A Methodology for Developing a Municipal-Scale Integrated Risk Index to Support Civil Protection Planning: A Case Study from Lombardy (N-Italy)

This study proposes a methodology for developing an integrated risk index at municipal level, applied to the entire territory of the Lombardy region. The conceptual framework adopts a pragmatic approach based on the formula R = H × D (Risk = Hazard × Damage), integrating diverse institutional datasets—from national or regional geoportals—with empirical evidence drawn from the regional damage register (Ra.S.Da.). The methodology harmonises data relating to six types of risk: wildfires, seismic, hydraulic, hydrogeological, avalanches and adverse weather events. The main methodological steps included normalising the data to a common scale. The normalised risk values associated with each analysed phenomenon were aggregated using an additive approach, yielding a single integrated risk index for each municipality in Lombardy. The results highlight marked spatial variability in risk, enabling the identification of areas where multiple hazard factors coexist. The final output consists of a composite risk map implemented within an interactive WebGIS platform, designed as a reproducible and transparent decision-support tool to assist stakeholders in designing tailored civil protection plans. This article aims to highlight the wide range of risks considered and guide both local and regional stakeholders in the design of ad hoc civil protection plans. This work synthesises the joint efforts of researchers and decision makers, aiming to develop a reproducible, adjustable, and transparent decision support tool.