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A safe separation distance (SSD) needs to be considered during firefighting activities (fire suppression or people evacuation) against wildfires. The SSD is of critical interest for both humans and assets located in the wildland–urban interfaces (WUI). In most cases, the safety zone models and guidelines assume a flat terrain and only radiant heating. Nevertheless, injuries or damage do not result exclusively from radiant heating. Indeed, convection must be also considered as a significant contribution of heat transfer, particularly in the presence of the combined effects of sloping terrain and a high wind velocity. In this work, a critical case study is considered for the village of Sari-Solenzara in Corsica (France). This site location was selected by the operational staff since high-intensity fire spread is likely to occur in the WUI during wind-blown conditions. This study was carried out for 4 m high shrubland, a sloping terrain of 12° and a wind speed of 16.6 m/s. The numerical simulations were performed using a fully physical fire model, namely, FireStar2D, to investigate a case of fire spreading, which is thought to be representative of most high wildfire risk situations in Corsica. This study is based on the evaluation of the total (radiative and convective) heat flux received by two types of targets (human bodies and buildings) located ahead of the fire front. The results obtained revealed that the radiation was the dominant heat transfer mode in the evaluation of the SSD. In addition, the predictions were consistent with the criterion established by the operational experts, which assumes that in Corsica, a minimum SSD of 50 m is required to keep an equipped firefighter without injury in a fuelbreak named ZAL. This numerical work also provides correlations relating the total heat flux to the SSD. [ABSTRACT FROM AUTHOR]

• Experimental burning of reconstructed rockrose hedges at field scale. • Anemometer measurements to perform a statistical analysis of the wind on site. • Visible flame geometry extracted using image processing analysis from several cameras. • Radiant and total heat fluxes gauge positioned downstream of the fire to quantify the thermal exposure. • Relationship between wind and flame features have been highlighted. • Low frequency flapping motion of the ensemble flame induced by the turbulent structure of the wind have been shown. With climate change, complex fire scenarios at Wildland Urban Interfaces (WUI) have become a growing concern for authorities worldwide. Such scenarios involve unfavorable wind conditions, which greatly increase the fire spread near communities and makes the intervention of firefighters even more complex. To design effective fire safety regulations to protect communities, it is important to have a clear understanding of the role of wind in the burning of vegetation to help identify the vectors of fire spread within the defensible zone. In this context, this paper attempts to relate the properties of the flames generated by the burning of a reconstructed rockrose hedge to the atmospheric wind turbulence using four field-scale experiments. The experimental setup includes 3 visible cameras to record the flame geometry, extracted by post-processing; 3 pairs of radiant and total heat fluxes to record the heat fluxes downstream of the hedge, and an anemometer to measure the wind speed and direction. The results show that the wind at the experimental site is composed of wall-bounded turbulent structures coupled with strong and short intermittent events such as gusts. Regarding the fire, the four replicates show similarities in phase durations and dynamics, but revealed dependencies on Reynolds number and turbulent kinetic energy when averaging over the fully developed flame phase. In addition, a slight flapping motion of the ensemble flame was observed and associated with wave numbers of the order of the turbulent cascade in the kinetic energy power spectra. Finally, the analysis of wind and fire intermittencies revealed that strong and short wind events generate large fluctuations of flame geometry and received heat fluxes that increase with the characteristic time of the event considered. [ABSTRACT FROM AUTHOR]

Exploring the human dimensions of forest fires is a crucial, although often overlooked, aspect of wildfire research, since wildfires often have important socio-economic impacts and humans are nowadays the main cause of wildfires in many areas of the world. We carried out a telephone survey (N = 345 interviews) in one of the most fire-prone areas in Europe (NW Spain) in order to assess citizens’ awareness about wildfire causes and risks, their perception of the value of the vegetation and of administrative measures to fight against fires. Perceptions of respondents about fire causes were in general realistic although fires caused by pyromaniacs and for profit were overestimated, while vegetation management was comparatively underestimated. Citizens were broadly aware of the fire risk associated with different vegetation types, rightly considering native oak forests and agricultural fields as less risky than shrublands and pine and eucalypt plantations. Tree-dominated vegetation was more valued than treeless formations, and native forests more than tree plantations, which seems related to a preference for ecological value over utilitarian considerations. In addition, the value of eucalypt plantations was clearly affected by the education level of respondents, being less valued as the education level increased. Most citizens considered that the administration was not doing enough to fight against fires. The law that compels landowners to reduce fuels in wildland-urban interfaces was considered effective by most respondents (72%), but 50% considered it difficult to implement by landowners. This may explain the poor degree of compliance of this law.

Exploring the human dimensions of forest fires is a crucial, although often overlooked, aspect of wildfire research, since wildfires often have important socio-economic impacts and humans are nowadays the main cause of wildfires in many areas of the world. We carried out a telephone survey (N D345 interviews) in one of the most fire-prone areas in Europe (NW Spain) in order to assess citizens' awareness about wildfire causes and risks, their perception of the value of the vegetation and of administrative measures to fight against fires. Perceptions of respondents about fire causes were in general realistic although fires caused by pyromaniacs and for profit were overestimated, while vegetation management was comparatively underestimated. Citizens were broadly aware of the fire risk associated with different vegetation types, rightly considering native oak forests and agricultural fields as less risky than shrublands and pine and eucalypt plantations. Tree-dominated vegetation was more valued than treeless formations, and native forests more than tree plantations, which seems related to a preference for ecological value over utilitarian considerations. In addition, the value of eucalypt plantations was clearly affected by the education level of respondents, being less valued as the education level increased. Most citizens considered that the administration was not doing enough to fight against fires. The law that compels landowners to reduce fuels in wildland-urban interfaces was considered effective by most respondents (72%), but 50% considered it difficult to implement by landowners. This may explain the poor degree of compliance of this law. [ABSTRACT FROM AUTHOR]

One of the most important environmental issues in Europe is the expansion of wildland-urban interfaces (WUIs) and how this trend may affect the occurrence of wildfires. Land use changes, the abandonment of farmland, and reduced grazing has led to an increase in forested areas with an accumulation and continuity of surface fuels available for combustion. Policies based exclusively on extensive fire suppression have become ineffective in different parts of Europe. To reduce the threat of damaging and costly wildfires, European countries must develop integrated fuel management programs. This approach has proven to be one of the most cost-effective for preventing wildfires and reducing economic loss. To this end, we have conducted a cost-effectiveness analysis to estimate how much fuel must be treated to determine fuel load removals with the lowest cost per hectare of unaffected WUIs threatened by wildfires in southern Italy (Apulia region). The analysis was carried out in three stages: (i) simulation of fire behavior in different fuel load reduction and wind direction scenarios; (ii) estimation of WUIs affected by wildfires within the study landscape; and (iii) the application of a cost-effectiveness ratio. Our results highlight the need to provide a method to evaluate the cost-effectiveness of fuel removal given the increasing number and extent of WUIs in the Mediterranean landscape of Europe. Optimizing the cost-effectiveness analysis of fuel removals offers the basis for appropriately assessing wildfire prevention and budgeting financial resources. Further, this method may be readily applied toward allocating any type of intervention in landscape management. [ABSTRACT FROM AUTHOR]