scholarly journals DESCRIBING FOREST FIRES — OLD WAYS AND NEW

1965 ◽  
Vol 41 (3) ◽  
pp. 301-305 ◽  
Author(s):  
C. E. van Wagner
Keyword(s):  
Forest Fires ◽  
Quantitative Measure ◽  
Verbal Description ◽  
Energy Output ◽  
Fire Behaviour ◽  
Fire Control ◽  
Linear Rate ◽  
Rate Of Spread ◽  
Fire Front ◽  
In Fire

This article deals with several ways of describing forest fires and their limitations. The simplest and oldest way is by simple verbal description. Then came the combination of rate of spread and resistance to control. The best quantitative measure of fire behaviour, however, is the rate of energy output per unit of fire front, quoted in conjunction with the linear rate of spread. If the full benefits of advances in fire control technology are to be realized, wider use of the energy output concept will probably be necessary, first among fire researchers and eventually among fire control people.

Calculating and interpreting forest fire intensities

1982 ◽  
Vol 60 (4) ◽  
pp. 349-357 ◽  
Author(s):  
Martin E. Alexander
Keyword(s):  
Forest Fire ◽  
International System ◽  
Unit Length ◽  
Fire Behavior ◽  
Energy Output ◽  
Fire Intensity ◽  
Linear Rate ◽  
Fire Front ◽  
Quantitative Basis ◽  
The Impact

Frontal fire intensity is a valid measure of forest fire behavior that is solely a physical attribute of the fire itself. It is defined as the energy output rate per unit length of fire front and is directly related to flame size. Numerically, it is equal to the product of net heat of combustion, quantity of fuel consumed in the active combustion zone, and a spreading fire's linear rate of advance. The recommended International System (SI) units are kilowatts per metre. This concept of fire intensity provides a quantitative basis for fire description useful in evaluating the impact of fire on forest ecosystems.

HISTORY OF A SMALL CROWN FIRE

1964 ◽  
Vol 40 (2) ◽  
pp. 202-209 ◽  
Author(s):  
C. E. Van Wagner
Keyword(s):  
Red Pine ◽  
Energy Output ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Pine Plantation ◽  
Rate Of Spread ◽  
Fast Spreading ◽  
History Of ◽  
Slow Moving ◽  
Extreme Fire

An 80-foot-square plot in a red pine plantation was burned at extreme fire danger as part of a study of fire behaviour and effect. When the wind reversed its direction, the original slow-moving back-fire changed within a few minutes to a fast-spreading crown fire. The transition from surface to crowns is described in terms of rate of spread, fuel weight consumed and energy output.

Modelling the dynamic behaviour of junction fires with a coupled atmosphere–fire model

2017 ◽  
Vol 26 (4) ◽  
pp. 331 ◽  
Author(s):  
C. M. Thomas ◽  
J. J. Sharples ◽  
J. P. Evans
Keyword(s):  
Fire Spread ◽  
Community Safety ◽  
Fire Behaviour ◽  
Ambient Conditions ◽  
Fire Model ◽  
Fire Propagation ◽  
Dynamic Propagation ◽  
Rate Of Spread ◽  
Steady Rate ◽  
In Fire

Dynamic fire behaviour involves rapid changes in fire behaviour without significant changes in ambient conditions, and can compromise firefighter and community safety. Dynamic fire behaviour cannot be captured using spatial implementations of empirical fire-spread models predicated on the assumption of an equilibrium, or quasi-steady, rate of spread. In this study, a coupled atmosphere–fire model is used to model the dynamic propagation of junction fires, i.e. when two firelines merge at an oblique angle. This involves very rapid initial rates of spread, even with no ambient wind. The simulations are in good qualitative agreement with a previous experimental study, and indicate that pyro-convective interaction between the fire and the atmosphere is the key mechanism driving the dynamic fire propagation. An examination of the vertical vorticity in the simulations, and its relationship to the fireline geometry, gives insight into this mechanism. Junction fires have been modelled previously using curvature-dependent rates of spread. In this study, however, although fireline geometry clearly influences rate of spread, no relationship is found between local fireline curvature and the simulated instantaneous local rate of spread. It is possible that such a relationship may be found at larger scales.

