The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1912-01-26
DUTY AND MEASUREMENT OF
WATER

DUTY AND MEASUREMENT @
WATER
By Don H. Bark, U. S. engineer
charge of irrigation investigation
in Idaho.
The greater part of the land in tt
west would be practically WORTHLESS
without water with which to irriga1
it, yet there Is far less attentio
given to the measurement of tn
water than there is to the measur,
ment of the land. Under the Care
act the land is sold to the settler fc
80 cents per acre and would hardl
be worth that without the waite
while water costs the settler all tn
way from $25 to 500 per acre. N
one would think of buying a farm o
any piece of property without havin
its boundaries located by the count
surveyor or a competent engineer, We
nine out of ten irrigators accept tn,
water that Is given them by the wa
ter master without measurement O
question, eve though it is ten time
as valuable as the land to which i
is applied. These conditions shoult
be changed. Every irrigator shoult
install a measuring device in his heaG
ditch and learn how to measure wa.
ter accurately and then see that he
secures whatever water he is enti.
tied to. We have been far too care.
less in the past about water meas.
urement.
Miners Inch-Water was first
used in Idaho and other western
states for mining purposes, the COM
mon method of measurement being
called the miners inch method. The
miners inch was the unit upon which
such measurement was based, being
the amount of water that would flow
through a sharp edged orifice n
inch square under a given pressure.
The quantity called for by a miners
inch, however, varied in different
states, due to the fact that the pres
sure over the orifice was not the
same. The Idaho statute called for
a pressure of 4 inches over the CEN
ter of the orifice while in Montana
law called for a 6-inch pressure. This
resulted in no end of confu-
sion and as the miners inch was not
to the measurement of large
it's S has been discontin-
led for the cubic foot per second.
The cubic foot per second which
represents a definite tangible amount
hat is easily understood, was adopt
I'd as the legal standard for the
Measurement of water by the Ida
10 legislature in 1899. 1t is COM
monty known as the second foot"
md represents the flow of water
which will exactly fill a vessel con-
one cubic foot each second
Il time for as long a period as it is
flowed to flow. Hence, a flow of
ne cubic foot per second delivers 60
ubic feet per minute, OF $500 cubic {
eet per hour, OF $1,000 cubic feet in
day of "a hours. I
1t is found that one cubic foot per s
econd equals a flow of almost ex- s
city so Idaho miners inches, or $50 I
allons per minute. A flume one foot C
ide and one foot deep, if filled with n
alter that is flowing at the rate of s
Sactly n foot per second, will car n
one cubic foot per second, and Il
her fumes or bitches i'm the same u
roportion. The quantity discharged fl
epends upon both the velocity of S;
le flow and the area of cross Sec Il
on of the advancing stream of wa a
r. These two factors are taken in O
consideration when determining -
e flow of large streams and canals, Of
being only necessary to determine lie
e area of the cross section and the d,
'erage velocity, which two amounts II,
ultiplied together gives the dis NJ
arge. The cross section is found st
multiplying the average depth of lie
e stream by the width. The aver
e velocity is found by measuring til
e rate of the same either with DC
'ats or with a current meter espec- ar
ly constructed for the purpose A til
'se approximation of the velocity III
be secured by noting the time is
is required for a surface float to so
vance through 100 or more lineal tn
It OF the ditch. This gives the or
velocity, and to find the aver on
. velocity n must multiply the VIZ
face velocity by eight-tenths, since an
} average velocity is that much an
wer than the surface velocity. ow- ur
to the friction on the sides and fro
tom of the channel.
While the above mentioned meth ne
are those used by engineers and ier
ers for the measurement of large tn,
ais and rivers, this method is not ate
pied to the continuous measure thu
Of small streams and bitches sh,
of the time involved and the an
'ility for error where the measure rec
Its are not carefully made. 1t
lcre Foot-Where large volumes emf
water are to be considered the ex- exa
'sion of the amount in cubic feet of
Id involve the use of such large ON
lbers that the same would be the
bers0me. In order to simplify dit,
9 expressions the term 'acre-foot' es
led, which represents enough wa str,
% cover an acre one foot in depth sho
$3.50 cubic feet. The use Of this wit
has the additional advantage as
cling easily compared with the box
lge; as for example, a reservoir mat
$4,000 acre feet of water foul
d furnish a depth Of 2 feet for mat
10 acres Of land. A cubic foot of I
49, a coonud fIru,fu~ norxfrG n