Beyond Frequency: Measuring Climate Disaster Risk Concentration in Indonesia Using a Herfindahl Index Approach

Abstract

Climate change not only increases the frequency of hydrometeorological disasters but also reshapes regional risk structures, depending on the dominance or diversity of hazard types. This study aims to measure and compare the concentration of climate hazards in Indonesia by moving beyond a purely frequency-based approach. The analysis utilizes village-level data derived from the 2021 Village Potential Census (Potensi Desa/PODES) conducted by BPS-Statistics Indonesia. Using information on floods, droughts, forest and land fires, and extreme winds, the study employs the Herfindahl–Hirschman Index (HHI) to quantify disaster concentration. The results show that most villages exhibit a concentrated risk structure, although substantial regional variation exists. At the provincial level, however, concentration patterns appear relatively uniform, reflecting the dominance of specific hazards shaped by geographic and climatic characteristics. These findings suggest that regions with similar disaster frequencies may nonetheless display markedly different risk profiles when assessed through the lens of hazard concentration. The primary contribution of this study lies in introducing a structural measurement framework for climate risk that remains underutilized in disaster research, while providing an empirical foundation for designing mitigation and adaptation strategies that are more responsive to regional risk configurations.