Introduction to Wildland Fire Behavior Calculations390RM

INSTRUCTOR’S NOTE:

• View Graphs 00-02-S390-VG thru

00-50-S390-VG are not in this Power Point

Presentation (tables, maps, nomograms, etc..).

• The instructor will have to have these transparencies and an overhead projector readily available.

• Instructor’s notes for these VG’s will appear in Power Point Presentation.

S-390 Introduction to Wildland Fire

Behavior Calculations

COURSE OBJECTIVES

Determine what input is needed for the surface fire behavior nomogram.

Perform fire behavior calculations of rate of spread, fireline intensity, flame length, and area/perimeter growth using a fire behavior processor (surface fire behavior nomograms).

Prepare a fire perimeter map showing head, flanks, and rear of the fire in hourly increments.

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COURSE OBJECTIVES

Based on predicted fire behavior, identify areas where fire suppression limitations exist, and make recommendations for fireline location and safe control tactics including the use of backfiring and burning out.

Discuss applications of fire behavior predictions and recognize when predictions may be different from the observed.

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UNIT 1- FIRE BEHAVIOR INPUTS OBJECTIVES

Select “best fit” fire behavior fuel models using a key and fuel model descriptions.

Determine dead and live fuel moisture contents and the probability of ignition.

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UNIT 1- FIRE BEHAVIOR INPUTS OBJECTIVES (cont.)

Determine midflame windspeeds when given the 20-foot winds, fuel type or model, and terrain features.

Calculate slope to the nearest 5% using topographic maps and the slope formula.

Convert fire spread distance to map distance.

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FUEL MODEL

A Set of parameters that define fuel input to the fire spread model.

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FUEL GROUPS

GRASS (3 MODELS)

SHRUB (4 MODELS)

TIMBER LITTER (3 MODELS)

LOGGING SLASH (3 MODELS)

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Fire Behavior Fuel Model Description GRASS GROUP

Fuel Model 1 (1 foot deep) Fire spread is governed by the fine herbaceous fuels that have cured or are nearly cured. Fires are surface fires that move rapidly through cured grass and associated material. Very little shrub or timber is present, generally less than one-third of the area.

Grasslands and savanna are represented along with stubble, grass-tundra, and grass-shrub combinations that meet the above area constraint. Annual and perennial grasses are included in this fuel model.

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Fuel Model 2 (1 foot deep) Fire spread is primarily through the fine herbaceous fuels, either curing or dead. These are surface fires where the herbaceous material, besides litter and dead-down stemwood from the open shrub or timber overstory, contribute to the fire intensity. Open shrub lands and pie stands or scrub oak stands that cover 1/3 to 2/3 of the area may generally fit this model but may include clumps of fuels that generate higher intensities and may produce firebrands. Some pinyon-juniper may be in this model.

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Fuel Model 3 (2.5 feet deep) Fires in this fuel are the most intense of the grass group and display high rates of spread under the influence of wind. The fire may be driven into the upper heights of the grass stand by the wind and cross over standing water. Stands are tall, averaging about 3 feet, but considerable variation may occur. Approximately one-third or more of the stand is considered dead or cured and maintains the fire.

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Fire Behavior Fuel Model Description SHRUB GROUPFuel Model 4 (6 feet deep) Fire intensity and fast spreading fires

involve the foliage and live and dead fine woody materials in the crowns of a nearly continuous secondary overstory. Examples are stands of mature shrub, 6 or more feet tall, such as California mixed chaparral, the high pocosins along the east coast, the pine barrens of New Jersey or the closed jack pine stands of the north-central states. Besides flammable foliage, there is dead woody material in the stand that significantly contributes to the fire intensity. Height of stands qualifying for this model vary with local conditions. There may be also a deep litter layer that confounds suppression efforts.

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Fire Behavior Fuel Model Description SHRUB GROUPFuel Model 5 (2 feet deep) Fire is generally carried in the surface

fuels made up of litter cast by the shrubs and the grasses or forbs in the understory. Fires are generally not very intense as surface fuel loads are light, the shrubs are young with little dead material, and the foliage contains little volatile material. Shrubs are generally not tall, but nearly cover the entire area. Young, green stands with little or no deadwood such as laurel, vine maple, alder, or even chaparral, mazanita, or chamise are examples. As the shrub fuel moisture drops, consider using a Fuel Model 6.

