Blue, green and grey water embodied in food supply chain in China
Abstract Food trade is transferring the water embodied in food production, which plays important role in balancing water resources between dry and wet regions. To identify the impact of food trade on reallocating water and pathways to mitigate the trade offs between food security and water resource conservation, we built food based virtual blue, green and grey water network. The gravity model and linear programming optimization were used to model interprovincial food trade of China in 2015, and the regional blue, green and grey water footprint of food crops were inventoried. Combing the food trade network and water footprint, the food based virtual blue, green and grey water network was built and used to quantify the water relationship along with national food supply chain. Our results showed that the proportion of green and grey water for the total water consumption were huge, while whose impacts were traditionally neglected. Especially, the food trade is playing important role in transferring the water used for assimilating the pollution. By identifying the critical food trade pathways, we aim to provide insights for reducing the structural tensions between spatial water reallocation and national food security.