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- Avaliação da exposição das comunidades locais a incêndios rurais: o caso de Alvares, GóisPublication . Gonçalves, Ana; Oliveira, Sandra; Sá, Ana; Zêzere, José; Pereira, José MiguelA freguesia de Alvares, no concelho de Góis, foi muito afetada pelos incêndios de junho de 2017, tendo ardido 70% da sua área. Para melhorar a proteção das comunidades locais e aumentar a sua capacidade de resposta, é fundamental avaliar o nível de exposição das povoações a grandes incêndios. Neste sentido, foi avaliado o nível de exposição das povoações da freguesia, combinando a densidade dos elementos expostos com probabilidade de arder. O nível de exposição foi calculado em duas vertentes: estrutural (baseado no número de vezes ardido desde 1980) e dinâmico (baseado em simulações de probabilidade de arder para diferentes cenários de gestão de combustíveis). Também foi estimada a vulnerabilidade social, tendo em conta características sociodemográficas dos residentes, assim como as características e condições de manutenção dos edifícios. Os resultados sugerem que: 1) as povoações localizadas a norte e nordeste da freguesia estão mais expostas a incêndios rurais; 2) quase metade das povoações apresentam vulnerabilidade elevada ou muito elevada; 3) a fração das povoações com exposição muito elevada diminui até 80% com a implementação de faixas de gestão de combustível. Estes resultados, à escala da povoação, podem contribuir para uma melhor hierarquização de ações de proteção e emergência, ajustando as estratégias e medidas de prevenção e mitigação de incêndios às características da população e da paisagem.
- Assessing wildfire exposure and social vulnerability at the local scale using a GIS-based approachPublication . Gonçalves, Ana; Oliveira, Sandra; Zêzere, JoséExposure and vulnerability analysis are valuable tools for wildfire management, especially important for local communities that suffer from very destructive events and that require mitigation approaches adjusted to their abilities and needs. We present a methodological procedure to analyze wildfire exposure levels, social vulnerability conditions and coping capacity at the local scale, for villages or small human settlements. The procedure was developed using GIS (Geographic Information Systems) and programming tools in R and Python, which can be adapted and updated depending on the data available. The development of accessible procedures and easily replicable methodologies facilitates knowledge transfer and supports the application of mitigation and adaptation strategies, tailored to the conditions of the exposed areas. • A step-by-step procedure for the assessment of Exposure, Vulnerability, and Coping Capacity, using Python and R programming language. • Automated processes, easily replicable and adjustable to other areas. • Indications for adapting the methodology using European/international databases.
- Avaliação das condições de capacidade de resposta a incêndios rurais na Freguesia de Alvares (Góis)Publication . Gonçalves, Ana; Oliveira, Sandra; Zêzere, JoséA freguesia de Alvares foi gravemente afetada em 2017, tendo ardido cerca de 70% da sua área, tornando-se necessário melhorar a sua capacidade de resposta. Para isso, foram aplicadas duas metodologias: com recurso a ferramentas SIG (cost path e cost distance) e com o Pedestrian Evacuation Analyst Tool (PEAT). Comparando ambas as abordagens, a população em 47% das povoações demora menos de 20 minutos a chegar ao abrigo. Estes resultados demonstram que ambas as metodologias são facilmente replicáveis, contribuindo para a definição de medidas de prevenção e mitigação de incêndios mais adequadas às características locais.
- A combined structural and seasonal approach to assess wildfire susceptibility and hazard in summertimePublication . Bergonse, Rafaello; Oliveira, Sandra; Gonçalves, Ana; Nunes, Sílvia; da Câmara, Carlos; Zêzere, JoséWildfre susceptibility and hazard models based on drivers that change only on a multiyear timescale are considered of a structural nature. They ignore specifc short-term conditions in any year and period within the year, especially summer, when most wildfre damage occurs in southern Europe. We investigate whether the predictive capacity of structural wildfre susceptibility and hazard models can be improved by integrating a seasonal dimension, expressed by three variables with yearly to seasonal timescales: (1) a meteorological index rating fuel fammability at the onset of summer; (2) the scarcity of fuel associated with the burned areas of the previous year, and (3) the excessive abundance of fuel in especially fre-prone areas that have not been burned in the previous ten years. We describe a new methodology for combining the structural maps with the seasonal variables, producing year-specifc seasonal susceptibility and hazard maps. We then compare the structural and seasonal maps as to their capacity to predict burnt areas during the summer period in a set of eight independent years. The seasonal maps revealed a higher predictive capacity in 75% of the validation period, both for susceptibility and hazard, when only the highest class was considered. This percentage was reduced to 50% when the two highest classes were considered together. In some years, structural factors and other unconsidered variables probably exert a strong infuence over the spatial pattern of wildfre incidence. These fndings can complement existing structural data and improve the mapping tools used to defne wildfre prevention and mitigation actions.
