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

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 Gm(3) water loss and increased the impacts on water scarcity and human health by 1.61 Gm(depoved)(3) and 3.42 x 10(4) DALY, respectively. Nevertheless, the grain virtual water flow generated benefits in ecosystem quality by 1.20 x 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.

Automated summary

This study analyzed the flow patterns of China's interprovincial and international grain virtual water, focusing on environmental impacts such as water scarcity, human health, and ecosystem quality. Results showed that maize trade was the main contributor to environmental impact flow, while exporting rice from certain provinces contributed mostly to water-saving and environmental benefits. Measures suggested to alleviate environmental impacts and ensure grain security include improving irrigation water productivity and developing a regional compensation mechanism for dominant maize exporters.