title: The water footprint of humanity.
abstract: This study quantifies and maps the water footprint (WF) of humanity at a high spatial resolution. It reports on consumptive use of rainwater (green WF) and ground and surface water (blue WF) and volumes of water polluted (gray WF). Water footprints are estimated per nation from both a production and consumption perspective. International virtual water flows are estimated based on trade in agricultural and industrial commodities. The global annual average WF in the period 1996-2005 was 9,087 Gm(3)/y (74% green, 11% blue, 15% gray). Agricultural production contributes 92%. About one-fifth of the global WF relates to production for export. The total volume of international virtual water flows related to trade in agricultural and industrial products was 2,320 Gm(3)/y (68% green, 13% blue, 19% gray). The WF of the global average consumer was 1,385 m(3)/y. The average consumer in the United States has a WF of 2,842 m(3)/y, whereas the average citizens in China and India have WFs of 1,071 and 1,089 m(3)/y, respectively. Consumption of cereal products gives the largest contribution to the WF of the average consumer (27%), followed by meat (22%) and milk products (7%). The volume and pattern of consumption and the WF per ton of product of the products consumed are the main factors determining the WF of a consumer. The study illustrates the global dimension of water consumption and pollution by showing that several countries heavily rely on foreign water resources and that many countries have significant impacts on water consumption and pollution elsewhere.
authors.affiliation: Department of Water Engineering and Management, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. a.y.hoekstra@utwente.nl
authors.forename: Arjen Y
authors.initials: AY
authors.lastname: Hoekstra
authors.forename: Mesfin M
authors.initials: MM
authors.lastname: Mekonnen
mesh_terms: D057914:Agricultural Irrigation / Q000706:statistics & numerical data; D000383:Agriculture / Q000706:statistics & numerical data; D003132:Commerce / Q000706:statistics & numerical data; D003247:Conservation of Natural Resources / Q000706:statistics & numerical data; D019049:Developed Countries / Q000706:statistics & numerical data; D003906:Developing Countries / Q000706:statistics & numerical data; D005502:Food; D005618:Fresh Water; D006802:Human Activities / Q000706:statistics & numerical data; D006801:Humans; D007221:Industry / Q000706:statistics & numerical data; D011891:Rain; D014872:Water Movements; D014876:Water Pollution / Q000706:statistics & numerical data; D014881:Water Supply / Q000706:statistics & numerical data