Irrigated agriculture expansion drives groundwater storage decline in Black Soil Region of Northeast China

The global expansion of irrigated agriculture is driving groundwater overexploitation and increasing the risk of aquifer depletion. However, the drivers of groundwater storage changes across different temporal scales remain unclear, posing challenges to regional agricultural and ecological sustainability. This study used high-resolution Gravity Recovery and Climate Experiment (GRACE) data (2003 – 2022) to analyze the spatiotemporal distribution of groundwater storage in the Black Soil Region of Northeast China, with a focus on key irrigated agricultural areas. The study identified long-term and seasonal trends of groundwater storage across key areas and applied a random forest regression model to quantify the relative contributions of natural and anthropogenic factors. The results indicate a significant overall decline in groundwater storage (GWSA) in the study region, with an annual rate of decrease of 3.72 mm (p < 0.01). Spatially, GWSA exhibited heterogeneous patterns, with increasing variation from south to north and west to east. Significant seasonal fluctuations were also observed, with the highest GWSA in July (−11.65 mm) and the lowest in January (−34.56 mm). Snowmelt in spring and monsoon precipitation in summer was major contributors to increased groundwater storage. The seasonal trends were mainly driven by natural factors, while the long-term trends were influenced by anthropogenic factors, particularly agricultural land expansion. Expansion of irrigated areas is a major driver contributing to 26.6 %, 31.2 %, and 31.6 % of GWSA in the Sanjiang Plain, Liaohe Plain, and West Liao River Basin, respectively. Precipitation was the main driver of seasonal trends in the West Liao River Basin (21.1 %), while actual evapotranspiration dominated in the Sanjiang Plain (41.3 %), Songnen Plain (40.8 %), and Liaohe Plain (25.8 %). Expansion of irrigated agriculture, through associated increases in water consumption for irrigation, is the fundamental driver of groundwater storage depletion in irrigated agricultural regions. These results provide scientific evidence to support for the sustainable management and use of groundwater in irrigated agriculture within the study area. • Downscaled GRACE data better reflects the spatial heterogeneity of GWSA. • GWSA exhibits significant long-term variations and seasonal characteristics. • Evapotranspiration and snowmelt are main natural drivers of GWSA seasonal trends. • Expansion of irrigated areas is the key human driver of long-term GWSA decline.