fbp: Fire Behavior Prediction System function

Description

fbp calculates the outputs from the Canadian Forest Fire Behavior Prediction (FBP) System (Forestry Canada Fire Danger Group 1992) based on given fire weather and fuel moisture conditions (from the Canadian Forest Fire Weather Index (FWI) System (Van Wagner 1987)), fuel type, date, and slope. Fire weather, for the purpose of FBP System calculation, comprises observations of 10 m wind speed and direction at the time of the fire, and two associated outputs from the Fire Weather Index System, the Fine Fuel Moisture Content (FFMC) and Buildup Index (BUI). FWI System components can be calculated with the sister function fwi.

Usage

fbp(input, output="Primary",m=NULL,cores=1)

Arguments

input

The input data, a data.frame containing fuel types, fire weather component, and slope (see below). Each vector of inputs defines a single FBP System prediction for a single fuel type and set of weather conditions. The data.frame can be used to evaluate th

output

FBP output offers 3 options (see details in Values section): ll{ Outputs Number of outputs Primary (default) 8 Secondary 34 All 42 }

Optimal number of pixels at each iteration of computation when nrow(input) >= 1000. Default m = NULL, where the function will assign m = 1000 when nrow(input) is between 1000 and 500,000, and m = 3

cores

Number of CPU cores (integer) used in the computation, default is 1. By signing cores > 1, the function will apply parallel computation technique provided by the foreach package, which significantly reduces the computation time

Value

fbp returns a dataframe with primary, secondary, or all output variables, a combination of the primary and secondary outputs. Primary FBP output includes the following 8 variables:
CFBCrown Fraction Burned by the head fire
CFCCrown Fuel Consumption [kg/m^2]
FDFire description (S=Surface, I=Intermittent, C=Crown)
HFIHead Fire Intensity [kW/m]
RAZSpread direction azimuth [degrees]
ROSEquilibrium Head Fire Rate of Spread [m/min]
SFCSurface Fuel Consumption [kg/m^2]
TFCTotal Fuel Consumption [kg/m^2]
Secondary FBP System outputs include the following 34 raster layers. In order to calculate the reliable secondary outputs, depending on the outputs, optional inputs may have to be provided.
BEBUI effect on spread rate
SFSlope Factor (multiplier for ROS increase upslope)
ISIInitial Spread Index
FFMCFine fuel moisture code [FWI System component]
FMCFoliar Moisture Content [%]
DoJulian Date of minimum FMC
RSOCritical spread rate for crowning [m/min]
CSICritical Surface Intensity for crowning [kW/m]
FROSEquilibrium Flank Fire Rate of Spread [m/min]
BROSEquilibrium Back Fire Rate of Spread [m/min]
HROStHead Fire Rate of Spread at time hr [m/min]
FROStFlank Fire Rate of Spread at time hr [m/min]
BROStBack Fire Rate of Spread at time hr [m/min]
FCFBFlank Fire Crown Fraction Burned
BCFBBack Fire Crown Fraction Burned
FFIEquilibrium Spread Flank Fire Intensity [kW/m]
BFIEquilibrium Spread Back Fire Intensity [kW/m]
FTFCFlank Fire Total Fuel Consumption [kg/m^2]
BTFCBack Fire Total Fuel Consumption [kg/m^2]
DHHead Fire Spread Distance after time hr [m]
DBBack Fire Spread Distance after time hr [m]
DFFlank Fire Spread Distance after time hr [m]
TITime to Crown Fire Initiation [hrs since ignition]
FTITime to Flank Fire Crown initiation [hrs since ignition]
BTITime to Back Fire Crown initiation [hrs since ignition]
LBLength to Breadth ratio
LBtLength to Breadth ratio after elapsed time hr
WSVNet vectored wind speed [km/hr]
TROS*Equilibrium Rate of Spread at bearing theta [m/min]
TROSt*Rate of Spread at bearing theta at time t [m/min]
TCFB*Crown Fraction Burned at bearing theta
TFI*Fire Intensity at bearing theta [kW/m]
TTFC*Total Fuel Consumption at bearing theta [kg/m^2]
TTI*Time to Crown Fire initiation at bearing theta [hrs since ignition]
*These outputs represent fire behaviour at a point on the perimeter of an elliptical fire defined by a user input angle theta. theta represents the bearing of a line running between the fire ignition point and a point on the perimeter of the fire. It is important to note that in this formulation the theta is a bearing and does not represent the angle from the semi-major axis (spread direction) of the ellipse. This formulation is similar but not identical to methods presented in Wotton et al (2009) and Tymstra et al (2009).

