Localising irrigation efficiency

Conventional (or classical) and “effective” (or neoclassical) concepts of irrigation efficiency are valid in different situations as long as the data, terms, circumstances and purposes of those situations are carefully defined. Recent thinking has usefully promoted a basin perspective of water based on effective irrigation efficiency, arguing that agricultural production is best expressed from depleted water. However, given the need to engage with the specifics affecting water management and productivity, a case is made for improving the understanding of the classical approach or “local irrigation efficiency”. The paper explores 13 issues which affect, or are affected by, local efficiency, and that support the case. Some of these issues are: the relevancy of scale in water management; the separation of design, management and monitoring activities; the relationship between efficiency and timing; and the coupling of net requirements and recovered and non-recovered losses. The paper introduces the term “attainable efficiency”, and posits that classical irrigation efficiency has significant utility because it reflects observations made by irrigation professionals and farmers that local efficiencies critically affect water management and productivity within a river basin system.