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Title: ESTIMATION OF GLOBAL DISTRIBUTION UNIFORMITY

Author
item Clemmens, Albert
item SOLOMON, KEN - CALIF STATE UNIV. FRESNO

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Competition for limited water supplies has escalated substantially over the past decades. Unfortunately there are many misconceptions about water use, particularly in irrigated agriculture. The potential water savings that might result from increases in irrigation efficiency are usually overestimated. Many of these misconceptions and erroneous estimates of water savings stem from misunderstandings about how irrigation performance measures are defined and used. In practice, field measurements of irrigation uniformity are often used and inappropriately extrapolated to infer efficiency. In addition, only part of the uniformity of the irrigation system is measured. A global measure of uniformity is needed to make field measured uniformities of different types of irrigation systems comparable. In this paper, we present methods for combining the components that contribute to irrigation uniformity from simple field measurements, so othat a representative, global uniformity can be estimated. The results of this work will benefit irrigation district personnel, consultants, and ultimately, farmers.

Technical Abstract: For most irrigation systems, the most practical method for determining the global distribution uniformity (i.e., experienced by the entire crop) is to measure the uniformity resulting from several components and combine them statistically. In this paper, procedures and equations are presented for determining global Distribution Uniformity from several components. Distribution uniformity is defined in terms of extreme values in the distribution, representing some fraction of the field area (e.g., low quarter). The equations and procedures provided herein apply regardless of the size of the area under consideration (e.g., low quarter, low half, etc.), or whether the low or high values are of concern. Procedures and equations for estimating the accuracy of these estimates are also provided.