Fire, Volume 4, Issue 1 (March 2021) – 14 articles

With an increase in the frequency and severity of wildfires across the globe and resultant changes to long-established fire regimes, the mapping of fire severity is a vital part of monitoring ecosystem resilience and recovery. The emergence of unoccupied aircraft systems (UAS) and compact sensors (RGB and LiDAR) provide new opportunities to map fire severity. This paper conducts a comparison of metrics derived from UAS Light Detecting and Ranging (LiDAR) point clouds and UAS image based products to classify fire severity. A workflow which derives novel metrics describing vegetation structure and fire severity from UAS remote sensing data is developed that fully utilises the vegetation information available in both data sources. UAS imagery and LiDAR data were captured pre- and post-fire over a 300 $\mathrm{m}$ by 300 $\mathrm{m}$ study area in Tasmania, Australia. The study area featured a vegetation gradient from sedgeland vegetation (e.g., button grass $0.2$$\mathrm{m}$) to forest (e.g., Eucalyptus obliqua and Eucalyptus globulus 50$\mathrm{m}$). To classify the vegetation and fire severity, a comprehensive set of variables describing structural, textural and spectral characteristics were gathered using UAS images and UAS LiDAR datasets. A recursive feature elimination process was used to highlight the subsets of variables to be included in random forest classifiers. The classifier was then used to map vegetation and severity across the study area. The results indicate that UAS LiDAR provided similar overall accuracy to UAS image and combined (UAS LiDAR and UAS image predictor values) data streams to classify vegetation (UAS image: 80.6%; UAS LiDAR: 78.9%; and Combined: 83.1%) and severity in areas of forest (UAS image: 76.6%, UAS LiDAR: 74.5%; and Combined: 78.5%) and areas of sedgeland (UAS image: 72.4%; UAS LiDAR: 75.2%; and Combined: 76.6%). These results indicate that UAS SfM and LiDAR point clouds can be used to assess fire severity at very high spatial resolution. Full article

Lightning-caused fires (LCFs) and fire environments influenced by thunderstorms are increasingly implicated in extreme wildfire events around the world, with devastating consequences to society and the environment. However, the disaster potential inherent to LCFs is often neglected, especially where the fire regime is determined mostly by anthropogenic ignitions. Such disconnect between perceived risk and actual risk is illustrated with the Iberian Peninsula, where thunderstorm-driven wildfires are comparatively rare but have resulted in large-scale burning and considerable loss of human life. Even low LCF regions should embrace fire management strategies able to cope with LCFs. Full article

Recent increases in destructive wildfires are driving a need for empirical research documenting factors that contribute to structure loss. Existing studies show that fire risk is complex and varies geographically, and the role of vegetation has been especially difficult to quantify. Here, we evaluated the relative importance of vegetation cover at local (measured through the Normalized Difference Vegetation Index) and landscape (as measured through the Wildland–Urban Interface) scales in explaining structure loss from 2013 to 2018 in California—statewide and divided across three regions. Generally, the pattern of housing relative to vegetation better explained structure loss than local-scale vegetation amount, but the results varied regionally. This is likely because exposure to fire is a necessary first condition for structure survival, and sensitivity is only relevant once the fire reaches there. The relative importance of other factors such as long-term climatic variability, distance to powerlines, and elevation also varied among regions. These suggest that effective fire risk reduction strategies may need to account for multiple factors at multiple scales. The geographical variability in results also reinforces the notion that “one size does not fit all”. Local-scale empirical research on specific vegetation characteristics relative to structure loss is needed to inform the most effective customized plan. Full article

