CHAPTER XX 

 SUPPLYING WATER FOR IRRIGATION 



Canals. One of the principal ways of obtaining irri- 

 gation water is by the diversion of natural streams by means 

 of canals. The design and construction of the canals vary 

 widely with localities; but in general the principles involved 

 are the same as those involved in the design of open ditches 

 or drainage canals, which have been considered in a previous 

 chapter. It is customary to compute the capacity of irri- 

 gation canals by Kutter's formula, which is given on page 105. 



Diversion canals lead the water of a river away from its 

 natural course to the upper side of the area to be irrigated. 

 The essential engineering features of a canal consist in 

 securing such a grade as to insure a sufficient velocity of 



' 









-S^fcr-- 



S 









Fig. 68. Riverside Canal in Colorado before the water was turned 

 in for the first time. This canal where shown is 18 feet wide at the 

 bottom. 



122 