- Reassessing wildfire susceptibility and hazard for mainland PortugalPublication . Oliveira, Sandra; Gonçalves, Ana; Zêzere, JoséRecent large wildfires have caused serious environmental and social impacts in different areas of the world, such as Portugal, Greece and Australia. Sociodemographic changes in rural areas and climate change issues create unprecedented and challenging circumstances that call for an adjustment of fire management strategies and planning tools. In this research, we revise the procedure to assess wildfire susceptibility and hazard for mainland Portugal in a structural perspective. Based on a dataset of burned areas covering 44 years and a set of predisposing factors related to topography and landcover, we tested several susceptibility models using the Likelihood Ratio method, to calculate favourability scores. Landcover classes were analysed using national detailed sources and considering different timeframes. Hazard levels were obtained by combining the susceptibility model with the best accuracy and the probability to burn estimated from fire history (1975-2018). The resulting hazard values were classified in 5 levels based on the breaks of the success curve, instead of quantiles as in previous maps, to ensure territorial continuity at different spatial scales. The results show where the combination of terrain features is more favorable to fire propagation. The higher favourability scores were found for shrubland-type vegetation, whereas agricultural areas, cork and holm forests show lower scores. Eucalyptus and maritime pine forests show similar intermediate scores and have increased since 2007. The two highest hazard classes classify correctly 90% of the burned area over 44 years, demonstrating the high accuracy of the model. If integrated in spatial planning instruments, in conjunction with municipal plans, the two most hazardous classes may hinder the expansion of built-up areas. About 2% of the municipalities have more than 90% of their territory classified as hazardous, whereas 32% of the municipalities have, instead, less than 10% of hazardous area. These structural maps are a useful baseline for a long-term approach and can be complemented by estimations regarding the behavior and severity of wildfires, which should be further explored.
- Defining priorities for wildfire mitigation actions at the local scale: insights from a novel risk analysis method applied in PortugalPublication . Benali, Akli; Aparício, Bruno A.; Gonçalves, Ana; Oliveira, SandraIntroduction: In Portugal, the 2017 fire season was particularly extreme, leading to an unprecedented large number of fatalities, injured people, destruction of houses and infrastructures. These dramatic outcomes have contributed to raise awareness regarding the importance of ensuring the safety of people and assets from high intensity uncontrollable wildfires. It is crucial to identify the settlements at higher risk and the most suitable mitigation actions that can maximize the protection of people and assets. Methods: We developed a simple methodology that combines exposure and vulnerability to estimate wildfire risk at the local level. Exposure was estimated using a fire spread simulation approach that was used to determine the probability of (i) a wildfire generating firebrands that could affect a settlement and (ii) a high intensity wildfire occurring adjacent to a settlement. Exposure was estimated using two fuel scenarios created to represent the current year of 2023 (short-term scenario) and 2030, assuming that no fuel management nor large fires occur in the meantime (medium-term worst-case scenario). Vulnerability was determined by the (i) Index of Total Dependence (IDT), and (ii) evacuation difficulty. Exposure and vulnerability metrics were normalized in percentiles, distributed into quadrants and combined to provide six levels of wildfire risk. For each vulnerability\exposure combination, we proposed a set of priority mitigation actions. The methodology was applied to three areas in Portugal where the risk estimates were analyzed and compared with the implementation rate of two risk mitigation programs already in place. Results: Results showed that 8.7% of the settlements had “very high” wildfire risk and about 19.5% had “high” wildfire risk, potentially affecting 8,403 and 34,762 inhabitants, respectively. The spatial distribution of settlements at higher risk was very heterogeneous across the study areas and the total fraction ranged between 14% in Coimbra to 36% in Barlavento Algarvio. The overall implementation of mitigation programs in the study areas is very low, with only around 1% of the settlements in “very high” risk having any of the mitigation programs implemented. Conversely, our results also suggest that the implementation rate in settlements classified in lower risk classes is disproportionately high. Discussion: The application of this risk analysis methodology can be used to assess the implementation status of mitigation actions, and contribute to tailor the actions that maximize the protection of people and assets according to the specific conditions found in each targeted area.
