Thirsty but not equal: Shifting water scarcity in China's grain production (1995–2022)

Ensuring water and food security under climate change is crucial for China’s grain production. Using provincial data for 1995-2022, we simulated spatiotemporal dynamics of blue and green water footprints (WF), available water resources (AWR), and water footprint scarcity (WFS) in China’s grain production. Nationally, total WF increased slightly (3.90*10 11 m 3 to 4.76*10 11 m 3 ), mainly due to expanded cultivated area and yields. The green water footprint (WF green ), dominated by rice, was 1.6 to 2.4 times larger than the blue water footprint (WF blue ) predominantly from maize. Spatially, the WF increased in northern China but decreased in the south, with major contributions from eastern and northern provinces such as Henan and Heilongjiang. However, a distinct spatial heterogeneity emerged: WF green prevailed in the humid east and south, while WF blue dominated in the arid northwest. Driven by WF and AWR, China’s grain production has faced increasing and high water scarcity, with WFS consistently above 0.6. This was more urgent in the North China Plain and the northwest (especially Ningxia and Henan provinces), where blue water scarcity (WFS blue ) became critical. Conversely, southwestern and southeastern provinces showed moderate or lower WFS, benefiting from higher AWR and lower WF. To mitigate these risks, we recommended integrated strategies focusing on water-saving technologies, optimized irrigation, enhanced rainfall utilization, crop structure adjustment, and interregional grain trade. Future research should adopt life-cycle- and nexus-based approaches while explicitly incorporating interregional virtual water flows to refine the water scarcity assessment and inform actionable policy. The spatial water footprint scarcity (WFS), blue water footprint scarcity (WFS blue ), and green water footprint scarcity (WFS green ) of China’ grain production from 1995 to 2022. • China’s grain WF slightly increased, being concentrated in the east and the north. • WF green dominated by rice was 1.6 to 2.4 times larger than WF blue mainly from maize. • In contrast to the east and south, WF blue exceeded WF green in Northwest China. • Water scarcity intensified steadily, with rising WFS blue in northern China. • Contrary to AWR, WFS in northern China was higher than in southern China.