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1
Artés, Tomàs, Marc Castellnou, Tracy Houston Durrant et Jesús San-Miguel. « Wildfire–atmosphere interaction index for extreme-fire behaviour ». Natural Hazards and Earth System Sciences 22, no 2 (16 février 2022) : 509–22. http://dx.doi.org/10.5194/nhess-22-509-2022.
Texte intégralRésumé :
Abstract. During the last 20 years extreme wildfires have challenged firefighting capabilities. Often, the prediction of the extreme behaviour is essential for the safety of citizens and firefighters. Currently, there are several fire danger indices routinely used by firefighting services, but they are not suited to forecast extreme-wildfire behaviour at the global scale. This article proposes a new fire danger index, the extreme-fire behaviour index (EFBI), based on the analysis of the vertical profiles of the atmosphere above wildfires as an addition to the use of traditional fire danger indices. The EFBI evaluates the ease of interaction between wildfires and the atmosphere that could lead to deep moist convection and erratic and extreme wildfires. Results of this research through the analysis of some of the critical fires in the last years show that the EFBI can potentially be used to provide valuable information to identify convection-driven fires and to enhance fire danger rating schemes worldwide.
2
Donovan, Victoria M., Carissa L. Wonkka, David A. Wedin et Dirac Twidwell. « Land-Use Type as a Driver of Large Wildfire Occurrence in the U.S. Great Plains ». Remote Sensing 12, no 11 (9 juin 2020) : 1869. http://dx.doi.org/10.3390/rs12111869.
Texte intégralRésumé :
Wildfire activity has surged in North America’s temperate grassland biome. Like many biomes, this system has undergone drastic land-use change over the last century; however, how various land-use types contribute to wildfire patterns in grassland systems is unclear. We determine if certain land-use types have a greater propensity for large wildfire in the U.S. Great Plains and how this changes given the percentage of land covered by a given land-use type. Almost 90% of the area burned in the Great Plains occurred in woody and grassland land-use types. Although grassland comprised the greatest area burned by large wildfires, woody vegetation burned disproportionately more than any other land-use type in the Great Plains. Wildfires were more likely to occur when woody vegetation composed greater than 20% of the landscape. Wildfires were unlikely to occur in croplands, pasture/hay fields, and developed areas. Although these patterns varied by region, wildfire was most likely to occur in woody vegetation and/or grassland in 13 of 14 ecoregions we assessed. Because woody vegetation is more conducive to extreme wildfire behaviour than other land-use types in the Great Plains, woody encroachment could pose a large risk for increasing wildfire exposure. Regional planning could leverage differential wildfire activity across land-uses to devise targeted approaches that decrease human exposure in a system prone to fire.
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Garvey, Nathan, Dror Ben-Ami, Daniel Ramp et David B. Croft. « Survival behaviour of swamp wallabies during prescribed burning and wildfire ». Wildlife Research 37, no 1 (2010) : 1. http://dx.doi.org/10.1071/wr08029.
Texte intégralRésumé :
Context. Prescribed (or controlled) burning is frequently advocated as a means of reducing fuel loads in peri-urban forests to minimise the risk of high-intensity wildfires. An important consideration in prescribed burns is the impact on native wildlife. Aims. An opportunity arose to follow the movements of radio-collared peri-urban swamp wallabies during a prescribed burn and after an unexpected wildfire in the same location a short time later. Movement data was used to assess the relative impacts of the prescribed burn and wildfire on mortality, emigration and habitat use; the behavioural responses and methods of avoidance used by swamp wallabies in response to an oncoming fire front; and the management implications for wildlife that inhabit fire-prone habitats in proximity to human settlement where wildfire mitigation is necessary. Methods. Here we report on the movements of radio-collared swamp wallabies, Wallabia bicolor, before, during and after a prescribed fire and after a wildfire on the same site 6 months later. Key results. No radio-collared swamp wallabies were killed during the prescribed burn and only one wallaby was observed to emigrate from the area post-fire. This contrasted to the wildfire where one wallaby died during or just after the fire and another perished in the post-fire environment a few months later. The wildfire also increased emigration post-fire. Conclusions. We demonstrate that wallabies can avoid fire fronts and that this avoidance behaviour may be more successful during cooler fires. The prescribed burn provided a suitable habitat for wallabies but did not result in a shift in habitat preference. Implications. Mitigation of the impact of prescribed burns on swamp wallabies may be achieved by allowing sufficient time for habitat complexity to re-establish between burns.
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Noble, JC. « Behaviour of a Very Fast Grassland Wildfire on the Riverine Plain of Southeastern Australia. » International Journal of Wildland Fire 1, no 3 (1991) : 189. http://dx.doi.org/10.1071/wf9910189.
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A grassland wildfire burnt 120,000 ha in the western Riverina of New South Wales and caused exten sive losses of sheep and fencing. The rate of spread of the fire was accurately recorded at 6.4 m s-1 (23 km h-1) as it traversed one property and on the basis of conservative estimates of fuel loads measured later on unburnt patches, a fireline intensity was calculated at around 20,000 kW m-1. This rate of spread is one of the highest recorded for grassland wildfires in southern Australia and represents an important datum point for wildfire behaviour models. Quite reasonable predictions of rate of spread were pro vided by the McArthur Mark 4 fire danger model, how ever, the Mark 5 model seriously underestimated rate of spread for this and two other grassland wildfires.
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Kelso, Joel K., Drew Mellor, Mary E. Murphy et George J. Milne. « Techniques for evaluating wildfire simulators via the simulation of historical fires using the AUSTRALIS simulator ». International Journal of Wildland Fire 24, no 6 (2015) : 784. http://dx.doi.org/10.1071/wf14047.
Texte intégralRésumé :
A methodology for validating fire spread simulation systems using historical fire data is presented. The key features of this methodology are (a) quantitative comparison between simulator-generated fire perimeters and fire perimeters from an independently produced fire reconstruction at multiple time points during the fire, and (b) extensive sensitivity analyses on simulation variables including simulation spatial resolution, weather, vegetation coverage and fire behaviour model selection to determine the effect of each simulation input on the simulation output. The methodology is demonstrated in a case study in which the ability of the Australis high-performance wildfire simulator to replicate a large wildfire in Western Australia was examined. Simulation accuracy was found to be lower in extreme fire danger conditions and exhibited under-prediction of the head fire rate of spread. This was caused by inaccuracies in at least one of wind speed data, vegetation data or the fire behaviour model applied; however, the source of the inaccuracy could not be further diagnosed with the available data. The gathering of accurate data during and after active wildfires would facilitate more rigorous simulator and fire behaviour model validation studies as well as more accurate prediction of ‘live’ wildfires.
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Sidman, Gabriel, D. Phillip Guertin, David C. Goodrich, David Thoma, Donald Falk et I. Shea Burns. « A coupled modelling approach to assess the effect of fuel treatments on post-wildfire runoff and erosion ». International Journal of Wildland Fire 25, no 3 (2016) : 351. http://dx.doi.org/10.1071/wf14058.
Texte intégralRésumé :
The hydrological consequences of wildfires are among their most significant and long-lasting effects. As wildfire severity affects post-fire hydrological response, fuel treatments can be a useful tool for land managers to moderate this response. However, current models focus on only one aspect of the fire–watershed linkage (fuel treatments, fire behaviour, fire severity, watershed responses). This study outlines a spatial modelling approach that couples three models used sequentially to allow managers to model the effects of fuel treatments on post-fire hydrological responses. Case studies involving a planned prescribed fire at Zion National Park and a planned mechanical thinning at Bryce Canyon National Park were used to demonstrate the approach. Fuel treatments were modelled using FuelCalc and FlamMap within the Wildland Fire Assessment Tool (WFAT). The First Order Fire Effects Model (FOFEM) within WFAT was then used to evaluate the effectiveness of the fuel treatments by modelling wildfires on both treated and untreated landscapes. Post-wildfire hydrological response was then modelled using KINEROS2 within the Automated Geospatial Watershed Assessment tool (AGWA). This coupled model approach could help managers estimate the effect of planned fuel treatments on wildfire severity and post-wildfire runoff or erosion, and compare various fuel treatment scenarios to optimise resources and maximise mitigation results.
