Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1880-02-04

} aPreliminarly desire to state that the figure
given in this discussion partial results of labor
Gus and extended computations made in this Office
These computation based upon the results of tn
e surveys examinations and observations Of this de
, partment, made during the past year and half
and more particularly during the Good seaon, wheI
the crossseetional size and the slope OF the rive
was constantly known througout its valley course
l and lis discharge was being measured frequently
: at Joints between Colusa and the head of Crane
Island (below which the operations Of The tides in
te1fered with current observations) And this worl
was supplemented by surveys or reconnaissance o.
all tributaries from stony creek, around the head Of
the valley, to the American river, together with OBJ
servations for discharge, during the flood period, in
some OF the largest of the streams as well as the
! smaller ones OF the number.
From the data thus obtained the rate of discharge
for each tributary throughout the flood period has
been approximately determined (knowing the char
acter and drainage area of alD, and tables of dis
charge made from which it cAn be told approx
mately what amount OF water entered the valley
during each hour OF freshet These food volumes
being traced down the stream and combined accord
ing to their time and place OF presentation TO the
main channel, by the rule that the toe OF the food
wave moves with the maximum velocity OF
the current, and the crest somewhat behind
the mean velocity varying according to the amount
OF reservoir space outside the channel itself to be
hied, and assuming the channel to be of good
regimen and sutieientin capacity throughout 1t has
been determined what would have been the maxi
MUM uiSclaiEe at the neaG or each DIVISION mad all
the waters been confined between banks
The results OF this work will be submitted more
IN detail in separate paper; meanwhile, T
eyltys sake, certain extracts only will be herein
used.
The difference between the ordinary and the
extraordinary floods of the valley has been hereto
lore exp aimed in this report and it has been
| mGmated that the immediate object should be to
plan for the rapid transmittal of the waters of
ordinary floods, only for the mitigation Of the
| evils from extraordinary floods such as that OF
1852, for instance, which probably must be allowed
| to spread
Now, the floods of February. 1873, and of March,
1879, may be taken as types OF the ordinary floods
OF the valley, and as more is known OF them than
OF others they only are discussed herein.
CHANNEL IMPRovEMENT-GRAND ISLAND TO
THE SAN JOAQUIN.
During the highest water of March, 1ST9-the
largest reshe of the season, and observed by this
department throughout its course-down the valley
the channel below Grand Island passed about 81 600
cubic feet OF water per second the largest average
| for "a hours of flow.
| Surprising the channel of the river to have been
of good regimen, and of sufficient capacity through
out-had the freshets last mentioned been confined
between banks and carried forward to the portion
OF this river below Grand lslaud-the greatest vol
ume here presented Qeaving Putah and Cache creeks
out, as being diverted over the Montezuma Hills)
would have been about 100, 600 cubic feet per
second.
By comparison of elevations, slopes and cross
sectional DIMENSIONS am enabled to estimate that
during the high water of lS7Swhen the large flood
volume came from the Yolo basn-the river channel
below Grand Island afforded passage to about 1875 900
cubic feet of water per second oman average, through
the tidal day. True, the levees on the south side
were overOpped for there was more water presented
than transmitted !; but, then, the channel would
carry the volume at lower level if its defects
We're removed as elsewhere spoken of.
Not having the data, it is difficult to say, what
would have been the greatest amount brought to
Al.
fined. But from some knowledge Of the facts, and
comparison of elevations at points where the
discharging capacity of the river is KNOWN am led
to believe that, had the creek waters been diverted,
it would have been less than actually presented and
transmitted under the circumstances of the rush Of
waters from the Yolo basin, as heretofore de-
scribed.
In short, the Sacramento river below Grand Island
be rendered amply capable of carrying the maxi
mum volume of ordinary floods, if that flow is pre-
sented it i'll due order it would be il the whole
river above was brought to a proper condition.
And the islands south of the Sacramento below
Grand Island can be protected from inundation dur
ing such ordinary flood flow in the river by levees
but little higher than they have if the river
put in good condition past them and at its mouth
provided the waters are brought regularly down
the river and not through the Yolo basin.
