Large Fires Research Articles

COST MANAGEMENT: THE USE OF FIRE FOR PASTURE RENEWAL IN ALTO MINHO

Portugal has been the target of large fires in recent years. There is no exception for the Alto Minho region, which year after year is ravaged by fire. This territory is characterized by the misfortune of occupying a prominent place in number of occurrences and burned area. Nevertheless, it brings together some peculiarities, which make it a unique territory. It is in relation to fire and one of its particularities that this study focuses: the fires for renovation of pastures in Alto Minho. Annually this cause of fire is around 10% of the total number of occurrences, but it may be responsible for more than 50% of the burnt area. Quantifying the cost of fighting these fires could be an initial way to alert and try to reverse a process with hundreds of years whose results are increasingly catastrophic. The values found in this investigation are high in relation to the reference value, so a change to the procedure as a whole is urgent, as a solution within the territory itself.

Estimation of biomass burning emission of NO2 and CO from 2019–2020 Australia fires based on satellite observations

Abstract. The bushfires that occurred in Australia in late 2019 and early 2020 were unprecedented in terms of their scale, intensity, and impacts. Using nitrogen dioxide (NO2) and carbon monoxide (CO) data measured by the Tropospheric Monitoring Instrument (TROPOMI), together with fire counts and fire radiative power (FRP) from MODIS, we analyzed the temporal and spatial variation of NO2 and CO column densities over three selected areas covering savanna and temperate forest vegetation. The ΔNO2/ΔCO emission ratio and emission factor were also estimated. The ΔNO2/ΔCO emission ratio was found to be 1.57 ± 1.71 for temperate forest fire and ranged from 2.0 ± 2.36 to 2.6 ± 1.92 for savanna fire. For savanna and temperate forest fires, satellite-derived NOx emission factors were found to be 1.48 and 2.39 g kg−1, respectively, whereas the CO emission factors are 107.39 and 126.32 g kg−1, respectively. This study demonstrates that the large-scale emission ratio from the TROPOMI satellite for different biomass burnings can help identify the relative contribution of smoldering and flaming activities in a large region and their impacts on the regional atmospheric composition and air quality. This method can be applied to study the emissions from other large fires, or even the burning of fossil fuel in megacities, and their impact on air quality.

Lithium fire protection design approach in IFMIF-DONES facility

Several experimental facilities, mainly focused on nuclear fusion applications, propose lithium as main coolant and/or tritium breeder material, limiter or divertor for its advantageous properties. Lithium fire hazard represents a critical risk for the production of an important population of reactive, corrosive and toxic aerosols, and for the potential mobilization, transport and release of radioactive species, initially retained in the molten metal, as in experimental facilities like the IFMIF-DONES accelerator neutron source. Consequently, a specific methodology should be developed for managing possible lithium fire scenarios that could occur during the lifetime of these unique facilities. Applying the Defense-in-Depth principle to minimize the fire risk in the particular case of the IFMIF-DONES plant, this work describes a set of passive and active measures for lithium fire prevention, detection and mitigation in compliance with main international and national standards on fire protection. According to the present safety analyses, active measures, including the use of fixed extinguishing systems employing chemical agents, do not seem to be entirely reliable in case of large lithium fires, for which more preferable passive fire protection measures are also being considered to be implemented in the final design of IFMIF-DONES, such as room inertization, catch pans and drain systems, constituting together a main line of defense to safely manage potential lithium fire scenarios.

Ratio pyrometry of emulated firebrand streaks

Firebrands can dramatically increase the spread rates of large outdoor fires. Although much is known about other aspects of firebrand behavior, their temperatures are poorly understood. In particular, the temperatures of burning airborne firebrands have never been measured. In a novel configuration, airborne firebrand motion is emulated here by rotating a camera while imaging a tethered maple ember as a streaking ember. Ratio pyrometry is performed using a color digital camera calibrated with a blackbody furnace at 600–1200 °C. Over 1600 images of 55 stationary and streaking embers were recorded and analyzed. The same ember temperatures were obtained for stationary embers as for streaking embers with either a horizontal or a vertical axis of camera rotation. The mean ember temperatures were 918 ad 955 °C for 1 and 2 m/s wind velocities. These were independent of ember distance and velocity, but generally increased with time after ignition at a mean rate of 0.77 °C/s. The diagnostic has an estimated measurement uncertainty of ±20 °C and similar accuracy for stationary and streaking embers.

