212 



THE IRRIGATION AGE. 



IRRIGATION WATER MEASURING DEVICES 



*By California Agents of Irrigation Investigations, Office of Experiment Stations, U. S. Department of Agriculture 



'T'HIS is the second of a series of articles prepared 

 * from a bulletin issued bv the College of Agricul- 

 ture of the University of California, at Berkeley. The 

 articles are illustrated u f ith photographs and drawings 

 of the various structures and devices used in com- 

 piling the data. THE EDITOR. 



When irrigation water is distributed in under- 

 ground pipes 

 measurement is 

 usually a c c o m- 

 plished at the hy- 

 drant through 

 which the water is 

 brought to the 

 surface. Three of 

 the measuring hy- 

 drants used in 

 southern Califor- 

 nia have been in- 

 stalled at the 

 Davis (Calif.) 

 field laboratory. 



The Azusa hy- 

 drant (Figs. 3 and 

 4) is chiefly used 

 in the vicinity of 

 Azusa, Calif., and 

 provides for 

 m easurement 

 through one or 

 more orifices on 

 the center of 

 which a pressure 

 head of 4 inches 

 is maintained by 

 means of a sheet- 

 iron spill crest set 

 at right angles to 

 the orifice plate. 

 The hydrant is in 

 the form of a con- 

 crete box placed 

 over the supply 

 pipe line. The 

 openings in the orifice plate are 4 inches high and 2 l / 2 , 

 3^4, 6%, and \2 l / 2 inches wide, giving areas of 10, 15, 

 25 and 50 square inches, respectively. When the water 

 surface on the upper side of these openings is held 4 

 inches above their centers they will discharge respec- 



GcemenT pipe 



lively, 10, 15, 25 and 50 inches. By using different 

 combinations of these openings, several different 

 amounts up to 100 inches can be measured. The water 

 enters through the pipe shown in the drawing (Fig. 3). 

 The orifices for the desired amounts to be turned out 

 are opened and the others closed with slides. By ad- 

 justing the gate below the spillway the water can be 



brought to the 

 crest of the spill- 

 way, the area of 

 the orifices in 

 square inches be- 

 ing then equal to 

 the number of 

 inches turned out. 

 If the wqter rises 

 above the open- 

 ings a large part 

 of the increase 

 will be carried 

 back to the supply 

 line over the spill- 

 way, but any in- 

 crease in depth on 

 the openings will 

 also increase the 

 amount turned 

 out. 



The Azusa box 

 as shown has 

 walls 6 inches 

 thick, all sides be- 

 ing vertical and 

 flat. The forms 

 required in mak- 

 ing are therefore 

 simple. The box 

 contains 78.3 cu- 

 bic feet of con- 

 crete. This can be 

 made of 1 part 

 cement to 4 parts 

 coarse sand. As 

 the walls are 6 



inches thick it is better to use some gravel when it can 

 be obtained. A good mixture when using gravel is 1 

 part cement, 3 parts sand, and 4 parts gravel. The 

 gravel should not be larger than I 1 /) inches. The con- 

 crete for this box including forms will cost from $18 



Opening for 

 50 Miner's /nches 



12 'cement pipe 



Fig. 3 Drawing of Azusa hydrant. 



*The installation of the measuring devices described in 

 this series of articles has been carried out chiefly by S. H. 

 Beckett and R. D. Robertson, irrigation engineers, assisted by 

 Roy Wray. The tests of the devices have been tnade under 

 the immediate direction of S. T. Harding, irrigation engineer, 

 in charge of irrigation investigations in Montana, temporarily 

 on duty in California, who has also prepared the reports of 

 the tests. The weir tables have been prepared by Wells A. 

 Hotchkiss. The drawings and diagrams have been prepared 

 by Stephen C. Whipple, scientific assistant. F. L. Bixby, irri- 

 gation engineer, in charge of irrigation investgatons n New 

 Mexico, temporarily on duty in California, assisted in design- 

 ing the general plan of installation. The full study has been 



planned and. in general, supervised, and the data has been ar- 

 ranged for publication by Frank Adams, irrigation manager. 

 The installation of the Davis field laboratory and the 

 testing of the devices have been jointly paid for from funds 

 contributed by the state engineering department of California, 

 the office of experiment stations of the United States depart- 

 ment of agriculture, and the California agricultural experiment 

 station. Co-operation with the state engineering department 

 of California has been effected through agreement between 

 that department and the office of experiment stations, the irri- 

 gation investigations at Davis having formerly been carried 

 mi by those two agencies without financial aid from the 

 California agricultural experiment station. 



