Basic Wildland Fire Management

Basic Wildland Fire Management
Fire Environment A strong working knowledge of the basic factors influencing the fire environment is important and will assist trainees in recognising dangerous or potentially hazardous fireline situations and using appropriate and effective fire control tactics.

Objectives Upon completion of this section, you will be able to: Explain significance of cold fronts, thunderstorms and upper ridge breakdowns on fire environment Describe 4 weather factors and their influence on FB Describe 4 topographic factors and their influence on FB Describe 4 fuel factors and their influence on FB Name 3 types of fire List parts of fire Describe 6 components of FWI System Recognize fire behaviour warning signals

Fire Triangle In order to control and manage wildland fires, we must first understand why a fire burns and what makes it spread. Three elements are required to create combustion: fuel, oxygen and heat. Fuel is composed of live and dead vegetation Oxygen derived from atmosphere Heat derived from ignition source such as lightning or a match Fuel, oxygen and heat must all be present to support combustion or burning. If any one of these elements is altered, the fire will behave differently. If any one of these elements is removed, the fire will be extinguished. The removal of one of these elements is the focus of all fire suppression work.

Phases of Combustion Combustion is the process during which combustible gases and charcoal combine with oxygen and release energy that was stored in the fuel as heat and light. Pre-ignition Phase. In this phase, heat from an ignition source or the flaming front heats adjacent fuel elements. Water evaporates from fuels and the process of pyrolysis occurs, the heat-induced decomposition of organic compounds in fuels. Flaming Phase. Combustible gases and vapors resulting from pyrolysis rise above the fuels and mix with oxygen. Flaming occurs if they are heated to the ignition point of about 450oC, or if they come into contact with something hot enough to ignite them such as flames from the fire front. The heat from the flaming reaction accelerates the rate of pyrolysis. This causes the release of greater quantities of combustible gases, which also oxidize, causing increased amounts of flaming. Glowing Phase. When a fire reaches the glowing phase, most of the volatile gases have been driven off. Oxygen comes into direct contact with the surface of the charred fuel. As the fuel oxidizes, it burns with a characteristic glow. This process continues until the temperature drops so low that combustion can no longer occur, or until all combustible materials are gone. Smoldering Phase. Smoldering is a very smoky process occurring after the active flaming front has passed. Combustible gases are still being released by the process of pyrolysis, but the rate of release and the temperatures maintained are not high enough to maintain flaming combustion. Smoldering generally occurs in fuel beds with fine packed fuels and limited oxygen flow such as duff and punky wood. An ash layer on these fuel beds and on woody fuels can promote smoldering by separating the reaction zone from atmospheric oxygen.

Heat Transfer Process 3 heat transfer processes: Radiation: Movement through air Convection: Movement of hot air masses Conduction: Movement through solid matter Mass transport another related form of heat transfer Heat Transfer: process by which heat travels from one body or object to another is known as heat transfer There are 3 processes by which heat is transferred. Radiation: Transfer of heat through the air from warm surfaces to cooler surroundings Convection: Transfer of heat by the movement of hot air masses; the natural direction is upwards Conduction: Transfer of heat through solid matter - this is the least important mechanism of heat transfer in the wildland fire environment Mass transport or spotting is another related form of heat transfer. This involves embers/burning debris being transported by air movement, away from an existing fire to unburned fuels. The distance may vary from meters to kilometres.

Fire Behaviour Triangle
Basic Wildland Fire Management Fire Behaviour Triangle Fire behaviour is influenced by three factors: fuel, weather, and topography. These three factors create another triangle: The Fire Behaviour Triangle.

