Fire Behavior Fuel Models: Making the right choice

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Fire Behavior Fuel ModelsMaking the right
choice

• Robert Ziel
• Michigan DNR

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My Points

• Emphasize the importance of projecting fire
  behavior for any situation or before conducting a
  prescribed burn.
• Examine the two primary fire behavior prediction
  systems (NFBPS and CFFBPS) used in MI and
  identify the significant differences between
  them.
• Compare the Fuel Model sets incorporated into
  each fire behavior prediction system, the way
  they are categorized, and the basis for each.
• Examine some of the interactions described in the
  Rothermel Surface Fire Spread Model and identify
  the ways in which the new fuel models can produce
  unexpected results.
• Outline a process to help you select a fuel model
  for your situation

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Importance of Fire Behavior Prediction

• Planning for resources needed
• Go-No Go Decision
• Action planning
• Briefing Purposes
• Addressing liability
• What level of detail is necessary?

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Creeping/Spreading Surface Fire
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Running Surface Fire
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Spotting and Ignition
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Crown Fire
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Extreme Fire Behavior Mack Lake - May 5, 1980
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Wildland Fire Behavior Characteristics

• Which are important to your safety?
• Drought stricken fuels may produce incredible
  heat
• Spread Rate may affect your ability to react
• Flame Length may affect fireline working
  conditions
• Spotting Distance Ignition Probability are
  wildcards

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Fire Modeling Tools in Michigan

• US Fire Danger and Fire Behavior prediction
  tools are separate, fuel moisture estimates are
  common but fuel models and measures of ignition,
  spread and intensity are separate

• CFFDRS Fire Weather Index System (FWI) assumes a
  pine fuel type, outputs (ISI BUI) are inputs to
  the Fire Behavior Prediction System

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CFFDRSFWI Tables and FBP Red Book
Celsius Km/hr
meters/min Kw/m
Metric Units! English unit lookup tables
available, software too
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Modeling Fire Behavior

• Tools with new 40
• BehavePlus
• NEXUS
• FARSITE
• FLAMMAP
• RERAP
• FSPRO
• Nomographs

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Modeling on the Landscape

• FARSITE FLAMMAP allow for fire spread and
  intensity projections across the landscape
• Fuel classifications like LANDFIRE need to be
  based on remote sensing characteristics to
  facilitate updates

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Access to FWI Infohttp//www.dnr.state.mi.us/www/
fmd/weather
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• Two Grass fuel types
• Seven Conifer types
• One leafless Deciduous type

• Four Mixedwood types that allow user to enter
  conifer percent
• 3 Slash types

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Grass

• O1a Matted Grass
• O1b Standing Grass
• user enters fuel load and percent cured

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Conifer

• C-1 Spruce-Lichen Woodland
• C-2 Boreal Spruce
• C-3 Mature Jack or Lodgepole Pine
• C-4 Immature Jack or Lodgepole Pine
• C-5 Red White Pine
• C-6 Conifer Plantation
• C-7 Ponderosa Pine / Douglas Fir

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Mixedwood

• M-1 Boreal Mixedwood Leafless
• M-2 Boreal Mixedwood Green
• M-3 Dead Balsam Fir Mixedwood Leafless
• M-4 Dead Balsam Fir Mixedwood Green
• User enters conifer

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Deciduous

• D-1 Leafless Aspen
• D-2 Can be created by using M2 and setting the
  conifer percent to 0

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Slash

• S-1 Jack or Lodgepole Pine Slash
• S-2 White Spruce/Balsam Fir Slash
• S-3 Coastal Cedar/Hemlock/
• Douglas Fir Slash

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Standard Fuel Models for the Rothermel Fire
Spread Model
original FBFM13
new FBFM 40
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FBFM 13 vs. FBFM 40

• 4 categories of fuels
• 3 Grass Models
• 4 Shrub/Brush Models
• 3 Timber Litter Models
• 3 Slash Models

