Using catastrophe theory to model wildfire behavior and control

1998 ◽  
Vol 28 (6) ◽  
pp. 852-862 ◽  
Author(s):  
Hayley Hesseln ◽  
Douglas B Rideout ◽  
Philip N Omi
Keyword(s):  
Cost Minimization ◽  
Fire Behavior ◽  
Fuel Moisture ◽  
Costs And Benefits ◽  
Fuel Loading ◽  
Marginal Costs ◽  
Management Objectives ◽  
Initial Fuel ◽  
In Fire ◽  
And Control

Forest wildfire managers are obligated to meetecosystem management objectives, such as cost minimization andresource allocation efficiency (J.T. Williams, R.G. Schmidt,R.A., Norum, P.N. Omi, and R.G. Lee. 1993. USDA For. Serv.Staffing Pap. Washington, D.C.), which is difficult because eachobjective is dependent upon wildfire controllability andbehavior. Currently, there is no functional formula that definesthe relationship between wildfire behavior and controllabilityand therefore, no physical basis for efficient economic analysis.This paper seeks to (1) identify environmental factors thatsystematically predict wildfire controllability and the rangeover which sudden changes in fire behavior occur, (2) quantifythe uncertainty of fire behavior in terms of the environmentalfactors, and (3) define a manageable environmental variablethat can be used to determine marginal costs and benefits ofwildfire management activities. We develop the theory and providean illustrative example of a cusp catastrophe using simulatedfire data. Preliminary results suggest that catastrophe theorymay be an effective tool to model wildfire controllability asmeasured by the modeled change in fireline intensity, windspeed,initial fuel moisture and fuel loading. Because the use of fuelloading as a control parameter describes the marginal physicaleffects on wildfire behavior, this framework may prove suitableas the production relationship for future economic analysis. Notethat the model specified in this paper is theoretical and shouldnot be applied until validated.

Fire Behavior and Fire Effects on Eastern Redcedar in Hardwood Leaf-Litter Fires

1995 ◽  
Vol 5 (3) ◽  
pp. 135 ◽  
Author(s):  
DM Engle ◽  
JF Stritzke
Keyword(s):  
Leaf Litter ◽  
Fire Behavior ◽  
Late Summer ◽  
Ambient Air ◽  
Fire Effects ◽  
Cross Timbers ◽  
Fuel Loading ◽  
Eastern Redcedar ◽  
Crown Scorch ◽  
In Fire

Treatment of stands of hardwoods in the cross timbers of the central United States with tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-dimethylurea) can significantly decrease canopy cover of hardwoods. However, at the rate used for hardwood control, tebuthiuron does not control eastern redcedar (Juniperus virginiana L.). Our objective was to determine the potential of using fires in the hardwood leaf litter, either before or after tebuthiuron, for controlling eastern redcedar. To do this, we compared fuelbed characteristics, fire behavior, and fire effects on eastern redcedar in naturally occurring hardwood leaf litter with those augmented by leaves dropped following a single application of tebuthiuron. Studies were conducted in 1988, 1989, and 1991 on a cross timbers site dominated by an overstory of post oak (Quercus stellata Wangenh.) and blackjack oak (Q. marilandica Muenchh.) and with eastern redcedar in the understory. Factors evaluated included herbicide treatment (tebuthiuron or no herbicide) and burning season (late summer or winter). Tebuthiuron at 2.2 kg a.i. Ha-1 was applied to plots (25 X 25 m) in March of the study years. In late summer, tebuthiuron-treated plots contained almost twice the 1-hr fuel loading as untreated plots. Fuel depth on untreated plots in late summer was about half that of other herbicide treatments and burning date combinations. Fuel loading on plots burned in winter was not affected by tebuthiuron treatment, and no differences in fuel consumption were detected among any treatments. Moisture content of 1-hr fuels on plots burned in winter was more than twice that of 1-hr fuels on plots burned in late summer. Fire intensity was low with all bums, and no differences in fire behavior were detected among any treatments. Crown scorch of 75% or greater on small eastern redcedar trees was considered a successful burn, and this resulted on all but the late summer-no tebuthiuron treatment. The natural log of fireline intensity explained about 47% (P<0.0006)) of the variation in fire success, and ambient air temperature explained an additional 19% (P<0.0468). Although tebuthiuron treatments effectively augmented leaf-litter fuel load by late-summer and provided a suitable fuelbed for burning, crown scorch and tree kill were not greatly improved by burning in late summer as compared to winter. We conclude that understory eastern redcedar can be controlled successfully by burning leaf-litter fuelbeds in either late fall or winter after natural leaf-fall from hardwood trees or in late summer, fall, or winter following a spring application of tebuthiuron for control of overstory hardwoods.

