32 



are in the process of construction will cost upwards of $50 an acre and 

 probably as high as $100 an acre. Those systems which are installed and 

 which consist largely of wooden flumes or wooden pipes, will before very 

 long require renewal to a large extent, and where these systems have 

 passed in to the hands of municipalities this cost of renewal will have to be 

 met directly by the farmers or fruit growers of the municipality. The in- 

 formation given in the following pages will, it is hoped, be of assistance in 

 the reconstruction of old systems and in the installation of new systems. 

 The subject has been subdivided and is taken up in the following order: 



1st. Seepage losses in canals. 



2nd. Canal linings to prevent seepage losses. 



3rd. Steel flumes. 



4th. Plain concrete pipes. 



5th. Reinforced concrete pipes. 



CONVEYANCE LOSSES OF WATER IX ( AXALS. 



All irrigators are well acquainted with the fact that the losses in con- 

 veying water in earth canals are in many cases very large and with newly 

 excavated canals are often so great that it is difficult to deliver water at the 

 lower end. On irrigation systems with unlined canals these losses usually 

 range from 25 to 60 per cent, of the water diverted and taken in the canal 

 system, and there are many instances where the losses are much greater. 

 In two miles of canal of the Canyon Creek Irrigation Company, near Ke- 

 lowna, the losses amounted to 60 per cent, of the water entering the canal. 

 This is not an exceptional case for on some California canals losses of 64 

 per cent, per mile have been observed. It is safe to state that on an irri- 

 gation system consisting of earth ditches, only 50 per cent, of the water 

 diverted is delivered to the fields. 



The water lost by seepage disappears through some underground drain- 

 age channel or raises the water table of the lands adjacent to and below 

 the canal. This causes the waterlogging of the land or accumulation of 

 alkali salts on the surface. This effect, combined with wasteful irrigation, 

 has been the cause of over ten per cent, of the irrigated lands of the West 

 becoming unfit for crop production. On one project in eastern Washington 

 after only the first irrigation season considerable land was waterlogged and 

 in some portions the water table had risen sufficiently to cover the land sev- 

 eral feet deep. These damages alone, in many cases, justify the expense of 

 lining the canals. But even if injury by waterlogging is not considered, 

 there are many localities where the water is sufficiently valuable to make 

 the lining of canals to stop the loss of water a paying proposition. The 

 amount of money which one is justified in spending will be in proportion 

 to the extent of the losses. 

 1. Extent of Seepage Losses in Canals. 



The extent of seepage losses depends on many factors such as porosity 

 of the soil, the form of cross section, the size of the canal, the number of 

 seasons the canal has been operated, the amount of silt in the water, the 

 velocity of flow, the depth to the water table, etc. 



The most valuable general observations as regards the amount of these 

 losses are those of the Irrigation Investigations Office of the United States 

 Department of Agriculture. From series of measurements on seventy-three 

 ditches in the western states, they have found that the average loss per mile 

 of ditch is 5.77 per cent, of the entire flow; the measurements range from 

 a maximum of 64 per cent, per mile to a slight gain in a few cases. Large 



