Vulnerability Assessment to Changing Water Conditions Using Composite Indices at a Regional Scale in Thessaly, Greece

Integrated Water Resources Management requires decision-support approaches capable of combining hydrologic, climatic, social, economic, technical, and governance dimensions. This effort evaluates the transferability and structural robustness of an already developed composite-index framework for drought, water stress, water scarcity, and changing water conditions in the Regional Unit of Karditsa, Thessaly, Greece. The published COROADO index structure was transferred in its original form to show its local applicability to the reference year 2016. The Drought Vulnerability Index (DVI) had a regional mean of 1.20 and ranged from 0.18 to 2.13, while the Water Stress Vulnerability Index (WSTVI) had a mean of 1.01 and ranged from 0.54 to 2.20. DVI showed strong spatial concordance with the independently formulated Standardized Drought Vulnerability Index (r = 0.823), which was interpreted as convergent evidence rather than independent validation. Within the inherited WCCVI formulation, WSTVI has the largest component weight (0.408), followed by DVI (0.298) and WSCVI (0.294), while the higher vulnerability classes were concentrated mainly in the eastern and northeastern lowlands. Global structural sensitivity analysis based on 250,000 realizations showed high rank stability under ±20% weight perturbations (minimum Spearman ρ = 0.992) and limited sensitivity to moderate shifts in the final class boundaries (maximum class reassignment = 3.40%). In contrast, leave-one-indicator-out experiments produced changes of up to 59.24%. The results support the operational transferability of the COROADO framework as a regional screening approach, leading towards its broader applicability across contrasting hydrological, climatic social and economic settings.