IRRIGATION INVE:STIGATIONS AN 0 PRACTICE FRANK ADAMS S. H. BECKETT F. J. VEIHMEYER C. M. TITUS H. A. WADSWORTH C. F. DUNSHEE MARTIN R. HUBERTY FRANK DAVIS CLARENCE N. JOHNSTON
J. B. BROWN, EXTENSION SPECIALIST
Mr. Ralph Par shall , Fort Collins, Colo.
Dear Mr. Parshall:
UNIVERSITY OF CALIFORNIA
COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION
September 'lwen ty Four
l 9 2 3
DAVID P. BARROWS, PRESIDr::NT THOMAS FORSYTH HUNT, DEAN
ADDRESS
BRANCH OF THE COLLEGE OF AGRICULTURE UNIVERSITY FARM, DAVIS, CALIFORNIA
Things have been rushing alo:ng so madly since I returned to California that I have not had time to completely analyze all the observations taken in your laboratory. I have, however, worked out with some great degree of detail the first 107 observations and I am sending these along to you now so that you will not think I have forgotten~ promise to you and the President. The rest of them will co~e aloll8 as fast as I can get at them.
You may remember that this first set of observations was made on a gate
24 inches wide and which had 2 x 4's nailed inside the flume to act as guides for the gate; ani 2 x 4' s nailed flat on the bottom of the flume gave support to the gate when closed, and, of course, created some bottom contraction. In plotting these points on logarithmic coordinate paper it is quite evident that
the points for a certain area lie along a definite straight line within the limits of experimental error. I have plotted these points and a.rawn lines for
J:hem. I an sending a blue print showing these points and their lines along with this.
You will note that the lines become closer and closer together as you get into the larger are~s. You will also note that the slope of the line becomes somewhat flat.ter as you get into the larger areas. I have computed the equations for these lines and have noted them on the tracing ~ediately below the line for which they are applicable. Inasmuch as a straight line on this type of paper represents a true parabola, the general equation for such a line would be
Q • K x
!fl.
By taking off the p.ro~r lues of the constant from the equa tiona noted on Plate 4 and plotting them against the areas from which they are obtained a rather sm:>o th curve will be obtained when the corresponding values of m are plotted &gainst the proper areas a second smooth curve is obtained with a peculiar sort of a hump between .5 of a square foot and 1.25 square feet. V:lhen these values of K and m are substituted in the for.mula for a given observationand the computation carried out to determine the discharge, the resulting discharsa coincides in most cases with the disCharge obtained by actual observation within
Page 2.
R • .P •
Sept. 24/23
You may remember tha. t the last thing I undertook at Port Col line was to
rebuild this two-£oot gate exactly as it was for the first test~ in an effort to note any effect which might be created by varying depths of submergence. Iou m~ also remember that I was u:ua.ble to obtain results consistent with thos• of the first series, although conditions seemed to be identical. Upon closer analysis of the results of this later series I have come to the conclusion that the results were not as inconsistent as they seemed §.t first. The curves for discharge which appeared on plot 4 are not identical with those I drew in the laboratory after the first run, but are adjusted so that they fit the conditions of the second series almost as well as they do of the first.
However, there is a great deal more work to do in the analysis of these results before anything definite can be said. As soon as I have succeeded in spendi~ a sufficient amount of time on the reat of the observations I shall int·orm you of my results and send you a copy of the tests upon which they are based.
With kindest personal regards, I am
Yours very truly,
~~
DET.A.ILS OF OBSERVATIONS ON 24rt ORIFICE - June 6, 1923.
Test No. nH'' Q, Area of Difference in Head H
Opening Upper Lower·
sq. ft. 1 .372 2.22 1.oo .932 .789 .130 2 .357 2.08 1.00 1.315 1.185 .117 3 .571 4.16 1.00 1.757 1-256 .488 4 .398 2.44 1.00 1.340 1.154 .173 5 .248 1.22 1.00 1.043 0.986 .044 6 .264 1.34 1.00 1.119 1.050 .056 7 .275 1.42 1.00 .850 .778 .059 8 .260 1.31 1.00 .845 .777 .053 9 .609 4.68 1.00 1.693 1.106 .• 574 10 .633 4.84 1.00 1.777 1.134 .630 11 .399 2.45 1.00 1.066
.ass
.165 12 .397 2.43 1.00 1.062 .891 .158 13 .34t0 1.94 1.00 0.943 .835 .095 14 .339 1.93 1.00 .943 .833 .97 15 .258 1.29 1.00 .802 .743 .046lo
.488 3.30 1.00 1.30S .994 .296 17 .493 3.35 1.00 1.307 1.00 .294 18 .307 1.67 1.00 .885 • 799 .073 19 .311 1.70 1.00 .875 .793 .069 20 .266 1.35 1.00 .817 .753 .051 21 .271 1.39 1.00 .823 .759 .050 22 .229 1.08 1.00 .752 .710 .029Test No.
