Multi-scale input-output analysis of consumption-based water resources: Method and application

Abstract

This work develops a method of multi-scale input-output analysis for the embodied water accounting of an economy. This method can distinguish between the different virtual water contents of imported and local products and is therefore capable of estimating the virtual water that is embodied in trade. As a simplified model rather than a multi-regional input-output analysis, this method substantially minimizes the data requirements. With the support of averaged Eora global embodied water intensity databases for the world and Chinese economies, a three-scale embodied water input-output analysis of the Beijing economy in 2007 has been conducted. Dozens of virtual water flows that relate to the Beijing economy have been identified and analyzed. Only 15% of the total water resources embodied in Beijing's local final demand were from local water withdrawal; 85% were from domestically and internationally imported products. The virtual water import is revealed to play a more important role than physical water transfer in easing Beijing's water shortage. Since the average water use efficiency of the Beijing economy is much higher than that of the Chinese economy but somewhat lower that of the rest of the world, Beijing is suggested to shifting its imports to foreign countries to optimize global water use. The method developed can be useful for water saving strategies for multiple responsible entities holding different opinions, and it can be easily applied to the embodied water accounting of a sub-national or even smaller economic community.