Flashover and instabilities in fire behavior

1980 ◽  
Vol 38 ◽  
pp. 159-171 ◽  
Author(s):  
P.H. Thomas ◽  
M.L. Bullen ◽  
J.G. Quintiere ◽  
B.J. McCaffrey
Keyword(s):  
Fire Behavior ◽  
In Fire

Changes in fire behavior caused by fire exclusion and fuel build-up vary with topography in California montane forests, USA

2022 ◽  
Vol 304 ◽  
pp. 114255
Author(s):  
Catherine Airey-Lauvaux ◽  
Andrew D. Pierce ◽  
Carl N. Skinner ◽  
Alan H. Taylor
Keyword(s):  
Fire Behavior ◽  
Montane Forests ◽  
Fire Exclusion ◽  
In Fire

Numerical Analysis of Fire Behavior of a Large Space Pre-Stressed Steel Structure under Fire

2011 ◽  
Vol 71-78 ◽  
pp. 3729-3732
Author(s):  
Ming Zhou ◽  
Zhi Guo Xie ◽  
Xin Tang Wang
Keyword(s):  
Numerical Analysis ◽  
Fire Behavior ◽  
Thermal Response ◽  
Structural Response ◽  
Steel Structure ◽  
Large Space ◽  
Fire Source ◽  
Lattice Shell ◽  
In Fire ◽  
Influence Degree

The computational model of numerical analysis of a suspended pre-stressed steel reticulated shell subjected to fire load is established with using the software Marc. Based on the model presented here, numerical analysis of thermal response and structural response of the pre-stressed steel structure are computed. The different space height and different rise-span ratio are considered for analysis of response temperature, displacements and stresses of the pre-stressed lattice shell under fire for one fire source. It is also shown that displacement of the node right above the inner cable is the maximum among the four nodes presented here as the fire source is located at the position right below the second-ring cable of the structure. It is concluded that the influence degree of space height of the structure on the fire response of the structure is not great, but rise-span ratio has obvious and great effect on displacements and stresses of the pre-stressed steel structure with large span in fire.

scholarly journals COMPORTAMENTO DO FOGO EM QUEIMAS CONTROLADAS DE VEGETAÇÃO DE ESTEPE NO MUNICÍPIO DE PALMEIRA, PARANÁ, BRASIL

FLORESTA ◽  
2013 ◽  
Vol 43 (4) ◽  
pp. 557
Author(s):  
Celso Darci Seger ◽  
Antonio Carlos Batista ◽  
Alexandre França Tetto ◽  
Ronaldo Viana Soares
Keyword(s):  
Fire Behavior ◽  
Fire Risk ◽  
Fire Spread ◽  
Flame Height ◽  
Fire Intensity ◽  
Average Moisture Content ◽  
Fuel Loading ◽  
Prescribed Burns ◽  
Controlled Burning ◽  
Heat Released