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Bentley, P. D., et T. D. Penman. « Is there an inherent conflict in managing fire for people and conservation ? » International Journal of Wildland Fire 26, no 6 (2017) : 455. http://dx.doi.org/10.1071/wf16150.
Texte intégralRésumé :
Wildfires are a natural disturbance in many ecosystems, creating challenges for land management agencies who need to simultaneously reduce risk to people and maintain ecological values. Here we use the PHOENIX RapidFire fire behaviour simulator to compare fuel treatment strategies that meet the twin objectives of reducing wildfire risk to human settlements and a fire sensitive endangered species, the koala (Phascolarctos cinereus) in south-eastern Australia. The local koala population is in decline and a conservation management plan is being prepared to exclude wildfire for a 10-year period to assist with population recovery. Twelve scenarios developed by the land management agencies were compared using four indicators: wildfire size; burn probability; impact from exposure to fire; and treatment cost. Compared with the current risk setting, three treatment scenarios were found to reduce wildfire size and burn probability concurrently to both people and koalas. These strategies worked by increasing the landscape area treated, which came with increased financial cost. However, the impact from exposure to fire for both property and koala habitat remains high. Additional complementary strategies beyond landscape fuel reductions are needed to reduce impact from exposure in the event of a wildfire.
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Davies, Kirk W., Chad S. Boyd, Jon D. Bates et April Hulet. « Winter grazing can reduce wildfire size, intensity and behaviour in a shrub-grassland ». International Journal of Wildland Fire 25, no 2 (2016) : 191. http://dx.doi.org/10.1071/wf15055.
Texte intégralRésumé :
An increase in mega-fires and wildfires is a global issue that is expected to become worse with climate change. Fuel treatments are often recommended to moderate behaviour and decrease severity of wildfires; however, the extensive nature of rangelands limits the use of many treatments. Dormant-season grazing has been suggested as a rangeland fuel treatment, but its effects on fire characteristics are generally unknown. We investigated the influence of dormant-season (winter) grazing by cattle (Bos taurus) on fuel characteristics, fire behaviour and area burned in Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) shrub-grassland communities in south-eastern Oregon, USA. Winter grazing was applied for 5 years before burning and compared with ungrazed areas. Winter grazing decreased fine fuels and increased fine fuel moisture, which reduced flame height and depth, rate of spread and area burned. Winter-grazed areas also had lower maximum temperature and heat loading during fires than ungrazed areas, and thereby decreased risk of fire-induced mortality of important herbaceous functional groups. These results suggest that winter grazing may be a fuel management treatment that can be applied across vast shrub-grasslands to decrease wildfire risk and fire intensity to mediate climate change effects on wildfire activity.
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Hilton, James, et Nikhil Garg. « Rapid wind–terrain correction for wildfire simulations ». International Journal of Wildland Fire 30, no 6 (2021) : 410. http://dx.doi.org/10.1071/wf20062.
Texte intégralRésumé :
Modelling the propagation of wildfires requires an accurate wind field to correctly predict the behaviour of the fire. Although numerical weather prediction models produce reliable and accurate mesoscale forecasts, these are typically either available at a spatial resolution many times greater than the typical resolution of a wildfire model or a spot forecast that must be spatially interpolated to the area of the modelled wildfire. Due to this, these forecasts may not account for fine-scale terrain interactions with the wind and must be downscaled to a higher spatial resolution before use in a wildfire model. These downscaling methods are typically computationally intensive, limiting their use for situations where rapid predictions are required. Despite this, a three-dimensional mass balancing method is commonly used in wildfire prediction as a preprocessing step. In this study we show that this mass balancing method can be reduced to a two-dimensional approach, greatly reducing the complexity and computational time required for the model. The two-dimensional method is compared with the existing three-dimensional method and experimentally measured datasets. Furthermore, a combination of rapid numerical solution techniques and modern computational processors allow these wind–terrain correction methods to be directly incorporated into wildfire propagation models.
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Ghodrat, Maryam, Farshad Shakeriaski, Sayyed Aboozar Fanaee et Albert Simeoni. « Software-Based Simulations of Wildfire Spread and Wind-Fire Interaction ». Fire 6, no 1 (31 décembre 2022) : 12. http://dx.doi.org/10.3390/fire6010012.
Texte intégralRésumé :
Wildfires are complex phenomena, both in time and space, in ecosystems. The ability to understand wildfire dynamics and to predict the behaviour of the propagating fire is essential and at the same time a challenging practice. A common approach to investigate and predict such phenomena is making the most of power of numerical models and simulators. Improved and more accurate methods for simulating fire dynamics are indispensable to managing suppression plans and controlled burns, decreasing the fuel load and having a better assessment of wildfire risk mitigation methodologies. This paper is focused on the investigation of existing simulator models applicable in predicting wildfire spread and wind fire interaction. The available software packages are outlined with their broad range of applications in fire dynamic modeling. Significance of each work and associated shortcomings are critically reviewed. Finally, advanced simulations and designs, accurate assumptions, and considerations for improving the numerical simulations, existing knowledge gaps in scientific research and suggestions to achieve more efficient developments in this area are revisited.
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Evans, Edward W., Lisa M. Ellsworth et Creighton M. Litton. « Impact of grazing on fine fuels and potential wildfire behaviour in a non-native tropical grassland ». Pacific Conservation Biology 21, no 2 (2015) : 126. http://dx.doi.org/10.1071/pc14910.
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Non-native grass invasion has increased fuel loads and fire frequency in areas throughout the tropics, resulting in a non-native grass–wildfire cycle with negative impacts on native biodiversity and ecological processes. Megathyrsus maximus (guinea grass) invades dry and mesic ecosystems throughout the tropics, increasing fuel loads and wildfire intensity. Eradication of M. maximus is difficult, making effective wildfire management critical to the protection of adjacent developed areas and remnant native ecosystems. The use of domestic livestock grazing in non-native grass ecosystems may be effective at decreasing fine fuel loads and potential wildfire behaviour. Our objectives were to: (1) quantify live and dead fine fuel loads and moistures in a M. maximus–dominated ecosystem before and after cattle grazing, and (2) use these data to model potential wildfire behaviour in grazed and ungrazed M. maximus grasslands with the BehavePlus fire modelling system. Fine fuel loads and moistures, climate variables, and predicted wildfire behaviour were quantified at the same site (n = 1) over two 5-month periods (March–July 2009, ungrazed; March–July 2010, grazed) in the Wai‘anae Kai Forest Reserve on the Island of O‘ahu, Hawai‘i. Strong to conclusive evidence existed that cattle grazing in this system decreased dead and total fuel loads, but did not alter live fuel loads, or live and dead fuel moistures. Modelled wildfire behaviour under both low and average fuel moisture scenarios revealed that grazing decreased the potential rate of spread by 44–52% and flame length by 36–41%. These results demonstrate that cattle grazing may be an effective approach for reducing fuel loads and potential wildfire behaviour in non-native-dominated grasslands on tropical islands.
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Cruz, Miguel G., N. Phillip Cheney, James S. Gould, W. Lachlan McCaw, Musa Kilinc et Andrew L. Sullivan. « An empirical-based model for predicting the forward spread rate of wildfires in eucalypt forests ». International Journal of Wildland Fire 31, no 1 (13 décembre 2021) : 81–95. http://dx.doi.org/10.1071/wf21068.