Details

The Canadian Forest Fire Behavior Prediction (FBP) System (Forestry Canada Fire Danger Group 1992) is a subsystem of the Canadian Forest Fire Danger Rating System, which also includes the Canadian Forest Fire Weather Index (FWI) System. The FBP System provides quantitative estimates of head fire spread rate, fuel consumption, fire intensity, and a basic fire description (e.g., surface, crown) for 16 different important forest and rangeland types across Canada. Using a simple conceptual model of the growth of a point ignition as an ellipse through uniform fuels and under uniform weather conditions, the system gives, as a set of secondary outputs, estimates of flank and back fire behavior and consequently fire area perimeter length and growth rate. The FBP System evolved since the mid-1970s from a series of regionally developed burning indexes to an interim edition of the nationally develop FBP system issued in 1984. Fire behavior models for spread rate and fuel consumption were derived from a database of over 400 experimental, wild and prescribed fire observations. The FBP System, while providing quantitative predictions of expected fire behavior is intended to supplement the experience and judgment of operational fire managers (Hirsch 1996). The FBP System was updated with some minor corrections and revisions in 2009 (Wotton et al. 2009) with several additional equations that were initially not included in the system. This fbp function included these updates and corrections to the original equations and provides a complete suite of fire behavior prediction variables. Default values of optional input variables provide a reasonable mid-range setting. Latitude, longitude, elevation, and the date are used to calculate foliar moisture content, using a set of models defined in the FBP System; note that this latitude/longitude-based function is only valid for Canada. If the Foliar Moisture Content (FMC) is specified directly as an input, the fbp function will use this value directly rather than calculate it. This is also true of other input variables. Note that Wind Direction (WD) is the compass direction from which wind is coming. Wind azimuth (not an input) is the direction the wind is blowing to and is 180 degrees from wind direction; in the absence of slope, the wind azimuth is coincident with the direction the head fire will travel (the spread direction azimuth, RAZ). Slope aspect is the main compass direction the slope is facing. Slope azimuth (not an input) is the direction a head fire will spread up slope (in the absence of wind effects) and is 180 degrees from slope aspect (Aspect). Wind direction and slope aspect are the commonly used directional identifiers when specifying wind and slope orientation respectively. The input theta specifies an angle (given as a compass bearing) at which a user is interested in fire behavior predictions; it is typically some angle off of the final spread rate direction since if for instance theta=RAZ (the final spread azimuth of the fire) then the rate of spread at angle theta (TROS) will be equivalent to ROS.

References

1. Hirsch K.G. 1996. Canadian Forest Fire Behavior Prediction (FBP) System: user's guide. Nat. Resour. Can., Can. For. Serv., Northwest Reg., North. For. Cent., Edmonton, Alberta. Spec. Rep. 7. 122p. 2. Forestry Canada Fire Danger Group. 1992. Development and structure of the Canadian Forest Fire Behavior Prediction System. Forestry Canada, Ottawa, Ontario Information Report ST-X-3. 63 p. http://cfs.nrcan.gc.ca/pubwarehouse/pdfs/10068.pdf 3. Wotton, B.M., Alexander, M.E., Taylor, S.W. 2009. Updates and revisions to the 1992 Canadian forest fire behavior prediction system. Nat. Resour. Can., Can. For. Serv., Great Lakes For. Cent., Sault Ste. Marie, Ontario, Canada. Information Report GLC-X-10, 45p. http://publications.gc.ca/collections/collection_2010/nrcan/Fo123-2-10-2009-eng.pdf 4. Tymstra, C., Bryce, R.W., Wotton, B.M., Armitage, O.B. 2009. Development and structure of Prometheus: the Canadian wildland fire growth simulation Model. Nat. Resour. Can., Can. For. Serv., North. For. Cent., Edmonton, AB. Inf. Rep. NOR-X-417.

Examples

Run this code

library(cffdrs)
# The dataset is the standard test data for FPB system
# provided by Wotton et al (2009)
data("test_fbp")
head(test_fbp)
#  id FuelType LAT LONG ELV FFMC BUI   WS WD GS  Dj  D0         hr PC PDF GFL
#1  1      C-1  55  110  NA   90 130 20.0  0 15 182  NA 0.33333333 NA  NA  NA
#2  2       C2  50   90  NA   97 119 20.4  0 75 121  NA 0.33333333 NA  NA  NA
#3  3      C-3  55  110  NA   95  30 50.0  0  0 182  NA 0.08333333 NA  NA  NA
#4  4      C-4  55  105 200   85  82  0.0 NA 75 182  NA 0.50000000 NA  NA  NA
#5  5       c5  55  105  NA   88  56  3.4  0 23 152 145 0.50000000 NA  NA  NA
# cc theta Accel Aspect BUIEff CBH CFL ISI
#1 NA     0     1    270      1  NA  NA   0
#2 NA     0     1    315      1  NA  NA   0
#3 NA     0     1    180      1  NA  NA   0
#4 NA     0     1    315      1  NA  NA   0
#5 NA     0     1    180      1  NA  NA   0

#Primary output (default)
fbp(test_fbp)
#or
fbp(test_fbp,output="Primary") 
#or 
fbp(test_fbp,"P")
#Secondary output          
fbp(test_fbp,"Secondary")
#or
fbp(test_fbp,"S")
#All output          
fbp(test_fbp,"All")
#or
fbp(test_fbp,"A")
#For a single record:
fbp(test_fbp[7,])  	
#For a section of the records:
fbp(test_fbp[8:13,])	
#fbp function produces the default values if no data is fed to
#the function:
fbp()

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