Fires are among the most frequently recurring hazards affecting museums and cultural heritage sites. The fires of the National Museum of Brazil in 2018 and of Notre Dame de Paris in 2019 showed that the consequences of such events can be heavy and lead to irreversible heritage losses. In Kosovo, few studies were made about the risks that can affect cultural heritage sites. A project led by the NGO Kosovo Foundation for Cultural Heritage without Borders (CHwB Kosova) in 2018 explored the most prevalent risks for the cultural heritage sites of the country and highlighted fire as a predominant risk in Kosovo. In order to better understand it, vulnerability assessments were conducted in several museums in Kosovo. Data were collected through field visits in the different museums, in which interviews with staff members as well as observations were conducted. The aim of this paper is to present the main results of the fire vulnerability assessments conducted in Kosovo’s museums in 2018. An important aspect of this project is the approach to collect information in data-scarce environments. It is believed that the questionnaires used to lead interviews with museums’ staff members could help other practitioners to collect data in such contexts and evaluate more easily the risk of fire for the museums and their collections. In the context of Kosovo, one of the main findings is the identification and prioritisation of measures to ensure better protection of Kosovar museums. Structural mitigation measures such as alarm and fire suppression systems are not the only elements necessary to improve the resilience of Kosovar museums to fire. Indeed, the promotion of risk awareness, the training of staff members and the realisation of crisis simulation exercises are just as important in order to prevent and detect a fire, and above all, to respond quickly and accurately if a fire occurs. Full article

Lightning strikes are pervasive, however, their distributions vary both spatially and in time, resulting in a complex pattern of lightning-ignited wildfires. Over the last decades, lightning-ignited wildfires have become an increasing threat in south-east Australia. Lightning in combination with drought conditions preceding the fire season can increase probability of sustained ignitions. In this study, we investigate spatial and seasonal patterns in cloud-to-ground lightning strikes in the island state of Tasmania using data from the Global Position and Tracking System (GPATS) for the period January 2011 to June 2019. The annual number of lightning strikes and the ratio of negative to positive lightning (78:22 overall) were considerably different from one year to the next. There was an average of 80 lightning days per year, however, 50% of lightning strikes were concentrated over just four days. Most lightning strikes were observed in the west and north of the state consistent with topography and wind patterns. We searched the whole population of lightning strikes for those most likely to cause wildfires up to 72 h before fire detection and within 10 km of the ignition point derived from in situ fire ignition records. Only 70% of lightning ignitions were matched up with lightning records. The lightning ignition efficiency per stroke/flash was also estimated, showing an annual average efficiency of 0.24% ignition per lightning stroke with a seasonal maximum during summer. The lightning ignition efficiency as a function of different fuel types also highlighted the role of buttongrass moorland (0.39%) in wildfire incidents across Tasmania. Understanding lightning climatology provides vital information about lightning characteristics that influence the probability that an individual stroke causes ignition over a particular landscape. This research provides fire agencies with valuable information to minimize the potential impacts of lightning-induced wildfires through early detection and effective response. Full article

Recent explosions with devastating consequences have re-emphasized the relevance of fire safety and explosion research. From earlier works, the severity of the explosion has been said to depend on various factors such as the ignition location, type of a combustible mixture, enclosure configuration, and equivalence ratio. Explosion venting has been proposed as a safety measure in curbing explosion impact, and the design of safety vent requires a deep understanding of the explosion phenomenon. To address this, the Explosion Venting Analyzer (EVA)—a mathematical model predicting the maximum overpressure and characterizing the explosion in an enclosure—has been recently developed and coded (Process Saf. Environ. Prot. 99 (2016) 167). The present work is devoted to methane explosions because the natural gas—a common fossil fuel used for various domestic, commercial, and industrial purposes—has methane as its major constituent. Specifically, the dynamics of methane-air explosion in vented cylindrical enclosures is scrutinized, computationally and experimentally, such that the accuracy of the EVA predictions is validated by the experiments, with the Cantera package integrated into the EVA to identify the flame speeds. The EVA results for the rear-ignited vented methane-air explosion show good agreement with the experimental results. Full article

