Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1880-11-17

the construction Of a machine capable Of perpetus
motion an impossibility. How impossible then, /.
1t for the river to transport immense quantity o
mining detritus without exhRusting . pert Of the
force which Is required 70 overcome the friction Of
It's led. VI the force necessary to do this be dimin
ished, slower currents must result the drainage ol
the valley be impaired, and the floods raised "a
greater hights
There are but two ways Of increasing the force Of
river. First, BY increasing its volume second.
by increasing the vertical space through which its
volume descends Ia given time.
Nature gives to all sedimentbearing rivers the
ability to increase their force when overtaxed by
their burdens Of sediment. This they do by de.
posting the excess In their beds, thereby raising
them and increasing their surface slopes or as It
is popularly called, their "fall per mile" An in
crease of this slope involves increase OF the verti
cal space through which the wafer falls and this in
creases the force and creates greater velocity Of
current.t This deposition in the bed continues
until velocity is produced sufficient to transport
the whole OF the sediment to the sea, after which
deposit ceases TO occur in it. II the filling the bed
of the stream in this manner be not sufficient to
produce the necessary current, the waters ex and
over the adjacent lands, and cover them With sedi
ment, until they OF sufficient hight to sustain
new channels OF the requisite slope.
WORK CT THE SACRAMENTO.
The Sacramento river ard its tributaries have
evidently been doing this kind of work for the last
score of ye,rs. Near the mines, we learn from Mr.
Halls Investigations the Yu0a now falls from an
increased hight Of 125 feet and that the bed Of the
Sacramento at Feather river is 20 feet higher than it
was formerly.
BY far the most i'm portant clement of resistanco
which prevents the rapid flow OF the waters Of the
vail-y, is the friction of the different chan
nels through which they move. Some idea
Of the magnitude Of this resistance may be in
ferred from the fact that nearly tenths of the
resistance OF weformed ships s the result of fric
ton between their surfaces and the water II we
can reduce this resistance in the river channels, We
can not only facilitate the discharge Of the floods
but We will have corresponding amount of surplus
rec TO excevate deeper in the rivers and to
transport the sediment.
FRICTIoNAL RESISTANCE.
The amount Of frictional res stance depends ,,pon
the extent OF the area in contact with the water
and arises from the mutual cohesion of the fluid
particles end from their adhesion to the su, faces
over which they slide. Hence, if q stream be ex-
cessivey wide the friction will be reduced by re-
Gucng its width, and an aeceleration of current
must result, although the surface slope may be no
greater than before II we use two pipes for drain
age, one being one foot in diameter and the other
four feet, each being the same length, and each
having the same head OF water, or SLOPE the frie-
tiona area In the Drger pipe will oe only four times
great it Is in the smaller one yet it will con-
tain sixteen times as much water. This is because
the surface in contact with the water, and which
causes the resistance, Increases with It's diameter
while its area increases with the square of Its danie
ter. The friction in pipes is therefore nversely as
tnetr QldmeterS. Inc 1OrU OF channel which Offers
he least frctional resistance to the flow of water is
'emi- i-cyndrlcai, and, in proportion the channel
departs from this form, widens and become fatter
his resistance increases and the surface slope has
10 be steepened to produce the velocity Of cur
rent. This stcepening of the slope is the direct
,ause Of the oyeIhows.
THE MAGNITUDE OF CHANNELS.
The magnitude of the channels of rivers flowing
through aluvia districts is determined by the size
of the foods that pass through them. At such
times the force Of the river snot only much greater
because OF the increased volume and SLOPE but be-
cause the ratio Of friction er unit Of volume is
greatly decreased hence, there is much greater
surplus OF force. This surplus increases the velocity
Of the current, AID gives it greater ability
port sediment, Ii the channel be too small at any
one or mors places. the surface above rises, and
sleeper slope is tbu9 made through the contraction
the current velocity is thus made greater there and
the extra amount Of sediment which can be then
ried by the water viii be taken up out of the ped
Of the stream, and thus II will be deepehed. As
this deepening progresses the slope is lowered and
the velocity reduced.
Friction is not only increased by the wiiening
and fa;tenng OF the channel, but also by lis sui
division. II VIC divide the water flowing in one
semi cylindrical channel into two equal ones OF half
the size must increase the slope OF each Of the
smalie- in the ratio Of u H. to produce the
same velocity because the frctions OF the two
smaller will he fiye-tTeliths greater than the
larger one. TO show that increase of slope
occurs from this cause on the Sacramento we have
only to compare the slope OF Steamboat slough
where the river is divided into two channels by
Grand Island with the slope Of the river above it.