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Reliable and accurate models of the speed of a wildfire front as it moves across the landscape are essential for the timely prediction of its propagation, to devise suitable suppression strategies and enable effective public warnings. We used data from outdoor experimental fires and wildfires to derive an empirical model for the rate of fire spread in eucalypt forests applicable to a broad range of wildfire behaviour. The modelling analysis used logistic and non-linear regression analysis coupled with assumed functional forms for the effect of different environmental variables. The developed model incorporates the effect of wind speed, fine dead fuel moisture, understorey fuel structure, long-term landscape dryness and slope steepness. Model evaluation against the data used for its development yield mean absolute percentage errors between 35 and 46%. Evaluation against an independent wildfire dataset found mean percentage errors of 81 and 84% for two landscape dryness conditions. For these wildfires, the mean error was found to decrease with increasing rates of spread, with this error dropping below 30% when observed rates of spread were greater than 2 km h−1. The modular structure of the modelling analysis enables subsequent improvement of some of its components, such as the dead fuel moisture content or long-term dryness effects, without compromising its consistency or function.
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Parisien, Marc-André, Denyse A. Dawe, Carol Miller, Christopher A. Stockdale et O. Bradley Armitage. « Applications of simulation-based burn probability modelling : a review ». International Journal of Wildland Fire 28, no 12 (2019) : 913. http://dx.doi.org/10.1071/wf19069.
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Wildland fire scientists and land managers working in fire-prone areas require spatial estimates of wildfire potential. To fulfill this need, a simulation-modelling approach was developed whereby multiple individual wildfires are modelled in an iterative fashion across a landscape to obtain location-based measures of fire likelihood and fire behaviour (e.g. fire intensity, biomass consumption). This method, termed burn probability (BP) modelling, takes advantage of fire spread algorithms created for operational uses and the proliferation of available data representing wildfire patterns, fuels and weather. This review describes this approach and provides an overview of its applications in wildland fire research, risk analysis and land management. We broadly classify the application of BP models as (1) direct examination, (2) neighbourhood processes, (3) fire hazard and risk and (4) integration with secondary models. Direct examination analyses are those that require no further processing of model outputs; they range from a simple visual examination of outputs to an assessment of alternate states (i.e. scenarios). Neighbourhood process analyses examine patterns of fire ignitions and subsequent spread across land designations. Fire hazard combines fire probability and a quantitative assessment of fire behaviour, whereas risk is the product of fire likelihood and potential impacts of wildfire. The integration with secondary models represents situations where BP model outputs are integrated into, or used in conjunction with, other models or modelling platforms.
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Storey, Michael A., Owen F. Price, Jason J. Sharples et Ross A. Bradstock. « Drivers of long-distance spotting during wildfires in south-eastern Australia ». International Journal of Wildland Fire 29, no 6 (2020) : 459. http://dx.doi.org/10.1071/wf19124.
Texte intégralRésumé :
We analysed the influence of wildfire area, topography, fuel, surface weather and upper-level weather conditions on long-distance spotting during wildfires. The analysis was based on a large dataset of 338 observations, from aircraft-acquired optical line scans, of spotting wildfires in south-east Australia between 2002 and 2018. Source fire area (a measure of fire activity) was the most important predictor of maximum spotting distance and the number of long-distance spot fires produced (i.e. >500m from a source fire). Weather (surface and upper-level), vegetation and topographic variables had important secondary effects. Spotting distance and number of long-distance spot fires increased strongly with increasing source fire area, particularly under strong winds and in areas containing dense forest and steep slopes. General vegetation descriptors better predicted spotting compared with bark hazard and presence variables, suggesting systems that measure and map bark spotting potential need improvement. The results from this study have important implications for the development of predictive spotting and wildfire behaviour models.
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Furlaud, James M., Grant J. Williamson et David M. J. S. Bowman. « Simulating the effectiveness of prescribed burning at altering wildfire behaviour in Tasmania, Australia ». International Journal of Wildland Fire 27, no 1 (2018) : 15. http://dx.doi.org/10.1071/wf17061.
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Prescribed burning is a widely accepted wildfire hazard reduction technique; however, knowledge of its effectiveness remains limited. To address this, we employ simulations of a widely used fire behaviour model across the ecologically diverse Australian island state of Tasmania. We simulate three broad scenarios: (1) no fuel treatment, (2) a maximal treatment, with the most possible prescribed burning within ecological constraints, and (3) 12 hypothetically more implementable state-wide prescribed-burning plans. In all simulations, we standardised fire-weather inputs to represent regionally typical dangerous fire-weather conditions. Statistical modelling showed that an unrealistically large maximal treatment scenario could reduce fire intensity in three flammable vegetation types, and reduce fire probability in almost every vegetation type. However, leverage analysis of the 12 more-realistic implementable plans indicated that such prescribed burning would have only a minimal effect, if any, on fire extent and that none of these prescribed-burning plans substantially reduced fire intensity. The study highlights that prescribed burning can theoretically mitigate wildfire, but that an unrealistically large area would need to be treated to affect fire behaviour across the island. Rather, optimisation of prescribed burning requires careful landscape design at the local scale. Such designs should be based on improved fire behaviour modelling, empirical measurement of fuels and analysis of actual wildfires.
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Cai, Longyan, Hong S. He, Yu Liang, Zhiwei Wu et Chao Huang. « Analysis of the uncertainty of fuel model parameters in wildland fire modelling of a boreal forest in north-east China ». International Journal of Wildland Fire 28, no 3 (2019) : 205. http://dx.doi.org/10.1071/wf18083.
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Fire propagation is inevitably affected by fuel-model parameters during wildfire simulations and the uncertainty of the fuel-model parameters makes forecasting accurate fire behaviour very difficult. In this study, three different methods (Morris screening, first-order analysis and the Monte Carlo method) were used to analyse the uncertainty of fuel-model parameters with FARSITE model. The results of the uncertainty analysis showed that only a few fuel-model parameters markedly influenced the uncertainty of the model outputs, and many of the fuel-model parameters had little or no effect. The fire-spread rate is the driving force behind the uncertainty of other fire behaviours. Thus, the highly uncertain fuel-model parameters associated with spread rate should be used cautiously in wildfire simulations. Monte Carlo results indicated that the relationship between model input and output was non-linear and neglecting fuel-model parameter uncertainty of the model would magnify fire behaviours. Additionally, fuel-model parameters have high input uncertainty. Therefore, fuel-model parameters must be calibrated against actual fires. The highly uncertain fuel-model parameters with high spatial-temporal variability consisted of fuel-bed depth, live-shrub loading and 1-h time-lag loading are preferentially chosen as parameters to calibrate several wildfires.
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Grant, Madeleine A., Thomas J. Duff, Trent D. Penman, Bianca J. Pickering et Jane G. Cawson. « Mechanical Mastication Reduces Fuel Structure and Modelled Fire Behaviour in Australian Shrub Encroached Ecosystems ». Forests 12, no 6 (20 juin 2021) : 812. http://dx.doi.org/10.3390/f12060812.
Texte intégralRésumé :
Shrub encroachment of grassland and woodland ecosystems can alter wildfire behaviour and threaten ecological values. Australian fire managers are using mechanical mastication to reduce the fire risk in encroached ecosystems but are yet to evaluate its effectiveness or ecological impact. We asked: (1) How does fuel load and structure change following mastication?; (2) Is mastication likely to affect wildfire rates of spread and flame heights?; and (3) What is the impact of mastication on flora species richness and diversity? At thirteen paired sites (masticated versus control; n = 26), located in Victoria, Australia, we measured fuel properties (structure, load and hazard) and floristic diversity (richness and Shannon’s H) in 400 mP2 plots. To quantify the effects of mastication, data were analysed using parametric and non-parametric paired sample techniques. Masticated sites were grouped into two categories, 0–2 and 3–4 years post treatment. Fire behaviour was predicted using the Dry Eucalypt Forest Fire Model. Mastication with follow-up herbicide reduced the density of taller shrubs, greater than 50 cm in height, for at least 4 years. The most recently masticated sites (0–2 years) had an almost 3-fold increase in dead fine fuel loads and an 11-fold increase in dead coarse fuel loads on the forest floor compared with the controls. Higher dead coarse fuel loads were still evident after 3–4 years. Changes to fuel properties produced a reduction in predicted flame heights from 22 m to 5–6 m under severe fire weather conditions, but no change in the predicted fire rate of spread. Reductions in flame height would be beneficial for wildfire suppression and could reduce the damage to property from wildfires. Mastication did not have a meaningful effect on native species diversity, but promoted the abundance of some exotic species.
