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Orientation Presentation Introduction to Danger Rating and the Fire Weather Index System.

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Presentation on theme: "Orientation Presentation Introduction to Danger Rating and the Fire Weather Index System."— Presentation transcript:

1 Orientation Presentation Introduction to Danger Rating and the Fire Weather Index System

2 Outline Introduction to Fire Danger Rating Introduction to the CFFRDS - break - Introduction to the FWI

3 Fire Danger A general term used to describe conditions of the fire environment including ease of ignition, rate of spread, difficulty of control and fire impact Indicates the ability of a fire to start, spread and do damage

4 Fire Danger There is no fire danger if a fire cannot start, spread and do damage Damage is largely based on human values such as life, property, timber, etc. Fire also has a natural, ecological role in the forest so fire can be beneficial and is not always damaging

5 Fire Danger Fixed factors that affect fire danger –fuel –topography –values at risk Variable factor –wind Fixed or variable –ignition sources

6 Fire Danger Rating Evaluation of factors that influence fire danger A system for fire danger rating evaluates the fire environment on regular intervals and in an objective way. Interpretation provides information and guidelines for fire management

7 Fire Danger Rating Systems An FDRS is used to solve fire management problems Each country and global region has unique fire problems Therefore the calculations and interpretations of an FDRS must be built or adapted to the local fire situation There is extensive research on FDR

8 Fire Danger Rating Systems Applications –Prevention –Pre-Suppression Planning –Suppression Decision Support –Seasonal Planning & Analysis –Wildfire Threat Assessment –Fire Statistics for Monitoring and Reporting

9 Fire Danger Rating Systems Best approach to developing a new FRDS is to take advantage of previous research and adapt to local conditions FDR research in Canada, US and Australia has been ongoing for about 75 years All 3 countries use a similar general approach (ie, weather and fuels)

10 Introduction to the CFFRDS CFFDRS

11 Canadian Forest Fire Danger Rating System Danger Rating Research Initiated in 1925 Current System Developed in Late 1960s Used in Canada, Alaska, Florida, New Zealand, Fiji Two Major Sub Systems –Fire Weather Index System –Fire Behavior Prediction System

12 Canadian Forest Fire Danger Rating System Risk of Ignition TopographyWeatherFuels Accessory Fuel Moisture System Fire Occurrence Prediction System CFFDRS Guides and Other Systems Developed by Fire Management and Fire Research Fire Weather Index System Fire Behavior Prediction System Fire Management Resources and Values at Risk Fire Management Problems and Opportunities Fire Management Decisions and Solutions

13 Canadian Fire Weather Index System Temperature RH Wind Rain Temperature RH Rain Wind Temperature Rain Fire Weather Observations DC Drought Code DMC Duff Moisture Code ISI Initial Spread Index BUI Buildup Index FWI Fire Weather Index FFMC Fine Fuel Moisture Code Fire Behavior Indexes Fuel Moisture Codes

14 Forest Fire Behavior Prediction System Spread Distances Flank & Back Fire Rates of Spread Flank & Back Fire Intensities Elliptical Fire Area & Perimeter Rate of Perimeter Growth Length-to Breadth Ratio FuelsWeatherTopography Foliar Moisture Type & Duration Fuel Type FWI, Wind Speed & Direction Slope & Direction Elevation, Lat, Long & Date Elapsed Time, Point or Line Ignition Canadian Forest Fire Behavior Prediction System PrimarySecondary Rate of Spread Fuel Consumption Head Fire Intensity Crown Fraction Burned Fire Description

15 Extreme High Moderate Fire Danger Classes Class FWIIgnitionSpreadControl Low 0 – 10UnlikelySlowEasy ReadilyRapidDifficult

16 Spatial Fire Management System (sFMS) Fire management information system GIS platform Fire science models (CFFDRS) Fire Weather Index (FWI) Fire Behaviour Prediction (FBP) Daily operations Functions as a set of ArcView extensions

17 Spatial Fire Management System (sFMS) Example outputs:

18 Spatial Fire Management System (sFMS) Requirements Computer hardware Computer software: ArcView with Spatial Analyst Weather station locations Daily local noon weather observations Elevation Fuels

19 Introduction to the FWI System

20 Outline Introduction Moisture Codes Behavior Indices Weather Measurements FWI calculation

21 FWI System evaluates the fire danger at any time based on the current and recent weather produce maximum amount of information with minimum amount of data. Used in fire management since 1970 although developed in Canada, FWI System can be adapted to other global regions (eg., New Zealand) Introduction