Effects of fuel load and moisture content on fire behaviour and heating in masticated litter-dominated fuels

2013 ◽  
Vol 22 (4) ◽  
pp. 440 ◽  
Author(s):  
Jesse K. Kreye ◽  
Leda N. Kobziar ◽  
Wayne C. Zipperer
Keyword(s):  
Moisture Content ◽  
Fuel Load ◽  
Maximum Temperature ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Pine Flatwoods ◽  
Rate Of Spread ◽  
Soil Temperatures ◽  
Fuel Moisture Content ◽  
In Fire

Mechanical fuels treatments are being used in fire-prone ecosystems where fuel loading poses a hazard, yet little research elucidating subsequent fire behaviour exists, especially in litter-dominated fuelbeds. To address this deficiency, we burned constructed fuelbeds from masticated sites in pine flatwoods forests in northern Florida with palmetto-dominated understoreys and examined the effects of fuel load and fuel moisture content (FMC) on fire behaviour. Flame lengths (49–140 cm) and fireline intensity (183–773 kJ m–1 s–1) increased with loading (10–30 Mg ha–1) and were reduced by 40 and 47% with increasing FMC from 9 to 13%. Rate of spread was not influenced by fuel load, but doubled under drier FMC. Fuel consumption was >90% for all burns. Soil temperatures were influenced by both fuel load and FMC, but never reached lethal temperatures (60°C). However, temperatures of thermocouple probes placed at the fuelbed surface reached 274–503°C. Probe maximum temperature and duration at temperatures ≥60°C (9.5–20.0°C min) both increased with fuel load, but were unaffected by FMC. The fire behaviour observed in these unique litter-dominated fuelbeds provides additional insight into the burning characteristics of masticated fuels in general.

scholarly journals EFICIÊNCIA DO USO DA ÁGUA EM MÉTODOS DE COMBATE A INCÊNDIOS EM FLORESTAS PLANTADAS

Nativa ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 309
Author(s):  
Weslen Pintor Canzian ◽  
Nilton Cesar Fiedler ◽  
Edmilson Bitti Loureiro ◽  
Leandro Christo Berude
Keyword(s):  
Forest Fires ◽  
Fire Retardant ◽  
Water Volume ◽  
Fire Control ◽  
Planted Forests ◽  
Forest Protection ◽  
Tukey Test ◽  
Time Usage ◽  
In Fire ◽  
Total Usage

O incêndio florestal é um dos maiores danos que as florestas estão sujeitas, e em geral, a maior dificuldade no seu combate está relacionada com a disponibilidade de água nas proximidades da ocorrência. Neste contexto, o objetivo desta pesquisa foi analisar a eficiência do uso da água em três diferentes métodos de combate a incêndios florestais (Kit combate, CAF’S e caminhão pipa convencional) em áreas de eucalipto no norte do Espírito Santo e sul da Bahia. Em cada um dos métodos foram analisados os seguintes parâmetros: vazão, tempo de uso total, tempo de uso para cada 1.000 litros de água, rendimento e volume total disponível. Todos os parâmetros avaliados apresentaram diferença estatística pelo teste de Tukey a 5% de probabilidade. O sistema CAF’S com a tecnologia de espuma pressurizada obteve os melhores índices, uma vez que, apresentou bons resultados em todos os aspectos avaliados, sendo o principal deles a elevada capacidade de transformação do volume de água em espuma, proporcionando um grande volume total disponível.Palavras-chave: proteção florestal, retardante de fogo, controle de incêndios. EFFICIENCY OF USE OF WATER IN FIRE FIGHTING IN PLANTED FORESTS ABSTRACT:The forest fire is one of the biggest damage that the forests are subject and the biggest difficulty in their fight is related to water availability near the occurrence. In this context, the objective of this research was to analyze the efficiency of water use when using combat kit, CAF’S and water truck in fighting forest fires. The study consisted of the analysis of three distinct fighting Forest fires systems (Kit combat, CAF’S and water truck), which were analyzed using the following parameters: flow, total usage time, usage time per 1,000 liters of water, incomeand total volume available. All parameters showed statistical differences by the Tukey test at 5% probability between combat systems and Technologies used. The CAF’S system with a pressurized foam technology achieved the best rates, since, showed good results in all aspects evaluated, the main one being the ability to transform the foam in water volume, providing a large total volume available.Keywords: forest protection, fire retardant, fire control. DOI:

