Virtual water flow pattern of grain trade and its benefits in China

Urbanization, industrialization and their associated water shortage pressures have brought great challenges to agricultural development and water security. Understanding the virtual water flow involved in the grain trade is critical to ensuring water security and agricultural production. However, there are few studies on the comprehensive benefits provided by virtual water flow in the grain trade. This paper proposes a linear optimization model to fill this gap. The model is used to estimate the virtual water flow via interregional grain trade within China in 2015 and corresponding benefits to resources, the economy, and the environment from both outflow and inflow comparative perspectives. Three results characterize the virtual water flow pattern of interprovincial grain trade in China in 2015: (1) In terms of resource benefit, 31. billion cubic meters of water resources were saved, accounting for approximately 39.7% of the total virtual water flow. (2) A positive economic benefit was realized, with an increase of 6.4 trillion yuan in industrial value added. (3) Certain regions with a high crop green water occupation index account for a considerable proportion of the green water of the local agricultural ecosystem. Simultaneously, massive output of virtual water would aggravate the destruction of terrestrial ecosystems. Finally, the results suggest that promoting the marketization of water resources, improving water productivity, exploring regional compensation mechanisms and improving green water conservation capacity should be considered for water security policies.