Large-Fire Ignitions Are Higher in Protected Areas than Outside Them in West-Central Spain

Managing protected areas requires knowing what factors control fire ignitions and how likely they are compared to non-protected ones. Here, we modelled fire ignition likelihood in west-central Spain as a function of biophysical and anthropogenic variables in 172 protected areas (PA) of the Natura 2000 network, their buffer zones (BZ, 1500 m area surrounding PA), and non-protected areas (NP). Ignition coordinates from fire statistics (2001–2015 period) were overlaid over maps of relevant biophysical and socioeconomic variables. Models were built for four different fire sizes, small (1–5 ha), medium (5–50 ha), large (50–500 ha), and very large (≥500 ha), using Maxent software. Additionally, PA were classified based on their land use and land cover types by cluster analysis. Mean ignition probabilities were compared between PA, BZ and NP, as well as among different types of PA, by generalized linear models. Maxent models’ accuracy increased as fires were of larger size. Ignitions of small fires were associated with anthropogenic variables, while those of larger fires were more associated with biophysical ones. Ignition likelihood for the small and medium fire sizes was highest in BZ, while being the lowest in PA. Conversely, the likelihood of large and, particularly, very large fires was highest in PA. Mean ignition likelihood varied among types of PA, being highest for very large fires in PA, dominated by pine and mixed forests. Our results support the hypothesis that PAs are at the highest risk of large fire ignition, but BZ were also at high risk for the rest of the fire sizes. This largely reflects the more hazardous nature of PA landscapes. This work provides the needed tools to identify critical fire ignition areas within and nearby protected areas, which should be considered in their conservation and management plans.

Human activity and demographics drive the fire regime in a highly developed European boreal region

Organization of successful wildfire prevention and suppression require detailed information on ignition causes, size distributions and relations to weather. From a large and highly detailed dataset of Swedish wildfire incidents (n = 124 000) we assess temporal, geographical and human-related patterns over a 25-year-period (1996–2020). We find strong positive correlations between population density and wildfire occurrence, primarily caused by a wide spectrum of human activities. However, fires >10 ha mostly occurred in sparsely populated regions and were more often ignited by lightning or heavy machinery. Further, large fires had a history of long response times and insufficient mop-up, in turn intimately linked to low population density. We detect no trend over the 25-year-period in either fire weather, number of ignitions or burned area, but a dramatic decline in wildfire caused by children's play as well as by springtime burning of dead grass, a traditional fire use in rural areas. Our results indicate that irrespective of climate change, societal changes such as rural depopulation and cultural shifts are imminently important for the future fire regime in this intensely managed part of the boreal, and may warrant more attention worldwide.

Predicting Spatially Explicit Composite Burn Index (CBI) from Different Spectral Indices Derived from Sentinel 2A: A Case of Study in Tunisia

Fire severity, which quantifies the degree of organic matter consumption, is an important component of the fire regime. High-severity fires have major ecological implications, affecting carbon uptake, storage and emissions, soil nutrients, and plant regeneration, among other ecosystem services. Accordingly, spatially explicit maps of the fire severity are required to develop improved tools to manage and restore the most damaged areas. The aim of this study is to develop spatially explicit maps of the field-based fire severity (composite burn index—CBI) from different spectral indices derived from Sentinel 2A images and using several regression models. The study areas are two recent large fires that occurred in Tunisia in the summer of 2021. We employed different spectral severity indices derived from the normalized burn ratio (NBR): differenced NBR (dNBR), relative differenced NBR (RdNBR), and relativized burn Ratio (RBR). In addition, we calculated the burned area index for Sentinel 2 (BAIS2) and the thermal anomaly index (TAI). Different tree decision models (i.e., the recursive partitioning regression method [RPART], bagging regression trees [Bagging], and boosted regression trees [BRT]), as well as a generalized additive model [GAM]), were applied to predict the CBI. The main results indicated that RBR, followed by dNBR, were the most important spectral severity indices for predicting the field-based CBI. Moreover, BRT was the best regression model, explaining 92% of the CBI variance using the training set of points and 88% when using the validation set. These results suggested the adequacy of RBR index derived from Sentinel 2A for assessing and mapping forest fire severity in Mediterranean forests. These spatially explicit maps of field-based CBI could help improve post-fire recovery and restoration efforts.

