The Blackfoot optimist. [volume] (Blackfoot, Idaho) 1907-1918, 1911-12-28

N 10 the measurement OF luis water
han there is to the measurement Of
he land. Under the Carey Act the
and sold to the settler for SO cents
per acre ard would hardly be worth
that without the water while water
costs the settler all the way from $25
to 500 per acre. No one would think
Of buying farm or any piece OF prop +
erty without having it's boundaries To-
Gated by the County Surveyor or a
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 is ten times as valuable as
the land to which it is applied. These !
conditions should he changed. Every
irrigator should install 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
too careless in the past about water
measurement A
Miners Inch
Water was first used in Idaho and
other Western states for mining pur-
poses, the common method of measure
ment being called the miners inch
method. The miners inch was the
was based, being the amount of water
that would flow through sharp edged
unit upon which such measurement
orifice one inch square under given
pressure. The quantity called for by
miners inch, however, varied in diff
ferent states, due to the fact that the
pressure over the orifice was not the
same. The Idaho statute called fer a
pressure of inches over the ter Of
the orifice while in Montana law cal
led for a 6 inch pressure. This varia-
ton resulted in no erd Of confusion a
as the miners inch was not adapted
to the measurement Of large streams
it's use has beeen discontinued for the
cubic foot per second.
The cubic foot per second which rer-
resents definite tangible amout that
is easily understood, was adapted as
the legsl standrd for he measurement
of water by the Idaho Legislature in
| 1899 1t is commonly known as the
second foot and represents the flow
of water which will exactly fill YES
sci containing one cubic foot each Sec
ond of time for as long period as it
is allowed to flow. Hence flow Of
one cubic foot per second delivers go
cubic f.et per minute, or $500 cubic
feet per hour, or $1,000 cubic feet in a
day Of "a hours.
| 1t is found that one cubic foot per
second equals q flow of almost exactly
80 Idaho niuer's inches, or $50 gallons
per Ioih.lfe A flume one foot wide
and one foot tcep, if filled with water
that is flowing at the rate of exactly
one foot per second, will carry one cub
ic foot per second, and other fumes or
bitches III the same proportion. The
quantity discharged depends upon the
velocity OF the flow and the area of
cross section of the advancing stream
of water. These two factors are taken
into consideration when determining
the flow Of large streams and canals,
: 1t being only necessary to determine
the area OF the cross section and the
average velocity, which two amounts
multiplied together gives the discharge
The crt ssl section is found by multi
plying the average depth of the stream
by the width. The average velocity
Is found by measuring the rate of tho
same either with floats or with a cur
rent meter especially constructed for
the purpose. A close approximation
of the velocity can be secured by not
ing the time that is required for sur
face float to advance through 100 or
more lineal feet of the ditch. This
gives the surface velocity, ard to find
. the average velocity one must multipl,
the surface velocity by g. since the
average velocity is that much slower
, than the surface velocity, owing to
the friction on the sides and bottom
of the channel.
While the above mentioned methods
pre- those used by engineers and other
, for the measurement of large 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 fol
error where the measurements are
not carefully made
Acre Foot *"
Where large volumes of water arr
to be considered the expression of the
amount in cubic feet would involve tn
use of such large numbers that Il
would be cumbersome. In order Il
simplify these expressions the tern
'acre-.OOt' is used, which represent
enough water to cover an acre one
foot in depth, or 1850 cubic feet. Th
/, use OF this term has the additional ad
!, vantage of being easily compared witt
the acreage; as for example, reser
, voir containing 50,000acre feet of wat
er would furnish q depth of feet tol
25.G00 acres of land. A cubic foot D
water per second flowing continuousl.
for "a hours furnishes almost exactl!
two acre feet Of water.
, Hydraulic equivalents Which will b
Found Useful to Irrisators
: l. Idaho miners inch, approximate
: ~ 1-5O of a cubic foot per second, d
} . gallons per minute.
2. The flowof cubic foot per see
. ond, approximately so miners inches
h or $50 gallons per minute.
: 8. One cubic foot per second for 2
I hours, approximately 2 acre feet.
!. 4. One acre foot, enough water +
cover an acre exactly foot in depth
or 43,560 cubic feet.
e 5. One miners inch per acre 70
: 100 days, 3.97 feet deep on the land.
6. One miners inch per acre 70
$50 days, sos feet deep on the land.