Wind Drives direction of fire spread Bends flame, heating, drying and igniting new fuels Carries embers into new fuels Feeds more oxygen to fire Can increase/decrease fuel moisture depending on airmass Wind is the single most important weather related factor affecting fire behaviour. Wind influences fire behaviour in a variety of different ways. Changes the environment surrounding fuels (i.e. increase or decrease fuel moisture depending on the amount of moisture in the airmass) Bends the flame over, heating, drying and igniting new fuels Carries sparks and embers into new fuel sources Directs fire spread in the absence of topographic features Wind speed and direction can change rapidly which makes it an important factor that wildland firefighters must observe in order to be safe on the fireline. Wind can also be difficult to forecast or predict. In most cases, wind decides the primary direction of fire spread, rate of spread and shape of the fire itself. If a fire burns under a light wind regime, it’ll spread slowly and have a low length to breadth ratio. The burn area will be almost circular, with the point of ignition near the centre of the burn, assuming flat terrain. If a fire burns under a strong wind regime, the rate of spread will be high, and the fire will have a high length to breadth ratio. The burn pattern will also be strongly influenced by the wind direction. Although the prevailing wind may dominate the wildfire during its initial stages, terrain effects play an increasingly important role as the fire intensifies.

Temperature Temperature affects RH which inturn affects fuel moisture Temperature also influences ease of ignition Variations result of time of day, elevation, land surface, amount cloud cover and/or wind Inversions bring different regimes of temperature, RH and wind to a fire site The temperature of forest fuels and the temperature of the surrounding air play a key role in determining how wildfires start and how they spread. The initial temperature of the forest fuels and surrounding air influence the amount of heat required to raise the temperature of the fuels to their ignition point. Nonetheless, how temperature affects other factors (e.g. relative humidity, wind, atmospheric stability) is most important. Temperature fluctuations affect relative humidity thereby affecting fuel moisture. There are a number of factors affecting temperature: cloud cover, time of day, angle of solar rays (i.e. latitude), forest cover, and elevation.

Relative Humidity Directly effects of fuel moisture When RH >35%, fine fuel moisture increases Variations in RH depend on proximity to water, amount of vegetation and/or frontal boundaries When fuels regain moisture, it’s known as recovery Relative humidity is the amount of water vapor in the air relative to the total amount of water the air is capable of holding at a given temperature, expressed as a percentage. Relative humidity effects fire behaviour by affecting fuel moisture content, which in turn affects the probability of ignition. When the air is dry (i.e. RH less than 30%), fuels are likely to lose moisture to the air. Conversely, when the air is moist (i.e. RH more than 50%), fuels are likely to take up moisture from the air.

Precipitation Duration rather than amount of precipitation determines effect of fuel moisture Fuel complex will affect distribution of moisture Fine fuels react quicker to moisture changes Precipitation influences fire behaviour by affecting fuel moisture. The effect of precipitation on fuel moisture is dependent on fuel size. Fine fuels react to moisture faster than heavy fuels due to increased surface area to volume ratio. Distribution of moisture through the fuel complex is determined by fuel spacing. For example, precipitation can’t penetrate a dense canopy to sufficiently wet ground fuel. Duration of precipitation, rather than quantity of precipitation, determines the effect of precipitation on fuel moisture.

Slope Slope affects rate of spread Flames are closer to fuels so fuels are preheated Burning logs, etc. can roll into unburned fuels and accelerate uphill Wind follows predictable flow pattern Downslope winds can be associated with glaciers, etc. Slope. Slope is the single most important topographical factor affecting fire behaviour, it affects rate of spread. Wildland fires spread faster on slopes because flames are closer to fuels so that fuels are preheated by radiation and convection and burn more readily. What’s more, burning logs and cones can roll downhill into unburned fuels where it can rapidly accelerate uphill. For this reason, downhill fireline construction is extremely hazardous. On slopes wind follows a predictable flow pattern. It generally flows upslope (i.e. blow uphill) during the day and downslope (i.e. blow downhill) at night. Notwithstanding, downslope winds can also be associated with thunderstorms, glaciers, etc.

Aspect More direct sunlight on SW slopes therefore higher temperatures, lower RH, lower FMC and lower fuel loading E N S W Temperature 1200LST Aspect. Aspect refers to the direction the slope faces. For example, a southwest aspect is a slope that faces southwest. Although it plays a larger role in the mountains, it can also play a role on a smaller scale (e.g. rolling prairie). Slopes facing the sun receive more direct sunlight, that’s why south and west aspects have higher ground and air temperatures than north and east facing slopes. Upslope winds are the result of convective heating on the slope. Downslope winds result as slopes cool at night, and are usually much slower. The diurnal pattern of relative humidity varies with aspect just as the temperature pattern does; that is, factors that result in high temperatures produce low relative humidity values. Fuel volume and type also vary with aspect; generally light, flashy fuels on south slopes and heavy, slow-burning fuels on north slopes, with gradients in between.