The world is burning: What exactly are firebrands and why should anyone care?

Large outdoor fires have become commonplace all over the world. The International Organization for Standardization (ISO) defines large outdoor fires as an urban fire, tsunami-generated fire, volcano-generated fire, wildland-urban interface (WUI) fire, wildland fire, or informal settlement fire, where the total burnout area is significant. Perhaps of all the large outdoor fires, it is wildland fires that spread into urban areas, simply called WUI fires that attract the most attention. A glance at the recent headlines in the summer of 2022 reveals numerous catastrophic WUI fires all over Europe. Across the Atlantic Ocean in the USA, there is yet another destructive WUI fire raging in the USA state of California. With the increasing risks from a changing climate, these large outdoor fire disasters are only going to become more and more commonplace all over the world. More homes will be lost and more lives will be lost. It is the authors opinion that a targeted, multi-disciplinary approach is needed to address the large outdoor fire problem. In this short, invited paper to Horizons in Mechanical Engineering, it is argued that large outdoor fire problem is a fascinating and challenging research area and that engineers have the necessary skills and training to impact a problem that influences millions upon millions of people all over the world. An important danger, present in all large outdoor fires, are firebrands. Firebrands are introduced for non-specialist readers, and the most recent literature is reviewed. Several challenges are discussed, in particular, areas where engineers may help move the needle forward on this globally important topic.

Examining the influence of mid-tropospheric conditions and surface wind changes on extremely large fires and fire growth days

Background Previous work by the author and others has examined weather associated with growth of exceptionally large fires (‘Fires of Unusual Size’, or FOUS), looking at three of four factors associated with critical fire weather patterns: antecedent drying, high wind and low humidity. However, the authors did not examine atmospheric stability, the fourth factor. Aims This study examined the relationships of mid-tropospheric stability and dryness used in the Haines Index, and changes in surface wind speed or direction, to growth of FOUS. Methods Weather measures were paired with daily growth measures for FOUS, and for merely ‘large’ fires paired with each FOUS. Distributions of weather and growth were compared between the two fire sets graphically and statistically to determine which, if any, weather properties correspond to greater growth on FOUS than on large fires. Key results None of the factors showed a robust difference in fire growth response between FOUS and large fires. Conclusions The examined measures, chosen for their anecdotal or assumed association with increased fire growth, showed no indication of that association. Implications Focus on wind changes and mid-tropospheric properties may be counterproductive or distracting when one is concerned about major growth events on very large fires.

Štabovi za vanredne situacije kao elementi sistema upravljanja rizikom kod velikih šumskih požara

In recent years, forest fires are becoming more frequent, which is partly a consequence of global warming and the appearance of extremely hot summers, more frequent occurrences of drought, as well as increased wind intensity, but primarily as a consequence of great human carelessness and sometimes evil intentions. Large forest fires are a serious danger and their occurrence and spread directly endangers people, buildings, material goods and the environment. Emergency situation during this type of fires can be declared when a large area of quality forest is affected, when there is an immediate danger to people, material goods or the environment. When declaring an emergency situation, emergency headquarters and expert operational teams are activated whose task is to manage the risk in forest fire protection and to take measures to reduce the risk and protect people and material goods. The functioning of the operations centers and the effective implementation of measures have a direct impact on the efficiency of extinguishing large forest fires and the degree of efficiency in protecting people, buildings and property. The main goal of this paper was the analysis of the work and significance of the headquarters for emergency situation as a risk management factor in forest fire protection.

