Mitigating trade-driven water scarcity via water-saving irrigation in China: Different role of surface water and groundwater

Examining virtual water flows in China, we identified a crucial gap in differentiating between groundwater (GW) and surface water (SW). Understanding the unique roles of virtual GW and SW is vital for local sustainable water use. We firstly track virtual GW and SW flows via inter-provincial trade, using a comprehensive inventory that included GW and SW uses in China. Our findings show nearly two-thirds of Chinese provinces face GW or SW scarcity in 2017, with about 34 % of GW and 31 % of SW use driven by interprovincial trade. Water rich regions acted as virtual SW exporters, while water scarce regions served as virtual GW exporters. Targeted irrigation efficiency improvement strategies, considering regional surface and groundwater pressures, could notably reduce interprovincial trade-driven GW and SW use by 12 % and 7 %. It's crucial to manage GW and SW as single resources, recognizing both their physical and virtual distinctions in local water use.