Integrating multi-hazard, socio-physical information in a holistic index for decision making on disaster risk reduction

Effective disaster risk management (DRM) requires a contextual understanding of the underlying risks that should account for: (1) the effects of multiple (natural) hazards on the systems/communities of interest; and (2) social vulnerability factors that influence how different sectors within a given community experience, respond to and cope with these effects. We propose a straightforward multi-hazard risk index for guiding high-level DRM decision making across a large spatial extent, which integrates both of these crucial considerations. The index represents a combination of spatially explicit, probabilistic indicators that collectively capture information on multiple risk dimensions (i.e., multiple hazards, physical and social vulnerability, and population exposure) within a given area. Each of these dimensions can be weighted (i.e., emphasised) to varying degrees in the index calculation, depending on stakeholder DRM priorities, that may vary in relation to different hazards. We apply the index to the entire country of Italy (at the resolution of municipalities) for earthquake and flood risk, using easily accessible open data, which identifies hotspots across the country where disaster risk reduction actions would be particularly beneficial. Sensitivity analyses of the weights assigned to the various risk dimensions reveal how these hotspots can change depending on the relative significance attached to managing different aspects of risk, including different hazards. This finding ultimately underlines the importance of accounting for accurate stakeholder feedback and a multi-layered (and multi-hazard) representation of risk in disaster-related decision making. A prominent advantage of the proposed index is that it is relatively simple and could be easily adopted for practical multi-risk decision support across any other national or transnational context of interest.