1t has been shown that the theory
of Captain Eads was sound that the way
to make the rivers carry their flood waters
is to increase their velocity and confne
their channels. Their velocity may be
increased in more than one way. We
have just seen it done by increasing the
volume Of water to be carried. 1t may
also be accomplished, however, by dimin-
ishing the amount of sediment to be car
ried, and this is what the brush dams are
intended to do. Velocity may be increased,
in other words, by increase OF momentum,
or by diminution OF friction. Nature is
at present employing the first method, and
the State Engineer has adopted the
second, because it was the only one
within his reach. We are now made to
perceive that the way to make river carry
its food waters is not to divide them.
| That method checks the velocity of the
current and disables the stream from doing
full amount of discharge work. This is
what happened in 1873. The Sacramento
was then scarcely confined to its banks,
and as result the water rose higher than
it had ever done before, though it must be
perfectly evident that the river was not
then carrying half as much water as it is
at this moment. The secret of safety
therefore is plain enough. 1t is to keep
the river IN its channel, and so to deepen
that channel by promoting securing that
there will be as little friction as possible.
II all the debris could be kept out OF
all the tributaries of the Sacramento
there can be no doubt that it would be
able to carry almost twice as much water
as now, and if even part of the debris
is held back, it will, if well leveed, in a
short time make for itself go deep chan
mel that all danger of destructive floods
will be agerted. This demonstrates the
scientific accuracy OF the methods which
have been recommended by the State and
consulting engineers, and which have been
to small extent applied. OF course it
would be hopeless to expect that the Sacra-
mento could be kept within its banks, or
that it could co its duty, if DO further
attempts were made to impound the
heavier debris in the mountains.
THE WHEAT QUESTION.
Some San Francisco commercial papers
have questioned the accuracy of the ssti-