Terrain Narrow, steep drainages act like chimneys for fire to channel up Narrow draws can also be affected by radiant heat on opposite slope Eddy effects are prevalent near ridge tops and convergence of two or more drainages Terrain. Terrain refers to variations in land features, which alter wind flow and affect fire behaviour. Mountains and their associated valleys influence local gradient winds by acting as channels and/or barriers. Narrow V-shaped valleys create a chimney effect (i.e. convective winds are funnelled up steep walls, drawing air from valley bottom to create strong upslope winds) so that fires in these chutes can be intense and spread upwards rapidly. Ridge shape, wind speed and direction will affect how the air behaves when it crosses a ridge. Sharp ridges may produce a significant amount of turbulence on the leeside. In wide U-shaped valleys the prevailing wind direction won’t be significantly altered by the direction of the valley.

Wind Topographical features can steer synoptic winds Local mountain winds result of daytime heating Land and sea breezes are local winds that result from temperature and pressure differences between land and water Topographical features can steer synoptic winds in certain directions. In a general sense, mountainous terrain can act as a barrier to wind producing erratic winds on the windward side of the mountain and calm winds on the lee. In other cases, mountains can act as funnels and channels, pushing wind in a particular direction making the wind much stronger than what would be indicated by the atmospheric pressure gradient. Local mountain winds are the result of daytime heating and nighttime cooling. During the day, winds begin to flow upslope (i.e. flow uphill) as the sun heats up the slope. Upslope winds increase in strength and depth as it moves up the slope, but winds may become erratic near the top as thermal currents are formed. As whole volume of air within the valley is heated, winds begin to flow up valley (i.e. generally noticeable mid to late afternoon depending on the size of the valley). Up valley winds can be rather turbulent due to the instability of the air and roughness of the terrain. At night, downslope winds (i.e. flown downhill) develop as cool air at the mountaintop begins to sink into the valley since it’s colder and denser than the air lower down the slope. Down valley wind begins early after sunset as more cold air flows down from the slopes, and is generally not as turbulent as up valley winds as the air is generally stable by this time. Land and sea breezes are local winds that arise from the temperature and pressure differences between land and large bodies of water. The greater the temperature difference between the land and the water, the stronger the local wind will be. During the day, land heats more readily than water causing the air over the land to become buoyant and rise thereby creating a void over the land. This creates circulation of air from the water to the land, which is known as a sea breeze. At night, the air over land cools more readily than air over water. This creates a void over the water. This creates a circulation from the land toward the water, which is known as a land breeze.

Unstable Atmosphere Indicators of stable atmosphere: Clouds in layers Winds steady and light Poor visibility Indicators of unstable atmosphere: Clouds grow vertically Lots of lightning Gusty, erratic winds Although normal changes in atmospheric stability don’t readily influence large fires, it does greatly affect wind flow, which in turn affects fire behaviour. Turbulent winds associated with atmospheric instability can cause fires to build up more rapidly and to behave erratically. Atmospheric stability is also the prime mechanism that generates thunderstorms. As lightning accounts for between 50-90% of all wildfires, instability is an important consideration when looking at ignition potential. Fireline personnel need to be particularly aware of the visual indicators of atmospheric stability. Indicators of a Stable Atmosphere Clouds in layers, no vertical motion Little lightning Winds often steady and light Poor visibility due to accumulation of smoke and haze Indicators of an Unstable Atmosphere Clouds grow vertically and smoke rises to great heights Lots of lightning Gusty winds with upward and downward currents