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Fire Behavior Fuel Model Description SHRUB GROUPFuel Model 6 (2.5 feet deep) Fires carry through the shrub layer where

the foliage is more flammable than Fuel Model 5, but require moderate winds (>8 mi/h) at midflame height. Fire will drop to the ground at low windspeeds or openings in the stand. Shrubs are older, but not as tall as shrub types of Model4, nor do they contain as much fuel as Model 4. A broad range of shrub conditions is covered by this model. Typical examples include intermediate stands of chamise, chaparral, oak brush, low pocosin, Alaskan spruce taiga, and shrub tundra. Cured hardwood slash can be considered. Pinyon-juniper shrublands may fit, but may overpredict rate of spread except at high winds; e.g., 20 mi/h at the 20-foot level.

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Fire Behavior Fuel Model Description

SHRUB GROUP

Fuel Model 7 (2.5 feet deep) Fire burns through the surface and shrub strata equally. Fire can occur at higher dead fuel moisture contents due to the flammable nature of live foliage. Shrubs are generally 2 to 6 feet high. Examples are Palmetto-gallberry understory-pine overstory sites, low pocosins, and Alaska Black Spruce-shrub combinations.

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TIMBER GROUPFuel Model 8 (0.2 feet deep) Slow burning ground fires with low

flame heights are generally the case, although an occasional “jackpot” or heavy fuel concentration may cause a flare up. Only under severe weather conditions do these fuels pose fire problems. Closed-canopy stands of short needle conifers or hardwoods that have leafed out support fire in the compact litter layer. This layer is mainly needles, leaves, and some twigs since little undergrowth is present in the stand. Representative conifer types are white pine, lodgepole pine, spruce, true firs, and larches.

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TIMBER GROUPFuel Model 9 (0.2 feet deep) Fires run through the surface

litter faster than model 8 and have higher flame height. Both long-needle conifer and hardwood stands, especially the oak-hickory types, are typical. Fall fires in hardwoods are representative, but high winds will actually cause higher rates of spread than predicted because of spotting caused by rolling and blowing leaves. Closed stands of long-needled pine like ponderosa, Jeffrey, and red pines or southern pine plantations are grouped in this model. Concentrations of dead-downed woody material will contribute to possible torching out of trees, spotting and crowning activity.

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Fire Behavior Fuel Model Description TIMBER GROUPFuel Model 10 (1 foot deep) The fires burn in the surface and

ground fuels with greater fire intensity than other timber litter models. Dead-down fuels include greater quantities of 3-inch or larger limb wood resulting from over-maturity or natural events that create a large load of dead material on the forest floor. Crowning out, spotting, and torching of individual trees are more frequent in this fuel situation leading to potential fire control difficulties. Any forest type may be considered when heavy down materials are present; examples are insect or diseased stands, wind-thrown stands, over-mature situations with deadfall, and cured light thinning or partial-cut slash. 01-06-S390-

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Fire Behavior Fuel Model Description LOGGING SLASH GROUPFuel Model 11 (1 foot deep) Fires are fairly active in the slash

and herbaceous material intermixed with the slash. The spacing of the rather light fuel load, shading from overstory, or the aging of the fine fuels can contribute to limiting the fire potential. Light partial cuts or thinning operations in mixed conifer stands, hardwood stands, and southern pine harvests are considered. Clear-cut operations generally produce more slash than represented here. The <3 inch material load is less than 12 tons per acre. The >3 inch material is represented by not more than 10 pieces, 4 inches in diameter along a 50-foot transect.

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Fire Behavior Fuel Model Description LOGGING SLASH GROUPFuel Model 12 (2.3 feet deep) Rapidly spreading fires with

high intensities capable of generating firebrands can occur. When fire starts, it is generally sustained until a fuel break or change in fuels is encountered. The visual impression is dominated by slash and much of it is <3 inches in diameter. These fuels total less than 35 tons per acre and seem well distributed. Heavily thinned conifer stands, clearcuts and medium or heavy partial cuts are represented. The >3 inch material is represented by encountering 11 pieces, 6 inches in diameter, along a 50-foot transect.

