|Author:||Fraiture, C. de ; Cai, X. M. ; Amarasinghe, U. ; Rosegrant, M. ; Molden, D.|
|Book Group Author:||NA|
Virtual water refers to the volume of water used to produce agricultural commodities. When these commodities enter the world market, trade in virtual water takes place. Countries importing agricultural commodities essentially purchase water resources from exporting countries, thereby saving water they would otherwise have required. Virtual water trade potentially reduces water use at two levels: national and global. Because it takes between 500 and 4,000 liters of crop water to produce one kilo of cereal, a nation reduces water use substantially by importing food instead of producing it on their own soil. At the global level, water savings through trade occur if production by the exporter is more water efficient than by the importer. Trade saves irrigation water when the exporting country cultivates under rainfed conditions, while the importing country would have relied on irrigated agriculture. A growing number of researchers propose international food trade as an active policy instrument to mitigate local and regional water scarcity. In their view, water short countries should import food from water abundant countries to save scarce water resources for "higher" uses, such as domestic purposes, industry and environment. This report, analyzing the impact of international cereal trade on the global water use, argues that the role of virtual water trade in global water use is modest. In 1995, all importers combined, imported 215 million tons of grain for which they would have otherwise depleted 433 km3 of crop water and 178 km3 of irrigation water. Because of crop productivity differences between importers and exporters, cereal trade reduces global water use by 164 km3 of crop water (effective rainfall or rainfall plus irrigation) and 112 km3 of irrigation water depletion. This implies that without trade, global crop water use in cereal production would have been higher by 6 percent and irrigation depletion by 11 percent. Trade and associated savings will most likely increase in the coming decades. Although the potential of trade to reduce water use may seem large - on paper - one should be careful when concluding that trade plays - or will play - an important role in global water scarcity mitigation. Occurring because of reasons unrelated to water, most trade takes place - and will continue to take place - between water abundant countries. Further, not all water "savings" can be reallocated to other beneficial uses. Furthermore, reductions in global water use relate to productivity differences between importers and exporters rather than water scarcity. Finally, political and economic considerations - often outweighing water scarcity concerns - limit the potential of trade as a policy tool to mitigate water scarcity.
|Journal:||Research Report - Comprehensive Assessment of WaterManagement in Agriculture|
agricultural products, cereals, commodities, cropproduction, exports, globalization, imports, international trade,irrigation, irrigation water, productivity, rain, water conservation,water management, water resources, water use, world, world markets,internationalization, rainfall, water resource management, watering,worldwide, Agricultural Economics (EE110), Natural Resource Economics(EE115) (New March 2000), Food Economics (EE116) (New March 2000),International Trade (EE600), Field Crops (FF005) (New March 2000), PlantProduction (FF100), Water Resources (PP200), Crop Produce (QQ050)