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ARS Home » Research » Publications at this Location » Publication #65660
Title: ACCURACY OF IRRIGATION EFFICIENCY ESTIMATES

Author
item Clemmens, Albert
item BURT, CHARLES - CAL POLY STATE U, SLO

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Competition for limited water supplies has escallated substantially over the last decade. 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. An ASCE task committee was formed to help clarify the definition of irrigation performance measures -- what they represent and what has to be measured in order to provide reasonable values. Unfortunately, field measurements of irrigation performance contain errors, regardless of the skill of the evaluator. In this paper, we provide mathematical equations for calculating the possible error in irrigation performance estimates based on the errors associated with each measurement. Examples are provided that demonstrate that the confidence intervals for irrigation performance parameters are fairly wide, regardless of how much effort goes into field measurements. The results of this research will benefit irrigation district personnel, consultants, and ultimately, farmers.

Technical Abstract: Evaluation of irrigation performance measures should rely on an accurate hydrologic water balance over the area considered. Once the components in the water balance have been determined, it is shown that the accuracy of irrigation performance parameters can be determined from the accuracy of the components in the water balance. Equations, procedures and examples are provided for making these calculations. It is shown that for typical field accuracies, it may be difficult to determine irrigation performance measures to better than one significant figure.