THE IRRIGATION AGE. 



311 



IRRIGATION WATER MEASURING DEVICES 



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



'T'HIS is the si.vth of a series 

 * of articles prepared from a 

 bulletin issued hy the College of 

 .lyicultnre of the University of 

 California, at Berkeley. The 

 articles are illustrated with pho- 

 tographs and drawings of the 

 various structures and denies 

 used in com piling the data. THE 

 EDITOR. 



Reference has been made in 

 the preceding pages to water 

 registers for recording the height 

 of water flowing over a weir or 

 in a ditch or flume. In the main 

 a water register is composed of 

 a cylinder on which a record 

 sheet is fastened, a float which 

 causes this cylinder to rotate as 

 the water being registered raises 

 and lowers, and an eight-day 

 clock which causes a pencil to 

 travel horizontally the length of 

 the cylinder each week, marking 

 on the record sheet the height of 

 the water as it travels. Water 

 registers are usually set at the 

 side of the ditch or weir carrying 

 the water being measured, the 

 float and counter-weight hang- 

 ing in a stilling well. The regis- 

 ter sheets fastened on the cylin- 

 der are ruled horizontally to 

 show feet and fractions of feet 

 and vertically to show days and 



fractions of days. These sheets are changed once each 

 week. To make use of the record they furnish it is 

 necessary to use discharge tables giving the flow with 

 different depths of water for the weir or flume in con- 

 nection with which the register is set. As a rule water 

 registers are not adapted to farm use. They require 

 constant care and attention and, as indicated, consider- 

 able computation is necessary to determine from the 

 register sheets and the discharge tables the quantity of 

 water that has passed. 



The standard instrument used for measuring the 

 velocity of water in ditches and other open channels is 

 the current meter. Current meters are not used by 

 farmers, but one should be a part of the equipment of 

 every canal superintendent or irrigation manager. 

 They are mentioned here merely with the hope of en- 



couraging their wider use by 

 canal companies which have not 

 been accustomed to use them and 

 to make them generally familiar 

 to farmers. Ordinarily it is not 

 feasible to measure the water 

 carried in main canals and main 

 laterals by means of the devices 

 that have been described in these 

 articles. Instead current-meter 

 ratings are made at selected por- 

 tions of the main canals and 

 main laterals and from these 

 tables are computed showing the 

 quantity of water flowing at va- 

 rious depths. Standard types of 

 current meters cost from about 

 $75 to about $90, depending 

 upon the style and equipment. 



A current meter and its equipment. 



AUTO-IRRIGATOR 



The auto-irrigator is a new 

 instrument for measuring the 

 water-attracting power of the 

 soil, devised in connection with 

 experiments by Professor B. E. 

 Livingston and Dr. L. A. Haw- 

 kins at Johns Hopkins Univer- 

 sity. It is essentially similar to 

 Livingston's porous-cup atmom- 

 eter, but the cup is buried in the 

 soil instead of being exposed to 

 the air. The experimenters have 

 made a series of measurements 

 upon potted plants irrigated automatically with this 

 device. The rate of water-loss from the irrigator 

 is found to be highest somewhat later in the day 

 than the time of maximum transpiration from the 

 plants. The rate of loss from the irrigator then falls 

 slowly, reaching its minimum in the early morning. 



U. S. STARTS POWER COMPETITION 



Competition makes the wheels turn. The Rec- 

 lamation Service offered to sell power for pumping 

 water onto the dry lands around the Klamath (Ore.) 

 project. The California-Oregon Power Company 

 immediately offered a low rate, and as a result a 

 large number of pumping plants will be installed. 



*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. 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 investigations in 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 

 on by those two agencies without financial aid from the Cali- 

 fornia agricultural experiment station. 



