Integrating rapid-onset dynamics and socio-hydrological exposure to assess flash drought vulnerability in Rajasthan, India

Flash droughts increasingly threaten water security due to their rapid onset and limited preparedness time. This study assesses flash drought dynamics across Rajasthan (1951–2024) by jointly analysing onset, drought duration, intensity, and cumulative deficit. A multivariate rapid flash drought index (RFDI), based on joint cumulative distribution and inverse normal transformation, is developed to quantify compound drought severity. Results reveal a clear shift towards shorter onset durations and higher intensities in recent decades, indicating rising drought susceptibility despite reduced mean duration and deficit. Severity hotspots persist in northeastern and eastern Rajasthan, emphasizing the role of rapid hydroclimatic transitions over long-term aridity. A complementary vulnerability framework integrating RFDI, population exposure, and water stress shows that high hazard does not always imply high risk; instead, vulnerability is greatest in densely populated, water-stressed regions. The framework offers a robust approach for identifying flash drought hotspots and supporting targeted early warning and adaptation strategies.