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Show ELEMENTS OF THE APPROPRIATIVE RIGHT 507 A 1945 publication on irrigation requirements of California crops, published by the California Department of Public Works, Division of Water Resources, in cooperation with United States Department of Agriculture, Soil Conservation Service, Division of Irrigation,356 contains a section entitled "Definition of Terms." Terms defined there, in the following order, are: Irrigation require- ment, water requirement, consumptive use (evapotranspiration), transpiration, duty of water, irrigation efficiency, field capacity, permanent wilting percent- age, moisture equivalent, available moisture, moisture percentage, apparent specific gravity (volume weight), soil moisture, and subirrigation. Comparisons of two commonly used newer terms with duty of water may be made from the following definitions: Irrigation Requirement: The quantity of water, exclusive of precipita- tion, that is required for crop production. It includes surface evaporation and other economically unavoidable wastes. Usually expressed in depth for given time (volume per unit area for given time). (See also water requirement.) Water Requirement: The quantity of water, regardless of its source, required by a crop in a given period of time, for its normal growth under field conditions. It includes surface evaporation and other economically unavoidable wastes. Usually expressed as depth (volume per unit area) for a given time. (See also irrigation requirement.) Duty of Water: The quantity of irrigation water applied to a given area for the purpose of maturing its crop, expressed as acre-feet or acre-inches per acre or as depth in feet or inches. For large areas, the term "consumptive use," including loss by evaporation and transpiration, may be employed. How the quantity is determined.-In the settlement of early contro- versies between claimants of rights to the use of water, scientific assist- ance was not available. Quantities of flowing water were measured in miner's inches flowing over a wier or through the orifice in a structure installed for the purpose; and observations were made and evidence was given as to the relation of measured quantities to cultivated tracts of land for given periods of time. Thus, in areas of irrigation farming, local standards were developed. The introduction of questions of quantitative irrigation requirements into western water jurisprudence appears to have been accepted with some diffidence by some high courts. Late in the 19th century, it was observed that "It is always proper to inquire into the question of the necessity and ability to 356 Young, Arthur A., "Irrigation Requirements of California Crops," Cal. Dept. Pub. Works, Div. Water Resources, Bui. 51, pp. 10-11 (1945). |