Virtual Water a Solution to Water Resources Management

The concept of virtual water trading has received an increasing amount of attention amidst a growing world population, with its increased need for food security and associated impacts on increasingly scarce water resources. Virtual water was defined originally as ―the water embodied in food crops that are traded internationally‖ and it is within the context of national and regional food security that the concept was developed. Essentially, the concept encourages a country to view agricultural crops in terms of the amount of water required to produce those crops. In this way, a country wishing to enhance food security and at the same time minimize impacts on its water resource, may opt to import crops from another country instead of producing the crops itself, and thus avoid the associated impacts of water use. Such virtual water considerations assist in the tough trade-offs between water resource protection and food security. Improved trade-offs of this kind can lead to better informed trade policies that a) improve food security, and b) ensure that scarce water resources are adequately protected as well as used to their optimal benefit. The notion of countries being able to conduct trade in virtual water is particularly relevant in highly water-scarce countries (e.g. North African and Middle Eastern countries) that rely almost exclusively on irrigation for crop production. Accordingly, it has been noted that ―the import of virtual water via imported food and the export of other commodities requiring less water will remain avalid concern for water-short nations seeking to maximise the value of their limited water resources‖Calculations of the virtual water content of crops have focussed on the total amount of water required to produce that crop (m3/tonne). More recently, studies have taken the relative contribution of diverse water sources, i.e. green water (derived from rainfall and available in soil) and blue water (contained in river, lakes, dams and aquifers) for agricultural production into account. Blue water has significantly higher opportunity costs associated with its use and trade-offs involving blue water allocation and use are therefore more relevant when evaluating the impacts of virtual water trading on water scarcity within a country or region. Importantly, water scarcity is a function of the volume as well as the quality of the water available. When the quality of the water is unacceptable for a specific use, it is, in effect, unavailable for that particular use. Agriculture is recognized world-wide as being the leading contributor to nonpoint source pollution of water resources. Nutrients from fertilizers (e.g. phosphorus, P; nitrogen, N) cause eutrophication, while pesticides have been shown to cause toxicity-related problems in humans, crops, livestock and wild life. In this study, application of virtual water as a solution to water resources management it was discussed.

کلیدواژه ها:

water resources ، virtual water ، food security ، green water ، blue water ، virtual water trade