Use and Waste of Water 



221 



irrigator. On some irrigation projects the loss has been proved to 

 exceed 10 percent of the water applied. In Arizona, however, and 

 especially in the Salt River Valley, there is a strong public senti- 

 ment against wilful or careless waste, and the total loss of this 

 character is comparatively small. The method of measuring the 

 water to each user and charging him for just what he uses has 

 made the water user more diligent in distributing the water over his 

 own fields and somewhat loath to turn it back into the system or 

 to let it run to waste. Would that he might take an equal interest 

 in preventing the water from escaping downward beyond his con- 

 trol, or upward by evaporation from a crusted soil. 



In the grading of a field the lower 40 or 50 feet should be graded 



This area represents 

 l"he p#rccntoj« of woter 

 lost in conols 



TViis isthe loss 

 b^ «voporQtion 

 jrom the (leld 



This is the loss bvj 



seepaa* down word 



below The r*acV< o\ 



plant rooti 



T>ii5-th« use- 

 •ful port-istreni- 

 pir«d b^ th«. 

 plant's 



Fig. 8. — What becomes of the Irrigating water supplies diverted from the 

 streams is shown by the diagram. The area of each rectangle is proportional ap- 

 proximately to the percentage of the total water supply lost or utilized as indi- 

 cated. 



level in the direction of the irrigation. The lands should terminate 

 in one common land running at right angles across the field, or the 

 furrows should be connected so that the furrow streams will be 

 equalized at their lower ends. Very few irrigators are able to 

 gauge the irrigation and shut off the water from each land at just 

 the right time ; invariably some lands receive too much and fre- 

 quently the water overflows the levee at the lower end of the land. 

 A common crosswise land prevents this loss and usually will have 

 the heaviest alfalfa. 



EFFICIENCY OF IRRIGATION 



Every progressive farmer can easily investigate the general effi- 

 ciency of his irrigation system. In the first place, he should set a 

 weir or other measuring device and keep a record of the amount 

 of water applied to each field. His records will serve as a basis for 

 comparisons. There are several simple means by which he can 

 ascertain the nature and extent of his water losses. Some of the 

 most useful are the following. 