22 FWI System Inputs Required inputs to the FWI system are the: –temperature, –relative humidity, –precipitation –10 m wind speed –previous day’s FWI calculations All inputs measured at 12:00 Local Standard Time Introduction

23 FWI Structure Provides a relative measure of fuel moisture and fire activity Can be applied to any fuel type by calibration with fire behavior data Introduction

24 FWI Structure Components used individually and in combination Introduction Wind speedRHRainfallTemperature Inputs FFMCDMCDC Moisture Codes Behavior indices ISIBUI FWI

25 FWI Moisture Codes FFMCDMCDC ISIBUI FWI Rainfall RH Wind Speed Temperature Rainfall RH Temperature Rainfall Temperature

26 Moisture Codes Fine Fuel Moisture Code (FFMC) tracks the amount of moisture in the fine dead fuels on the forest floor. Duff Moisture Code (DMC) tracks the amount of moisture in the loosely compacted duff and small branchwood beneath the forest floor. Drought Code (DC) tracks the amount of moisture in the deeper compacted organic soil and larger branchwood and logs. FWI Moisture Codes

27 Moisture Content moisture content is the ratio between the mass of water and the mass of tissue in a quantity of fuel saturation moisture is the maximum amount of moisture a fuel can hold equilibrium moisture is the point at which the fuel’s moisture is equal to that of the surrounding air FWI Moisture Codes

28 Moisture Content vs. Moisture Code each moisture code corresponds directly do the actual moisture content of the fuel FWI Moisture Codes % Moisture Content Moisture Code Value

29 Wetting and Drying Phases The Moisture Codes are an accounting method to keep track of moisture content through the wetting and drying phases in the fuel layers. FWI Moisture Codes Surface Litter Upland Duff (organic soil or humus) Deep Duff

30 Wetting Phase Wetting phase adds moisture only if the amount of precipitation is greater than the threshold for a fuel class. FWI Moisture Codes As moisture content increases, the Fuel Moisture Codes decrease to represent a decrease in fire danger

31 Drying Phase Subtracts moisture lost through evaporation. Drying rate of fuel is exponential Fuel moisture will reach equilibrium point under constant conditions. FWI Moisture Codes As moisture content decreases, the Fuel Moisture Codes increase to represent an increase in fire danger

32 Drying Phase Time-lag constant is time required for fuels to lose 2/3 of available moisture under constant conditions Time-lag constant determines how quickly each of the fuel types will reach their equilibrium moisture levels. Each moisture code has a different time-lag constant. FWI Moisture Codes

33 Drying Phase FWI Moisture Codes

34 FFMC: Fine Fuel Moisture Code Measures moisture content in litter and other fine cured fules at a depth of 1-2cm. Indicates of the ease of ignition and flammability of fine fuels. FWI Moisture Codes

35 FFMC Inputs Temperature Relative Humidity Wind Speed Humidity Previous day’s FFMC FWI Moisture Codes

36 FFMC Scale FFMC has scale of 0-99 Fires seldom start when FFMC<70 Fire starts increase dramatically when FFMC reaches FFMC>90 is explosive burning conditions FWI Moisture Codes

37 FFMC Wetting & Drying Wetting phase threshold of 0.5 mm to account for tree canopy interception. Saturation (100%) corresponds to < 1 mm of water. Time-lag of 2/3 of a day. From saturation, FFMC takes only a few days to reach its ignition threshold level of 78. FWI Moisture Codes

38 FFMC Drying Phase FWI Moisture Codes under standard conditions

39 Diurnal FFMC Changes 12:00 weather used for 16:00 forecast can make hourly FFMC calculations with hourly weather data FWI Moisture Codes

40 DMC: Duff Moisture Code Tracks the moisture content in duff layers at a depth of 5-10 cm below the litter and medium sized woody fuel. Indicates the fuel consumption of woody fuels and in the duff layer. FWI Moisture Codes

41 DMC Inputs Temperature Relative Humidity Precipitation Previous day’s DMC FWI Moisture Codes

42 DMC Scale DMC scale has no upper bound. DMC is usually less than 150 Threshold DMC required for ignition of these fuels is 20 High fuel consumption at DMC=40. FWI Moisture Codes