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Guelpa, Elisa, Adriano Sciacovelli, Vittorio Verda et Davide Ascoli. « Faster prediction of wildfire behaviour by physical models through application of proper orthogonal decomposition ». International Journal of Wildland Fire 25, no 11 (2016) : 1181. http://dx.doi.org/10.1071/wf15150.
Texte intégralRésumé :
Physical models of wildfires are of particular interest in fire behaviour research and have applications in firefighting, rescue and evacuation. However, physical models present a challenge as a result of the large computational resources they often require, especially for the analysis of large areas or when multiple scenarios are investigated. The objective of this paper is to explore the opportunity to reduce the computation time requested by physical wildfire models through application of a model order reduction technique, specifically the proper orthogonal decomposition (POD) technique. POD is here applied to a simple one-dimensional physical model. The full physical model for illustration of the concept is first tested with experimental data to check its ability to simulate wildfire behaviour; it is then reduced using the POD technique. It is shown that the reduced model is able to simulate fire propagation with only small deviations in results in comparison with the physical model (~6.4% deviation in the rate of spread, ROS) and a drastic reduction (~85%) in computational cost. The results demonstrate the advantages of applying effective reduction techniques to create new generations of fire models based on reduced physical approaches. The potential applicability of POD to more complex models is also discussed.
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Rodríguez y Silva, Francisco, Juan Ramón Molina Martínez et Armando González-Cabán. « A methodology for determining operational priorities for prevention and suppression of wildland fires ». International Journal of Wildland Fire 23, no 4 (2014) : 544. http://dx.doi.org/10.1071/wf13063.
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Traditional uses of the forest (timber, forage) have been giving way to other uses more in demand (recreation, ecosystem services). An observable consequence of this process of forest land use conversion is an increase in more difficult and extreme wildfires. Wildland forest management and protection program budgets are limited, and managers are requesting help in finding ways to objectively assign their limited protection resources based on the intrinsic environmental characteristics of a site and the site’s interrelationship with available firefighting resources and existing infrastructure. A Fire Suppression Priority Index, integrating information on both the potential fire behaviour risk (Potential Fire Behaviour Index) and the fire suppression difficulty (Suppression Difficulty Index), provides managers with fundamental information for strategic planning and development of tactical operations to protect the natural environment. Results in the Córdoba Province, Andalusia’s autonomous region, Spain, showed a statistically significant relationship between wildfire size and all three indices, demonstrating the utility of the methodology to identify and prioritise forest areas for strategic and tactical fire management operations. In addition, the methodology was tested and validated by trained and qualified wildfire management personnel in Chile and Israel, obtaining similar results as in Spain.
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Hart, Henry, Daniel D. B. Perrakis, Stephen W. Taylor, Christopher Bone et Claudio Bozzini. « Georeferencing Oblique Aerial Wildfire Photographs : An Untapped Source of Fire Behaviour Data ». Fire 4, no 4 (22 octobre 2021) : 81. http://dx.doi.org/10.3390/fire4040081.
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In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31–118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from −19° to −50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.
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Tavakol Sadrabadi, Mohammad, et Mauro Sebastián Innocente. « Vegetation Cover Type Classification Using Cartographic Data for Prediction of Wildfire Behaviour ». Fire 6, no 2 (18 février 2023) : 76. http://dx.doi.org/10.3390/fire6020076.
Texte intégralRésumé :
Predicting the behaviour of wildfires can help save lives and reduce health, socioeconomic, and environmental impacts. Because wildfire behaviour is highly dependent on fuel type and distribution, their accurate estimation is paramount for accurate prediction of the fire propagation dynamics. This paper studies the effect of combining automated hyperparameter tuning with Bayesian optimisation and recursive feature elimination on the accuracy of three boosting (AdaB, XGB, CatB), two bagging (Random Forest, Extremely Randomised Trees), and three stacking ensemble models with respect to their ability to estimate the vegetation cover type from cartographic data. The models are trained on the University of California Irvine (UCI) cover type dataset using five-fold cross-validation. Feature importance scores are calculated and used in recursive feature elimination analysis to study the sensitivity of model accuracy to the different feature combinations. Our results indicate that the implemented fine-tuning procedure significantly affects the accuracy of all models investigated, with XGB achieving an overall accuracy of 97.1% slightly outperforming the others.
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Strahan, Kenneth, et John Gilbert. « Protective Decision-Making in Bushfire Part 1 : A Rapid Systematic Review of the ‘Wait and See’ Literature ». Fire 4, no 1 (1 février 2021) : 4. http://dx.doi.org/10.3390/fire4010004.
Texte intégralRésumé :
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.
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Savenets, Mykhailo, Larysa Pysarenko, Svitlana Krakovska, Alexander Mahura et Tuukka Petäjä. « Enviro-HIRLAM model estimates of elevated black carbon pollution over Ukraine resulted from forest fires ». Atmospheric Chemistry and Physics 22, no 24 (16 décembre 2022) : 15777–91. http://dx.doi.org/10.5194/acp-22-15777-2022.
Texte intégralRésumé :
Abstract. Biomass burning is one of the biggest sources of atmospheric black carbon (BC), which negatively impacts human health and contributes to climate forcing. In this work, we explore the horizontal and vertical variability of BC concentrations over Ukraine during wildfires in August 2010. Using the Enviro-HIRLAM modelling framework, the BC atmospheric transport was modelled for coarse, accumulation, and Aitken mode aerosol particles emitted by the wildfire. Elevated pollution levels were observed within the boundary layer. The influence of the BC emissions from the wildfire was identified up to 550 hPa level for the coarse and accumulation modes and at distances of about 2000 km from the fire areas. BC was mainly transported in the lowest 3 km layer and mainly deposited at night and in the morning hours due to the formation of strong surface temperature inversions. As modelling is the only available source of BC data in Ukraine, our results were compared with ground-level measurements of dust, which showed an increase in concentration of up to 73 % during wildfires in comparison to average values. The BC contribution was found to be 10 %–20 % of the total aerosol mass near the wildfires in the lowest 2 km layer. At a distance, BC contribution exceeded 10 % only in urban areas. In the areas with a high BC content represented by both accumulation and coarse modes, downwelling surface long-wave radiation increased up to 20 W m−2, and 2 m air temperature increased by 1–4 ∘C during the midday hours. The findings of this case study can help to understand the behaviour of BC distribution and possible direct aerosol effects during anticyclonic conditions, which are often observed in mid-latitudes in the summer and lead to wildfire occurrences.
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Page, Wesley G., Martin E. Alexander et Michael J. Jenkins. « Wildfire’s resistance to control in mountain pine beetle-attacked lodgepole pine forests ». Forestry Chronicle 89, no 06 (décembre 2013) : 783–94. http://dx.doi.org/10.5558/tfc2013-141.