I channel corrections necessary below Grand
island are three in number, as follows
First-Removal of the bar at the point OF junction
with the San joaquin, opposite Collnsvlle to be Ell
fected though the medium II the securing action Of
the waters confined to channel OF proper width by
jetties.
Second Removal of the bar Just above Rio VISTA
opposite Newport, and the enlargement of the Rio
Vista channel past Wood Island to be effected in
the same manner by the construction of jettes from
the mouth of Old river channel to the head of Wood
Island.
Third Widening of the channel and protection of
Sherman Island shore in the Horseshoe bend, just
above Emmaton to be effected by placing a series
OF spur d. kes in the concave side of the bend to
throw the current off and cutting in the other
Shore which is a low marshy island not reclaimed.
The flst two of these corrections OF the class
sometimes undertaken by the General Government
for the improvement of navigation in similar cases.
and probably if any considerable appropriation
made for the Sacramento river, these works would
be carried forward in that way for the necessity for
them is now being felt by the shipping interest of
the river.
CHANNEL MPRovEMRNT-HEAD TO FOOT OF
GRAND ISLAND.
In description heretofore given of the present
condition of the river it has been stated that the
channels either side of Grand Island are not now
large enough to pass the waters which could be
brought to them by the one main channel above;
that is if its evees were maintained at hight uni
form with and otherwise up to the standard OF those
on Grand Island and along the east side OF the river
generally, below Sacramento.
As the effect of this deficient capacity we find a
banking up of the stream at the head of Grand Is
land, and an increased grade in the flood slope down
the channels on eacn OF slough Is
the shortest of these channels, and hence has the
most grade. Owing, however, to its exceedingly
uneven cross sectional form, to the unfavorabe dis
position of its head to receive the currents and
probably to other causes connected with the flood
flow from the Yoo basin into and across its channel
near the lower end, as well as to diminished tidal
action hereafter explained this slough has been
shoaliug rapidly OF late years
II is really cutoff in the channel but these cir
cumstances will not permit it TO be effective
Cut-offs have the effect OF lowering the food
hight above them, and unless they lead into place
of free outfal they also raise it below them. That
is to saw in shortening stream between two points
which cutoff does-a certain amount OF fall In its
surface is saved and this distributed partly above
by drawing down the water line, and partly below
by raising it. Experience and observation have
shown that owing to bend resistance being done
away with lofts generally draw down the level at
their heads about twice as much as they raise it
their lower ends.
rec,ifed as heretofore described, may be regarded
a free outfall for the streams above
First because it will be of ample capacity to pass
ordinary food waters and second, because its flood
elevation heretofore, at the foot of Grand Island
has been controlled by the waters which have en-
tered it through Cache slough and otherwise from
the Yolo basin, and not by the waters which have
zone down the river. So, as the amount which
would reach it at any time of ordinary flood,
through the channel if all were forced to into
it. would not be much it was called on to trans
nit during the rush Of waters S7S, the flood line
would not be raised by sending the flood waters into
it ON the route of Steamboat slough.
TO MAKE STEAMBOAT SLOUGH THE MAIN
CHANNEL.
Now in view of the foregoing, and on the prn-
ciple elsewhere spoken Of that the greater the vol
unes concentrated, the less the grades necessary in
streams it may be readily understood that by max.
ing Steamboat slough the principal ood-carrying
channel of the river we would lower the grade.
IT, then, In diminishing this slope do not raise
the lower end as already shown would not be the
case the upper end would be lowered. This is the
desired result-a relief OF the river at the head of
Grand Island-to induce greater slope, securing
power and capacity above.
For instance the observations made by this de-
partment during the last fiood-season have shown
that the flood Slope at half tide, through the lower
division of the river proportion Colinsyille to the
foot of Grand Island-(l5.7s mies) 1888 feet
per mile and above the head of the island for L. SO
miles of distance-to Freeport-this flood slope was
| 1904 feet per mile.
Ii this river one of good regimen, the slope
of the middle division considered-thst past Grand
| Island-woud approximate very closely to mean
| between the two adjacent to it-above and below.
But we find it to be in Old river channel 3447 feet
| per mile, and in the Steamboat slough channel
| 53o5; in both instances greater than that above