With river and groundwater reserves declining globally, a study reveals that the maximum limit to direct rainwater use has been reached in many regions and exceeded in several countries in Europe, Central America, the Middle East, and South Asia. Rainfall feeds rivers and groundwater reserves, known as blue water, but a portion of rainfall is used directly by plants and returns to the atmosphere as evapotranspiration. This so-called green water sustains terrestrial biodiversity and is a major source of water for the production of food, fiber, feed, timber, and bioenergy. Joep Schyns, Arjen Hoekstra, and colleagues expand the analysis on water scarcity, which is traditionally focused on blue water, by assessing green water scarcity. The authors estimated the amount of green water used for biomass production for the human economy in 10km x 10km land sectors across the globe and compared the results with green water availability in the sectors. The authors accounted for the inability to use all rainfall when, for example, it falls in inaccessible areas or those important for biodiversity conservation. According the authors, the study quantifies limits to green water availability, given limited annual rainfall.
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Article #18-17380: "Limits to the world's green water resources for food, feed, fiber, timber, and bioenergy," by Joep F. Schyns, Arjen Y. Hoekstra, Martijn J. Booij, Rick J. Hogeboom, and Mesfin M. Mekonnen
MEDIA CONTACT: Joep Schyns, University of Twente, NETHERLANDS; tel: +31534894799; email: < j.f.schyns@utwente.nl >
Proceedings of the National Academy of Sciences