Texte intégralRésumé :
Concerns about the impacts of mountain pine beetle (Dendroctonus ponderosae Hopkins)-caused tree mortality on wildfire potential in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) forests have to date largely focused on the potential for extreme fire behaviour, including the development and spread of crown fires. Given that the wildland fire environment in which fire managers and firefighters work is composed of many interacting physical and human factors, viewing crown fire behaviour as the only or even the most important outcome of the tree mortality associated with a mountain pine beetle outbreak is questionable. Proper assessment of wildfire potential entails a broader approach, which requires expanding the concept of wildfire resistance to control to include an analysis of all relevant factors and their interactions. In this paper we describe a holistic concept of analyzing the impacts of mountain pine beetle-caused tree mortality on wildfire potential in lodgepole pine forests on the basis of fire behaviour characteristics, fire suppression operations, and firefighter safety considerations within the framework of three recognizable stages of the approximate time since the initiation of an outbreak (i.e., “red” ∼1 to 5 years, “gray” ∼5 to 15 years, and post-epidemic ∼15+ years).
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Volokitina, A. V., M. A. Sofronov et T. M. Sofronova. « Surface wildfire behaviour prediction using vegetation fuel maps ». Forest Ecology and Management 234 (novembre 2006) : S115. http://dx.doi.org/10.1016/j.foreco.2006.08.156.
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Salis, Michele, Bachisio Arca, Fermin Alcasena, Margarita Arianoutsou, Valentina Bacciu, Pierpaolo Duce, Beatriz Duguy et al. « Predicting wildfire spread and behaviour in Mediterranean landscapes ». International Journal of Wildland Fire 25, no 10 (2016) : 1015. http://dx.doi.org/10.1071/wf15081.
Texte intégralRésumé :
The use of spatially explicit fire spread models to assess fire propagation and behaviour has several applications for fire management and research. We used the FARSITE simulator to predict the spread of a set of wildfires that occurred along an east–west gradient of the Euro-Mediterranean countries. The main purpose of this work was to evaluate the overall accuracy of the simulator and to quantify the effects of standard vs custom fuel models on fire simulation performance. We also analysed the effects of different fuel models and slope classes on the accuracy of FARSITE predictions. To run the simulations, several input layers describing each study area were acquired, and their effect on simulation outputs was analysed. Site-specific fuel models and canopy inputs were derived either from existing vegetation information and field sampling or through remote-sensing data. The custom fuel models produced an increase in simulation accuracy, and results were nearly unequivocal for all the case studies examined. We suggest that spatially explicit fire spread simulators and custom fuel models specifically developed for the heterogeneous landscapes of Mediterranean ecosystems can help improve fire hazard mapping and optimise fuel management practices across the Euro-Mediterranean region.
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Katan, Jeffrey, et Liliana Perez. « ABWiSE v1.0 : toward an agent-based approach to simulating wildfire spread ». Natural Hazards and Earth System Sciences 21, no 10 (19 octobre 2021) : 3141–60. http://dx.doi.org/10.5194/nhess-21-3141-2021.
Texte intégralRésumé :
Abstract. Wildfires are a complex phenomenon emerging from interactions between air, heat, and vegetation, and while they are an important component of many ecosystems’ dynamics, they pose great danger to those ecosystems, as well as human life and property. Wildfire simulation models are an important research tool that help further our understanding of fire behaviour and can allow experimentation without recourse to live fires. Current fire simulation models fit into two general categories: empirical models and physical models. We present a new modelling approach that uses agent-based modelling to combine the complexity possible with physical models with the ease of computation of empirical models. Our model represents the fire front as a set of moving agents that respond to, and interact with, vegetation, wind, and terrain. We calibrate the model using two simulated fires and one real fire and validate the model against another real fire and the interim behaviour of the real calibration fire. Our model successfully replicates these fires, with a figure of merit on par with simulations by the Prometheus simulation model. Our model is a stepping-stone in using agent-based modelling for fire behaviour simulation, as we demonstrate the ability of agent-based modelling to replicate fire behaviour through emergence alone.
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Potter, Brian E., et Matthew A. Anaya. « A Wildfire-relevant climatology of the convective environment of the United States ». International Journal of Wildland Fire 24, no 2 (2015) : 267. http://dx.doi.org/10.1071/wf13211.
Texte intégralRésumé :
Convective instability can influence the behaviour of large wildfires. Because wildfires modify the temperature and moisture of air in their plumes, instability calculations using ambient conditions may not accurately represent convective potential for some fire plumes. This study used the North American Regional Reanalysis to develop a climatology of the convective environment specifically tied to large fire events. The climatology is based on the period 1979–2009 and includes ambient convective available potential energy (CAPE) as well as values when surface air is warmed by 0.5, 1.0 or 2.0 K or moistened by 0.5, 1.0 or 2.0 g kg–1. Results for the 2.0 K and 2.0 g kg–1 modifications are presented. The results reveal spatial and seasonal patterns of convective sensitivity to added heat or moisture. The patterns suggest that use of ambient CAPE to estimate the potential plume growth of a large wildfire may underestimate that potential in heat- or moisture-sensitive regions.
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Heilman, Warren E., et Xindi Bian. « Turbulent kinetic energy during wildfires in the north central and north-eastern US ». International Journal of Wildland Fire 19, no 3 (2010) : 346. http://dx.doi.org/10.1071/wf08076.
Texte intégralRésumé :
The suite of operational fire-weather indices available for assessing the atmospheric potential for extreme fire behaviour typically does not include indices that account for atmospheric boundary-layer turbulence or wind gustiness that can increase the erratic behaviour of fires. As a first step in testing the feasibility of using a quantitative measure of turbulence as a stand-alone fire-weather index or as a component of a fire-weather index, simulations of the spatial and temporal patterns of turbulent kinetic energy during major recent wildfire events in the western Great Lakes and north-eastern US regions were performed. Simulation results indicate that the larger wildfires in these regions of the US were associated with episodes of significant boundary-layer ambient turbulence. Case studies of the largest recent wildfires to occur in these regions indicate that the periods of most rapid fire growth were generally coincident with occurrences of the product of the Haines Index and near-surface turbulent kinetic energy exceeding a value of 15 m2 s–2, a threshold indicative of a highly turbulent boundary layer beneath unstable and dry atmospheric layers, which is a condition that can be conducive to erratic fire behaviour.
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Jahdi, R., M. Salis, M. Arabi et B. Arca. « FIRE MODELLING TO ASSESS SPATIAL PATTERNS OF WILDFIRE EXPOSURE IN ARDABIL, NW IRAN ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W18 (18 octobre 2019) : 577–81. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w18-577-2019.
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Abstract. Fire exposure describes the spatial juxtaposition of values with fire behaviour in terms of likelihood and intensity. Wildfire exposure analysis is based on the estimation of the potential wildfire intensity and on the burn probability. Fire modelling can produce spatially explicit information on fire spread and behaviour, and offers a feasible method to simulate, map, and analyse fire exposure. FlamMap Minimum Travel Time (MTT) algorithm (Finney, 2006) was used to conduct wildfire simulations considering historical data of fuel moisture conditions and winds, as well as the most frequent wind directions and historical ignition locations (2005-2018). Analysis was conducted on spatial and quantitative variations in selected fire hazard and exposure factors, namely Burn Probability (BP), Conditional Flame Length (CFL) and Fire Size (F). We observed pronounced spatial variations among and between municipalities in the factors, especially for those in the northern and southern parts of Ardabil. The variations across the burnable area of the municipalities can be fundamentally related to a number of factors, including spatial variation in ignition locations, fuel moisture and load, weather conditions, and topography of the terrain. The findings can provide information and support in wildfire management planning and fire risk mitigation activities.
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Aparício, Bruno A., José M. C. Pereira, Francisco C. Santos, Chiara Bruni et Ana C. L. Sá. « Combining wildfire behaviour simulations and network analysis to support wildfire management : A Mediterranean landscape case study ». Ecological Indicators 137 (avril 2022) : 108726. http://dx.doi.org/10.1016/j.ecolind.2022.108726.
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Morvan, D., J. L. Dupuy, E. Rigolot et J. C. Valette. « FIRESTAR : A Physically based model to study wildfire behaviour ». Forest Ecology and Management 234 (novembre 2006) : S114. http://dx.doi.org/10.1016/j.foreco.2006.08.155.