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LOGGING SLASH GROUPFuel Model 13 (3 feet deep) Fire is generally carried by a

continuous layer of slash. Large quantities of >3inch material are present. Fires spread quickly through the fine fuels and intensity builds up as the large fuels start burning. Active flaming is sustained for long periods and a wide variety of firebrands can be generated. These contribute to spotting problems as the weather conditions become more severe. Clear-cut and heavy partial-cuts in mature and over-mature stands are depicted where the slash load is dominated by the >3inch material. The total load may exceed 300 tons per acre, but the <3 inch fuel is generally only 10 percent of the total load. Situations where the slash still has “red’ needles attached, but the total load is lighter like a Model 12, can be represented because of the earlier high intensity and faster rate of spread.

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FUEL MODEL SIZE CLASS KEY

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FuelModel

Fuel Loading Approx. Fuel Bed

Depth(ft.)

Moist.Of Ext.

(%)

ROS*(ch/h)

FL* (ft)

1-Hour

10-Hour

100-Hour

Live

Grass Group

123

xxx

x x x1.01.02.5

121525

7835

104

46

12

Shrub Group

4567

xxxx

xxxx

x

xx

xx

x

6.02.02.52.5

20202540

75183220

19465

Timber Litter Group

89

10

xxx

xxx

xxx x

0.20.21.0

302525

288

135

Logging Slash Group

111213

xxx

xxx

xxx

1.02.33.0

152025

61314

48

11

*ROS and FL are representatives values under a fine dead fuelmoisture of 8%, a midflame windspeed of 5 mi/h, and live fuel moisture (if present) is 100%.

FIRE BEHAVIOR FUEL MODEL KEY

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ALWAYS CHECK THE SELECTED MODEL WITH FUEL MODEL DESCRIPTION.

I. PRIMARY CARRIER OF FIRE IS GRASS. EXPECTED RATE OF SPREAD IS MODERATE TO HIGH, WITH LOW TO MODERATE INTENSITY.

•GRASS HAS FINE STRUCTURE, GENERALLY BELOW KNWEE LEVEL, AND CURED OR PRIMARILY DEAD. GRASS IS ESSENTIALLY CONTINUOUS……………………………………………………....MODEL 1.

•GRASS IS COURSE STRUCTURED, ABOVE KNWEE LEVEL(AVERAGE ABOUT 3 FEET) AND DIFFICULT TO WALK THROUGH…………………………………………………...…MODEL 3.

•GRASS IS USUALLY UNDER AND OPEN TIMBER OR BRUSH OVERSTORY. LITTER FROM OVERSTORYIS INVOLVED, BUT GRASS CARRIES THE FIRE…………………………………………..MODEL 2.


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II. PRIMARY CARRIER OF FIRE IS BRUSH. EXPECTED RATE OF SPREAD AND INTENSITY ARE BOTH MODERATE TO HIGH.

•VEGETATION TYPE IS SOUTHERN ROUGH OR LOW POCOSIN. BRUSH IS GENERALLY 2 TO 4 FEET HIGH…………....MODEL 7.

•LIVE FUELS ARE ABSENT OR SPARCE WITH NO CAPACITY TO REDUCE FIRE SPREAD. REQUIRES MODERATE WINDS OT CARRY FIRE. …………………………………………….…………...…MODEL 6.

•LIVE FUEL MOISTURE CAN HAVE A SIGNIFICANT DAMPING EFFECT ON THE FIRE BEHAVIOR:

–BRUSH IS ABOUT 2 FEET HIGH, WITH LIGHT LOADING OF BRUSH LITTER UNDERNEATH, WHICH MAY CARRY FIRE……………………………………………………….MODEL 5.

–BRUSH IS HEAD HIGH (6 FEET), WITH HEAVY LOADINGS OF 1-HOUR DEAD FUELS…………………………...……..MODEL 4.


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III. PRIMARY CARRIER OF FIRE IS TIMBER LITTER BENEATH A TIMBER STAND. SPREAD RATES ARE LOW-TO-MODERATE; FIRELINE INTENSITY MAY B LOW-TO-HIGH.

