The Sauk Centre herald. (Sauk Centre, Stearns County, Minn.) 1886-current, 1907-01-31
WEERS FOR MEASUREMENT
OF WATER SERVICE
Provide Accurate Guide to Amount
Used and Enable Regulation of
Flow to Plant Needs-By G.
e. p. Smith, Arizona.

How can they be measured?" are
often suggested to the mind of the
irrigator. Ordinarily, however, they
do not meet with a satisfactory solu-
ton and the matter is deferred to a
more convenient season.
There are at least two strong rea-
sons which should urge the owner or
user of an irrigating stream to make
| frequent measurements of the guam
| tity of water carried in his bitches.
appropriation of water can never make
| any definite assertion as to how much
water he actually uses and in the
event of question he can furnish nc
| satisfactory proof as to his estab-
lished appropriation. In legal cases
involving water rights the evidence
| is usually of the most chaotic and
contradictory character, composed of
much prejudiced speculation with lit
tie or no real evidence.
The second reason why an irrigator
should know the amount of water re-
ceived through his ditch is because of
the advantages offered in the manage
ment of his property. The duty of
water, that is, the amount required
per acre per year or, preferably, per
month, should be determined. The
| duty of water varies greatly on diff
| ferent kinds of soil and with different
crops, and information regarding it
will assist in determining the more
profitable course of farming to be fol
lowed. This argument should appeal
especially to those who pump water
for irrigation, for the cost of pumping
often leaves very small net profit.
In many instances, also, measure
ments have proven the existence OF
an excessive loss by seepage from
bitches, and the loss, once discovered,
has been properly remedied Other
| advantages of equal value will result
from a careful record of the ditch
waters.
1t is usually assumed that water
measurements are too difficult for the
rancber and that the task must be left
to an engineer. This feeling is I'M
! warranted 1t is possible for the
rancher, with proper directions, to
make his own measurements with lit
tie outlay of time and expense.
OF the various methods Of meaSur-
ing water, the miners inch box has
long since fallen into disrepute, and
for good reasons. The use of current
meters is too expensive for general
use, and rating fumes are open to the
same objection, as the rating itself is
difficult and expensive. But in weirs
we have a method which is both cheap
and simple.
What constitutes weir? Briefly, it
is notch cut in the side of wide
board which is then set on edge in the
channel so that the stream of water
passes through it and falls into the
ditch again on the lower side. OF sew
eral forms of notches the trapezoidal
is to be preferred. 1t has level crest
and the sides are inclined to the verti-
cal with slope of one to four. For
example, Pinch weir is u inches
wide on the crest and if it be eight
inches deep, the width at the top is 16
inches This gives the correct side
slopes. An 1S-inch weir ten inches
deep is 10 inches wide on the crest
and 90 inches wide at the top of the
notch.
For measuring small stream, such
a weir can be made of a redwood or
pine board is inches wide and six feet
long The board must then be placed
crosswise of the stream with its ends
held in place by earth and boulders or
by stakes. The following precautions
should be observed:
First.-The weir must be set high
enough to give free fall of several
inches on the downstream side. This
will back the water upstream for a
short distance. 1t is best, therefore,
to select a point ON the ditch which
has considerable grade.
Second-The notch should be
bevelled away from the inner edge 40
that the water shall touch along that
edge and no more. The inner edge
should be carefully laid out and cut
with sharp tool so as to be smooth
and true to the intended dimensions.
Third.-The crest of the weir, that
is, the bottom of the 1Otch, must be
laid level, This can be accomplished
with the aid of spirit level.
Fourth.-If the approaching waters
are turbulent, they must be made
calm and free from waves and eddies
by laying brush or a board on the
water surface ten or IL feet above the
weir.
Fifth.-The stream should be broad
er and deeper for few feet on the
upstream side, that is, it should form
there miniature lake. Otherwise
the water approaches the weir with so
great velocity as to increase the
fiow. This increase may be computed
for any particular case, but it is not
worth while to do SO, when a little
shovelling will usually suffice to form
the quiet pool, as is desired.
Sixth.-Leakage under the weir
board must be prevented. This is
sometimes best accomplished by pack
ing sods, weeds or straw around the
board. These substances are easily
held in place by banking up with
earth.
Briefly, the conditions are these.
The water must approach the weir
calmly and slowly, must touch the
notch on the inner edge only, and
must have free fall on the down.