"H"
tt0_tt Area of Difference in Headopening Upper Lov.er
sq. ft • 23 • 227 1.0'1 1.00 .748 .707 .028 24 .223 1.~ 1e25 .734 .718 .016 25 .22.7 1.07 1.25 • 741 .713 .015 26 .315 1.73 1.25 .871 .814 .044 27 .319 1.76 1.25 .877 .821 .043 28 .700 5.61 1.25 1.784 1.220 .551 29 .666 5.21 1.25 1.687 1.193 .482 30 .641 4.93 1.25 1.597 1.166 .418 31 .544t 3.87 1.25 1.306 1.034 ·259 32 .486 3.28 1.25 1.172. .989 .170 33 .491 3.33 1.25 1.179 .993 .173 34 .467 3.09 1.25 1.127 .964 .150 85 .302 1.63 1.25 .850 .796 .041 36 .357 2.08 1.25 .918 .849 .056 37 .369 2.19 1.25 .956 .874 .069 38 .419 2.64 1.25 1.033 .926 .09~ 39 .425 2.69 1.25 1.046 .932 .101 40 .403 2.49 1.50 .979 .911 .068 41 .496 3.38 1.50 1.113 .998 .102 42 .510 3.52 1.50 1.135 1.015 .120 43 .808 6.93 1.50 1.886 1.406 0.480 44 .808 6.93 1.50 1.892 1.417 .475 45 .757 6.27 1.50 1.719 1.334 .375 46 .756 6.28 1.50 1.728 1.339 .389 47 .683 5.41 1.50 1.512 1.250 .262 48 .613 4.62 1.50 1.340 1.179 .161 2.
Test No.
''H''
"
Q
••
Area of Diffenmce in Head Hopening Upper Lower
sq. ft. 49 .544 3.87 1.50 1,201 1.089 .112 50 .461 3.04 1.50 1.055 .995 .06 51 .407 2.52 1.50 .975 .925 .05 52 .326 1.84 1.50 .862 .836 .026 53 .337 1.92 1.75 .863 .851 .012 54 .423 2.68 1.75 .973 .946 .027 55 .463 3.06 out 1.031 .988 .043 56 .54? 3.89 It 1.131 1.091 .04:0 57 .903 8.16 1.75 1.947 1.536 .411 58 .898 8.09 1.75 1.972 1.568 .404 59 .854 7.51 1.75 1.811 1.447 .364 60 .772 6.48 1,75 1.589 1.335 .2M 61 .073 5.97 1.75 1.484 1.286 .198 68 .640 4.92 1.75 1.315 1.197 .118 63 .575 4.19 1.75 1.185 1.118 .067 64 .493 3.35 1.75 1.071 1.030 .041 65 .635 4.86 1.75 1.307 1.186 .121 66 .638 4.90 1.75 1.309 1.194 .115 67 .661 5.16 2.00 1.278 1.201 .077 68 .663 5.18 2.00 1.281 1.202 .079 69 .780 6.58 2.00 1.499 1.333 .166 70 .780 6.58 2.00 1.503 1.343 .160 71 .784 6.60 2.00 1.508 1.337 .171 72 .622 4.71 2.00 1.211 1.157 .054 73 .610 4.59 2.00 1.202 1.142 .060 74 .895 8.06 2.00 1.721 1.462 .259 3.
Test No. ttH'' "Q, tt Area of Difference in Head "f n
opening Upper Lower
sq. ft. 75 .891
s.oo
z.oo
1.737 1.466 .271 76.ass
7.96 2.00 1. 7Zt 1.468 .259 June 12. 1923. 77 )466 3.08 2.00 1.006 .992 .014 78 .457 3.00 2.00 1.00 .981 .019 79 .458 3.01 2.00 .995 .983 .012 80 .639 4.91 2.25 1.193 1.165 .028 81 .638 4.90 2.25 1.210 1.167 .043 82 .820 7.08 2.25 1.464 1.354 .110 83 .825 7.14 2.25 1.475 1.362 .113 ~ .961 8.94 2.25 1.714 1.498 .216 85 .953 8.83 2.25 1.702 1.494 .208 86 .874 7.77 2.25 1.570 1.404 .166 87 .873 7.76 2.25 1.562 1.407 .152 88 .357 2.08 0.75 1.089 .856 .233 89 .353 2.05 0.75 1.073 .853 .220•
90 .430 2.74 0.75 1.310 .926 • 384 91 .420 2.65 0.75 1.287 .920 .367 92 .221 1.03 .75 .771 .718 .053 93 .~9 1.08 .75 .786 .728 .058 94 .236 1.13.so
.863 .719 .144* 95 .237 1.1~ .50 .859 .720 .139 96 .398 2.44 .50 1.517 .860 .657 97 .397 2.43 .50 1.518 .860 .658 June 13 98 .365 2.06 .50 1.329 .837 .491 99 .357 2.09 .50 1.305 .833 .472 100 .202 .90 .50 .762 .682.os
101 .209 .947 ·50 4. .777 .689.oaa
Difference in Head.
Test No.
"H''
"'J." Area of Upper Lower t'H"opening sq. ft • 102 • 210 .954 0.25 .903 .658 .245 103 .204 .914 0.25 .881 .667 .214 104 .351 .203 .25 1.921 .738 1.183 105 .342 1.96 .25 1.855 j'736 1.119 106 .308 1.67 .25 1.477 .732 .745 10'1 .317 1.75 .25 1.539 .734 .805 5.