•LIVE FUELS ARE PRESENT AND CAN INFLUENCE FIRE BEHAVIOR. THERE IS A SIGNIFICANT AMOUNT OF LARGER FUELS WITH ATTACHED TWIGS AND BRANCHES………MODEL 10.

•SURFACE FUELS ARE MOSTLY FOLIAGE LITTER, WITH LITTLE OR NO LIVE FUEL. LARGER FUELS ARE SCATTERED AND LIE FLAT ON THE LITTER:

–DEAD FOLIAGE IS TIGHTLY COMPACTED, SHORT NEEDLED CONIFER OR HARDWOOD LITTER………………………………………………………MODEL 8.

–DEAD FOLIAGE LITTER IS LOOSELY COMPACTED LONG NEEDLED PINE OR HARDWOODS.…………...……..MODEL 9.


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IV. PRIMARY CARRIER OF FIRE IS SLASH, USUALLY PRODUCED FORM LOGGING. SPREAD RATES ARE LOW-TO-HIGH, FIRELINE INTENSITIES ARE LOW-TO-VERY HIGH.

•SLASH IS NOT CONTINUOUS. NEEDLE LITTER OR SMALL AMOUNTS OF GRASS OR SHRUBS MUST BE PRESENT OT HELP CARRY THE FIRE, BUT PRIMARY CARRIES IS STILL SLASH. LIVE FUELS ARE ABSENT OR NONINFLUENCING. AVERAGE SLASH DEPTH IS ABOUT 1 FOOT………………………………..…MODEL 11.

•SLASH IS CONTINUOUS. SLASH IS NOT EXCESSIVELY COMPACTED. LIVE FUELS ARE ABSENT OR NONINFLUENCING. AVERAGE SLASH DEPTH IS ABOUT 2 FEET………..….MODEL 12.

•SLASH IS GENERALLY CONTINUOUS. HEAVIER FUEL LOADING THAN MODEL 12. AVERAGE SLASH DEPTH IS ABOUT 3 FEET. LIVE FUELS ARE NOT EXPECTED TO INFLUENCE FIRE BEHAVIOR………………………………………………….….MODEL 13.

LIVE FUEL MOISTURE

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STAGE OF VEGETATIVE DEVELOPMENT________________________________________

Fresh foliage, annuals developing early in growing cycle.

Maturing foliage, still developing with full turgor.

Mature foliage, new growth complete and comparable to older perennial foliage.

Entering dormancy, coloration starting, some leaves may have dropped from stem.

Completely cured.

MOISTURE CONTENT

Percent300

200

100

50

Less than 30, treat as a dead fuel.

PROBABILITY OF IGNITIONPIG

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A rating of the probability that a glowing firebrand will cause a fire.

Display Transparency:

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HELLROARING MAP

MIDFLAME vs. 20-FOOT WINDS

10 mi/h

20 mi/h

3 mi/h

20 mi/h

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20 FOOT WINDSPEED IS ADJUSTED TO MIDFLAME

BASED ON OVERSTORY

Fuel exposure to windFuel exposure to wind

Partly shelteredPartly sheltered(patchy timber)(patchy timber)

WindWind

Unsheltered (no foliage, Unsheltered (no foliage, near clearings)near clearings)

Fully shelteredFully sheltered(under timber,(under timber,flat or gentle flat or gentle slope, near baseslope, near baseof steep mtn.)of steep mtn.)

Partly shelteredPartly sheltered(under timber(under timbermidslope, windmidslope, windon slope)on slope)

UnshelteredUnsheltered(ridgetops)(ridgetops)

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EXERCISE 3-DETERMINING MIDFLAME WINDSPEED

PERCENT SLOPE

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% SLOPE = RISE IN FEETRUN IN FEET

X 100 %

RISE

RUN

UNIT 1- FIRE BEHAVIOR INPUTS OBJECTIVES

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1 Select “best fit” fire behavior fuel models using a key and fuel model descriptions.

2 Determine dead and live fuel moisture contents and the probability of ignition.

UNIT 1- FIRE BEHAVIOR INPUTS OBJECTIVES (cont.)

