Regional-scale assessment of post-fire hydrological and soil erosion risk using GIS and MCDA approaches

Context/Purpose: Wildfires generate severe socio-economic impacts and environmental consequences, including increased soil erosion and hydrological instability in forested slope areas. The need to prioritize post-fire interventions has motivated the development of spatially explicit methods to support decision-making at regional scales. Previous studies have largely addressed local contexts; this research extends the approach by integrating multi-criteria evaluation and expert knowledge into a re-gional framework. Methods: The study applied a Multi-Criteria Decision Analysis (MCDA) within a GIS environment. Expert-based weights were derived using the Analytical Hierarchy Process (AHP), and suitability maps were generated with the Ordered Weighted Averaging (OWA) method. The criteria included are fire frequency, slope characteristics, and proximity to infrastructures. Results: Results indicate that fire recurrence, slope gradi-ent, length, and infrastructure presence are the most influential determinants of post-fire risk. The OWA method produced a range of suitability scenarios, from low to high risk, and revealed consistent spatial patterns across weighting strategies. These maps delineate priority zones for intervention and provide a base for targeted erosion and hydrological risk mitigation. Interpretation: The findings demonstrate that combining expert judgment with a GIS-based MCDA approach produces a reproducible and scalable approach to wildfire impact assessment. The flexibility of OWA enables decision-makers to adjust the analysis according to different risk tolerance levels, while the regional-scale application enhances the efficiency of mapping and resource allocation. Conclusion: In conclusion, the integration of AHP and OWA within a GIS-based MCDA framework constitutes a robust tool for identifying priority areas for post-fire rehabilitation at the regional scale.