The impact of virtual water trade on urban water scarcity: A nested MRIO analysis of Yangtze River Delta cities in China

With the aim of balancing and reducing the inflows and outflows of water between cities, urban water man-agement is critical in China's goal of alleviating water stress and promoting water sustainability. In facilitating further understanding of the supply and demand of urban water resources, analysis of the direct and indirect water profiles of cities is considerably beneficial. In the present study, by compiling a nested multi-regional input output table, for the first time, the city-level water footprints for 26 Yangtze River Delta cities were estimated and the virtual water trade patterns at home and abroad were investigated as well as the impact thereof on urban water resource stress. The results show that the total water footprint of the urban agglomeration was 114.8 Gm3 in 2012 and over 50% of the water footprint could be attributed to virtual water inflows which were mainly shaped by agriculture and light industry. The net virtual water inflow was 9.0 Gm3, indicating that virtual water trade alleviates the shortage of water resources in the region. At the city level, richer cities tended to have a higher water footprint by importing large amounts of virtual water to satisfy their higher requirements for the quality of life and larger household consumption. However, less developed water-abundant cities had more water footprint from infrastructure construction, and exported considerable virtual water to other cities, thereby exacerbating local water stress of these cities. The inter-city virtual water flows within the Yangtze River Delta were contributed by multiple industry sectors and the inequality of urban water scarcity among cities therein has been alleviated to a certain extent. Our results highlight the importance of simultaneously considering both the volume and the impact of water use in virtual water trade analyses. The present authors conclude that attention needs to urgently shift from supply-oriented water management to urban water demand management.