Linking repeat lidar with Landsat products for large scale quantification of fire-induced permafrost thaw settlement in interior Alaska

The permafrost–fire–climate system has been a hotspot in research for decades under a warming climate scenario. Surface vegetation plays a dominant role in protecting permafrost from summer warmth, thus, any alteration of vegetation structure, particularly following severe wildfires, can cause dramatic top–down thaw. A challenge in understanding this is to quantify fire-induced thaw settlement at large scales (>1000 km2). In this study, we explored the potential of using Landsat products for a large-scale estimation of fire-induced thaw settlement across a well-studied area representative of ice-rich lowland permafrost in interior Alaska. Six large fires have affected ∼1250 km2 of the area since 2000. We first identified the linkage of fires, burn severity, and land cover response, and then developed an object-based machine learning ensemble approach to estimate fire-induced thaw settlement by relating airborne repeat lidar data to Landsat products. The model delineated thaw settlement patterns across the six fire scars and explained ∼65% of the variance in lidar-detected elevation change. Our results indicate a combined application of airborne repeat lidar and Landsat products is a valuable tool for large scale quantification of fire-induced thaw settlement.

Future regional increases in simultaneous large Western USA wildfires

Background Wildfire simultaneity affects the availability and distribution of resources for fire management: multiple small fires require more resources to fight than one large fire does. Aims The aim of this study was to project the effects of climate change on simultaneous large wildfires in the Western USA, regionalised by administrative divisions used for wildfire management. Methods We modelled historical wildfire simultaneity as a function of selected fire indexes using generalised linear models trained on observed climate and fire data from 1984 to 2016. We then applied these models to regional climate model simulations of the 21st century from the NA-CORDEX data archive. Key results The results project increases in the number of simultaneous 1000+ acre (4+ km2) fires in every part of the Western USA at multiple return periods. These increases are more pronounced at higher levels of simultaneity, especially in the Northern Rockies region, which shows dramatic increases in the recurrence of high return levels. Conclusions In all regions, the models project a longer season of high simultaneity, with a slightly earlier start and notably later end. These changes would negatively impact the effectiveness of fire response. Implications Because firefighting decisions about resource distribution, pre-positioning, and suppression strategies consider simultaneity as a factor, these results underscore the importance of potential changes in simultaneity for fire management decision-making.

Interactions of non-intersecting oblique lines of fire burning in surface fuels in a combustion wind tunnel with and without wind

Background High-intensity wildfires are often characterised by the interaction of multiple coalescing fires. Previously, results of investigation of obliquely intersecting lines of fire in a ‘V’ configuration in dry eucalypt forest litter were reported. Aim This article reports on investigation of the behaviour of separated non-intersecting lines of fire in the absence and presence of wind. Methods Experiments in the CSIRO Pyrotron combustion wind tunnel investigated interactions of lines of fire of 800 and 1500 mm lengths located at incident angles of 30° and 45° and separated at the closest point by 150 mm. Key results The behaviour of separated fires in wind was fundamentally different to that of fires burning in no wind and previous non-separated fires, sustaining separation for some time and distance before merging. Conclusions Although all fires showed evidence of interactions, the strength of interaction was greater in larger fires with more energetic flames, suggesting a key influence of the magnitude and rate of release and transfer of heat to unburnt fuels. Implications Future research should focus on quantifying contributions of aspects such as fuel combustibility and bulk density that contribute to and determine the convecto–radiative interactions of fires so such behaviour can be predicted a priori.

Coupled fire-atmosphere simulation of the 2018 Camp Fire using WRF-Fire

Background Accurate simulation of wildfires can benefit pre-ignition mitigation and preparedness, and post-ignition emergency response management. Aims We evaluated the performance of Weather Research and Forecast-Fire (WRF-Fire), a coupled fire-atmosphere wildland fire simulation platform, in simulating a large historic fire (2018 Camp Fire). Methods A baseline model based on a setup typically used for WRF-Fire operational applications is utilised to simulate Camp Fire. Simulation results are compared to high-temporal-resolution fire perimeters derived from NEXRAD observations. The sensitivity of the model to a series of modelling parameters and assumptions governing the simulated wind field are then investigated. Results of WRF-Fire for Camp Fire are compared to FARSITE. Key results Baseline case shows non-negligible discrepancies between the simulated fire and the observations on rate of spread (ROS) and spread direction. Sensitivity analysis results show that refining the atmospheric grid of Camp Fire’s complex terrain improves fire prediction capabilities. Conclusions Sensitivity studies show the importance of refined atmosphere modelling for wildland fire simulation using WRF-Fire in complex terrains. Compared to FARSITE, WRF-Fire agrees better with the observations in terms of fire propagation rate and direction. Implications The findings suggest the need for further investigation of other possible sources of wildfire modelling uncertainties and errors.

