Can grain virtual water flow reduce environmental impacts? Evidence from China

Abstract

The irrational grain virtual water flow caused by spatial mismatch in water and available arable land threatens grain security in China. However, systematic and quantitative assessment of grain virtual water flow on environmental impacts has rarely been conducted. This study analyzes the flow patterns of China's interprovincial and international grain virtual water and resulting environmental impacts during 2019–2020, with a focus on water-saving and environmental benefits. Results showed that the main importers and exporters of environmental impact flow were inconsistent with those of virtual water flow, and maize trade was the main contributor to these flows. China's grain virtual water flow resulted in approximately 2.21 Gm3 water loss and increased the impacts on water scarcity and human health by 1.61 Gm3deprived and 3.42 × 104 DALY, respectively. Nevertheless, the grain virtual water flow generated benefits in ecosystem quality by 1.20 × 10−3 species. yr, compared with the no-grain transfer scenario. Exporting maize from Shanxi, Inner Mongolia, Gansu, and Xinjiang provinces dominated water loss and environmental burdens, whereas exporting rice from Hubei, Hunan, Anhui, and Jiangxi provinces contributed mostly to water-saving and environmental benefits. Importing grains from abroad also contributed to water-saving and ecosystem quality impact reduction. Measures, including improving irrigation water productivity and developing a regional compensation mechanism for dominant maize exporters, strengthening green water management in dominant rice-exporting areas, achieving the diversified development of China's trade partners, and implementing strict tariff quota administration, are suggested to alleviate environmental impacts and ensure grain security.