Calculation and Sustainability Evaluation of Grain Virtual Water Flow Among Provinces in China

Under the spatial distribution of water resources, with more water resources in the southern regions and less in the northern regions, and the “north–south grain transport” pattern, calculating the virtual water flow in food trade between provinces in China and analyzing its sustainability is crucial for ensuring the country’s water resources and food security. By considering various products and consumption types, the virtual water flow in inter-provincial grain trade is estimated using the Minimum Transport Cost Method and the Penman-Monteith formula. The sustainability of this virtual water flow is evaluated at the provincial level. (1) The results show that the top three provinces with the largest net virtual water outflow from inter-provincial grain trade are Heilongjiang, Henan, and Anhui, with net outflows of 43.166 billion m 3 , 18.974 billion m 3 , and 13.089 billion m 3 , respectively. The top three provinces with the largest net virtual water inflows are Hebei, Guangxi, and Liaoning, with net inflows of 18.875 billion m 3 , 10.076 billion m 3 , and 8.795 billion m 3 , respectively. (2) The largest inter-provincial virtual water flow occurs from Henan to Hebei (15.06 billion m 3 ), followed by Inner Mongolia to Hunan (9.57 billion m 3 ), and Heilongjiang to Hubei (9.04 billion m 3 ). (3) Overall, the current pattern of virtual water flow in China’s grain trade is sustainable, though several exporting provinces are under greater stress. In the actual scenario, the average water resource pressure index across all provinces is 0.43, 17.31% lower than the average of 0.52 in the scenario without inter-provincial grain trade. Compared with the scenario without inter-provincial grain product trade, in the actual scenario, Heilongjiang, Jilin, and Inner Mongolia show a higher increase in water resource pressure index, with increases of 94.74%, 73.68%, and 48%, respectively; Beijing, Shanghai, and Qinghai show a greater decrease in water resource pressure index, with reductions of 94.64%, 79.41%, and 66.67%, individually. And then, efforts should be made to adjust and optimize the structure of grain production and circulation; provinces with virtual water net outflow (such as Heilongjiang, Henan, Anhui, etc.) need to adjust their grain cultivation types and grain export structures.; provinces with virtual water net inflow (such as Hebei, Guangxi, Liaoning, etc.) can appropriately expand the scale of grain cultivation, while adjusting their diets to reduce the demand for water-intensive grains.