THE IRRIGATION AGE. 



277 



THE CONSTRUCTION OF IRRIGATION DITCHES. 



Ditches Which are Permanent Waterways Compared with 



Those Constructed with No Thought of 



Nature's Laws. 



There are few irrigation projects which do not rep- 

 resent more or less open ditch construction. Since the 

 enactment of the Irrigation law, government engineers 

 have been engaged in measuring the rivers and streams 

 of the West and calculating the quantity of water avail- 

 able for irrigation purposes, and many persons have pre- 

 dicted that there will be ultimately as much as 150,000,- 

 000 acres reclaimed west of the one hundredth meridian 

 and converted into the thrifty fields of a land of plenty 

 in the heart of a desert. 



But while effort is making to conserve every avail- 



Drainage Investigations of the United States Depart- 

 ment of Agriculture, gives an exhaustive report of the 

 losses from canals from seepage and evaporation in the 

 eleven principal arid States of the West. The general 

 average of all these measurements shows that 6.76 per 

 cent of the water entering the canals is lost in each 

 mile in length, the losses range from 0.3 to 64 per cent 

 per mile. Investigations also show that the seepage is 

 proportionately much larger in small ditches than 

 larger ones, and that there is an advantage, where pos- 

 sible to do so, in carrying water in large ditches rather 

 than in several small ones. 



It is well known that an open ditch ten feet wide, 

 with a grade of three feet per mile and with a depth of 

 six inches of water, has a mean velocity of only 1.4 

 feet per second, but if flowing eight feet deep in the 



This Ditch Was Built by the Austin Drainage Excavator and was Two and a Half Years Old and Had Withstood the Frosts and Freshets of 



Two Winters at the Time This Photograph Was Taken. 



able drop of water for irrigation by the construction of 

 dams and reservoirs, and a more economical application 

 of the use of water for irrigating crops is advocated, 

 few realize the enormous waste of water caused by im- 

 properly constructed ditches. Not many residents of 

 irrigated districts realize that in many instances 90 per 

 cent of the water entering irrigation ditches is lost 

 through seepage in the mains alone, and this could be 

 largely prevented if the ditches were constructed on a 

 scientifically correct principle. 



Mr. R. P. Teele, in his review of irrigation work of 

 the year 1904, in the Annual Report of Irrigation and 



same ditch the mean velocity is increased to 3.8 feet 

 per second. It is therefore evident that irrigation 

 ditches should not only be constructed as deep as prac- 

 ticable, but in a manner which will maintain or in- 

 crease the original depth. It is also self-evident that 

 ditches containing loose earth or caved banks offer more 

 obstructions to the flow of water, and the seepage is far 

 greater than in ditches built true to grade with sides 

 and bottom perfectly smooth and containing no loose 

 earth. 



In ditches built with dipper dredges or steam 

 shovels it is impossible to construct sloping sides, and 