- Assessing risk and prioritizing safety interventions in human settlements affected by large wildfiresPublication . Oliveira, Sandra; Gonçalves, Ana; Benali, Akli; Sá, Ana; Zêzere, José; Pereira, José MiguelThe large wildfires of June 2017 disturbed many communities in central Portugal. The civil parish of Alvares was severely affected, with about 60% of its area burnt. Assessing the risk of large wildfires affecting local communities is becoming increasingly important, to reduce potential losses in the future. In this study, we assessed wildfire risk for the 36 villages of Alvares parish, by combining hazard, exposure and vulnerability analysis at the settlement scale. Hazard was obtained from fire spread simulations, which integrated exposure together with population and building density within each village. Vulnerability was based on the sociodemographic characteristics of the population, ranked with a hierarchical cluster analysis. Coping capacity was also integrated, considering the distance of each village to the fire station and the time needed for residents to reach a shelter. We simulated 12 different land management scenarios, regarding the implementation of a fuel-break network and the level of forest management activities. The potential effects of each scenario in the exposure and risk levels of the settlements were evaluated. The results show that, for a business-as-usual scenario, 36% of the villages are at high or very high risk of wildfires. Examining each risk component, 28% of the villages are highly exposed, 44% are highly vulnerable, and 22% do not have a potential shelter on-site, calling for different intervention strategies in each specific risk dimension. All the land management scenarios, even if designed for other purposes than the protection of settlements, could decrease the proportion of highly exposed villages at different levels, up to a maximum of 61%. These findings can contribute to adjust prevention and mitigation strategies to the risk levels and the characteristics of the population and the territory, and to prioritize the protection and emergency actions at the local scale.
- Identifying priority villages for wildfire mitigation based on exposure and vulnerability levels at the local scalePublication . Oliveira, Sandra; Gonçalves, Ana; Barbosa, Bruno; Rocha, JorgeThis study aimed to assess wildfire risk specifically for human settlements, testing the procedure in three regions of mainland Portugal, representing the west coast (Oeste), the south coast (Algarve) and a central inland sector (Viseu-Dão-Lafões).
- Avaliação de risco de incêndio rural à escala local na região Centro de PortugalPublication . Oliveira, Sandra; Bergonse, Rafaello; Santos, Pedro Pinto; Gonçalves, Ana; Melo, Raquel; Zêzere, JoséUm índice de risco de incêndio foi aplicado às 972 freguesias da região Centro de Portugal Continental, integrando três dimensões: perigosidade, exposição e vulnerabilidade social. As freguesias do setor centro-sul apresentam níveis de risco mais elevados. Os padrões espaciais variam para cada dimensão; a vulnerabilidade mais elevada ocorre nas freguesias dos setores oriental e centro-sul, enquanto a perigosidade mais alta se localiza numa faixa N-S no setor central da região. As estratégias de redução de risco devem ser ajustadas de acordo com a relevância de cada dimensão.
- Predicting burnt areas during the summer season in Portugal by combining wildfire susceptibility and spring meteorological conditionsPublication . Bergonse, Rafaello; Oliveira, Sandra; Gonçalves, Ana; Nunes, Sílvia; DaCamara, Carlos; Zêzere, JoséWildfire susceptibility maps are a well-known tool for optimizing available means to plan for prevention, early detection, and wildfire suppression in Portugal, especially regarding the critical fire season (1 July 30 September). These susceptibility maps typically disregard seasonal weather conditions on each given year, being based on predisposing variables that remain constant on the long-term, such as elevation. We employ logistic regression for combining wildfire susceptibility with a meteorological index representing spring conditions (the Seasonal Severity Rating), with the purpose of predicting, for any given year and ahead of the critical fire season, which areas will burn. Results show that the combination of the index with wildfire susceptibility slightly increases the capability to predict which areas will burn, when compared with susceptibility alone. Spring meteorological context was found better suited for predicting if the following summer wildfire season will be more severe, rather than predicting where wildfires will effectively occur. The model can be updated yearly after the critical wildfire season and can be applied to optimize the allocation of human and material resources regarding the prevention, early detection and suppression activities, required to reduce the severity of wildfires in the country.