A Spatially Explicit Assessment of Growing Water Stress in China From the Past to the Future

In this study, we examine the spatial and temporal characteristics of water stress in China for the historical (1971–2010) and the future (2021–2050) periods using a multimodel simulation approach. Three water stress indices (WSIs), that is, the ratios of water withdrawals to locally generated runoff (WSI), to natural streamflow (WSI), and to natural streamflow minus upstream consumptive water withdrawals (WSI), are used for the assessment. At the basin level, WSI estimates generally match the reported data and indicate severe water stress in most northern basins. At the grid cell level, the WSIs show distinct spatial patterns of water stress wherein WSI (WSI) estimates higher (lower) water stress compared to WSI. Based on the WSI estimates, 368 million people (nearly one third of the total population) are affected by severe water stress annually during the historical period, while WSI and WSI suggest 595 and 340 million, respectively. Future projections of WSI indicate that more than 600 million people (43% of the total) might be affected by severe water stress, and half of China's land area would be exposed to stress. The found aggravating water stress conditions could be partly attributed to the elevated future water withdrawals. This study emphasizes the necessity of considering explicit upstream and downstream relations with respect to both water availability and water use in water stress assessment and calls for more attention to increasing levels of water stress in China in the coming decades.