Virtual water accounting for the globalized world economy: National water footprint and international virtual water trade

This study investigates the virtual water profile of the world in 2004 based on a multi-region input–output model. The water footprints of 112 nation-level regions are calculated and the footprint compositions of major water consumers are analyzed. Less than 35% of the global virtual water requirement is provided by agricultural products, in spite of the fact that 69% of the total water withdrawal is associated with agricultural sector. At the national scale, India, the United States, and mainland China are the world's largest virtual water consumers. Per capita water footprint varies from 30 m3 for Rest of South Central Africa to 3290 m3 for Luxembourg. As one of the major determinants of national footprint, international virtual water trade sums up to 30% of the direct water withdrawal of the world. Meanwhile, results show that 57% of the international virtual water flows is embodied in non-food trade, confirming the importance to take not only food product but also non-food product into account when overall water budget is considered. Mainland China is the world's leading exporter and deficit receiver in terms of virtual water trade (204 Gm3 and 142 Gm3, respectively), in contrast to the United States as the leading importer (178 Gm3) and Japan as the leading surplus receiver (77 Gm3). Finally, the virtual water trade connections of China and the United States with their major trading partners are revealed via introducing the index of virtual water dependency. Results presented in this study are of essential implications for policy making regarding water using pattern adjustment and water security enhancement.