• 6 categories of fuels
• 9 Grass Models
• 4 Grass-Shrub Models
• 9 Shrub Models
• 5 Timber Understory Models
• 9 Timber Litter Models
• 4 Slash/Blowdown Models

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GRASS FUELS

• FB1 Short Grass, dry
• FB2 Timber (grass understory)
• FB3 Tall Grass, humid
• ----------------------------------------------
• GR1 Short, Sparse, dry
• GR2 Low load, dry
• GR4 Moderate load, dry
• GR7 High load, dry
• ------------------------------------------------
• GR3 Low Load, coarse, humid
• GR5 Low Load, humid
• GR6 Moderate load, humid
• GR8 High load, very coarse, humid
• GR9 Very high load, humid

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GRASS SHRUB

• GS1 low load, dry climate
• GS2 moderate load, dry climate
• ----------------------------
• GS3 Moderate load, humid climate
• GS4 High load, humid climate

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SHRUBFUELS

• FB4 Chaparral (6 ft)
• FB5 Brush (2 ft)
• FB6 Dormant brush
• FB7 Southern rough
• -------------------------------------------------
  ------------------------------
• SH1 Low load, dry (D)
• SH2 Moderate load, dry
• SH5 High load, dry
• SH7 Very high load, dry
• -------------------------------------------------
  ----------------------------
• SH3 Moderate load, humid
• SH4 Low load, humid
• SH6 low load, humid
• SH8 high load, humid
• SH9 VH load, humid (D)

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TIMBERUNDERSTORY

• FB10 Timber (litter and understory)
• --------------------------------
• TU1 Low load, dry (D)
• TU4 Dwarf conifer with understory
• TU5 Very High load, dry
• --------------------------------
• TU2 Moderate load, humid
• TU3 Moderate load, humid (D)

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TIMBERLITTER

• FB8 Closed timber litter
• FB9 Hardwood litter
• ------------------------------------------------
  -------------------------------------------
• TL1 low load compact conifer litter
• TL3 moderate load conifer litter
• TL5 High load conifer litter
• TL8 long needle litter
• -------------------------------------------------
  ------------------------------------------
• TL4 Small downed logs
• TL7 Large downed logs
• -------------------------------------------------
  ------------------------------------------
• TL2 low load broadleaf litter
• TL6 Moderate load broadleaf litter
• TL9 Very high load broadleaf litter

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SLASHBLOWDOWN

• FB11 light logging slash
• FB12 Medium logging slash
• FB13 Heavy logging slash
• ---------------------------------------
• SB1 low load slash
• SB2 Moderate load slash, low load blowdown
• SB3 High load slash, moderate load blowdown
• SB4 High load blowdown

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Comparing the two Systems

• 40 New models suggest wider range of fire
  behavior due to seasonality than original 13
• More choices allow better correlation between
  fuels vegetation for mapping
• 14 of 40 new model fuels that burn under high
  dead fuel moisture conditions. Only 1 of 13 did.
• Better simulates changes in fire behavior related
  to fuel treatments in forest fuels
• Other info needed for crown fire prediction

• Still a relatively small set of fuel types (16).
• Fuel types are characterized by forest cover
  rather than surface fuels
• Fuel Types are specific to Northern fuels
• No Shrub fuel types modeled
• Easy to apply with given FFMC, BUI and onsite
  windspeed
• Automatically accounts for transition to crown
  fire

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Rothermel Spread Model
Reaction Propagation Wind
Slope Intensity Flux Ratio
Coeff Coeff
Ir x ( 1 fw fs ) R
-------------------------------- rb e
Qig
HEAT SOURCE
HEAT SINK
Bulk Effective Heat
of Density Heating Number Preignition
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US Fire Behavior Fuel Models

• Intrinsic Fuel Properties
• Dead Fuel Moisture of extinction ()
• Live fuel moisture of extinction is calculated
• Dead and Live Heat Content (btu/lb)
• Mineral/ash content ()
• Fixed in the current version of BehavePlus

