PROPAGATION OF CRISES ON THE VWTN
Abstract. The international trade of agricultural goods is associated to the displacement of the water which is used to produce such goods and is 'embedded' in trade as a factor of production. Water virtually exchanged from producing to consuming countries, named virtual water, defines flows across an international network which is associated to (and driven by) the international commodity trade. This “virtual water trade” enables the assessment of environmental forcings and implications of trade, such as global water savings or country dependencies on foreign water resources. Given the recent expansion of commodity (and virtual water) trade, in both displaced volumes and evolution of the network, concerns have been raised about the exposure to crises of individuals and societies. In fact, if one country had to decrease or stop its export following a socio-economical or environmental crisis (such as a war or a drought), many -if not all- countries would be affected by such modification, due to a cascade effect. The present contribution drafts a model describing the propagation of a local crisis into the virtual water trade network and proposes some indicators to quantify the impact of such perturbation on the network.
Impact of a variation of export of 1 km3 in USA in 2010: