Integrated assessment of flood and drought risk in a context of declining terrestrial water storage in Northwest China: A broad perspective analysis

Study region Northwest China (NWC), a typical arid inland region. Study focus Based on Gravity Recovery and Climate Experiment (GRACE) satellite data and multi-source assimilated datasets, this study analyzed the dynamics of terrestrial water storage (TWS) and assessed the associated flood and drought risks as a broad perspective analysis. The spatiotemporal variations in TWS were examined using non-parametric trend analysis methods, and the contributions of different water storage components to TWS change were quantified using partial least squares regression (PLSR). A comprehensive risk assessment framework was developed by integrating hazard probability, socioeconomic exposure, and ecological vulnerability. The associations between large-scale atmospheric circulation and hydrological extremes were explored using cross-wavelet transform analysis. New hydrological insights for the region TWS decreased by 85.54 Gt/yr in NWC from 2003 to 2023, with significant spatial heterogeneity: increasing trends in southern NWC and decreasing trends in most other regions. Groundwater storage accounted for 75.95% of the total TWS variations. Middle- to high-risk zones for drought, flood, and compound disasters were concentrated in eastern Lanzhou and areas surrounding the Tianshan Mountains. The Southern Oscillation (SO) and the El Niño-Southern Oscillation (ENSO) showed exploratory associations with drought and flood variability, respectively. By linking TWS changes and atmospheric circulation with hydrological hazards, this study provides new insights for improving disaster risk identification and management in arid inland regions.