Payette enterprise. (Payette, Canyon Co., Idaho) 1909-1935, 1912-01-25

ing easily compared with the acre
age; as for example. a reservoir con-
tanning $4,000 acre feet of water
would furnish a depth of 2 feet for
$4,000 acres of land. A cubic foot
of water per second flowing contin-
uously for "a hours furnishes almost
exactly two acre feet of water.
Hydraulic Equivalents Which Will Be
Found Useful to lrrlgators.
l. Idaho miners inch, approximate
ly one fiftieth of cubic foot per
second, or 8 gallons per minute.
2. The flow OF cubic foot per
second, approximately so miners inch
es, or $50 gallons per minute.
3. One cubic foot per second for
"a hours. approximately 2 acre feet.
4. One acre foot, enough water to
cover an acre exactly foot in depth,
or 1880 cubic feet.
5. One miners inch per acre for
100 days, 3.97 feet deep on the land.
6. One miners inch per acre fo-
$50 days, SOS feet deep on the land.
Z. Five-eighths miners inch per
acre for 100 days, 2.4S feet deep on
the land.
s. Five-eighths miners inch per
acre for $50 days. S.72 feet deep on
the land.
8. One half miners inch per acre
Ger 100 days, 19S feet deep on the
land
10. One-half miners inch per acre
for $50 days, 2.9S feet deep on the
land.
Wolrs and Weir Measurements.
The most accurate, practical and
economical method of water meas
urement that has been devised for
the measurement of comparatively
small heads of water is the weir
measurement. The weir consists es-
sentially Of thin notch of a specif-
ic shape, which the water is caused
to flow over The amount of flow
depends upon the depth of water flow
ing over the crest, as the bottom
of the notch is called The weir
has been used for the measurement
of water for hundreds of years and
the method of its installation and
the discharge of water over il have
both been worked out so carefully
that water can be measured over it
with an error of less than one per
cent, if care is used.
There are several forms of weirs,
the name of each designating the
shape of the notch. Cippoletti, an
Italian engineer, evolved and per
fected the weir which bears his
name, many years ago, this being the
weir that is now most generally us
ed in the West Other weirs, name
ly, the rectangular and the triangu-
lar weirs, are constructed and op-
Grated in much the same way, the
same rules being observed in the
measurement, practically the only
difference existing being, as has been
stated, in the shape Of the notch and
the formula used in the computation
of the discharge. The Cippoletti weir
notch is trapezoidal in shape, hav-
ing a straight bottom or crest with
sides that slope. outward from the
vertical at the rate of one horizon
tai to four vertical. A one foot Clip
poletti weir has a straight horizon
tai bottom or crest one foot in
length with a width between the sid
cs of Is inches at height of 6
inches above the crest. If the notch
is made of wood the sides and bot
tom should be beyeled off on the
down stream side, leaving a sharp
thin edge on the upstream side.
This is necessary in order to secure
a sharp clear-cut issuing stream
which it is necessary to secure if
accurate measurement is to be OBJ
tanned 1t is usually the best policy
to line or face the upper side of
the weir board with a piece of gal
vanized iron sloping or beveling the
edges in the same manner as be-
fore. The use of the galvanized iron
or other metallic crest is especially
as it not only insures
a sharp clear-cut issuing stream
upon which accurate meast rement |
depends, but in addition, it also fur
nishes a permanent Interchangeable |
crest for the water to flow through.
Provided the necessary requirements |
are observed in the construction and |
of a weir, the amuont Of
water flowing over it depends upon
but two factors-the length of crest
and the depth of the water on the
crest. The length of crest being
known, the depth of the water
should be measured, not on the
crest, but from a point level with
he crest and up stream from it
equal to its length.
Weir Box-In order to maintain