Regional disparities in flood vulnerability and adaptive capacity: a national-scale assessment for South Korea

Increasing flood frequency and intensity due to climate change pose a significant global threat, necessitating robust regional vulnerability assessments. However, national-scale vulnerability assessments often overlook local-level socioeconomic drivers and institutional financial capacity. This study addresses this gap by developing and applying a comprehensive, indicator-based framework to assess flood vulnerability across all 228 administrative districts of South Korea. Using the entropy-weighting method, we constructed a Flood Vulnerability Index (FVI) encompassing exposure, sensitivity, and adaptive capacity. Notably, this study innovates by integrating local government expenditure data as a direct proxy for financial adaptive capacity. To examine the robustness of the indicator-based regional vulnerability assessment, we also conducted spatial autocorrelation analysis using Global Moran’s I. Results reveal significant regional disparities, uncovering two distinct vulnerability patterns. First, an urban vulnerability paradox exists where the high adaptive capacity of major metropolitan areas is dangerously offset by immense population and asset exposure. Second, a pattern of rural decline is identified, where low physical exposure is critically undermined by high social sensitivity (e.g., aging populations, fragile infrastructure) and chronically low financial capacity to manage flood events. Spatial autocorrelation analysis confirmed that high-vulnerability regions statistically cluster in major metropolitan areas. This framework provides an evidence-based tool for policymakers to move beyond a one-size-fits-all approach. It enables the strategic allocation of national resources for flood mitigation and climate adaptation in both urban and rural contexts.