High-resolution reconstruction of groundwater table depth in China (2005–2021): evidence for recovery under large-scale water management

Groundwater is irreplaceable in sustaining populations, maintaining agriculture, and supporting socioeconomic development, especially in arid and semi-arid regions where surface water is limited. However, a comprehensive understanding of groundwater table depth (WTD) changes across China remains constrained, especially following large-scale water management. Here, we present a monthly 0.1° resolution WTD dataset for China from 2005 to 2021, built by random forests using 470,967 monthly measurements from 9,011 stations and 25 predictors across topographic, geological, environmental, and anthropogenic categories. Validation results for nine river basins using testing dataset and compared with the published regional GWD data indicated that the constructed models exhibited reasonable performance, with high R² (0.85 to 0.95, median 0.89) and low RMSE (2.11 to 13.44, median 3.82). Nationally, WTD is generally shallow in the southeastern regions and deep in the northwest, with a non-significant increasing trend of 3.79×10^-3 m/year over the study period. Spatially, WTD experienced significant increases in the Huaihe and Yellow River basins, while exhibiting apparent decreases in the Yangtze and Southeast River basins. With the implementation of a series of water management strategies, such as the designation of groundwater extraction prohibited areas, the operation of the South-to-North Water Diversion Project in late 2013, the WTD in North China Plain's cities such as Beijing and Tianjin had decreased significantly, indicating groundwater table recovery. Similarly, through adjustments in planting structure and irrigation practices, cropland WTD in North China Plain decreased significantly from 2014-2021. These findings highlight the positive impact of the enacted series of water management measures on the recovery of WTD in urban and agricultural regions. Our study provides a high spatiotemporal groundwater table depth dataset for China, offering valuable insights for optimizing water management and enhancing groundwater protection strategies.