Assessment of Agricultural Drought Vulnerability in the Transboundary Danube River Basin: Integrating Exposure, Sensitivity, and Adaptive Capacity Indicators

ABSTRACT Agricultural drought increasingly threatens food security and water sustainability in transboundary river basins. This study presents the Integrated Drought Vulnerability Index (IDVI), a composite metric based on the Drought Vulnerability Index (DVI) framework, assessing agricultural drought vulnerability across eight Danube River Basin countries. The IDVI combines 12 sub‐indices covering exposure, sensitivity, and adaptive capacity into a single normalised score for eight countries, providing a comprehensive vulnerability assessment from 2001 to 2022. The DVI‐based Exposure sub‐index uses the Standardised Precipitation Evapotranspiration Index (SPEI‐3) to capture drought frequency (DF), duration (DD), and intensity (DI). The Sensitivity sub‐index incorporates arable land share (ALS), population density (PD), elderly population proportion (EP), poverty rate (PR), and agriculture's GDP contribution (AGS). The Adaptive Capacity sub‐index integrates Gross Domestic Product per Capita (GDP per Capita), water use efficiency (WUE), renewable water resources (RWR), and Income Inequality (II). Three weighting approaches—Equal Weighting (EqW), Factor‐Based Weights (FbW), and Monte Carlo simulation (MC)—were systematically compared. Exposure indicators showed consistent contributions across methods, with DI identified as the most influential factor (MC weight = 0.34), exhibiting high stability (Spearman's r > 0.90; KS < 0.30). The DVI‐based Sensitivity sub‐index showed agricultural dependence, mainly ALS and AGS, as the key drivers, reaching 72% of sensitivity weight in eastern countries. Adaptive Capacity showed significant regional variation; MC simulations delivered statistically robust weights (Spearman's r up to 0.98, KS < 0.04), emphasising differences in WUE, economic capacity, RWR, and institutional strength. IDVI results show that 27% of the study area faces high drought vulnerability, primarily driven by demographic pressure, social inequality, and water scarcity. The study identifies the regions and populations most vulnerable to agricultural drought, highlighting the urgent need for region‐specific adaptation strategies and targeted drought mitigation efforts to enhance resilience in these high‐risk areas.