Wildland Fire Behaviour: Dynamics, Principles and Processes

by Jason M. Forthofer, Mark A. Finney, Sara S. McAllister, Torben P. Grumstrup

Length: 376 pages
Edition: 1
Language: English
Publisher: CSIRO Publishing
Publication Date: 2021-11-04
ISBN-10: 1486309089
ISBN-13: 9781486309085
Sales Rank: #1122715 (See Top 100 Books)

Wildland fires have an irreplaceable role in sustaining many of our forests, shrublands and grasslands. They can be used as controlled burns or occur as free-burning wildfires, but can also be dangerous and destructive to fauna, human communities and natural resources. Through scientific understanding of their behavior, we can develop the tools to reliably use and manage fires across landscapes in ways that are compatible with the constraints of modern society while benefiting the ecosystems.

The science of wildland fire is incomplete, however. Even the simplest fire behaviors – how fast they spread, how long they burn and how large they get – arise from a dynamical system of physical processes interacting in unexplored ways with heterogeneous biological, ecological and meteorological factors across many scales of time and space. The physics of heat transfer, combustion and ignition, for example, operate in all fires at millimeter and millisecond scales but wildfires can become conflagrations that burn for months and exceed millions of hectares.

Wildland Fire Behaviour: Dynamics, Principles and Processes examines what is known and unknown about wildfire behaviors. The authors introduce fire as a dynamical system along with traditional steady-state concepts. They then break down the system into its primary physical components, describe how they depend upon environmental factors, and explore system dynamics by constructing and exercising a nonlinear model. The limits of modelling and knowledge are discussed throughout but emphasized by review of large fire behaviors. Advancing knowledge of fire behaviors will require a multidisciplinary approach and rely on quality measurements from experimental research, as covered in the final chapters.

Features:

Approaches wildland fire behavior as the product of a dynamical system rather than as a steady-state property of fuels, topography and weather
Introduces and applies the physical principles of heat transfer, combustion and ignition to the wildland fire context
Explores dynamical fire behaviors using a simplified model of wildfire spread
Surveys the state of knowledge of large wildfire behavior
Summarizes methods for studying fire behaviors at laboratory and field-scales

Cover
Title Page
Copyright
Foreword
Contents
Preface and acknowledgements
About the authors
Nomenclature
1 - Introduction to wildfire science
    Fire science and the need for experiments
    Wildland fire science since 1900
    Modelling and field-scale research
    The challenge of validation
    Outline of the book
    References
2 - Fire and wildland fire behaviour
    The burning candle as a fire process
        Igniting and burning a candle
        Flame shape
        Flame size
        Candles and wildfires as coupled systems
    Wildfire behaviour triangle: fuels, weather, topography
        Wildfire classification
    Initial fire growth
    Line fire concept
    Wildfire behaviour
        Fire spread rate
        Fire shapes
        Fire area and perimeter
        Heat release and fireline intensity
        Flame length
        Fire characteristics chart
        Fire acceleration
    Summary
    Supplementary calculations
    Endnote
    References
3 - Thermodynamics, fluid mechanics and heat transfer
    Basic concepts, material properties and terminology
    Thermodynamics
    Fluid mechanics
        Boundary layers
        Vortex flows
        Ember lofting
    Heat transfer
        Conduction heat transfer
        Radiation heat transfer
        Convection heat transfer
        Combined heat transfer
    Summary
    Endnote
    References
4 - Combustion
    Fuels
    Thermodynamics of combustion
        Combustion reactions
        Heat of combustion
        Flame temperatures
    Brief discussion of chemical kinetics
    Types of flames
        Premixed flames
        Non-premixed or diffusion flames
    Smouldering and glowing
    Summary
    Endnotes
    References
5 - Ignition
    The ignition process
    Flaming ignition criteria
    Types of ignition
    Critical heat flux for ignition
    Predicting ignition times
    Factors that affect ignition time
    Live fuels
    Summary
    Endnotes
    References
6 - The environment in wildfire dynamics
    Wildland fuel
        Fuel particles and fuel beds
        Fuel moisture
        Live fuels
        Implications for fuel characterisation and classification
    Weather
        Winds
        Solar radiation
    Topography
    Fire configurations
        Flame front width and shape
        Backing fires and flanking
        Multiple flame zones and air-flow interactions
    Summary
    References
7 - Wildfire spread
    System behaviour
    Model framework
        Fuel particles
        Burning rate
        Flame radiation heat transfer
        Solid glowing radiation
        Ambient environment radiation heat transfer
        Convection heat transfer
    Model function
    Modelled fire spread and behaviour
        Simple fire spread dynamics
        Fuel particle heating and ignition
        Fuel loading
        Flame front width
        Effects of wind
        Non-steady wind
        Effects of slope
        Effects of dead fuel moisture
        Effects of fuel continuity
    Positive and negative feedbacks
    Model improvements
        Combustion
        Ignition
        Wind
        Flame zone orientation
        Heat transfer
        Crown fire
    Summary
    References
8 - Behaviours of large fires
    Crown fire
    Spotting and spot fires
    Fire shapes and growth patterns
    Burn streets
    Plumes and pyroconvective atmospheric storms
    Vorticity
        Pulsating or puffing
        Fire whirls
        Counter-rotating vortex pairs and wake vortices
        Vorticity-driven lateral spread
    Mass fires
    Summary
    References
9 - Measurements in fire behaviour
    Sampling and experimental design
    Fire measurements
        Combustion and heat release
        Fuel consumption
        Heat release
        Flame zone properties
    Heat transfer
        Radiation
        Convection
    Ignition
    Rate of spread
        One-dimensional spread rate
        Two-dimensional spread rate and fire growth
    Environmental measurements
        Fuel moisture
        Weather and wind
        Temperature
        Relative humidity
    Summary
    References
10 - Ignition techniques for experimental burning
    Point ignition
    Single line ignition
        Heading fires
        Backing fires
        Flanking fires
        Other line ignitions
    Multiple line fires
        Strip head fire
        Flank fire
    Multiple spot ignitions
    Ring fire, centre fire, mass ignition
    Summary
    References
11 - Conclusions
    Key principles and insights
    Principal value to researchers
    Principal value to managers
Appendix A: Physical quantities and units
Appendix B: Thermal and physical properties of air
Index