Global Virtual Water Flow Analysis

7. Chapagain and Hoekstra (2008) explained the issues of freshwater in a global context. A comprehensive estimate of International virtual water flows in the period 1997–2001 was made to analyze what these virtual water flows mean in terms of water import dependency of regions. The paper considers International trade in 285 crop products and 123 livestock products. Trade in industrial products is dealt with all-inclusively as well with the average virtual water content per dollar of traded industrial product as a key parameter. The calculation shows that the global virtual water flows during the period 1997–2001 added up to an average of 1625 BCM/yr. The major share (61%) of the virtual water flows between countries is related to the International

According to the analysis done, the major water exporters are the US, Canada, France, Australia, China, Germany, Brazil, the Netherlands and Argentina. The major water importers are the US, Germany, Japan, Italy, France, the Netherlands, the UK and China. The results shows that the current global trade pattern significantly influences water use in most countries of the world, either by reducing domestic water use or by enhancing it. They recommend that future water policy studide at national level include an assessment of the effects of trade on water policy. The study shows that for water-scarce countries, it would also be wise to do the reverse: studying the possible implications of national water scarcity on trade. Finally, by showing virtual water flows, the study visualizes the connection between consumption in one place and water use for production in another

Oki and Kanae, (2006) explained that the amount of water stored in all the rivers in the world is only 2000 km3, much less than the annual water withdrawal of 3800 km3/year. Clearly, a more adequate measure of water availability is the 45,500 km3/year of annual discharge, which flows mainly through the rivers from continents to the sea. Renewable fresh water resources (RFWR) is naturally re-cycled, the circulation rate is determined by the climate system, and there is an upper limit to the amount of RFWR available to human society. On the global scale, current withdrawals are well below this limit, and if the water cycle is managed wisely, RFWR can cover human demand far into the future.About3800 km3/year of RFWR (blue water) is currently withdrawn by human beings, and that accounts for less than 10% of the maximum available RFWR in the world. Transporting water over long distances from regions, where water is abundant to dry regions under water stress, is only feasible when gravity can be used. The demand for high-quality drinking water is limited to a few liters per person per day and can be met through the International trade or by desalination. Water demand for food and industrial production in dry regions can be offset by importing food or industrial goods. Such trade is called "virtual water trade". The weight of traded goods is normally just a small fraction of the weight of the water required to produce that goods, so transporting goods is considerably easier