Consumptive Use of Water for Agriculture

Transpiration and evaporation, together accounting for practically all consumptive use of water, have been shown by experimental investigations to be influenced by climatic factors, of which temperature gives one of the better ·correlations. Consumptive use in a number of adequately watered irrigated valleys and humid watersheds, representing a wide range in climate, latitude, elevation, and type of crops, is shown in this paper to bear a straight-line relation, within narrow limits, to accumulated daily maximum temperatures above 32° F during the growing season. Factors responsible for deviations from average consumptive use are discussed. The relation of consumptive use to growing-season temperatures offers to the engineer a ready means of estimating probable consumptive use on projects under investigation as an initial step in· determining the irrigation requirement at the farm or at the point of diversion. Short descriptions of each area studied, with summaries of annual data, are given in the Appendix.