Fires are accidents that can cause numerous human casualties in multiplexes. The simple sprinkler systems applied in South Korea employ sprinklers to protect people against residential fires, as specified by the National Fire Protection Association (NFPA) standard 13D. Therefore, it is necessary to evaluate the fire control performance of multiplexes, which are at a greater risk than residential facilities. This study aims to verify the fire control performance of simple sprinklers in multiplexes and to develop a fire source that can be used as a protocol for testing fire suppression methods. The fire source was evaluated by using a 3 MW large-scale calorimeter (ISO 13784). The proposed fire source for multiplexes was applied in various forms according to the application methods, with ignition sources including cotton wick, wood crib, and heptane, and then the fire tests were conducted. Full article

The intent of this article is to raise awareness about an underutilized funding mechanism that possesses the capacity to help tribal and federal land management agencies meet their goal of restoring fire-adapted ecosystems to historic conditions in the American Southwest. We attempt to achieve this through an exploration of the Reserved Treaty Rights Lands (RTRL) program and how it has been used to implement collaborative fuel management projects on National Forest lands. RTRL is a funding program administered by the Bureau of Indian Affairs (BIA) that is designed to protect natural and cultural resources important to tribes on non-tribal lands that are at high risk from wildfire. Over the last year, our research team has studied the RTRL program in the Southwest by conducting in-depth, face-to-face interviews with tribal land managers as well as U.S. Forest Service tribal liaisons and other personnel who work with tribes. Our interviews revealed enthusiasm and support for RTRL but also concern about the fairness of the program as well as insufficient outreach efforts by the U.S. Forest Service. In response, we propose a policy alteration that (we contend) would incentivize the BIA to increase funding allocations to the RTRL program without losing the support of partnering agencies. The aim is to strengthen and expand shared stewardship efforts between tribes and federal land management agencies. We situate these implications against the backdrop of the Pacheco Canyon Prescribed Burn, an RTRL funded project that was instrumental in containing the Medio Fire that broke out in the Santa Fe National Forest in the summer of 2020. Full article

The objectives of this study are to evaluate landscape-scale fuel and terrain controls on fire rate of spread (ROS) estimates derived from repetitive airborne thermal infrared (ATIR) imagery sequences collected during the 2017 Thomas and Detwiler extreme wildfire events in California. Environmental covariate data were derived from prefire National Agriculture Imagery Program (NAIP) orthoimagery and USGS digital elevation models (DEMs). Active fronts and spread vectors of the expanding fires were delineated from ATIR imagery. Then, statistical relationships between fire spread rates and landscape covariates were analyzed using bivariate and multivariate regression. Directional slope is found to be the most statistically significant covariate with ROS for the five fire imagery sequences that were analyzed and its relationship with ROS is best characterized as an exponential growth function (adj. R² max = 0.548, min = 0.075). Imaged-derived fuel covariates alone are statistically weak predictors of ROS (adj. R² max = 0.363, min = 0.002) but, when included in multivariate models, increased ROS predictability and variance explanation (+14%) compared to models with directional slope alone. Full article

In recent years, glass has been a largely used material for load-bearing or non-structural components in buildings and constructions. For this reason, dedicated calculation methods and approaches are required for the major loading and boundary conditions that are of technical interest for safe design purposes. Among others, the resistance and mechanical performance of glass elements under fire exposure still represents an open challenge. This paper elaborates on the failure detection methods for out-of-plane loaded glass panels that are subjected to fire loading and simultaneous mechanical loads. As known, the conventional method for thermal failure detection is based on the maximum temperature gradient in glass, and its comparison with a set of allowable standardized values. However, especially for ordinary glass components in buildings that are required to sustain combined mechanical loads, the overall structural performance is even more complex to predict. This design issue is given to a combination of pure mechanical aspects (i.e., sustained loads and corresponding stress–strain analysis) and thermo-physical phenomena, that depend on the progressive modification of material properties while increasing temperatures. This research study, accordingly, investigates the sensitivity of input parameters on the failure time of a given glass element under fire and sustained mechanical loads. A major advantage is taken from finite element (FE) numerical analyses and standardized failure detection methods of literature, that are selected for comparative purposes. Further, the paper also introduces the “stress approach” that can be used to quantify (in place of the conventional thermal gradient) the actual effects of assigned thermal exposure and mechanical loads. Full article

