Irrigation efficiency and water-policy implications for river basin resilience

Publicado en Hydrology and Earth System Sciences Discussions

Scott, C.A., Vicu na, S., Blanco-Gutiérrez, I., Meza, F.J. and Varela-Ortega, C.

Año de publicación 2014
  • University of Arizona, School of Geography & Development, and Udall Center for Studies in Public Policy, Tucson, Arizona, USA
  • Pontificia Universidad Católica de Chile, Centro Interdisciplinario de Cambio Global, Santiago, Chile
  • Universidad Politécnica de Madrid, Department of Agricultural Economics and Social Sciences, Madrid, Spain




Proyecto CRN3056


Rising demand for food, fiber, and biofuels drives expanding irrigation withdrawals from surface water and groundwater. Irrigation efficiency and water savings have become watchwords in response to climate-induced hydrological variability, increasing freshwater demand for other uses including ecosystem water needs, and low economic productivity of irrigation compared to most other uses. We identify three classes of unintended consequences, presented here as paradoxes. Ever-tighter cycling of water has been shown to increase resource use, an example of the efficiency paradox. In the absence of effective policy to constrain irrigated-area expansion using "saved water", efficiency can aggravate scarcity, deteriorate resource quality, and impair river basin resilience through loss of flexibility and redundancy. Water scarcity and salinity effects in the lower reaches of basins (symptomatic of the scale paradox) may partly be offset over the short-term through groundwater pumping or increasing surface water storage capacity. However, declining ecological flows and increasing salinity have important implications for riparian and estuarine ecosystems and for non-irrigation human uses of water including urban supply and energy generation, examples of the sectoral paradox. This paper briefly considers three regional contexts with broadly similar climatic and water-resource conditions &ndash central Chile, southwestern US, and south-central Spain &ndash where irrigation efficiency directly influences basin resilience. The comparison leads to more generic insights on water policy in relation to irrigation efficiency and emerging or overdue needs for environmental protection.