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When a new canal is to be constructed the choice between an unlined 

 canal and a concrete lined canal will depend largely on the first cost of 

 construction. When there is sufficient fall available, a concrete lined canal 

 can be given a steeper grade than an unlined canal which could not resist 

 the erosion due to high velocity. The steep grade and also the smoother 

 cross section will give a high velocity which will make the necessary size 

 of the canal much smaller. The concrete lined ditch can also be given 

 steeper side slopes which will decrease the excavation. For these reasons, 

 the amount of excavation, especially on side hill work, will be much smaller 

 for the concrete lined canal than for the unlined canal. This will reduce 

 the cost of excavation sufficiently to balance for at least part of the cost of 

 lining, and in some cases where the excavation is in hard material, the con- 

 crete lined canal may cost less than an unlined canal. Where there is not 

 sufficient fall available to give the lined canal a steep grade, the com- 

 parison will not be quite as favorable but even then a lined canal because 

 of its smooth bed and sides will have a greater velocity than an unlined 

 canal on the same grade, and therefore a smaller cross section, and on side 

 hill work in hard material the saving in cost of excavation will be con- 

 siderable. Other benefits which must be considered are the decreased cost 

 of maintenance and operation and the greater safety. There are no weeds 

 to contend with, no breaks to mend and consequently the cost of patrolling 

 is eliminated. To this must be added the value of the water saved and the 

 prevention of waterlogging of the land below a leaky ditch. These benefits 

 can not be closely estimated when a new canal is to be constructed but 

 should be considered before deciding the feasibility of a concrete lining. 



With existing canals the problem is to prevent the seepage losses or to 

 increase carrying capacity by either enlarging the canal or by lining it 

 with concrete. The extent of the seepage losses can be obtained by meas- 

 urements, the damages done to adjacent land below and the maintenance 

 of the canal are fairly well known and will furnish sufficient data to esti- 

 mate what can reasonably be spent in concrete lining. When the capacity 

 of the canal must be increased, the choice is between making a larger un- 

 lined canal or to use a lined canal of smaller cross section which will have 

 a higher velocity because of the smoothness of the sides and bed. There 

 are many cases where the value of the water loss alone will justify the im- 

 provement of the canals by lining. This is obtained when the value of the 

 water loss will be equal to or larger than the depreciation and interest on 

 the capital invested. As an illustration, if a canal carrying 50 cubic feet 

 per second throughout the irrigation of 4 months or 120 days, loses 3 per 

 cent, per mile, which is not excessive, this loss is equal to a continuous flow 

 of 1.5 cubic feet per second or 3 acre feet, which gives a total of 360 acre 

 feet whose value at $1.50 an acre foot is $540. For this case we would be 

 justified in spending per mile a capital, the interest of which plus depreci- 

 ation is equal to $540. If we assume interest and depreciation at 8 per 

 cent., the capital is about $6,700. In most cases this would be more than 

 enough to build a concrete lined canal of that carrying capacity, depending 

 on the velocity which can be used. 



STEEL FLUMES. 



During the past two seasons several miles of steel flumes have been used 

 on the irrigation systems of the Kelowna Irrigation Company and of the 

 Fruitlands Irrigation and Power Company, near Kamloops. The flumes are 

 semi-circular and are made of metal sheets curved in a semi-circular form 

 with a bead or corrugated groove rolled in each edge of the sheet. The 



