Integrating Critical Infrastructures and Nature-based Solutions as responses in an index-based flood risk mapping for the Cávado Region (Portugal)

This study presents a comprehensive risk assessment methodology tailored to the Cávado region, Portugal, an area vulnerable to flood hazards. The approach integrates the four core IPCC risk components (hazard, exposure, vulnerability, and response), leveraging open-source datasets to ensure transparency, replicability, and transferability. An index-based modelling framework is applied at 100m spatial resolution, combining flood simulations for multiple return periods (RP10, RP50, RP100, and RP500) to capture the spatial variability of flood risk.

A key novelty of this work lies in the integrated assessment of multiple response indicators aimed at risk mitigation, with particular attention to the spatial distribution and accessibility of critical infrastructure, including healthcare and educational facilities. A network-based analysis is implemented to evaluate access to essential services under different flood scenarios, assessing both walking and driving modes. Travel distances and times from road nodes to health-related points of interest are quantified to support emergency response planning.

The methodological framework was developed through continuous stakeholder engagement with regional authorities, involving an iterative dialogue to support data acquisition, define the baseline risk situation, jointly identify relevant Nature-based Solutions (NBS) to be modelled, and validate the modelling outcomes. 

Results include spatially explicit flood risk maps across different return periods, as well as an evaluation of how different response measures, including NBS, influence overall risk patterns. The proposed approach provides a robust, scalable, and policy-relevant tool to support data-informed decision-making in disaster risk reduction, emergency planning, health infrastructure investment, and climate adaptation strategies.