The high water slope Of this slough is 81 100 of
foot per mile while the slope Of the river above and
below 1t Is only 43 100 When the enti volume g
made 10 flow through Steamboat slough, ~ Mr.
Hall proposes, lowering OF fully twenty inches in
the food hight at Sacramento can be confidently
looked for from this Improvement alone.
DIvIDING THE RIVER.
channels the increase of slope would be still greater
Ii it divided into four equal channels each hay
ing oneguarter OF the capacity in the main channel
the of the surface OF their beds would be twice
as great as that OF the main channe atd the slope
Of the surface Of the water would have to be doubled
in that part Of the river to produce the same ve-
velocity in them.
At Butte slough the water is divided into two
one Of viii h, viz, Sutter Basin, is OF
width, and, consequently. the frietional
The oiher is the main channel of the river and in
this the ratio OF frictiona resistance To the volume
carried IS also much greater, owing to the diminu-
ton Of the volume in It. This resistance is also in
this part OF the channels and the result is that the
rlver here falls nearly one foot Der mile from Butte
slough, through sutter Basin, TO Feather river,
while below Feather 20 the American, the fall is
only one-third as steep.
TIE FOLLY OF MULTIPLYING CHANNELS.
With such evidences OF increase OF slope which
follows the widening of the surface over
which the foods pass, the subdivision Of the
main channel into smaller ones, IL seems astonish.
ing that anyone can seriou4ly propose to give per-
manent protection against 5yerfows by multiplying
the channels through which the floods now struggle
10 reach the sea. Those who advocate such means
OF relief have vet to learn three OF the grand
est but simplest laws controlling the motions of
matter throughout every part OF the universe
They have yet TO learn first, that no atom OF sand
or u'u.c m ran t1y
motion except through the impulse of force sec
ond, that matter in motion must encounter the re-
distance of some other force or forces and third
that the relocity Of the matter depends upon the
amount OF force urging it onward, and tho amount
OF resistance retarding its progress.
Friction being the chief element OF resistance,
and this being greater and greater In proportion
the water is suhdivded, the advocates Of drainage
canals and other outlets propose TO increase the
velocity of discharge By increasing the friction
which retards that velocity; or, in other words,
they propose to reverse the laws Of nature.
EFFECT OF A oREvAssE.
As the immediate effect Of crevasse is 10 lower
the hight of tile flood IN its vicinity aud below it.
many persons i'm gine that natural artificial out
lets, by which part Of a rivers food volume is
drawn off, tend TO lessen the recurrence Of dfstrlc-
tive inundations.
This process would undoubtedly prove effective
il the waters Of the Sacramento were not charged
with an immense quantity Of sediment. To prevent
this settling on the bottom certain velocity of
current must be maintsined. Rivers which flow
through beds formed OF their own deposits almost
always have their waters charged with ali the sedi.
ment which the waite. will s.s.an. One Of the
dynamic elements Of the force OF tho riyer Is its
volume. II portion q this passed through the
ereyass- It is absurd to suppose that the force re-
msiDing will be az great as before; 4, as the ratio
Of frict! nal resistance must increase in proportion
to the remaining volume, 1t is equally absurd to
supp se that the dimiiIisbed fo.eo can iBpei the
diminished volume with the zane vchocity where
there has been no increase of slope The equilib-
rum which had previously existed hefyee1 these
forces being disturbed by the creation Of new out
let the river at sets up natural prcee.s for
its restoration. As it cannot prevent the loss Of
one element of it's force, Though the outlet Il pro-
ceeds 70 increase another of its dynamic e!e-
raents It begins at once TO increase the hight OF
vertical space, through which. Ii flis that Is, il
Increases its strface elope by the deposit of ma
sThe resistance caused by winds is net included
here, because it s n4il and variable factor In
the problem. The tidal force IS also omitted, be.
c1use the resistance of the incoming tide IS com.
pensated By that OF the ebb.
This facs verified literally on the Missouri
river last year. Screens of No 10 wre having rneses
about one foot square. placed across the current
with their lower edges anchored by bags OF stone
and their upper ones sustained by large huoys
caused such rapid deposit OF sediment beio:y ther
IS to raise the bottom, in some cases as much 4,
sixteen fest during one food season.