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3 Determine midflame windspeeds when given the 20-foot winds, fuel type or model, and terrain features.

4 Calculate slope to the nearest 5 % using topographic maps and the slope formula.

5 Convert fire spread distance to map distance.

UNIT 2- FIRE BEHAVIOR CALCULATIONS OBJECTIVES

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1. Give the five necessary input values and four output values of the surface fire behavior nomograms.

2. Describe the differences between point source and line source fire behavior predictions.

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3. Use the surface fire behavior nomogram to calculate rate of spread, fireline intensity, heat per unit area and flame length.

4. Determine perimeter, area and shape of a wildland fire originating from a point source.

5. Determine maximum spotting distance.

SURFACE FIRE BEHAVIOR NOMOGRAM

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INPUTS

OUTPUTS

ACME NUMBER CRUNCERPATENT PEND.

SURFACE FIRE BEHAVIOR NOMOGRAM

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GARBAGE INPUTS

GARBAGEOUTPUTS

ACME NUMBER CRUNCERPATENT PEND.

?????

A MATHEMATICAL MODEL IS A SET OF

EQUATIONS

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ASSUMPTIONS OF THE FIRE SPREAD MODEL

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1. Fire is spreading at the flame front.

2. Fire is free burning.

3. Fine fuels control rate of spread.

4. Uniform and continuous fuels.

5. Surface fire.

6. Uniform weather and topography.

FUEL MODEL

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A set of numbers which define fuel input to the fire spread model.

FORMULA FOR CALCULATING FUEL

MOISTURE

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MC=Net Wet Weight - Net Dry Weight

X 100Net Dry Weight


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EFFECTIVE WINDSPEED

RATE OF SPREADDISTANCE/TIME

ROSCH/HR

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STARTING TIME

TIME

ENDING TIME

DISTANCE

HEAT PER UNIT AREABtu/sq ft

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STARTING TIME

ENDING TIME

FIRELINE INTENSITYBtu/ft/s

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ONE FOOT

FLAME LENGTHFEET

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Display Transparencies:

02-13-S390-VG = Fire Beh. Fire Characteristics Chart

02-14-S390-VG = Fire Beh. Fire Characteristics Chart

for heavy fuels

POINT SOURCE

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Point source model is designated for firesburning on flat ground or where the wind is blowing in the direction of the slope plus

or minus 30°.

upslope

max

slop

e

± 30º

SPREAD CALCULATION

SD=PT X ROS

SD = SPREAD DISTANCEPT= PROJECTION TIMEROS = RATE OF SPREAD

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LINE SOURCE

LINE SOURCEFire has become large and no

longer has a basic elliptical shape because of changing conditions (fuel type, fuel

moisture, weather).

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1

21200

1600

Refer to View Graph

SPREAD DIRECTION

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WIN

D

NO

WIN

D

WIN

DUP

SLOPEUP

SLOPEUP

SLOPE

WIN

D

DOWN SLOPE

DOWN SLOPE

DOWN SLOPE

FIRE BEHAVIOR FUEL MODEL LIMITATIONS

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All the assumptions made in fuel models and fire behavior model.

FIRE MODEL LIMITATIONS

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SURFACE FIRES-Not crown fires.-Doesn’t consider spotting.

BEHAVIOR AT THE FIRE FRONT-Not pile burning.-Not burnout.

FIRE MODEL LIMITATIONS

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BEHAVIOR NO LONGER INFLUENCED BY METHOD OF IGNITION.

NOT IMPEDED BY FIRE SUPPRESSION ACTIVITIES.

FUEL CONTINUOUS, UNIFORM.

BURNING CONDITIONS CONSTANT.

POINT SOURCE PREDICTION LIMITATIONS

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Calculations with windspeeds less than 2.5 miles per hour are generally too low.

Better predictions result withwindspeeds greater than 2.5 milesper hour.

THE PERIOD OF BURNING TIME IS USUALLY SHORT

UP TO ONE HOUR.

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FIRE PERIMETER AND SHAPES

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Fire perimeter and shapes are based on smooth ellipses - actual perimeter of the fire edge would likely be greater length and follow topographic relief.

APPROXIMATE FIRE SHAPES ASSOCIATED WITH MIDFLAME

WINDSPEEDS OF…..

