Large variations in global irrigation withdrawals caused by uncertain irrigation efficiencies. (1st April 2022)

• Record Type: Journal Article
• Authors: Puy, Arnald; Lankford, Bruce; Meier, Jonas; van der Kooij, Saskia; Saltelli, Andrea
• Is Part Of: Environmental research letters. Volume 17:Number 4(2022)
• Publication Date: 2022-04-01
• Subjects: sensitivity analysis -- agriculture -- water sustainability -- climate change; Environmental sciences -- Periodicals; Human ecology -- Research -- Periodicals; Environmental health -- Periodicals; 333.7
• DOI: 10.1088/1748-9326/ac5768
• Languages: English
• ISSNs: 1748-9326

Abstract

Abstract: An assessment of the human impact on the global water cycle requires estimating the volume of water withdrawn for irrigated agriculture. A key parameter in this calculation is the irrigation efficiency, which corrects for the fraction of water lost between irrigation withdrawals and the crop due to management, distribution or conveyance losses. Here we show that the irrigation efficiency used in global irrigation models is flawed for it overlooks key ambiguities in partial efficiencies, irrigation technologies, the definition of 'large-scale' irrigated areas or managerial factors. Once accounted for, these uncertainties can make irrigation withdrawal estimates fluctuate by more than one order of magnitude at the country level. Such variability is larger and leads to more extreme values than that caused by the uncertainties related with climate change. Our results highlight the need to embrace deep uncertainties in irrigation efficiency to prevent the design of shortsighted policies at the river basin-water-agricultural interface.