某型号大流量导流式消防水炮喷嘴设计与改进

某型号大流量导流式消防水炮喷嘴设计与改进

A Numerical Study on the Smoke Control System Performance for a Large Fire in a Long Tunnel

In this study, a numerical simulation was performed using the fire dynamics simulator to examine the performance of a smoke control system in the case of a large fire in a long tunnel. A regional long tunnel that facilitates frequent movement in the port area was simulated. The fire scenario was set as a heavy goods vehicle fire corresponding to a large fire based on the existing real-scale experimental research data. A jet fan with an inner diameter of 1250 mm used in the regional tunnel was included in the tunnel simulation. For the evaluation of the smoke control system performance, the effects of the flow rate and installation interval of the jet fan on the smoke behavior, visibility, and temperature was analyzed. As the flow rate of the jet fan decreased, backlayering was lengthened, which reduced the time to achieve life safety standard.

Štetno djelovanje šumskih požara na području Srednje Bosne

In this paper, the occurrence of large forest fires in the management area of ŠPD “Srednjobosanska šume” in 2020 was analyzed with regard to forest types and management classes. The period of April–May 2020 was characterized as a period with a particularly high occurrence of forest fires, where the burnt area was 1,030.36 ha, and the material damage was 1,893,559.15 KM. The causes of the fires are unknown, as are the instigators. In most cases, the human factor was found to be the cause, and in three cases it was determined that the fire was caused intentionally. The danger of certain categories of forests (and forest land) from fire is different. The biggest financial damage was caused by the burning of areas under young cultures, i.e. due to damage to seedlings. The aim of the research was to assess the number, frequency and damage caused by fires, as well as the risk of certain categories of forests from fires. Such research is essential for assessing the degree of threat to forests and forest land from fire.

The processes of firebrand deposition and accumulation from wind‐driven firebrand showers

AbstractFirebrands, or smoldering and/or flaming particles, are in fact the main culprit to destroy structures in large outdoor fires. A recent comprehensive review of firebrand combustion reported that deposition and subsequent accumulation processes remain largely unexplored. As part of this work, a series of experiments were undertaken to investigate firebrand deposition and accumulation processes in the National Research Institute of Fire and Disaster (NRIFD)'s wind facility. A reduced‐scale firebrand generator was utilized, and various flow obstructions were placed downstream of these firebrand generators to better understand these complex deposition processes. Results of these investigations for multiple wind speeds, firebrand size and mass distributions, and obstacle placement are presented and discussed.

Short-Term Effects of Forest Fire on Water Quality along a Headwater Stream in the Immediate Post-Fire Period

Changes in water quality were examined during selected rainfall events in a headwater stream severely damaged by a forest fire on 21–23 February 2021. Seven water quality parameters were analyzed: pH, electrical conductivity, biochemical oxygen demand, chemical oxygen demand, total suspended solids (TSS), total nitrogen, and total phosphorous. First-flush effect and event mean concentration analyses were conducted in spring (dry season) and summer (wet season) immediately after the forest fire. In spring, the non-biodegradable organic matter concentrations increased along with pollutants related to ash-enhanced soil water repellency in water affected by first-flush effects. In summer, TSS and nutrient concentrations increased along with pollutants related to fire-induced soil surface disturbances after a series of rainfall events. First-flush analyses indicated that cumulative pollutant loads were greater in the spring than in the summer due to a higher concentration of forest fire ash in the early storm runoff immediately after the forest fire. The event mean concentrations revealed that pollutant loads were associated with both forest fire ash and storm events in the immediate post-fire period. Therefore, this study indicated that water quality along a headwater stream is affected by short-term effects of large and intense forest fires and rainfall seasonality.

Consideration of the contribution of operating a firefighting robot system for large fires to prevent COVID-19 infection among firefighters

A firefighting robot system has been developed to replace firefighters in dangerous firefighting activities near the source of a large fire. Firefighting activities at the scene of a fire are tasks that require many people working in dense, coordinated cooperation, and there is concern about the spread of COVID-19 infection. This paper outlines the firefighting robot system developed by the authors and discusses its contribution to preventing COVID-19 infection when the robot system is applied to firefighting activities, taking into account the new normal.