The Coalville times. [volume] (Coalville, Utah) 1894-1923, 1912-03-15
Duty and Measurement
Xxx Of Water Xxx
By DON n. BARK, U. S. Engineer,
In Charge Of irriaation Invest.
cations In Idaho.
OREGON Short Line Railroad Dem
onstration Train Lecture

tCOutinued from last week.
4 The issuing stream Of water
must have full contraction. that is. It
must be sharp and clear cut This
10 brought about by making the up
stream edge Of the weir board as
nearly \ knife edge an possible. and
by keeping the sides and bottom OF
the box below the weir NJ n good dis.
lance from the falling stream 40 that
the air may pass freely clear around
aud In under the issuing stream. The
water below the weir should never be
allowed to back ny TO the level ol
the crest 40 as to exclude the air
from under the issuing stream. else
complete contraction will not be &c
cured and the discharge will be affect
ed. n air can pass freely underneath
the issuing stream the level Of the
water below the weir has no influence
on the discharge An Observance Of
the following rules will usually In
sure complete contraction
a. The opening Of the weir or the
weir notch must be made In n plane
surface perpendicular TO the direction
OF tho flow OF water.
b. Tho opening itself must have n
sharp edge on the upstream side and
tho walls should be bevolcd away on
the downstream side.
C. The distance OF the crest Of tho
weir from the bottom OF the boz OF
basin should be ht least three times
the depth Of tho water on the crest
d. The distance Of the sides OF IN,
weir notch from the sides OF the DO,
or channel should be at least twic,
M great a. the depth OF the water
| flowing over the crest.
g. In order that the lateral con
traction should not be disturbed IN,
length Of the weir crest should b,
approximately three times that Of th'
depth Of water flowing over H.
&. The depth Of water flowing owe
the weir should not be less than tw,
inches nor more than one.third Of IN,
length Of the crest. and II should b,
measured where II will not be affect
ed by waves, wind or eddlcs. and IA
enough up stream 40 that II will no
be Influenced by the curvature In
duced by the falling water. This ca
not be done by measuring II oxnctl
over the crest The distance abOy
the crest which Ia usually found stuff
Client. Is up stream from the crest
distance equal 10 the length OF IN
crest.
| ma. ..... ,...,,.u, 1850. - -.
in weir measurements IN excess v,
loclty Of approach and this must b
guarded against by providing n 600
sized pool above the welrs while
must be- kept clean and free froi
sediment.
"Don'ts" In Regard 10 Welrs.
J.. DO not set weir immediatel
below a curve In the ditch. for N
curve will cause the water 10 flow
the side Of the crest
2. 10 not set II Immediately belo
or too close 10 "a head cato where IN
water has high velocity. M by NJ d,
ing II will cause too high yelocit
OF approach.
3. Don't allow the water below m
weir to back up even with the crei
as II will not allow complete confirm
toln and will cut down tho discharg
4, DO not set the weir any 9th,
way than perpendicular and at rlgl
angles TO the flow OF the stream.
Q. 10 not attempt 10 use too sma
weir. Put In a larger weir wheI
the water 20 be measured exceeds
depth on tho crest Of 10 the creI
length
G. DO not allow the pool above m
weir 10 MI up with sediment. RB m
resulting decrease In the cross ne,
tion will increase the velocity OF al
proach.
I. T'he weir box should be set wit
its floor even with the bottom OF N
Duty Of Water.
To know the proper amount Of 4
rigation water that should be apple
20 the different soils and crops In o
der 10 make the greatest posslbl
yield. has always been serious pro-
lem 10 all irrigntors. II has Away
been known that In order TO secuT
the biggest possible crop II In neceI
sary TO apply different amounts
different crops aud 10 different soil
with the same crop, but Just no
much this amount should be has new,
been known only In an Indefinite wa,
The Irrigation Investigations d
partment. which ! represent In N
state Of Idaho. has, In cooperate
with the state engineers office. bee
carrying on series Of experiment
for the past two years by means {
which II In hoped 10 determine III
very important factor. and we has
secured vast amount Of data Co
corning II. These experiments hay
all been carried out on comparativel
large areas and In practical way.
II does not give any indication I
how much water II necessary Il
maximum crop production on m
soil TO merely measure the amour
that some farmer applies for the re-
son that the same or larger Gro
. hug. haau nrnhnaHh With aifhf