China's strictest water policy: Reversing water use trends and alleviating water stress

Growing water problems have promoted the Chinese government to implement the strictest water resources management system (SWRMS), the first national policy that puts into practice the concept of "safe operating space" for human water use. Here, we investigate the impact of the SWRMS on China's water use and water stress based on a newly compiled high-resolution and multi-sectoral water use dataset. Results indicate that China's total water use (TWU) increased significantly from 549 km³ yr^-1 to 610 km³ yr^-1 between 2000 and 2012 (i.e., the pre-SWRMS period), but decreased remarkably in the post-SWRMS period (2012-2020), reaching 565 km³ yr^-1 by the year 2020. The decline in TWU was attributed to the improvements of irrigation and industrial water use efficiency (WUE), which were strictly controlled by the SWRMS at various administrative levels of China. The improved WUE has yielded about ∼90 km³ of water savings per year, freeing 17 prefectures from extreme water stress that affects 6% of China's population and 10% of its GDP. Although the improved WUE caused a significant decrease in TWU, the reduction in China's average water stress was insignificant due to the considerable influence of water availability. We further identified hotspots with great potential for water stress reduction, mainly in northwestern China, and hotspots at high risks of water security, primarily on the North China Plain. This study underscores the crucial role of the SWRMS in addressing China's water shortage and provides valuable insights to other countries grappling with water problems in defining their own "safe water operating spaces".