Integrated analysis of groundwater storage dynamics and drought migration in the Tarim River Basin

The Tarim River Basin (TRB), an arid inland river basin in northwestern China. This study investigates groundwater drought dynamics in the TRB from 2002 to 2024 using groundwater storage anomalies (GWSA). By integrating GRACE total water storage, GLDAS soil moisture, and JRC surface water datasets, a Groundwater Drought Index (GGDI) was developed to analyze spatiotemporal drought evolution, long-term trends, seasonal variability, and drought centroid migration under combined climatic and anthropogenic influences. Results reveal a significant long-term groundwater decline of −8.6 mm yr⁻¹ (p < 0.01), equivalent to a cumulative loss of 198 mm (23.4 billion m³), indicating persistent imbalance between recharge and abstraction, particularly in irrigated midstream and downstream areas. Over 65 % of the basin experienced moderate to extreme groundwater drought for more than a decade. Spring and winter show heightened vulnerability due to early irrigation withdrawals, frozen-soil constraints, and delayed recharge. A southeastward shift of drought centroids is associated with glacier retreat and increasing groundwater extraction, reflecting reorganization of recharge–discharge processes. The GGDI proves effective for groundwater drought assessment and water management in data-scarce arid regions. • Basin groundwater declined at −8.6 mm/year, totalling over 198 mm depletion. • A new GGDI index detects both long-term and seasonal groundwater drought. • 65 % of the basin faced moderate–extreme drought in ≥ 10 of the past 23 years. • Drought centers shifted ∼250 km southeast, revealed by spatial centroid analysis.