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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Studying at Cambridge

JodyKay Maxwell



Globally water is becoming an increasing scarce resource. According to the World Business Council for Sustainable Development (2006), less than 3% of the world’s water is fresh, 2.5% of that amount is frozen with only 0.5 % fresh water is available from aquifers, rainfall, lakes, reservoirs and rivers. Virtual water has been championed by J Anthony Allan of the School of Oriental and African Studies (1994), as the chief means by which water scarce countries can alleviate water stress through importing water intensive products and commodities from water rich countries. International trade directly links the wealth and resources of countries providing critical channels through which virtual water can be transferred from producer to consumer countries.

This study introduces a new concept of avoided water in order to attempt to assess whether avoided water is a different manifestation of virtual water or if there is a net difference which could be revealing. The concept of avoided water is analogous to the concept of avoided burden in life cycle analysis and was coined by R A Fenner, Centre for Sustainable Development at the  University of Cambridge (2013). Avoided water is water that has not been used for productive  nd consumptive purposes which would otherwise be needed to produce the amount of goods  mported under local conditions by the consumer. This is calculated at the consumer end of the  upply chain, rather than the producer end in the case of virtual water.

The methodology of research consisted of an extensive literature review, to assess the main  rivers of virtual water and highlight the dominant international flow paths and nodes. This  rovided the basis for selection of virtual water flow paths between USA and Saudi Arabia on the global virtual water network for greater analysis. CROPWAT 8.0 parameters were utilised to  alculate and estimate the avoided water at the consumer end and virtual water generated at the producer end against the total water sources.

The findings suggested that avoided water may have direct and indirect social and  nvironmental implications on the producer end of the chain. These include habitat degradation, and bio-diversity and ecosystem losses.  Two critical ratios were derived: relative avoidance the ratio of avoided water to available water resources), and relative water use (ratio of virtual water to available water resources). These demonstrated that the relative water use in North Dakota was 2.5 times larger than the relative avoidance in Saudi Arabia, indicating that the consumer in this case was exporting water stress by importing wheat. This suggests that avoided water is a useful measure  in  assessing  the  burdens  placed  on  producer  countries.  Further  tudies  on  other dominant routes (e.g. Brazil to China) are recommended to confirm the findings of this work.