Fictions, fractions, factorials and fractures; on the framing of irrigation efficiency

Irrigation efficiency, as a complex and useful measure of irrigation performance, is in a vulnerable scientific position. Knowledge gaps feed through to naïve views of a sector held to be highly inefficient, ‘wasting’ freshwater which could be allocated to other purposes. Confusions and lack of evidence allow room for policy errors – for example the notion that micro-drip technology should replace surface canal irrigation – and underpin an incomplete scientific debate over whether recoverable losses matter resulting in a dismissing of classical irrigation efficiency. Thus with regards to the water challenge of how and why to improve efficiency, society finds itself facing multiple risks; errors in terminology employed, poor engagement with local users on the issue; inappropriate computational methods and a lack of well-executed analyses to challenge commonplace views. In addition, the nuances of an ‘efficiency and productivity’ debate seem not to feed through to interest groups; engineers continue to think in classical terms when not appropriate; incomplete science does little to inform serious policy-making; and scientists seem unable to agree on methods of performance assessment. This paper explores these fault-lines and tensions by taking the view that local losses and classical efficiency matter, and postulates that irrigation systems are locally individuated and have particular distributional and bifurcating properties. As a contribution to the debate, and in framing efficiency, two paradigms are discussed; ‘basin allocation irrigation efficiency’ utilising fractions and effective efficiency, and; ‘socialised localised irrigation efficiency’, utilising classical efficiency.

► The paper explains the two main paradigms in irrigation efficiency.
► The paper argues that classical irrigation efficiency (CIE) has merit.
► It posits a variety of situations where CIE should be utilised carefully.
► It argues for a bifurcating model of irrigation systems.
► A lack of research and evidence is a key risk to understanding irrigation.