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Wind Direction

Fire Start

2.5 mi/h

5 mi/h

7.5 mi/h

15 mi/h

10 mi/h

AREAS OF USE SUPPRESSION

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Determination of locations to place crews,equipment, helicopters and fuel breaks.

Development of the wildland fire situation analysis.

PRESUPPRESSION PLANNING

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Determination of staffing requirements.

Need for retardant.

Attack priorities in multiple fire situations.

PRESCRIBED BURNING

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Distance between spot fires to accomplishan objective.

Calculating timing of ignition to take advantage of diurnal weather patterns.

Managing wilderness fires.

Development of escaped fire contingencyplanning.


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THRU

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EFFECTIVE WINDSPEED

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The midflame adjusted for the effectof slope on uphill fire spread.

EXAMPLES OF EFFECTIVE WINDSPEED

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EFFECTIVE WINDSPEEDIS 5 mi/h

3 mi/h

60%5 mi/h

FIRE SHAPES ARE DEPENDENT ON EFFECTIVE WINDSPEEDS

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Wind Direction

Origin

1 mi/h

3 mi/h11 mi/h

15 mi/h

13 mi/h5 mi/h

9 mi/h

7 mi/h

NOT TO SIZE,SCALES ARE ARBITRARY


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THRU

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MAXIMUM SPOTTING DISTANCE

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When torching trees, piles or wind-driven surface fires loft firebrands,which are then carried by the prevailing wind.

SOURCES OF FIREBRAND

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•Torching trees

•Burning pile

•Spreading surface fire

FACTORS RELATING TO THE SPOTTING PROBLEM

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•Probability of production of firebrands.

•Windspeed.

•Fire intensity.

•Number of firebrands

ASSUMPTIONS AND LIMITATIONS FOR MAXIMUM SPOTTING DISTANCE NOMOGRAMS

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•Level terrain

•Flame source is a torching tree

•Uniform forested terrain

•Tree species from the IntermountainWest

REQUIRED INFORMATION FOR SPOTTING DISTANCE

NOMOGRAMS

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•Torching tree height•Torching tree species•Torching tree DBH•Average treetop height where brand may fall.•20-foot windspeed


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1. Give the five necessary input values and four output values of the surface fire behavior nomograms.

2. Describe the differences between point source and line source fire behavior predictions.

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3. Use the surface fire behavior nomogram to calculate rate of spread, fireline intensity, heat per unit area and flame length.

4. Determine perimeter, area and shape of a wildland fire originating from a point source.

5. Determine maximum spotting distance.

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UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES

1. Describe the sensitivity of fire behavior

model outputs to inputs using the surface

fire behavior nomograms.

2. Describe how the wildland fire behavior

prediction system can be used in fire

planning.

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UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES3. Determine rate of spread, flame length, area,

perimeter, maximum spotting distance, and probability of ignition for wildland fires in a variety of fuel types.

4. Describe four methods to measure rate of spread and two methods to estimate flame length.

5. List five reasons why the results of a fire behavior prediction model may differ from the observed fire behavior.

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UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES6. Describe methods used to adjust fire

behavior predictions.

OPTIONAL

7. Determine crown fire potential for wildland fire scenarios in a variety of fuel types.

Use Northern Rockies Crown Fire Nomogram to calculate rate of spread and to estimate if the fire will be wind-driven or plume-dominated.

OBJECTIVE #1

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Describe the sensitivity of fire behaviormodel outputs to inputs using the surface fire behavior nomograms.

Fuel Models 1,2,4,8, and 13.


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FIRE BEHAVIOR

Fire Characteristics Chart (Haul Chart)

OBJECTIVE #2

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Describe how the wildland fire behaviorprediction system can be used in fire planning.

Dispatching Priorities

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FUELSWEATHER

TOPOGRAPHY

Predicting “Real Time” Fire Behavior

Running Surface Fire

Wildland Fire Situation Analysis(WFSA)

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Prescribed Burning

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•Estimate the behavior of escapes or spots.

•Assess fuel and weather conditions at burn time.

•Develop burn prescriptions.

•Develop containment and control plans.

