December, 1908. J 



565 



Scientific Agriculture, 



an average loss of main canals of about 

 1 per cent, for each mile that water is 

 carried ; on laterals the loss amounted 

 to between 11 and 12 per cent, per mile ; 

 while on some California canals the loss 

 in a single mile was 64 per cent. • , . 

 Measurements made in 1906 on a storage 

 reservoir having a surface of 10,000 square 

 feet showed a seepage loss of 1,000 cubic 

 feet per day. The reservoir is filled by 

 a windmill, and this loss was 10 per cent, 

 of the average quantity pumped each 

 day— a loss too heavy to be borne. The 

 problem of this reservoir owner is the 

 problem of hundreds of irrigators. . . • 



"The water which escapes is often 

 worse than wasted. It collects in the 

 lower lands, fills the soil, drowns the 

 roots of trees and plants, brings alkali 

 to the surface, and is a prolific breeding 

 place for mosquitoes." 



In the course of the same investiga- 

 tions attempts were made to find prac- 

 tical means of lining storage works and 

 canals and ditches to prevent, or at least 

 to reduce- this waste and consequent loss. 

 "From the results obtained the con- 

 clusion was reached that on large and 

 costly aqueducts or important storage 

 works, linings of cement, concrete, or 

 asphaltum may be employed without 

 the expense being prohibitve." It is 

 pointed out, however, that a very large 

 proportion of the irrigation of the 

 country is done by means of the smaller, 



cheaper reservoirs and other works, the 

 owners of which "cannot afford the 

 expense needed to line the reservoir 

 with concrete or asphalt because the 

 value of the water stored will not justify 

 this expense." 



In view of the fact that the greater 

 proportion of the losses occur in lateral 

 ditches and small storage basius, it is 

 necessary to find some simpler and 

 cheaper, but efficient, lining which can 

 be applied by farmers and unskilled 

 labourers. It is clear that the general 

 use of such a method would result in a 

 great improvement of irrigation practice 

 and a marked increase in the duty of 

 water. 



Puddling was tried, but as a rule there 

 was not sufficient clay in the soil to make 

 this efficient. A natural silting up, with 

 consequent improvement of water-hold- 

 ing capacity, of reservoirs and ditches 

 carrying muddy water frequently occurs, 

 but a large proportion of the irrigation 

 water used, notably that obtained by 

 pumping, is clear, and therefore no silt- 

 ing results. 



Of the large number of available raw 

 materials promising well as ditch and 

 reservoir lining, cement, clay and crude 

 petroleum were tested as ditch linings in 

 the California experiments. The prin- 

 cipal results of the test are given in brief 

 in the following table : — 



Results of Tests of Various Ditch Linings. 



Description of lining. 



Cement concrete, 3 inches thick 

 Cement-lime concrete, 3 inches thick 

 Cement mortar .... 

 Heavy oil, 3 £ gals, per sq. yard 

 Clay puddle, 3i inches thick 

 Heavy oil, 3 gals, per square yard ... 

 Heavy oil, 2 § gals, per sq, yard 

 Thin oil, 2k gals, per square yard 

 Earth (no lining) 



The table shows wide variations in the 

 efficiency and cost of the different lining 

 materials. 



"While there is no doubt that cement 

 concrete is the most efficient as regards 

 seepage, it is also the most expensive, 

 being more than six times the cost of the 

 heavy oil lining (3 2jf gallons per square 

 yard), which saves 50'4 per cent, of the 

 water which would seep were the ditch 

 not lined. This saving with the concrete 







Experimental 



Actual cost 



Efficiency 



Saving. 



cost of lining 



of lining 



per square 



per square 



ratios, 





foot. 



foot. 





Per cent. 



Cents. 



Cents. 



7-17 



86-6 



8-30 



7-50 



2-90 



65-5 



8-30 



7-50 



2-73 



63*3 



3-88 



3-25-3-50 



202 



50-4 



1-20 



1-20 



1-78 



47-8 



3-90 



1-20 



1-50 



38-0 



1-00 



1-00 



1-37 



27-3 



•77 



•77 



1-08 



7-3 



1-00 



•80 



1-00 



O'O 







ditch is 86*6 per cent, or one and three- 

 fourths times as large. Where water is 

 very valuable there is no doubt but 

 that the concrete is more permanent and 

 economical. But where tne water is not 

 so scarce and a little waste will do no 

 damage, the expense of lining the ditch 

 with oil may be justified, while a more ex- 

 pansive lining would be impracticable." 

 — Hawaiian forester and Agriculturist, 

 July, 1908, Vol. V., No, 7. 



