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

Abstract Effective disaster-risk management requires holistic risk-modelling approaches, which: (1) capture the effects of multiple (natural) hazards on the system/community of interest; and (2) account for social vulnerability factors that influence how different sectors within the community experience, respond to and cope with these effects. We propose a straightforward multi-risk index that integrates both of these crucial considerations. The index represents a combination of indicators for individual risks of interest. It appropriately accounts for uncertainties in the underlying dimensions of risk, relying on probabilistic distributions of hazard, physical and social vulnerability, and population exposure information. Furthermore, these dimensions are weighted in the index calculation to explicitly reflect variable stakeholder priorities on associated matters (e.g., policymaking). We demonstrate the index for earthquake and flood risk across the entire country of Italy (at the resolution of municipalities), using easily accessible open data. The proposed index identifies hotspots across the country that should be prioritised for disaster risk reduction actions. Sensitivity analyses of the applied weights reveal how these hotspots can change as a function of stakeholder preferences and/or variations in the emphasis placed on different types of hazards, ultimately underlining the importance of accounting for accurate stakeholder feedback and adopting a multi-layered view 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.