43 DMC Wetting & Drying Wetting phase threshold of 1.4 mm due to interception by tree canopy and FFMC fuels. Time-lag of 15 days. From saturation, DMC takes a week or so to reach its ignition threshold level of 20. DMC has a longer memory than FFMC. FWI Moisture Codes

44 DMC Drying Phase FWI Moisture Codes under standard conditions

45 DC: Drought Code Tracks the moisture content in deep compacted organic matter at a depth of cm below the litter and logs. Indicates seasonal drought effects, total fuel consumption and smoldering in deep layers. It also indicates mop-up problems. FWI Moisture Codes

46 DC Inputs Temperature Precipitation Previous day’s DC FWI Moisture Codes

47 DC Scale DC scale has no upper bound. deep burning fires are not a concern when DC<300 deep burning peat fires become a problem when DC approaches 500 Maximum likely values under severe drought about FWI Moisture Codes

48 DC Wetting & Drying DC has a wetting threshold of 2.8 mm due to interception by the tree canopy and other fuels Saturation (400 %) corresponds to 100 mm water. Time-lag of 53 days. From saturation, the DC takes 65 days to reach its ignition threshold level of DC has longest memory. FWI Moisture Codes

49 DC Drying Phase FWI Moisture Codes under standard conditions

50 FWI Moisture Codes Summary Each code corresponds to a different fuel size or density class in the forest floor Each is calculated from yesterday’s code and today’s weather. Rain is added to moisture content only if the threshold precipitation value is exceeded. Different fuels take different amount of time to dry. FWI Moisture Codes

51 FWI Moisture Codes Summary FWI Moisture Codes FFMC DMC DC litter small branches, loosely compacted humus branches and logs, deep compacted humus Threshold precip. Appropriate Fuel class 0.5 mm 1.4 mm 2.8 mm Timelag constant. 18 hrs 15 days 53 days Scale unbounded usually < 150 unbounded usually < 800 Ignition threshold

52 FWI Behavior Indices are indicators of physical fire characteristics, or fire activity FFMCDMCDC ISIBUI FWI

53 ISI: Initial Spread Index Numerical rating of the spread rate of fire that can be expected soon after ignition. ISI is well correlated with spread rates of fires of all sizes across many different fuel types ISI is a function of windspeed and the FFMC. Varies between 0 and 70 ISI above 10 is generally considered high. FWI Behavior Indices

54 ISI Function ISI increases exponentially with windspeed Doubles with every 13 km/h increase in wind speed. FWI Behavior Indices Windspeed (km/h) Initial Spread Index FFMC 95 FFMC 90 FFMC

55 ISI in Different Fuels FWI Behavior Indices A grass fuel type A forest fuel type ISI ROS

56 BUI: Buildup Index The BUI is a numerical rating of the total fuel available for combustion. BUI is a function of the DMC and the DC, primarily controlled by the DMC DC only increases the BUI when deep organic layers become dry if DMC=0 then BUI=0, regardless of the DC value BUI greater than 60 is generally considered high. FWI Behavior Indices

57 BUI and Fuel Consumption FWI Behavior Indices Surface fuel consumption (kg/m 2 ) Build up Index

58 FWI: Fire Weather Index FWI is a numerical rating of fire intensity The FWI is suitable as a general index of fire danger FWI is a function of the BUI and the ISI. Maximum value of 130 FWI value greater than 25 is generally considered high. FWI Behavior Indices

59 Underlying Principle Each of the behavior indices corresponds to a variable in Byram’s line fire intensity equation: I = HWR where FWI estimates: I = energy output per unit length of fire front (kw/m) BUI estimates: W = weight of available fuel (kg/m 2 ) ISI estimates: R = rate of spread (m/min) and H = heat of combustion, (considered constant) FWI Behavior Indices

60 FWI Interpretation Various combinations of ISI’s and BUI’s can produce the same FWI For example, an FWI of 24 can result from combinations of: –ISI of 5 and BUI 200, or from –ISI 18 and BUI 24. FWI Behavior Indices

61 FWI Interpretation in Different Fuel Types FWI Behavior Indices Fire Behavior Indexes can also be interpreted by fuel type through calibration with field data. FWI 17 for both fires Jack pine Intensity of 950 kW/m Black Spruce Intensity of 12,700 kW/m

62 FWI Interpretation in Jack pine FWI Behavior Indices FWI 9 FWI 15

63 FWI Interpretation FWI 17 FWI 34

64 FWI Behavior Indices Summary Behavior indices are relative ratings of fire behavior Each index corresponds to a key characteristic of fire behavior: ISI: rate of spread BUI: amount of fuel consumed FWI: fire line intensity and general fire danger FWI intensity values interpreted individually, and in combination with other values. FWI Behavior Indices