Cold Front

Thunderstorm Thunderstorm clouds during all stages of development can influence the fire environment and create hazardous conditions for ground crews. During the cumulus phase, updrafts associated with the developing cloud can be strong enough to influence the local wind pattern near a wildfire. As the cell nears the burn area, the local wind pattern can often be seen to shift as winds are drawn into the developing cell. Therefore, spotting potential is increased and the in-flow to the fire is strengthened. Both up and downdrafts are present during the mature phase making winds at a fire site erratic. As the thundershower develops, the downdraft will strengthen, often leading to the development of a strong gust front (i.e. leading edge of the downdraft). The gust front often extends up to 30km away from the parent thundershower. If fire crews notice a line of raggedy-looking cloud preceding a thundershower, they should be aware that a gust front is likely headed their way. During the dissipating stage, only outflow winds need to be considered. Observations have shown that the downdrafts associated with the dissipating stage can be as severe as those in the mature phase. In a decaying storm, the gust front may actually outrun and outlast the parent cell and appear as isolated phenomena miles away from the cumulonimbus cloud that generated it. In this scenario, the crews may have discounted any danger from the storm, as it had appeared to have already weakened and moved out of the region. It’s important to point out that downdrafts associated with thundershowers may produce strong downslope winds during the day (i.e. when upslope winds are expected) that may put fire suppression crews at risk.

Upper Ridge Breakdown Implications of temporary URB: Lightning outbreak Strong, gusty surface winds and abrupt wind shifts Spotty precipitation of variable amount Possible severe thunderstorms Return to warm and dry conditions Permanent URB result of major re-organization of weather pattern An upper ridge breakdown often brings significant changes in the weather, which can result in explosive and potentially dangerous fire behaviour. When an upper ridge breaks down, the atmosphere is transformed from a stable to an unstable environment as cold air replaces warm air aloft. This transformation often takes place suddenly, creating significant lightning outbreaks, strong winds and abrupt wind shifts. As fire danger is often at critical levels at the time of the upper ridge breakdown, these lightning outbreaks often lead to major fire busts. In addition, any existing or new wildfires may take significant runs during an upper ridge breakdown scenario. Most often, the weakening of an upper ridge (i.e. temporary upper ridge breakdown) is triggered by the passage of an upper disturbance. Once the disturbance has passed, the ridge rebounds bringing the return of warm and dry conditions. A permanent upper ridge breakdown is the result of a major re- organization of the weather pattern. It’s similar to the temporary breakdown in that it leads to a significant lightning outbreak, but in the case of the permanent breakdown, the upper ridge does not rebound. Relief in the form of cooler temperatures, higher RH values and precipitation may settle over a region for a period as the pattern shifts.

Fuel Characteristics Fuel Moisture Content Fuel Size: higher surface:volume ratio means less time to ignite Fuel Loading Fuel Spacing Vertical spacing may be continuous or separated Horizontal spacing may be continuous or patchy Fuel factors that influence fire behaviour are: moisture content, size, loading, and spacing. Fuel Moisture Content. Fuel moisture content is the single most important fuel-related factor affecting fire behaviour. Fuel moisture content is defined as the amount of water in a fuel component expressed as a percentage based on oven‑dry weight. For example, a stick with an oven‑dry weight of 100g is found to weigh 108g. The stick has 8% fuel moisture. Fuels with lower fuel moisture will ignite more easily and spread fire more rapidly. Fuel moisture of wildland fuels is determined by weather (e.g. amount and type of precipitation) and percentage of living or dead fuel (e.g. green grass will not burn as well as cured grass). Fuel Size: Light Fuels vs. Heavy Fuels. Light, fast burning fuels (e.g. grass, dead leaves, needles, immature trees) take less time to ignite because it takes less heat to ignite the fuels due to their high surface area to mass ratio. Energy release (i.e. fire intensity) is high and of short duration. Heavy, slow burning fuels (e.g. logs, stumps, large branches, deep organic soils) take more time to ignite because it takes more heat to ignite the fuels due to their low surface area to mass ratio. Energy release is high and of longer duration. Fuel size also influences how fast the fuel will shed moisture. Light fuels will lose moisture more quickly because of their surface area to volume ratio. More of the fuel is affected by weather factors. Fuel Loading. Fuel loading refers to the mass of fuels in a given area, usually expressed in tonnes per hectare. Fuel loads may vary greatly across a landscape. Higher density fuel loads will burn at higher intensities if fuel moisture conditions make all of the fuel available for combustion. Fuel Spacing: Horizontal Spacing vs. Vertical Spacing. Fuel spacing refers to the arrangement of fuel on a landscape. Horizontal spacing refers to the continuity of the vegetation on a horizontal plane. Continuous vegetation provides a continuous fuel source, which enables fire to spread more easily. Horizontal spacing is usually described as ‘continuous’ or ‘patchy.’ In contrast, vertical spacing refers to the vertical distance between the surface fuels and the lowest branches of the tree. The fuels that make up the complex between the surface fuels and the crowns are known as ladder fuels. Vertical spacing is usually described as ‘continuous’ or ‘separated.’