scholarly journals Resolving vorticity-driven lateral fire spread using the WRF-Fire coupled atmosphere–fire numerical model

2014 ◽  
Vol 14 (9) ◽  
pp. 2359-2371 ◽  
Author(s):  
C. C. Simpson ◽  
J. J. Sharples ◽  
J. P. Evans
Keyword(s):  
High Spatial Resolution ◽  
Wildland Fire ◽  
Fire Spread ◽  
Weather Research And Forecasting ◽  
Grid Spacing ◽  
Fire Behaviour ◽  
Model Framework ◽  
Rate Of Spread ◽  
Fire Front ◽  
Vertical Grid

Abstract. Vorticity-driven lateral fire spread (VLS) is a form of dynamic fire behaviour, during which a wildland fire spreads rapidly across a steep leeward slope in a direction approximately transverse to the background winds. VLS is often accompanied by a downwind extension of the active flaming region and intense pyro-convection. In this study, the WRF-Fire (WRF stands for Weather Research and Forecasting) coupled atmosphere–fire model is used to examine the sensitivity of resolving VLS to both the horizontal and vertical grid spacing, and the fire-to-atmosphere coupling from within the model framework. The atmospheric horizontal and vertical grid spacing are varied between 25 and 90 m, and the fire-to-atmosphere coupling is either enabled or disabled. At high spatial resolutions, the inclusion of fire-to-atmosphere coupling increases the upslope and lateral rate of spread by factors of up to 2.7 and 9.5, respectively. This increase in the upslope and lateral rate of spread diminishes at coarser spatial resolutions, and VLS is not modelled for a horizontal and vertical grid spacing of 90 m. The lateral fire spread is driven by fire whirls formed due to an interaction between the background winds and the vertical circulation generated at the flank of the fire front as part of the pyro-convective updraft. The laterally advancing fire fronts become the dominant contributors to the extreme pyro-convection. The results presented in this study demonstrate that both high spatial resolution and two-way atmosphere–fire coupling are required to model VLS with WRF-Fire.

Fire spread in canyons

2004 ◽  
Vol 13 (3) ◽  
pp. 253 ◽  
Author(s):  
Domingos Xavier Viegas ◽  
Luis Paulo Pita
Keyword(s):  
Forest Fires ◽  
Numerical Study ◽  
Fire Spread ◽  
Laboratory Scale ◽  
Experimental Program ◽  
Small Scale ◽  
Geometrical Parameters ◽  
Fire Behaviour ◽  
Fatal Accidents ◽  
Rate Of Spread

