A distribution system of irrigation water for Manitoba

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Buhr, Lawrence Arthur
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This study of irrigation in Manitoba concentrates on the preliminary design and costing of a proposed distribution system. It attempts to define the total water requirements for irrigation in terms of upset or limit values. Arbitrary assumptions on land suitability and availability of water have been made to limit the extent of this study and some of the related subjects are only briefly discussed. The gross area considered suitable for irrigation in Manitoba equals 6.4 million acres with an average consumptive use requirement of 1.72 million acre feet, an average annual diversion requirement of 4.5 million acre feet and a maximum annual diversion requirement of 15.0 million acre feet. These requirements compare with an estimated available supply of water to this area in the order of 50 million acre feet. It appears that there is a surplus water in the order of 35 million acre feet per year. Costs of water diverted for delivery to the farm vary from $10 to $58 per acre foot depending on relative location of source and farm. Average costs for the Province are $20 to $30. The economics of canal lining are dependent on the cost of water supplied to Southern Manitoba. The costs in this study are based on water available in the upper Assiniboine River. If all water had to be obtained in Lake Manitoba, all of the foregoing costs would be appreciably higher. Further study is recommended in the general areas of smaller irrigation district design, methods of water application, use of return flows, drainage improvement requirements, ground water movements, and pumping costs. Also with particular reference to this study, the long term storage requirements, local runoff and return flow use, and the irrigation of clay soils warrant further attention.