Types of Wildland Fire Each type of wildland fire is associated with certain forest fuels. Ground fires burn under the forest floor. Fuels include litter (i.e. needles, twigs, etc.), duff (i.e. organic soils), and roots. Because these fuels are generally compact and protected from wind, ground fires are generally slow moving, very hot and difficult to extinguish. Surface fires burn at or above the ground. Fuels include ground debris, brush, young trees, branches of standing timber up to 25ft and windfall. Crown fires burn the crowns (i.e. tops and upper foliage) of standing timber and are usually associated with a surface fire. Passive crown fires burn into the crowns intermittently as a result of intense heat from a surface fire spreading into ladder fuels. Active crown fires travel through the crowns of trees with a well-defined wall of flame extending from the ground to above the treetops. These fires are difficult to control due to their high fire intensity and rate of spread.

Parts of a Fire The following anatomical descriptors are important to remember and understand. Head. The head is the portion of the fire that has the greatest rate of spread. It’s the direction in which the fire is growing, and is usually on the downwind or upslope part of the fire. Back. The back is opposite the head, and usually has the slowest rate of spread. It’s also known as the heel or the base. Flank. The flanks are any areas between the head and the back. The flanks are often referred to in relation to a geographic feature (e.g. north flank). Finger. A finger is an elongated burn area projecting from the main body of the fire. Fingers often occur on wind driven fires. Bay. A bay is a marked indentation in the fire perimeter. It’s usually located between two fingers. Island. An island is an area of an unburned fuel located within the fire perimeter. Spot. A spot fire is a fire ignited by firebrands outside the main perimeter of the fire. Short-range spotting can occur within 100m of the main fire or several kilometers ahead of the fire under windy conditions. Hot Spot. A hot spot or flare-up is any part of the fire that is particularly active.

Canadian Forest Fire Danger Rating System
Basic Wildland Fire Management Canadian Forest Fire Danger Rating System National system for rating risk of forest fires in Canada Major subsystems: Fire Weather Index System Fire Behaviour Prediction System

Fire Weather Index System
Basic Wildland Fire Management Fire Weather Index System Uses daily weather observations to estimate moisture content of 3 different fuel classes, and then uses these to generate a set of indicators for ROS, fuel consumption and intensity. Primary inputs are dry-bulb temperature, RH, 10m open wind and 24hr accumulated rain, which are recorded at 1200LST. However, codes and indices are considered representative of the peak burning period about 1600LST.

Fuel Moisture Codes Fuel Moisture Code Represents Time Lag 24hr Rain Needed to Lower Value Fine Fuel Moisture Code (FFMC) Surface litter 2/3 day 0.6mm Duff Moisture Code (DMC) 5-10cm duff 12 days 1.5mm Drought Code (DC) 10-20cm duff 52 days 2.9mm N.B. Time lag is time required for fuel to lose 2/3 of its moisture under standard drying conditions (i.e. 25oC and 45% RH) FFMC nominal depth up to 2cm and nominal fuel load 0.25kg/m2. DMC nominal depth 5-10cm and nominal dry fuel load 5kg/m2. DC nominal depth 10-20cm and nominal dry fuel load 25kg/m2. Fuel Moisture Codes are numerical ratings that express a relative valuation of moisture content for 3 classes of fuels. These codes relate to the amount of each fuel class that is available for combustion. Fuel Moisture Code values increase with lower fuel moisture - a high value means that the moisture content is low. It’s very important to understand that Fuel Moisture Codes provide a relative valuation of fuel moisture. A value in one location (e.g. Boreal forest in Wood Buffalo NP) may relate to fire behaviour very differently then the same value in a different fuel type (e.g. sub-alpine in Banff NP). Fine Fuel Moisture Code (FFMC). FFMC is a numeric rating of the moisture content of litter and other cured fine fuels. This code is an indicator of the relative ease of ignition and the flammability of fine fuel. Duff Moisture Code (DMC). DMC is a numeric rating of the average moisture content of loosely compacted organic layers of moderate depth. This code gives an indication of fuel consumption in moderate duff layers and medium-size woody material. Drought Code (DC). DC is a numeric rating of the average moisture content of deep, compact organic layers. This code is a useful indicator of seasonal drought effects on forest fuels and the amount of smouldering in deep duff layers and large logs.

