On 29 October 2018, the Vaia storm hit the Alpine forests of Italy with winds at 200 km h⁻¹. The forest areas totally or partially damaged by the storm were about 41,000 ha, of which about 12,000 ha were in the Veneto Region. Large areas and stands of spruce and beech forests, usually not very prone to wildfires, were blown down. Only limited portions of areas with downed trees were harvested in the first year after the storm. Due to the changes in surface fuel conditions, timber understory fuel models in the area affected by the storm were converted to slash-blowdown models, which results in significant short-term changes in potential wildfire behavior. To investigate how wildfire behavior and spread were affected by the above changes, we applied wildfire simulation modeling to assess the variations in wildfire exposure characteristics (such as burn probability and conditional flame length) before and after the storm in the three Veneto provinces (Belluno, Treviso, and Vicenza) where the blown down trees were concentrated. We simulated 50,000 fire events using the MTT algorithm as implemented in Randig, and considering the historical wildfire occurrence data in the study area. Regarding fuel input data for the simulations, we modified the existing fuel map (pre-storm) of the Veneto Region and modified the fuel models of the damaged forest areas considering different standard models of slash, according to the percentage of downed trees. The results highlighted spatial variation in wildfire exposure before and after the storm, with an overall increase of wildfire risk conditions in those areas characterized by both significant levels of blowdown and high historical likelihood of fire ignitions. The methodology proposed and the findings of this study can be useful to inform future wildfire risk and land management in the areas affected by the storm.

Vista la rilevanza che il problema degli incendi boschivi ha in Italia, risulta quindi quanto mai necessario migliorare gli strumenti a disposizione per la prevenzione degli incendi boschivi, a partire da una corretta e dettagliata valutazione del rischio. Attualmente, la maggior parte dei piani AIB a livello nazionale non considerano, o considerano solamente con metodi empirici, il comportamento e la propagazione potenziale degli incendi per caratterizzare il rischio di incendio. In questo lavoro, si presenta la metodologia adottata dalla Regione del Veneto per la mappatura del rischio di incendi boschivi. L’applicazione della simulazione della propagazione degli incendi ha permesso di realizzare mappe di rischio con elevato dettaglio e di ottenere importanti informazioni sulle potenzialità di incendio che altrimenti non sarebbero state disponibili con metodi empirici.

The cooperation between the civil protection organizations of conterminous administrations is fundamental because natural hazards do not stop at borders. Natural hazards, such as wildland fires, are prominent threats to human lives and activities, and they put civil protection organizations under stress when they occur. These organizations have for long been preparing protocols and procedures to face these hazards. Nonetheless, this expertise is not always shared between the administrations. Bureaucratic barriers, different languages and the accessibility of the information can reduce the coordination before and during an emergency. In most cases, the personal goodwill of the operators solves the problems, but a formal agreement is preferable. A useful agreement should facilitate exchanges between the civil protection organizations and foster research in natural hazards management. Common exercises, harmonization of procedures and protocols, and applied research on risk assessment and planning are the tools to level up different organizations. This effort is of particular importance during wildland fires and across international borders. The CROSSIT SAFER Project, part of Interreg V-A Italia-Slovenija, aims at reinforcing the cooperation among project partners. Nine partners located along the border between Italy and Slovenia joined to make the area more secure against natural hazards, with a focus on wildland fires and interface fires. The coordination between all partners is mandatory in the specific area due to the presence of an international border and the susceptibility of the area to natural hazards, including wildland fires. The project strengthened the bounds between the civil protection organizations, and it will yield new procedures and protocols to manage natural hazards. Thanks to the common exercises, the signature of a formal protocol of agreement and the enhancement of procedures to assess, map and observe natural hazards, the area will become more secure. The results will be of help to local administrators and to the civil protection organizations involved.