• Extrinsic Fuel Properties
• Surface Area to Volume (sq ft/cu ft)
• Fine Dead Fuel SVOL
• Live Woody SVOL
• Live Herbaceous SVOL
• Quantity or Loading by size class (tons/acre)
• Fuel bed depth (ft)
• New in the 40 Dynamic Herbaceous Fuel Load
  Transfer

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Dry vs. Humid Climate
GR4
GR5
GR5
GR4

• Dead Moisture
• of Extinction
• GR4 15
• GR5 40

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US Fire Behavior Fuel Models

• Intrinsic Fuel Properties
• Dead Fuel Moisture of extinction ()
• Live fuel moisture of extinction is calculated
• Dead and Live Heat Content (btu/lb)
• Mineral/ash content ()
• Fixed in the current version of BehavePlus

• Extrinsic Fuel Properties
• Surface Area to Volume (sq ft/cu ft)
• Fine Dead Fuel SVOL
• Live Woody SVOL
• Live Herbaceous SVOL
• Quantity or Loading by size class (tons/acre)
• Fuel bed depth (ft)
• New in the 40 Dynamic Herbaceous Fuel Load
  Transfer

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Dynamic Fuel Load Transfer
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Dynamic Fuel Load Transfer
All new Grass, Grass-Shrub, Shrub19, Timber
Understory 1 3 are dynamic fuels

• Herbaceous load is converted to dead load, either
  manually or based on HFM

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Fire Behavior Predictions
Fire Environment Triangle
Fuel Models
Load Transfer
Fuel Moistures
Live Herbaceous FM
Fuel
Fuel
Slope
Wind
Environmental
Topography
Weather
Only applies to dynamic fuel models
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Differences between static and dynamic models
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Fosberg and Schroeder, 1971

• We have made several other assumptions (lacking
  better information) and developed a linear
  equation for the extinction moisture content for
  live fuels.

• Live Fuel Moisture of Extinction is a function
  of
• Dead fuel moisture
• Dead fuel moisture of extinction
• Ratio of live fuels to total fuel
• Beware dynamic models

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Moisture Damping Coefficient (?M)
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Rapid Increase in Live Fuel Intensity
FB2
GR3
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Why is this important

• Live fuels determine potential fire behavior over
  much of the growing season here.
• The Rothermel surface fire spread model can be
  very sensitive to changes in the ratio of live to
  dead fuel loads, which the new dynamic models can
  cause.
• Small errors in your input parameter choice could
  lead to large errors in fire behavior predictions
  with some fuel models

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Effective Windspeed Limit
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Dynamic fuel models and wind limits

• Some of the new dynamic models start with very
  little dead fuel loading resulting in low
  reaction intensities
• With dynamic load transfer, the reaction
  intensity changes as some of the herbaceous fuels
  are shifted into dead fuel categories
• With this shift, lots of changes occur which can
  result in rapid increase in Reaction intensity.
  Watch the result

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Effective Windspeed Limit
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It is possible to select from 53 models

• Determine the Carrier (GR, GS, SH, TU, TL, SB)
• Evaluate the need to model herbaceous fuel curing
• Consider the Moisture of Extinction (Humid or Dry
  Climate)
• Match the fuel load distribution and loading
• Evaluate the fire behavior produced by expected
  weather Live Fuel Moisture/Condition

ftp//ftp.dnr.state.mi.us/pub/forestry/FBFuelModel
Parameters.xls
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Conclusions

• Simpler tools (FWI, FLAME, CFFBP) may be
  sufficient for many of our small burns with
  mitigated hazards
• When making projections, always make predictions
  over ranges of conditions rather than a single
  forecast scenario.
• Know where the effect of live fuel moisture is
  greatest. It may dictate the fire model as well
  as the fuel model you use.
• Your depiction of live fuels in modeling will
  take skill, judgement, and practice

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Tools for More Background on New US Fire Behavior
Fuel Models

• NIFTT training course
• Help File, spreadsheet, and reference publication
  at FRAMES (Subject Area Fuels)
• BehavePlus
• Reference table

www.niftt.gov
www.frames.nbii.gov
www.firemodels.org
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Questions