Fire Behaviour Indices
Basic Wildland Fire Management Fire Behaviour Indices Initial Spread Index (ISI) is measure of expected rate of fire spread Buildup Index (BUI) is measure of amount of fuel available for combustion Fire Weather Index (FWI) is general index of fire danger Fire Behaviour Indexes are numerical ratings that express fire behaviour potential in terms of rate of spread, fuel availability and fire intensity. Fire Behaviour Index values increase as fire weather severity worsens. Like Fuel Moisture codes they provide a relative index not a direct relationship. Initial Spread Index (ISI). ISI is a numeric rating of the expected rate of fire spread. It combines the effects of wind and the FFMC on rate of spread without the influence of variable quantities of fuel. Buildup Index (BUI). BUI is a numeric rating of the total amount of fuel available for combustion. It combines the DMC and the DC. Fire Weather Index (FWI). FWI is a numeric rating of fire intensity. It combines the Initial Spread Index and the Buildup Index. It is suitable as a general index of fire danger throughout the forested areas of Canada.

Interpreting Codes & Indices
Basic Wildland Fire Management Interpreting Codes & Indices Component Rating Interpretation FFMC <77 Generally a fire will not start without a concerted effort >94 Almost 100% of ignition sources will ignite forest fuels DMC <20 Considered point of extinguishment, fire unlikely to be sustained >40 Fuels in this class is available for combustion DC <300 Very little involvement of this fuel in most fires >500 Extensive fuel involvement, intense fires, difficult mop-up ISI <10 When FFMC is less than 86, fire spread generally is not great >10 Rapid spread rates that escalate rapidly as FFMC increases BUI <40 Meduim-heavy fuels not a significant factor >100 Full involvement of fuels in this class

FWI 101 Given the following information, what type of fire behaviour do you expect? Fine Fuel Moisture Code (FFMC): Duff Moisture Code (DMC): Drought Code (DC): Initial Spread Index (ISI): Buildup Index (BUI): Estimated Time: 30 minutes Objective: To have the group consider FWI elements in relation to weather inputs and fire behaviour outputs The class should be split into groups based on fire experience and where they come from. Have the groups consider fire behaviour (i.e. fire type, intensity, etc.) and expected control concerns under a variety of fire moisture codes and fire behaviour indices. To challenge the group give them some codes and/or indices and have them tell you what the others would be (e.g. given a low DMC and a high BUI, what should the DC be?). For an advanced group you can introduce photos of various fuel types and have them discuss concerns with a given set of codes and indices.

Fire Behaviour Prediction System
Basic Wildland Fire Management Fire Behaviour Prediction System Based on observations of 495 fires, of which 409 were experimental burns. Experimental fires generally 0.3ha burned under low-moderate fire danger. 14 primary inputs divided into 5 categories: fuels, weather, topography, foliar moisture content, and type and duration of prediction. Primary outputs based on fire intensity equation, while secondary outputs calculated based on elliptical growth model. The FBP System provides quantitative estimates of potential head fire spread rate, fire intensity as well as fire descriptions. Rate of Spread (ROS). ROS is the predicted speed of the fire at the head of the fire and takes into account both crowning and spotting. It’s measured in m/min and is based on the ISI, BUI and several fuel-specific parameters such as phenological state (i.e. leafless or green) in deciduous trees, crown base height in coniferous trees, and percent curing in grasses. Head Fire Intensity (HFI). HFI is the predicted intensity, or energy output, of the fire at head of the fire. It has become one of the standard gauges by which fire managers estimate the difficulty of controlling a fire and select appropriate suppression methods. It’s measured in kW/m of fire front. Fire Type. Fire type provides a general description of the fire. It’s based on the Crown Fraction Burn (CFB), which is an output of the FBP System. If the CFB is less than 10%, then the fire is a surface fire. If the CFB is 90% or more, the fire is a continuous crown fire. If the CFB is between 10-90%, the fire is an intermittent crown fire.

