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Show 1376 CONSUMPTIVE USE OF WATEE IN IRRIGATION 3.-Some of the common difficulties in measuring consumptive use are enumerated. 4.-That measurement of project and valley consumptive use under some physical conditions is impractical is indicated. 5.-Investigations concerning consumptive use, as made in California, Colorado, Idaho, Nevada, Nebraska, Oregon, and Utah, and in Alberta, Canada, are briefly reviewed- / / 0 y / / / / e c o n. F 5 ( »«y 10 / y 3 Valley Consu / 2 / / / / / a / 3 4 5 Heat Available During Crop Year Qi UnK=1 000 Day-Degrees Fig. 2.-Vallbt Consumptive Use of Wateb on Typical Pboject as Related to Available Heat. 6.-The engineering reports and publications reviewed contain information which is considered valuable as a guide to approximations of consumptive use. If the factors affecting the consumptive use do not vary greatly, and particularly if the crop yield is approximately the same throughout a valley as on experimental plots within the valley, then the valley consumptive use must be either equal to or greater than the net consumptive use. It, therefore, seems reasonable to believe that quantities of valley consumptive use, Uv, which are less than the net consumptive use, U, if obtained by careful measurements, indicate that the soil conditions and crop yields for the valley are too low, and that, if the average yields for the valley are increased to those secured on experimental plots, the valley consumptive use will also be increased. |