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Plucinski, Matt P., et Elsa Pastor. « Criteria and methodology for evaluating aerial wildfire suppression ». International Journal of Wildland Fire 22, no 8 (2013) : 1144. http://dx.doi.org/10.1071/wf13040.
Texte intégralRésumé :
Aircraft are often used to drop suppressants and retardants to assist wildfire containment. Drop effectiveness has rarely been measured due to the difficulties in collecting data from wildfires and running field experiments and the absence of definitions and measures. This paper presents a set of criteria and methodologies for evaluating the effectiveness of aerial suppression drops. These consider drop placement, coverage and effect on fire behaviour. This paper also details drop site and delivery conditions that are required for determining causal factors that influence drop effectiveness and allow drops to be compared. Examples of drop impact evaluations made during experimental fires are used to demonstrate these methodologies. The main methods proposed are based on the analysis of orthorectified airborne infrared imagery of drops, which can be used to measure drop dimensions, proximity to fire perimeter and their effect on fire spread. These evaluations can be used to compare tactics, suppressants and delivery systems and to inform cost–benefit analyses of aerial suppression.
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Linn, Rodman, Judith Winterkamp, Carleton Edminster, Jonah J. Colman et William S. Smith. « Coupled influences of topography and wind on wildland fire behaviour ». International Journal of Wildland Fire 16, no 2 (2007) : 183. http://dx.doi.org/10.1071/wf06078.
Texte intégralRésumé :
Ten simulations were performed with the HIGRAD/FIRETEC wildfire behaviour model in order to explore its utility in studying wildfire behaviour in inhomogeneous topography. The goal of these simulations is to explore the potential extent of the coupling between the fire, atmosphere, and topography. The ten simulations described in this paper include five different topographies, each run with two different ambient wind speeds of 6 and 12 m s–1. The five topologies explored are: an idealised hill (which serves as the base centerline for the other topographies), two variations of the hill with lateral gradients downwind from the ignition line (one sloping up from the ‘hill’ at the centerline to form an upward sloping canyon parallel to the ambient wind, and the other sloping down from the centerline to form a ridge parallel to the ambient flow), one with a second hill upwind of the ignition line such that the fire is ignited in the bottom of a canyon that runs perpendicular to the ambient wind, and finally a flat terrain. The four non-trivial topographies have the same profile along the centerline downwind of the ignition line to help assess the impacts of topographic gradients that are perpendicular to the ambient wind. It is hoped that analysis of these simulations will help reveal where point-functional models are sufficient, where topographically modified wind fields are needed, and where fully coupled fire and transport models are necessary to properly describe wildfire behaviour.
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Manzano-Agugliaro, F., J. Pérez-Aranda et J. L. De La Cruz. « Methodology to obtain isochrones from large wildfires ». International Journal of Wildland Fire 23, no 3 (2014) : 338. http://dx.doi.org/10.1071/wf13166.
Texte intégralRésumé :
In Mediterranean countries, a change in traditional uses of land has caused an increase in both the number of fires and the land area affected by fires. This situation creates a need to improve the efficiency and effectiveness of wildfire extinguishing devices. This improvement should be based on knowledge of the fire behaviour of various fires affecting similar areas. To study these fires, we considered a methodology to obtain isochrones at different stages of a wildfire through temporal georeferencing of aerial fire photographs. This methodology was applied to two large wildfires (1098 and 4609ha) that occurred in 2009 in the south of Spain. A total of 463 and 611 photographs were considered to respectively obtain seven and nine isochrones. These isochrones are representative of the development of the fires. In periods of greater intensity, this study exhibits a rate of propagation much higher than expected, reaching 7.8hamin–1 of burned surface and 160.0mmin–1 of perimeter growth in one example, whereas if we considered only the final perimeter of the fire, the speed of burned perimeter generation would be 28.2mmin–1 and of burned surface, 2.4hamin–1.
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Burrows, Neil, Malcolm Gill et Jason Sharples. « Development and validation of a model for predicting fire behaviour in spinifex grasslands of arid Australia ». International Journal of Wildland Fire 27, no 4 (2018) : 271. http://dx.doi.org/10.1071/wf17155.
Texte intégralRésumé :
Large wildfires are common in spinifex grasslands of arid Australia. Threat mitigation measures including fire preparedness, prescribed burning and wildfire suppression are greatly enhanced by the ability to predict fire behaviour. The new spinifex fire behaviour model presented here was developed and validated from 186 experimental fires across a wide range of fuel and weather conditions. Because spinifex fuels are discontinuous, modelling is a two-step process; once ignition is achieved, the first step is to determine the likelihood of fire spread, which is dependent on conditions of wind speed, fuel cover and fuel moisture content. If spread thresholds are met, the second step is to predict rate of spread and flame height using the same three independent variables. Thirty-six of the 186 experimental fires not used in modelling were used to validate the model, which proved to be reasonably accurate and an improvement on the previous model.
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Salis, Michele, Liliana Del Giudice, Peter R. Robichaud, Alan A. Ager, Annalisa Canu, Pierpaolo Duce, Grazia Pellizzaro et al. « Coupling wildfire spread and erosion models to quantify post-fire erosion before and after fuel treatments ». International Journal of Wildland Fire 28, no 9 (2019) : 687. http://dx.doi.org/10.1071/wf19034.
Texte intégralRésumé :
Wildfires are known to change post-fire watershed conditions such that hillslopes can become prone to increased erosion and sediment delivery. In this work, we coupled wildfire spread and erosion prediction modelling to assess the benefits of fuel reduction treatments in preventing soil runoff. The study was conducted in a 68000-ha forest area located in Sardinia, Italy. We compared no-treatment conditions v. alternative strategic fuel treatments performed in 15% of the area. Fire behaviour before and after treatments was estimated by simulating 25000 wildfires for each condition using the minimum travel time fire-spread algorithm. The fire simulations replicated historic conditions associated with severe wildfires in the study area. Sediment delivery was then estimated using the Erosion Risk Management Tool (ERMiT). Our results showed how post-fire sediment delivery varied among and within fuel treatment scenarios. The most efficient treatment alternative was that implemented near the road network. We also evaluated other factors such as exceedance probability, time since fire, slope, fire severity and vegetation type on post-fire sediment delivery. This work provides a quantitative assessment approach to inform and optimise proactive risk management activities intended to reduce post-fire erosion.
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Charney, Joseph J., et Daniel Keyser. « Mesoscale model simulation of the meteorological conditions during the 2 June 2002 Double Trouble State Park wildfire ». International Journal of Wildland Fire 19, no 4 (2010) : 427. http://dx.doi.org/10.1071/wf08191.
Texte intégralRésumé :
On the morning of 2 June 2002, an abandoned campfire grew into a wildfire in the Double Trouble State Park in east-central New Jersey, USA. The wildfire burned 526 ha (1300 acres) and forced the closure of the Garden State Parkway for several hours due to dense smoke. In addition to the presence of dead and dry fuels due to a late spring frost prior to the wildfire, the meteorological conditions at the time of the wildfire were conducive to erratic fire behaviour and rapid fire growth. Observations indicate the occurrence of a substantial drop in relative humidity at the surface accompanied by an increase in wind speed in the vicinity of the wildfire during the late morning and early afternoon of 2 June. The surface drying and increase in wind speed are hypothesised to result from the downward transport of dry, high-momentum air from the middle troposphere occurring in conjunction with a deepening mixed layer. This hypothesis is addressed using a high-resolution mesoscale model simulation to document the structure and evolution of the planetary boundary layer and lower-tropospheric features associated with the arrival of dry, high-momentum air at the surface coincident with the sudden and dramatic growth of the wildfire.
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Gallego Arrubla, Julián A., Lewis Ntaimo et Curt Stripling. « Wildfire initial response planning using probabilistically constrained stochastic integer programming ». International Journal of Wildland Fire 23, no 6 (2014) : 825. http://dx.doi.org/10.1071/wf13204.