Fire Intensity I = 300L2 where L is flame length (m) Fire intensity is directly related to to flame length. Firefighters can visually determine fire intensity by estimating flame length (not flame height) in metres, squaring it and multiplying it by a constant of For example, flame length of 3m will have a fire intensity of 2700kW/m, while 4m flame lengths will produce 4800kw/m of fire intensity. Students must also understand the importance of flame depth and flame height. Flame heights 1.2m or greater, including flame depths 2m or more are considered a fatal zone. Basically if a firefighter cannot see through the flame zone he/she should not be there.

Radiation Intensity 7 2.3 675/1.5m 16 3100/3.2m 1200/2m This chart demonstrates the importance of understanding fire intensity, and the direct effects radiation intensity has on the firefighter. 3m from flame front FI 3100kW/m RI 16kW/m2 Exposed skin will begin to blister 2m from flame front FI 1200kW/m RI 7kW/m2 Second degree burns after 90s with single layer of Nomex 1m from flame front FI 675kW/m RI 2.3kW/m2 Upper limit that FF can withstand without injury for short period Note: Radiation intensity can be considered as 1m by 1m pane of ‘glass’ being projected from the flaming front, thus it differs from fire intensity which is strictly a linear measurement.

Canadian Wildland Fire Information System
Basic Wildland Fire Management Canadian Wildland Fire Information System CWFIS creates fire weather and fire behaviour maps year-round, and hotspot maps throughout the season

Fire Behaviour Warning Signals
Basic Wildland Fire Management Fire Behaviour Warning Signals Watch out for: Change in wind speed and/or direction Light fuels Steep slopes Change in slope and/or aspect Change in fuel type The atmosphere provides us with a number of visual and intuitive clues, which, when pieced together, often point to extreme fire behaviour conditions. A prudent fire manager should be diligent in remembering these signals and be alert to their appearance in the atmosphere. Topography (i.e. steep slopes, narrow valleys, rolling debris) Dry, plentiful fuel, since fire intensity is directly related to the amount of fuel available to burn Gusty, variable wind, which produces erratic fire behaviour Cold front, which is associated with lightning, wind shifts, up-/downdrafts Upper ridge breakdown, which is associated with lightning, wind shifts, strong and gusty winds Unexpected downslope wind (i.e. associated with thunderstorms, glacial winds, etc.) High to Extreme codes and indices Spotting, which is indicative of updrafts and presence of convective column

Advisories & Warnings Fire Behaviour Advisory Flame lengths >3.5m Consider working flanks/rear Extreme Fire Behaviour Warning Flame lengths >3.5m and strengthening or changing winds Consider no action at all Wind Advisory Conditions forecast to present hazards Wildland fire suppression activities present many hazards to firefighters. When conditions warrant, a heads up may be issued to firefighters, helping them recognize that the weather and/or fire behaviour may create unsafe work conditions. The 3 types of heads up are: (1) Fire Behaviour Advisory, (2) Extreme Fire Behaviour Warning, and (3) Wind Advisory. Most advisories/warnings regarding fire behaviour are calculated assuming flat ground. If your particular fire is on a slope, be aware that fire intensities and rates of spread may be even greater than forecasted. Fire Behaviour Advisory. A fire behaviour advisory is issued when flame heights are predicted to be greater than 3.5m (i.e. 4000kW/m) for a particular fuel type. The fire intensity is considered to be the threshold above which firefighters performing direct attack actions may be at risk. A fire behaviour advisory will contain information related to the FBP System. It’s a heads up that can’t be ignored. If your fire receives a fire behaviour advisory, ensure your crew has: Assessed your fuel type to see if the advisory applies to your fire Considered limiting ground suppression to flanks and rear of fire Reassessed all escape routes and safety zones Ensured everyone on your crew has received a safety briefing Extreme Fire Behaviour Warning. An extreme fire behaviour warning indicates that fire behaviour is expected to exceed 3.5m flame heights (i.e. 4000kW/m) for a particular fuel type, and that conditions may rapidly escalate due to strengthening or changing winds. Common causes are dry cold fronts, severe localized thunderstorms with associated downdrafts, and development of low-level jet streams. It’s issued independent of any other advisory. This warning means conditions pose an extreme threat to worker safety and it can’t be ignored. If your fire receives an extreme fire behaviour warning, stop all action until your crew has: Recognized that fire intensity, rate of spread and direction will likely change Posted lookouts whose sole responsibility is to watch the fire and incoming weather Considered limiting action or not actioning at all Wind Advisory. A wind advisory is issued when conditions are forecasted to present hazards (e.g. falling trees, hazardous flying conditions, etc.) to workers. It includes severe turbulence, downdrafts and occasionally thunderstorms and hail. A wind advisory may be issued in the absence of aggressive fire behaviour. It’s issued independent of any other advisory. It’ll include a description of the type and intensity of the predicted disturbance (e.g. cold front with associated winds gusting to 50kph). A wind advisory is a safety heads up and can’t be ignored. If your fire receives a wind advisory, ensure your crew has: Assessed how predicted winds may create unacceptable risks to personnel Terminated activities that present unacceptable risk