Delaying protective action decision making in wildfire is inconsistent with fire authorities’ advice and is associated with fatalities. A comprehensive understanding of why at-risk residents wait and see whether they will evacuate from a wildfire or remain to shelter or defend can better inform wildfire safety policy and practice. This systematic review reports the findings of 40 papers selected from 255 identified through a search of papers in Scopus, Science Direct and Google Scholar published between 1995 and December 2020 in English. This review establishes the extent of wait and see behaviour; grounds for concern for such behaviour; reasons protective action is delayed; the influence of information and warnings; relevance of gender and other characteristics; delay by those who defend their property; and policy implications. This review also details 11 seminal studies that capture much of the evidence on the delay of protective action in wildfire. Full article

Landscape fires are substantial sources of (greenhouse) gases and aerosols. Fires in savanna landscapes represent more than half of global fire carbon emissions. Quantifying emissions from fires relies on accurate burned area, fuel load and burning efficiency data. Of these, fuel load remains the source of the largest uncertainty. In this study, we used high spatial resolution images from an Unmanned Aircraft System (UAS) mounted multispectral camera, in combination with meteorological data from the ERA-5 land dataset, to model instantaneous pre-fire above-ground biomass. We constrained our model with ground measurements taken in two locations in savanna-dominated regions in Southern Africa, one low-rainfall region (660 mm year${}^{-1}$) in the North-West District (Ngamiland), Botswana, and one high-rainfall region (940 mm year${}^{-1}$) in Niassa Province (northern Mozambique). We found that for fine surface fuel classes (live grass and dead plant litter), the model was able to reproduce measured Above-Ground Biomass (AGB) (R${}^2$ of 0.91 and 0.77 for live grass and total fine fuel, respectively) across both low and high rainfall areas. The model was less successful in representing other classes, e.g., woody debris, but in the regions considered, these are less relevant to biomass burning and make smaller contributions to total AGB. Full article

Fire management is becoming increasingly relevant in our changing climate as fire frequency and intensity increases both on a global scale and locally in Tasmania. The distribution of fuel across the landscape has significant impacts on fire regimes, influencing connectivity and flammability of fuel load. Remote sensing techniques are often used to assess current fuel loads, but projections of future fuel distributions are necessary for longer term planning of fire management. Eucalyptus species are an important, dominant component of many Tasmanian forests, influencing fuel load and flammability. We modelled the current and future climate suitability for two Eucalyptus species (E. delegatensis and E. obliqua), using a suite of species distribution models (SDMs) and global climate models (GCMs) for mid (2041–2060) and end of century (2061–2080) time periods. The implications these changes may have for the distribution of these important fuel species in the future are discussed. All GCMs projected notable changes in potential distribution, with both species contracting substantially in some areas and E. obliqua also exhibiting considerable expansions in the west of Tasmania. On average, suitability for E. delegatensis expanded by 5% ± 1.8% (1658 km²), contracted by 67% ± 22.7% (24,591 km²) and remained unchanged in 26% ± 7.8% (8783 km²) by the end of the century. For E. obliqua suitability expanded by a much greater 17% ± 6.3% (24,398 km²), contracted by slightly less at 55% ± 16.8% (81,098 km²) and remained unchanged in 45% ± 16.8% (63,474 km²) by the end of the century. These changes in climate suitability have the potential to cause changes in the composition and structure of Tasmania’s forests, impacting fuel loads. However, the two species exhibited different responses, reflecting their current distributions and suggesting that generalisations regarding species’ responses to changing climates are not appropriate, even where the species are closely related. These results suggest that future fuel loads and flammability at the landscape scale may change, requiring longitudinal, flexible and adaptive future fire management. Assessing the specific effects of distributional changes and the mechanisms driving different responses to climate change are highlighted as further research opportunities. Full article