Texte intégralRésumé :
This paper presents a new methodology for making strategic dozer deployment plans for wildfire initial response planning for a given fire season. This approach combines a fire behaviour simulation, a wildfire risk model and a probabilistically constrained stochastic integer programming model, and takes into account the level of risk the decision-maker is willing to take when making deployment and dispatching plans. The new methodology was applied to Texas District 12, a Texas A&M Forest Service fire planning unit located in East Texas. This study demonstrates the effect of the decision-maker’s risk attitude level on deployment decisions in terms of the dozers positioned at each operations base, fires contained and their associated wildfire risk, and total containment cost. The results show that the total number of fires contained and their associated total expected cost increase when the tolerance towards risk decreases. Thus, more dozers are deployed to operations bases in areas with high wildfire risk and a high need for initial response.
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Marino, Eva, Carmen Hernando, Javier Madrigal et Mercedes Guijarro. « Short-term effect of fuel treatments on fire behaviour in a mixed heathland : a comparative assessment in an outdoor wind tunnel ». International Journal of Wildland Fire 23, no 8 (2014) : 1097. http://dx.doi.org/10.1071/wf13175.
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Fuel management is one of the main challenges for wildfire prevention in the Mediterranean region, where wildfires have important environmental and socioeconomic effects. Different treatments are usually applied in fire-prone shrubland to try to modify its flammability. However, a knowledge gap on the effectiveness of fuel management techniques still exists. We studied the effects of two mechanical treatments (shrub crushing and shrub clearing with removal) and of prescribed burning, on fire behaviour, and compared them with untreated vegetation. Experimental burns in 0.8 × 6 m samples of regenerated shrubs 2 years after treatments were performed in an outdoor wind tunnel. All fuel treatments effectively modified fire behaviour, but no significant difference between treatment types was observed. Shrub fuel structure was the main factor affecting fire behaviour. Reduction of fuel load and height, especially necromass fraction, decreased flame height and fire intensity but did not affect fire rate of spread. Moisture contents of live and dead fuel fractions were not significant as independent parameters, but the average moisture level of the shrub fuel complex showed a relevant effect in determining fire behaviour. Temperature regime within and above the shrubs was also related to shrub fuel structure. This study contributes to understanding fuel management in shrubland by providing information about different fuel treatments effects on fire behaviour.
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Hyde, Kevin, Matthew B. Dickinson, Gil Bohrer, David Calkin, Louisa Evers, Julie Gilbertson-Day, Tessa Nicolet, Kevin Ryan et Christina Tague. « Research and development supporting risk-based wildfire effects prediction for fuels and fire management : status and needs ». International Journal of Wildland Fire 22, no 1 (2013) : 37. http://dx.doi.org/10.1071/wf11143.
Texte intégralRésumé :
Wildland fire management has moved beyond a singular focus on suppression, calling for wildfire management for ecological benefit where no critical human assets are at risk. Processes causing direct effects and indirect, long-term ecosystem changes are complex and multidimensional. Robust risk-assessment tools are required that account for highly variable effects on multiple values-at-risk and balance competing objectives, to support decision making. Providing wildland fire managers with risk-analysis tools requires a broad scientific foundation in fire behaviour and effects prediction as well as high quality computer-based tools and associated databases. We outline a wildfire risk-assessment approach, highlight recent developments in fire effects science and associated research needs, and recommend developing a comprehensive plan for integrated advances in wildfire occurrence, behaviour and effects research leading to improved decision support tools for wildland fire managers. We find that the current state of development in fire behaviour and effects science imposes severe limits on the development of risk-assessment technology. In turn, the development of technology has been largely disconnected from the research enterprise, resulting in a confusing array of ad hoc tools that only partially meet decision-support needs for fuel and fire management. We make the case for defining a common risk-based analytic framework for fire-effects assessment across the range of fire-management activities and developing a research function to support the framework.
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Calheiros, Tomás, Akli Benali, Mário Pereira, João Silva et João Nunes. « Drivers of extreme burnt area in Portugal : fire weather and vegetation ». Natural Hazards and Earth System Sciences 22, no 12 (19 décembre 2022) : 4019–37. http://dx.doi.org/10.5194/nhess-22-4019-2022.
Texte intégralRésumé :
Abstract. Fire weather indices are used to assess the effect of weather on wildfire behaviour and to support fire management. Previous studies identified the high daily severity rating percentile (DSRp) as being strongly related to the total burnt area (BA) in Portugal, but it is still poorly understood how this knowledge can support fire management at a smaller spatial scale. The aims of this study were to (1) assess whether the 90th DSRp (DSR90p) threshold is adequate for estimating most of the BA in mainland Portugal; (2) analyse the spatial variability of the DSRp threshold that explains a large part of BA, at higher resolution; and, (3) analyse whether vegetation cover can justify the DSRp spatial variability. We used weather reanalysis data from ERA5-Land, wildfire and land use data from Portuguese land management departments for an extended summer period (15 May to 31 October) from 2001 to 2019. We computed and related DSRp to large wildfires (BA > 100 ha) and land use to clarify the effectiveness of the DSRp for estimating BA in Portugal and assess how vegetation influences it. Results revealed that the DSR90p is an adequate indicator of extreme fire weather days and BA in Portugal. In addition, the spatial pattern of the DSRp associated with most of the total BA shows variability at the municipality scale. Municipalities where large wildfires occur with more extreme weather conditions have most of the BAs in forests and are in coastal areas. By contrast, municipalities where large wildfires occur with less extreme weather conditions are predominantly covered by shrublands and are situated in eastern and inland regions. These findings are a novelty for fire science in Portugal and should be considered by fire managers and fire risk assessors.
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Zapata, Rodolfo, Jose-Vicente Oliver-Villanueva, Lenin-Guillermo Lemus-Zúñiga, Miguel A. Mateo Pla et Jorge E. Luzuriaga. « Electrical Responses of Pinus halepensis Mill. as an Indicator of Wildfire Risk in Mediterranean Forests by Complementing Live Fuel Moisture ». Forests 13, no 8 (27 juillet 2022) : 1189. http://dx.doi.org/10.3390/f13081189.
Texte intégralRésumé :
Pinus halepensis forests, as Mediterranean-type ecosystems, are subject to high levels of wildfire risk in times of drought, with meteorological conditions of water stress and very high temperatures, mainly in summer. Considering the difficulty of knowing the phenological state of this species, the objective of this research was to evaluate the possibility of implementing the electrical responses (voltage and short-circuit current) as a variable in fire risk management models, compared to live fuel moisture. On the one hand, the obtained results demonstrate non-significant differences between the moisture content of the different fractions of the living branches (base and half of the branch and live fuel), even in times of drought with hydric stress and very high temperatures. Live fuel moisture of Pinus halepensis does not show significant seasonal variations under the influence of extreme fire risk factors. For this reason, it should be complemented with other variables for fire risk management models. On the other hand, the differences registered in the electrical signal show oscillations with significant variations, which are strongly correlated with the periods of extremely favourable meteorological conditions for wildfires. So, the voltages measured show ranges that correspond with great accuracy to the FWI. Voltage variation is dependent on the hydraulic dynamic plant behaviour and a result of the physiological response of pine trees to abiotic stress of drought. It is an easy-to-measure electrical parameter as well as a very reliable indicator with a high correlation with wildfire risk. Thus, electrical responses could add more knowledge about the phenological state of the trees in dependence on stress climatic conditions, allowing integration of these variables in the preventive wildfire modelling and management.
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García-Santos, Glenda, Mariana Madruga de Brito, Britta Höllermann, Linda Taft, Adrian Almoradie et Mariele Evers. « Methodology to explore emergent behaviours of the interactions between water resources and ecosystem under a pluralistic approach ». Proceedings of the International Association of Hydrological Sciences 379 (5 juin 2018) : 83–87. http://dx.doi.org/10.5194/piahs-379-83-2018.