Managing Prescribed Natural Fires

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FIRE PLANNING

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•Preattack

•Describing consequences

•Environmental documents

Determine rate of spread, flame length,area, perimeter, maximum spottingdistance, and probability of ignition,for wildland fires in a variety of fuel types.

Review Units 1 & 2Surface Fire Nomogram

Spotting Distance NomogramArea/Perimeter Tables

Probability of Ignition Tables

OBJECTIVE #3

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THRU

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Describe four methods to measure rate of spread and two methods to estimate flame length.

OBJECTIVE #4

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Rate of Spread =

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Spread DistanceElapsed Time

WAYS TO MEASURE RATE OF SPREAD

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1. Metal tags - aluminum pipes.

2. Hand held “Range Finder”.

3. Aerial platform - high resolution maps or photos.

4. Aerial photos, infrared imageryor video.

5. Global Positioning System (GPS).

FLAME LENGTH*

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Indicator of intensity

Observable

*Remember flame length is not equal to flame height.

1. Compare flames to objectives of known dimensions.-firefighter-fence post-post with painted stripes

2. Photos, infrared imagery, anddigitized videotape.

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List five reasons why the results of a fire behavior prediction model may differ from the observed fire behavior.

OBJECTIVE #5

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DIFFICULTY IN OBSERVING FIRE BEHAVIOR

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•individual perceptions

•observations made incorrectly

•fire travels in pulses; need average

MODEL APPLICABILITY

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Fuel Bed - continuous, uniform, homogenous

Spotting - not considered in spreadmodel

Fire vortices and other fire inducedphenomena

ACCURACY OF MODEL RELATIONSHIPS

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Formula used to describe real world.

Built on theoretical and limited observed relationships.

Experience helps improve accuracy.

ACCURACY OF INPUT DATA

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Garbage “IN” garbage “OUT”

Environmental factors important

Custom fuel models where existing FBPS models do not apply

ADVANCED FIRE PREDICTION TECHNIQUES

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Two fuel model concept

Cross-slope wind

Rough terrain spotting

Describe methods used to adjust fire behavior predictions.

OBJECTIVE #6

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VALUE OF INFORMATION

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Is increased accuracy valuable?

Will information be timely?

STATISTICAL ADJUSTMENTS

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-When value is high

-Observed and predicted vary

-Costs justifiable

-”Line of closest fit”


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THRU

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Regression Analysis

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Regression Line Calculated

Ro = m * Rp + b

Ro = Corrected Rate

Rp = Predicted Rate

b = y intercept (positive or negative)

M = Slope of line

INPUT DATA ACCURACY

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-Measure windspeed

-Custom fuel models

EXPERIENCE

LOCAL KNOWLEDGE

VALIDITY

“LOOK UP” “LOOK DOWN”“LOOK AROUND”

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THRU

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NOMOGRAM OVERVIEW

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•Early spring before greenup

•Late spring or early summer

•Normal dry summer

•Summer drought

•Late summer severe drought


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THRU

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03-61-S390-VGPage 1 of 3

UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES

1. Describe the sensitivity of fire behavior

model outputs to inputs using the surface

fire behavior nomograms.

2. Describe how the wildland fire behavior

prediction system can be used in fire

planning.

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UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES3. Determine rate of spread, flame length, area,

perimeter, maximum spotting distance, and probability of ignition for wildland fires in a variety of fuel types.

4. Describe four methods to measure rate of spread and two methods to estimate flame length.

5. List five reasons why the results of a fire behavior prediction model may differ from the observed fire behavior.

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UNIT 3- FIRE BEHAVIOR APPLICATIONS OBJECTIVES6. Describe methods used to adjust fire

behavior predictions.

OPTIONAL

7. Determine crown fire potential for wildland fire scenarios in a variety of fuel types.

Use Northern Rockies Crown Fire Nomogram to calculate rate of spread and to estimate if the fire will be wind-driven or plume-dominated.

THE END

This fine presentation brought to you by:

Hector H. Madrid Great Basin Training UnitNIFC-BLM Smokejumpers

Introduction to Wildland Fire Behavior Calculations390RM

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Transcript of Introduction to Wildland Fire Behavior Calculations390RM