Spatiotemporal Changes of Drought Conditions Over the Hindu-Kush Himalayan Region During the Recent Century: Insights for Climate Adaptation

The Hindu Kush Himalayan (HKH) region, a critical water source for 2 billion people, exhibits contrasting drought patterns under climate change. Using the Self-Calibrating Palmer Drought Severity Index (scPDSI) and spatiotemporal analyses (1901–2022), we reveal a regional dichotomy: significant drought reduction in Afghanistan, China, and Pakistan (scPDSI slope ≤ +0.016/year, p < 0.05) versus intensifying aridity in Bangladesh, Bhutan, Myanmar, and Nepal (slopes ≥ − 0.015/year, p < 0.05), with India stable (slope = −0.002/year, p > 0.05). Precipitation dominates drought recovery in western HKH (e.g., Pakistan and Afghanistan: r = 0.77), whilst Arctic Oscillation (AO) teleconnections amplify resilience in China (β = 0.43, p < 0.05). Eastern regions face temperature-mediated drought intensification (Bangladesh: r = −0.33) and divergent ENSO impacts (Myanmar: r = −0.32). Spatial clustering (Moran's I = 0.753, p < 0.001) confirms drought trends are non-random, driven by climatic drivers. Mechanistic contrasts emerge: western HKH recovery links to precipitation and snowmelt, whilst eastern regimes integrate AO and Australian Summer Monsoon synergies. Drought relief areas doubled (1.15–2.34 million km², 1901–2022), accelerating post-1960, contrasting with lowland drought expansion (e.g., Indus Basin). These findings demand spatially targeted adaptation: water-efficient agriculture in precipitation-sensitive lowlands and climate-resilient storage in high-elevation zones. By bridging hydroclimatic trends with hybrid modelling of threshold-driven drivers, this study advances transboundary governance frameworks to mitigate the HKH's water insecurity.