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Abstract. Understanding the interactions between water resources and its social dimensions is crucial for an effective and sustainable water management. The identification of sensitive control variables and feedback loops of a specific human-hydro-scape can enhance the knowledge about the potential factors and/or agents leading to the current water resources and ecosystems situation, which in turn supports the decision-making process of desirable futures. Our study presents the utility of a system dynamics modeling approach for water management and decision-making for the case of a forest ecosystem under risk of wildfires. We use the pluralistic water research concept to explore different scenarios and simulate the emergent behaviour of water interception and net precipitation after a wildfire in a forest ecosystem. Through a case study, we illustrate the applicability of this new methodology.
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Fischer, A. Paige, Jeffrey D. Kline, Alan A. Ager, Susan Charnley et Keith A. Olsen. « Objective and perceived wildfire risk and its influence on private forest landowners’ fuel reduction activities in Oregon’s (USA) ponderosa pine ecoregion ». International Journal of Wildland Fire 23, no 1 (2014) : 143. http://dx.doi.org/10.1071/wf12164.
Texte intégralRésumé :
Policymakers seek ways to encourage fuel reduction among private forest landowners to augment similar efforts on federal and state lands. Motivating landowners to contribute to landscape-level wildfire protection requires an understanding of factors that underlie landowner behaviour regarding wildfire. We developed a conceptual framework describing landowners’ propensity to conduct fuel reduction as a function of objective and subjective factors relating to wildfire risk. We tested our conceptual framework using probit analysis of empirical data from a survey of non-industrial private forest landowners in the ponderosa pine (Pinus ponderosa) region of eastern Oregon (USA). Our empirical results confirm the conceptual framework and suggest that landowners’ perceptions of wildfire risk and propensity to conduct fuel treatments are correlated with hazardous fuel conditions on or near their parcels, whether they have housing or timber assets at risk, and their past experience with wildfire, financial capacity for conducting treatments and membership in forestry and fire protection organisations. Our results suggest that policies that increase awareness of hazardous fuel conditions on their property and potential for losses in residential and timber assets, and that enhance social networks through which awareness and risk perception are formed, could help to encourage fuel reduction among private forest landowners.
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Knapp, Eric E., J. Morgan Varner, Matt D. Busse, Carl N. Skinner et Carol J. Shestak. « Behaviour and effects of prescribed fire in masticated fuelbeds ». International Journal of Wildland Fire 20, no 8 (2011) : 932. http://dx.doi.org/10.1071/wf10110.
Texte intégralRésumé :
Mechanical mastication converts shrub and small tree fuels into surface fuels, and this method is being widely used as a treatment to reduce fire hazard. The compactness of these fuelbeds is thought to moderate fire behaviour, but whether standard fuel models can accurately predict fire behaviour and effects is poorly understood. Prescribed burns were conducted in young ponderosa pine (Pinus ponderosa Laws.) forests at two sites in northern California where the midstorey layer dominated by shrubs had been masticated. Surface fuels were raked from the base of a subset of trees before burning. Rate of spread and flame length were estimated for both backing and heading fires, soil heating measured with thermocouples and tree fire injury recorded. Standard fuel models often over-predicted rate of spread or under-predicted flame length. Custom models generally provided a better balance between the slow rates of spread and moderate flame lengths observed in prescribed burns. Post-fire tree mortality was most strongly associated with crown scorch and tree size; raking fuels from the base of trees did not improve survival. Under severe fire weather conditions, fire behaviour and effect models as well as observations from wildfires suggest that mastication may be more effective for moderating fire behaviour than reducing residual tree mortality. Treating masticated fuels with prescribed burns could potentially improve the resilience of stands to wildfire.
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Pimont, F., J. L. Dupuy et R. R. Linn. « Coupled slope and wind effects on fire spread with influences of fire size : a numerical study using FIRETEC ». International Journal of Wildland Fire 21, no 7 (2012) : 828. http://dx.doi.org/10.1071/wf11122.
Texte intégralRésumé :
Wind and slope are commonly accepted to be major environmental factors affecting the manner in which wildfires propagate. Fire-line width has been observed as having a significant effect on fire behaviour in some experimental fires. Most wildfire behaviour models and fire behaviour prediction systems take wind and slope effects into account when determining the rate of spread, but do not take into account the influence of fire width on the coupled effects of slope and wind. In the present study, the effect of topographic slope on rate of spread under weak (1 m s–1), moderate (5 m s–1) and strong (12 m s–1) wind speeds is investigated for two different initial fire widths (20 and 50 m) in a typical Mediterranean garrigue, using the coupled atmosphere–fire HIGRAD-FIRETEC model. The results show non-trivial combined effects and suggest a strong effect of fire width under low-wind conditions, especially for steep slopes. Simulated spread rates were compared with predictions of existing models of operational systems and a reasonable agreement was found. Additional exploratory simulations of fire behaviour in small canyons are provided. These simulations show how combined effects of wind, slope and fire-front size can induce different fire behaviours that operational models could fail to predict and provide insight that could be valuable for analysis of blow-up fires. These preliminary results also suggest that 3D physically based models could be used in the future to investigate how operational models can include non-local effects of fire propagation.
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Martinson, Erik J., et Philip N. Omi. « Assessing mitigation of wildfire severity by fuel treatments - an example from the Coastal Plain of Mississippi ». International Journal of Wildland Fire 17, no 3 (2008) : 415. http://dx.doi.org/10.1071/wf06067.
Texte intégralRésumé :
Fuel treatments such as prescribed fire are a controversial tenet of wildfire management. Despite a well-established theoretical basis for their use, scant empirical evidence currently exists on fuel treatment effectiveness for mitigating the behaviour and effects of extreme wildfire events. We report the results of a fire severity evaluation of an escaped prescribed fire that burned into an area previously treated with repeated prescribed fires. We observed significantly lower scorch heights, crown damage, and ground char in the treated area. We attribute the moderated fire severity in the treated area to a significantly altered fuel profile created by the repeated prescribed fires. Though our results represent just one treatment area in a single wildfire, they add to a depauperate database and bring us a step closer to defining the conditions under which fuel treatments are an effective pre-suppression strategy.
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Paveglio, Travis, Tony Prato, Douglas Dalenberg et Tyron Venn. « Understanding evacuation preferences and wildfire mitigations among Northwest Montana residents ». International Journal of Wildland Fire 23, no 3 (2014) : 435. http://dx.doi.org/10.1071/wf13057.
Texte intégralRésumé :
There is currently insufficient information in the United States about residents’ planned evacuation actions during wildfire events, including any intent to remain at or near home during fire events. This is incompatible with growing evidence that select populations at risk from wildfire are considering alternatives to evacuation. This study explores the evacuation preferences of wildland–urban interface residents in Flathead County, Montana, USA. We compare the performance of wildfire mitigation and fuel reduction actions across groups of residents with different primary evacuation preferences. We also explore what factors (e.g. actions, demographics, attitudes towards government, risk perceptions) help explain residents’ preferences for evacuation. Results suggest that relatively high proportions of residents are interested in staying and defending their homes, with smaller proportions favouring evacuation or passively sheltering in their homes during wildfire. Vegetation management behaviour differs significantly among residents with different evacuation preferences, including significantly higher rates of forest thinning among those intending to remain at home and actively defend their residence. Other results suggest that sex, part-time residency, income and attitudes towards loss from fire are statistically associated with differences in evacuation preferences.
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Buckley, Andrew J. « Fire behaviour and fuel reduction burning : Bemm River wildfire, October 1988 ». Australian Forestry 55, no 1-4 (janvier 1992) : 135–47. http://dx.doi.org/10.1080/00049158.1992.10676107.
Texte intégral