168 



THE IRKIGATION AGE. 



IRRIGATION WATER MEASURING DEVICES 



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



THIS is the first 

 of a series of 

 articles prepared 

 from a bulletin 

 issued by the Col- 

 lege of Agricul- 

 ture of the Uni- 

 versity of Cali- 

 fornia, at Berke- 

 ley. The articles 

 are illustrated 

 with photographs 

 and drawings of 

 the various struc- 

 tures and devices 

 used in compiling 

 the data. THE 

 EDITOR. 



The public and 

 private advan- 

 tages attending 

 the measurement 

 of individual de- 

 liveries of irriga- 

 tion water have 

 for many years 

 been appreciated 

 in the older irri- 

 gated countries 



and in some portions of the western United States 

 where irrigation water has had a high sale value. 

 Now the rapidly increasing utilization of the avail- 

 able water supplies and the better understanding of 

 the principles underlying the wise making of rates 

 to be charged for irrigation water are causing these 

 advantages to be better understood in every irri- 



Concrete standardizing box, used in irrigation measuring device tests at the Davis 

 Field Laboratory. 



practicable means 

 of measuring ir- 

 rigation deliveries 

 at least exceed- 

 ingly desirable. 



The measure- 

 ment of irriga- 

 tion water, while 

 theoretically sim- 

 ple, is rendered 

 quite perplexing 

 in practice be- 

 cause of the vary- 

 ing conditions al- 

 most any irrga- 

 t i o n measuring 

 device is required 

 to meet. While 

 extreme accuracy 

 is not expected 

 and thus far is 

 almost never 

 reached, measure- 

 ments within, say 

 from two to five 

 per cent of cor- 

 rect, are reason- 

 able to expect, 

 and no device can 

 b e considered 



very satisfactory that does not accomplish such a 

 result. Sometimes, and especially in the flatter val- 

 leys, irrigation ditches are but very little higher 

 than the land to be watered, making measurement 

 over a weir or other device requiring a free 'over- 

 fall of the water impossible. In such cases some 

 form of the submerged orifice or some kind of 



gated section of the West. Citing only California mechanical registering meter must' be used. \Yith 



as an illustration of this, it needs only to be said 

 that while, outside of the southern citrus sections, 



almost any one of these, silt or debris carried in the 

 water, as well as temporary changes in the canal or 



appliances for measuring water deliveries were sel- ditch above or below the measuring point (as from 



dom considered in the design of irrigation systems 

 ten or fifteen years ago, today no competent Cali- 

 fornia irrigation engineer laying out an irrigation 



checking up the water to get it on to the higher 

 land) sufficiently change conditions to alter results 

 and to impair the accuracy of measurements if they 



project would fail to give due consideration to are not taken account of. An additional element of 



necessary means for measuring the water supplied 

 to irrigators. Furthermore, the recent giving to one 

 central public authority the power to fix rates 



difficulty is found in the fluctuations in flow that 

 almost invariably occur on every system, the same 

 device sometimes being required to measure less 



charged for irrigation water by California public and sometimes more than the quantity it is best 

 utilities has made a more general understanding of suited to take account of. 



*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 made under the immediate direction of S. T. Hard- 

 ing, irrigation engineer, in charge of irrigation investiga- 

 tions 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, irrigation engineer, in 

 charge of irrigation investigations in New Mexico, tem- 

 porarily on duty in California, assisted in designing the 

 general plan of installation. The full study has been 

 planned and, in general, supervised, and the data has 



been arranged 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 department of agriculture, and the California agri- 

 cultural experiment station. Co-operation with the state 

 engineering department of California has been effected 

 through agreement between that department and the office 

 af experiment stations, the irrigation investigations at 

 Davis having formerly been carried on by those two agen- 

 cies without financial aid from the California agricultural 

 experiment station. 