Canyons or ridges are associated with a large number of fatal accidents produced during forest fires all over the world. A contribution to the understanding of fire behaviour in these terrain conditions is given in this paper. The basic geometrical parameters of the canyon configuration are described. An analytical model assuming elliptical growth of point ignition fires and constant values of rate of spread is proposed. A non-dimensional formulation to transfer results from analytical, numerical, laboratory or field simulations to other situations is proposed. An experimental study at laboratory scale on a special test rig is described. A wide set of canyon configurations were covered in the experimental program. In spite of the relatively small scale of the experiments they were able to put in evidence some of the main features found in fires spreading in this type of terrain. They show that in practically all cases the rate of spread of the fire front is non-constant. On the contrary, the fire has a dynamic behaviour and its properties depend not only on the canyon geometry but on the history of fire development as well. The convection induced by the fire is enhanced by terrain curvature and the fire accelerates causing the well-known blow-up that is associated with canyon fires. The rate of spread of the head fire increases continuously even in the absence of wind or any other special feature or change of boundary conditions that are sometimes invoked to justify such fire behaviour. The results of the present study confirm the predictions of a previous numerical study of the flow and fire spread in canyons that showed the important feedback effect of the fire on the atmospheric flow and how this affects fire behaviour in canyons. Results from a field experiment carried out in a canyon-shaped plot covered by tall shrubs were used to validate the laboratory scale experiments. Case studies related to fatal accidents that occurred in canyon-shaped configurations are analysed and recommendations to deal with this problem are made. It is shown that these accidents may occur even in the absence of special fuel or atmospheric conditions as they are intrinsically related to terrain configuration.

Study of the jump fire produced by the interaction of two oblique fire fronts. Part 1. Analytical model and validation with no-slope laboratory experiments

2012 ◽  
Vol 21 (7) ◽  
pp. 843 ◽  
Author(s):  
Domingos X. Viegas ◽  
Jorge R. Raposo ◽  
David A. Davim ◽  
Carlos G. Rossa
Keyword(s):  
Analytical Model ◽  
Large Scale ◽  
Experimental Tests ◽  
Intersection Point ◽  
High Rate ◽  
Energy Concentration ◽  
Fire Behaviour ◽  
Rate Of Spread ◽  
In Fire ◽  
Intense Radiation

When two fires approach each other, convective and radiative heat transfer processes are greatly enhanced. The interaction between two linear fire fronts making an angle θoi between them is of particular interest as it produces a very rapid advance of their intersection point with intense radiation and convection activity in the space between the fire lines. This fire is designated here as a ‘jump fire’ for when the value of θoi is small, the intersection point of the fire lines can reach unusually high rate of spread values that decrease afterwards in the course of time. A very simple analytical model based on the concept of energy concentration between the fire lines is proposed to explain this behaviour, which in large-scale fires can be of great concern to personnel and property safety. Experimental tests performed at laboratory scale on a horizontal fuel bed confirmed the basic assumptions of the model and provide a framework to extend the present analysis to more general conditions, namely to explain the behaviour of real fires. Given the rapid changes in fire behaviour, ‘jump fires’ can be considered as a form of extreme fire behaviour.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

Le feu : agent de contrôle des insectes

1994 ◽  
Vol 70 (4) ◽  
pp. 468-472
Author(s):  
M. Martin Dupuis
Keyword(s):  
Forest Fires ◽  
Insect Pests ◽  
Weather Conditions ◽  
Fire Intensity ◽  
Fire Control ◽  
Fire Use ◽  
Wild Fire ◽  
Controlled Burning ◽  
Long Run ◽  
Evolution Understanding

For millenia, fire and insects have played an important role in forested land evolution. Understanding the roles they play can be important in helping us not only to control them, but to use them as an ecological tool. Also, we notice some important interactions between these two agents. As insects affect fire, fire may control insect pests. Controlled burning may provide excellent results, but allows a very slight margin for possible errors. Fire use as an insect mangement tool, requires a very precise and wide knowledge of weather conditions, fire intensity, insect's life cycle, available fuels, and type of ecosystem involved.After a long run of experiences and research, we notice that fire has been and will always be an important factor in equilibrium of some ecosystems. Since wild fire prevention campaigns and the emergence of insecticides, some forests have become excessively vulnerable to insect pests. Proper knowledge, and use of fire control, rather than immediate suppression of forest fires, would allow us to conserve various ecosystems in a healthy balance.

Sign in / Sign up

Export Citation Format

Share Document