As queimas controladas constituem práticas de manejo utilizadas em diferentes tipos de vegetação e difundidas em vários países. No entanto, para a realização de tais práticas com segurança e eficiência é fundamental o conhecimento do comportamento do fogo. O objetivo desse trabalho foi caracterizar o comportamento do fogo em queimas controladas de vegetação Estepe Gramíneo-Lenhosa no estado do Paraná. Para isso, foi instalado um experimento no município de Palmeira, onde 20 parcelas foram queimadas, sendo metade a favor e metade contra o vento. A carga de material combustível fino estimada foi de 2,26 kg.m-2, com teor médio de umidade de 50,45%. A quantidade de material consumido pela queima foi de 1,76 kg.m-2, com uma eficiência média de queima de 76,86%. As médias obtidas, a favor e contra o vento, foram respectivamente: velocidade de propagação do fogo de 0,049 e 0,012 m.s-1, altura das chamas de 1,34 e 0,843 m, intensidade do fogo de 210,53 e 50,68 kcal.m-1.s-1 e calor liberado de 4.067,19 e 4.508,92 kcal.m-2. Os resultados permitiram concluir que as queimas controladas em vegetação de campos naturais, realizadas dentro dos critérios estabelecidos de planos de queima, são viáveis e seguras sob o ponto de vista de perigo de incêndios.Palavras chave: Queima prescrita; material combustível; intensidade do fogo; perigo de incêndios. AbstractFire behavior of prescribed burns in grassland on Palmeira county, Paraná, Brazil. The prescribed burns are practices of management used in different types of vegetation and widespread in several countries. However, to carry out such practices safely and effectively is fundamental knowledge of fire behavior. The aim of this study was to characterize the fire behavior in controlled burning of grassland vegetation in Paraná state. For this, an experiment was conducted in Palmeira County, where 20 plots were burned, half in favor and half against the wind. The estimated fine fuel loading was 2.26 kg.m-2, with average moisture content of 50.45%. The fuel consumption by burning was 1.76 kg.m-2 with an average efficiency of burning of 76.86%. The averages, for and against the wind, were: speed of fire spread of 0.049 and 0.012 m.s-1, the flame height of 1.34 m and 0.843, fire intensity of 210.53 and 50.68 kcal.m-1.s-1 and heat released from 4,067.19 and 4,508.92 kcal.m-2. The results show that the controlled burnings of grasslands vegetation, carried out within the established criteria burning plans are feasible and safe from the aspect of fire danger.Keywords: Prescribed burns; fuel loading; fire intensity; fire risk.

scholarly journals When marginal costs and benefits should be used in screening

BMJ ◽  
1996 ◽  
Vol 312 (7037) ◽  
pp. 1041-1042 ◽  
Author(s):  
N. Wald ◽  
H. Watt
Keyword(s):  
Costs And Benefits ◽  
Marginal Costs

Economic appraisal in public healthcare: assessing efficiency and equity

2021 ◽  
pp. 365-380
Author(s):  
David Parkin ◽  
Stephen Morris ◽  
Nancy Devlin
Keyword(s):  
Public Health ◽  
Good Practice ◽  
Public Health Intervention ◽  
Population Group ◽  
Sensitivity Analyses ◽  
Public Healthcare ◽  
Costs And Benefits ◽  
Economic Appraisal ◽  
Marginal Costs ◽  
Cost Measurement

This chapter is an introduction to economic appraisal. It explains underlying concepts, describes methods used, and discusses the application to public health. Economic appraisal comprises techniques that weigh up the costs of an action, such as providing a public health intervention to an at-risk population group, against the benefits that it provides. Important underlying principles are opportunity cost, social versus private costs and benefits, marginal costs and benefits, efficiency, and equity. There are different types of economic appraisal, each of which measures the costs and benefits of options being compared. Measuring costs involves identifying and describing resource use changes, quantifying them in physical units and valuing them. Issues in cost measurement include use of macro or micro-costing and dealing with inflation and time preference. There are several approaches that can be used to measure benefits depending on the type of economic appraisal being used; a measure of special interest is quality-adjusted life years (QALYs). Modelling is often used in economic appraisal to combine data on the costs and benefits of an intervention. Given the inherent uncertainties involved in economic appraisal it is good practice to undertake sensitivity analyses that investigate the impact of uncertainty. Methodological challenges in undertaking economic appraisals of public health interventions include the importance of equity and inequality considerations, establishing robust evidence of the effect of public health programmes, the relevance of QALYs, and accounting for multisectoral costs and benefits.

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