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ARS Home » Research » Publications at this Location » Publication #59665
Title: DEFINING EFFICIENCY AND UNIFORMITY: PROBLEMS AND PERSPECTIVES

Author
item Clemmens, Albert
item STRELKOFF, THEODOR - UNIVERSITY OF AZ, TUCSON
item BURT, CHARLES - CAL POLY, SAN LUIS OB, CA

Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/15/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Competition for limited water supplies has escalated 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 to clarify the definition of irrigation performance measures -- what they represent and what has to be measured in order to provide reasonable values. This paper provides new definitions for irrigation performance measures -- Irrigation Efficiency, Application Efficiency, Distribution Uniformity. These modifications were necessary so that the intent of the original definitions could be properly interpreted under all conditions. In addition, two new terms are defined -- Irrigation Sagacity which define reasonable water use and Irrigation Consumptive Use Coefficient which separates consumptive from nonconsumptive uses. The results of this work will benefit irrigation district personnel, support and regulatory agencies, consultants, farmers, and other water users.

Technical Abstract: Fractions of irrigation water leaving a defined region through its boundaries are categorized in several ways: consumed or not consumed; beneficial or nonbeneficial; reasonable or unreasonable. Water stored within the region is considered neutral. Irrigation efficiency is defined in terms of actual disposition of irrigation water and is elevated after the facto, over a period of time, e.g., an irrigation interval or a season Application efficiency is defined in terms of a perceived requirement and applies to a single event; it can be predicted. The influence of nonuniform application of water over the field is highlighted. An average minimum application depth on plant area is defined; distribution uniformity follows.