Embodied water demands, transfers and imbalance of China's mega-cities.

Water resources are of fundamental significance as the basis of human life, economy, and society. Especially as the essential socioeconomic factors, water resources transferred through merchandise trade of China's mega-cities (Beijing, Tianjin, Shanghai and Chongqing) play an increasingly crucial role in China's regional water use allocation. On the whole, the four municipalities in China are all embodied water recipients along supply chains. However, it is found that embodied water transfers (including direct and indirect water) related to these mega-cities have exacerbated the regional water use imbalance and affected the water use efficiency of China as a whole to some extent. In consideration of the increasing trading exchanges among cities and regions, ignoring water transfers embodied in trades will lead to failure in depicting actual water demands. In such a context, the embodied water demands and transfers of China's municipalities are analyzed systematically, and the water use efficiencies and allocation imbalance are assessed for the first time. Outcomes of this study through systems accounting of water use profiles of China's mega-cities can be strong supports for reasonable allocation and utilization of China's water resources, showing important implications for water pressure mitigation. [ABSTRACT FROM AUTHOR]