Forest Fire Meteorology Research and Application

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Forest Fire Meteorology Research and Application
WWRP Wildfire Workshop Melbourne, 6 and 10 June

• by
• Domingos Xavier Viegas
• Dep. Mech. Engineering, Fac. Science and
  Technology
• University of Coimbra, Portugal

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Presentation

• Introduction
• Meteorological fire danger index
• Fuel characterization
• Wind and slope effects on fire behaviour
• Case studies

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Introduction

• Forest fires are a very complex phenomena that
  depend on many factors, some of them of
  socio-economic nature, but also and mainly on
  physical factors.
• Climatical and meteorological factors are by far
  those that have an overwhelming importance on
  fire occurrence.

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• The author has investigated several aspects
  related with forest fire meteorology and fire
  behaviour.
• This work was carried out in the scope of various
  projects supported by the European Union.
• A brief account of the methodology and some
  results on topics that may be of interest to this
  Workshop are presented.

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Meteorological Fire Danger Index

• This is one very fundamental component of every
  forest fire management system.
• It is basically a method to assess the
  probability of having fires or large fires in a
  given day in a given region.
• There are many methods to estimate fire danger
  related to meteorological factors.

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• Some methods to estimate fire danger index
•            Fire Weather Index (Canada) V. Wagner
  et al.
•            Orieux Index (France)
•            Carrega Index (France)
•            Numerical Index (France) B. Sol
•            IREPI Index (Italy) G. Bovio
•            Portuguese Index Nesterov
•            Icona Index (Spain)
•            National Fire Danger Rating System
  (USA)
•            Keetch-Byram Index (USA)
•            Mac-Arthur Index (Australia)
•           
•            Angstrom Index (Sweden)
• Lourenço Index (Portugal)
•            Montalegre Index (Brasil) R. Soares
•           

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Comparative study of various methods
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Best performing methods in each region
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Calibration of FWI for Portugal
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Data from IM and DGF 1987-97
Number of fires (INC)
Inc Escala da esquerda
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Portugal
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Drought Code for Coimbra (June to September)
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Fuel characterization

• In fire behaviour modeling it is very important
  to have a correct assessment of the fine fuels
  moisture content.
• It is a parameter of great relevance for many
  aspects related to fire occurrence and behaviour.

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Daily measurement of moisture content and
flammability
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Teor de humidade de folhas de arbustos em função
do DC
Significado do DC
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Fire behaviour modelling

• Fire spread regimes
• Ground fire
• Surface fire
• Crown fire
• Spot fire
• Wind and slope effects.
• Eruptive fire behaviour.

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Wind and slope effects on fire behaviour

• Wind and slope are some of the major factors
  affecting fire behaviour, due to their effect on
  the convection that is induced by the fire.
• Quite often the role of natural convection
  induced by the fire is overlooked.
• Wind is very difficult to predict.

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Slope effect
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Rate of spread variation of a point fire in a
slope
End of test
Start of test
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Fire spread with wind R1
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DE 3
Oct.2002
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Point ignition in a canyon
Leito de pinus pinaster
d40º
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• The rate of spread is not sufficient to describe
  the evolution of a fire front.
• In the general case the fire line movement is
  composed by
• A translation
• A rotation
• An extension.

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Joint effect of slope and wind
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• There is not an assimptotic form of the fire
  front in the case of wind or slope driven fires.

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Eruptive Fire behaviour

• Fire in steep slopes and in canyons has a
  peculiar behaviour.
• Its rate of spread increases continuously and
  produce a fire eruption

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Viatura de Vigilância e Monitorização
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Sistema Firestation
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2123 h
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Application of the Photochemical System to the
Identified Urban/Wildland Fires
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Case studies
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Wind field prediction at 0 h of 10 July 99
13.00 h
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19.00 h
16.00 h
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Freixo de Espada-a-Cinta

• The year 2003 was particularly bad in terms of
  forest fires in Portugal. There were 21 persons
  killed in 18 fire related accidents.
• This case occurred in the North of Portugal on
  the 5th of August of 2003.
• Two persons (a couple 50 and 40 years old) were
  killed in this accident.

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Air temperature
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Wind direction
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Average and maximum Wind velocity
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Model prediction
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Conclusion

• Some problems related to forest fire meteorology
  were discussed.
• Fire danger is well described by the Canadian
  FWI.
• Fine fuel moisture content cam be estimated with
  reasonable accuracy using meteorological data.

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• It was shown that the general problem of wind or
  slope induced fires can not be solved assuming
  simple steady state conditions.
• It was shown that in some conditions the
  convective flow induced by the fire can
  accelerate can modify the local meteorological
  conditions and have a dominant role.

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