The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1912-01-05
DUTY AND MEASUREMENT OF
WATER
By Don H. Bark,
u. S. Engineer in Charge of Irrigation
Investigations in Idaho.


Investigations in Idaho.
The greater part of the land in the
west would be practically worthless
without water with which to irrigate
it, yet there is far less attention given
to The measiir efnent of this water than
there. is 70. the, measurement. OF the
land. Under the Carey Act the land
is sold to the settler for. so cents per
acre and would hardly be worth that
without the. swater while water costs
the. settler all the. way from SIS to
500 per..acre. No. one would think
of buying farm or any piece Of prop
erty without having its boundaries To-
Gated by the county surveyor or a
, competent engineer yet nine out OF
ten irrigators accept. the water that is
given them by the water master with
out measurement or question, even
though it. Isl ten times as valuable as
the land to which tits applied. These
conditions should be changed. Every
irrigator should install a measuring
device in his head ditch and learn how
to measure water accurately and then
see that he secures whatever water he
is entitled to-. We have been far tod
careless in: the past about water measI
urement. I
a.. - - Miners Inch.
- Water was first used in Idaho and
other western states for mining pur7
poses, the common method of meas :.
urement 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 edg-.
ed orifice one inch square under a givl
en- pressure. The. quantity called for
by miners inch, however, varied I'M
different states, due to the fact that,
the pressure over the orifce was not.
the same. The. Idaho statute called,
for pressure. of inches over the
center of the orifce while in Montana.
law called for a 6-inch pressure. This.
variation. resulted in no end of con-,
fusion and as the miners inch was not,
adapted to the measurement of largeI
streams its use.has been discontinued
for the cubic foot per second.
Cubic Foot Per Second.
1.-The. cubic:..foot per: second which.
represents definite tangible amount
that is easily understood, was adopted
as the legal standard for the measure,
rent; ofsWatef' by the Idaho legisla-s
.ture of. 1899. 1t is, commonly known,
as the Second foot" and represents
the, flow of water which will exactly
fiji a vessel containing one cubic foot,
each second Of time for as long a.
period as dt:is. allowed to flow. Hence,
a flow. of one, cubic foot per second'
delivers so cubic feet per minute, orr
5000 cubic feet per hour, or 86.400 cu-i
bic feet.in ;day'of "a hours.
1t is found that one cubic foot peri
second equals a.Row.of almost exactly,
50 Idaho: miners inches, or. $50. gall
Ions per minute: A. f}ume one FOOT
wide and one foot deep, if filled with,
water that is flowing at the rate of;
exactly one. foot per. second; will car!
~. one, cubic. foot. per second, andi
other fumes. or. bitches in the same,
proportion The quantity discharged,
depends upon both the velocity of thei
flow and the area of cross section of.
the advancing stream of water. These
two. factors are taken into considera-,
ton when determining the flow Of
large streams and canals, it hcrg only
necessary to-. determine the area Of,
the cross. section and the average We.
locity which two amounts multiplied
together, gives the discharge. The
cross section is found by multiplyings
.theSaverage depth of the stream by:
the. width. Lhe- average velocity isl
found, by. measuring the rate of thes
same either with floats or with a cur
rent Meter especially constructed for,
the purpose, IA close, approximations
OF the velocity can be secured by not.
ing. the time that is required for a,
surface float to advance through 100
or more .lintal. feet OF the ditch. This.
gives the surface velocity, and to find
the average velocity one must multi
ply @ths surface velocity by 8, since
the average velocity is that much
slower than the surface velocity, ow,
ing to the friction on both sides and
bottom Of the channel. !
= While the above mentioned methods
are those used by engineers and others,
tor the, measurements of larg canals.
and rivers, this method is not adapted
to. the continuous measurement of
Small Streams and bitches because Of
THE time involved and the liability for
.arIor where, the measurements are NOT
.carefully. made. I
>, ;... j. 4: Acre Foot. !
WheEe large volumes of wat. II ard
to be considered, the expression of the
amount in cubic feet would involve
:the-use of such large numbers that tho
same would be cumbersome. In orr
der: to, simplify these expressions the
term "acre-foot"' is used, which rep:
fesents enough water to cover an acre
one foot in depth, or $500 cubic feet
The use of this, term has the addition,
al advantage of being easily compare
ed with the acreage; as for example;
reservoir containing $4,000 acre feel
of'@ater, woudl furnish depth of q
teet' for 2s,0W acres, OF land. A CUBIC
loot of water per second flowing cons
tinuously. for "a hours furnishes al,
most exactly two acre feet of waters
Hydraulic Equivalents Which Will be
!; ~ Found Useful, to Irrigators. .
ak Idaho miners inch-approxi4
mately l-SO Ola cubic foot per second.
or 9. gallons per minute. Il
z; The flow of cubic foot per sec
ohd-,approximately 50 miners inches!
- III H.