65 Weather Measurements for the FWI System

66 Observing Practices Observing practices must be carefully specified if effective management decisions are to be based on the results. Wx Measurements

67 Time of Observations FWI based on weather observations taken at a standard time, usually noon Local Standard Time Indicative of conditions during period of peak afternoon fire activity Early enough to have indices available for operational purposes Wx Measurements

68 Accuracy of Measurement Temperature (nearest 0.5 degree Celsius) Relative Humidity (nearest 1 % point) Precipitation (nearest 0.2 mm) Wind Speed (nearest whole km/hr-average 10- minute period) Wx Measurements

69 Sudden Weather Changes Sudden weather changes occur frequently during early afternoon For local use, up to 1600 hrs LST, acceptable to determine a revised FWI to reflect new weather regime For record purposes, values at noon remain basic observations for the day Wx Measurements

70 Recording Practices Observations recorded directly on permanent record form Deviations of more that 15 minutes from regular time should be noted Observer write initial on records Wx Measurements

71

72 Missing Observations Key accuracy of FWI is continuous daily records An estimate of weather elements for missing day or days is required Missing values must be replaced by average or extrapolated values Wx Measurements

73 Location Standards FWI stations conform to WMO standards for agrocultural meteorological observations (WMO 1968) Wx Measurements

74 FWI Calculation

75 Methods of Calculation Standard set of tables Computer program FWI Calculation

76 Startup Moisture Code Values The standard default startup values are: FFMC = 85 DMC = 6 DC = 15 Startup values reflect saturated fuel conditions For Indonesia, these start up values were used after a weather station had received a 200 mm rain event. Adjusting the DMC and DC to unsaturated conditions is critical because of their long memory. FWI Calculation

77 Truthing Startup Values startup values can be obtained directly by: –take fuel sample at the location for which calculations are being made –calculate the moisture content of sample in laboratory –use moisture curves to calculate indices from moisture content FWI Calculation

78 Daily Calculations FWI system codes and indices calculated each day using the current day’s 12:00 LST weather, and yesterday’s moisture codes. Because of the “memory”-based nature of the FWI system, errors can accumulate over the course of the season Critical to keep consistent daily records. FWI Calculation

79 Forecasted Calculation FWI system values can be forecast by using current moisture codes and forecasted weather. Accuracy decreases rapidly after more than a two days. FWI Calculation

80 The basic calculation process Moisture codes wetting Moisture codes drying Behaviour indices FWI Calculation

81 Step 1, Is there rain? If there is rain, go to step 2. If there is no rain, go to step 5. FWI Calculation

82 Step 2 Rain effect on yesterday’s FFMC Open Table 1 Use yesterday’s FFMC to select row Use today’s rain to select column Enter rain code value in weather record FWI Calculation

83 Step 3 Rain effect on yesterday’s DMC Open Table 3. Use yesterday’s DMC to select row Use today’s rain to select column Enter rain code value in weather record FWI Calculation

84 Step 4 Rain effect on yesterday’s DC Open Table 5 Use yesterday’s DC to select row Use today’s rain to select column Enter rain code value in weather record FWI Calculation

85 Step 5 FFMC Drying Use temperature to select between tables 2A- 2P Use RH & Wind to select row Use Rain code or yesterday’s FFMC to select colum Enter new FFMC code in weather record FWI Calculation

86 Step 6 DMC Drying Open Table 4 Use temperature and RH to select row Use current month to select column Enter drying code on weather record Add drying code to rain code or yesterday’s DMC Enter new DMC code in weather record FWI Calculation

87 Step 7 DC Drying Open Table 6 Use temperature to select row Use current month to select column Enter drying code on weather record Add drying code to rain code or yesterday’s DC Enter new DC code in weather record FWI Calculation

88 Step 8 ISI: Initial Spread Index Open Table 7 Use wind to select row Use FFMC to select column Enter ISI in weather record FWI Calculation

89 Step 9 BUI: Buildup Index Open Table 8 Use DMC to select row Use DC to select column Enter BUI in weather record FWI Calculation

90 Step 10 FWI: Fire Weather Index Open Table 9 Use ISI to select row Use BUI to select column Enter FWI in weather record FWI Calculation

91 Repeat as necessary FWI Calculation


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