Grasslands Fire Behaviour Potential
Basic Wildland Fire Management Grasslands Fire Behaviour Potential

Grasslands Fire Danger
Basic Wildland Fire Management Grasslands Fire Danger Degree of curing can drastically influence fire behaviour potential Fully cured grasses are particularly volatile

Grasslands Fire Behaviour Pocket Card
Basic Wildland Fire Management Grasslands Fire Behaviour Pocket Card Grasslands Fire Behaviour Pocket Card offers a practical field guide for quickly estimating the near worst care fire behaviour potential in grasslands. An estimate of the probable fire behaviour characteristics in grasslands can be obtained based solely on an on-site estimate of the prevailing wind speed. For example, if the wind raises dust and moves small branches, the estimated (10m) wind speed is 20-28kph, which is a Beaufort wind force of 4. Note assumptions (i.e. FFMC 93.2, flat terrain)

Grasslands Fire Behaviour Pocket Card
Basic Wildland Fire Management Grasslands Fire Behaviour Pocket Card If the Beaufort wind force is 4, expect (forward) rates of spread of 5.3km per hour and flame lengths of 5.2m. The Grasslands Fire Behaviour Pocket Card reinforces an awareness of the need for adopting safe work practices when attempting to contain grass fires. Note assumptions (i.e. constant wind direction, fully cured fuel)

Grasslands Firefighting
Basic Wildland Fire Management Grasslands Firefighting Safe work practices when engaged in grassland firefighting include: (a) ‘anchor and flank’ and (b) ‘1 foot in the green and 1 in the black’. Under no circumstances should a frontal assault be undertaken. Map shows fire spread pattern following a major change in wind direction. PC and SK developed Grasslands Firefighter course which is a 3d training session designed to train individuals in safe and effective response to grassland wildfires. Individuals trained in this program are recognized to participate in fire operations involving the grassland fuel type only. This is the only grassland specific fire operations course offered in Canada. For further information, please contact your local FMO.

Conclusion Fire Triangle consists of fuel, heat and oxygen Fire Behaviour Triangle consists of fuel characteristics, weather conditions and topography Canadian Forest Fire Danger Rating System provides relative index of fire risk in Canada A strong working knowledge of the basic factors influencing the fire environment is important and will assist trainees in recognising dangerous or potentially hazardous fireline situations and using appropriate and effective fire control tactics.

Objectives Upon completion of this section, you will be able to: Explain significance of cold fronts, thunderstorms and upper ridge breakdowns on fire environment Describe 4 weather factors and their influence on FB Describe 4 topographic factors and their influence on FB Describe 4 fuel factors and their influence on FB Name 3 types of fire List parts of fire Describe 6 components of FWI System Recognize fire behaviour warning signals

Basic Wildland Fire Management

Similar presentations

Presentation on theme: "Basic Wildland Fire Management"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Basic Wildland Fire Management

Similar presentations

Presentation on theme: "Basic Wildland Fire Management"— Presentation transcript:

Similar presentations

About project

Feedback