How to create parameters to run r.ros

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r.ros' parameters

  • model Name of an existing raster map layer in the user's current mapset search path containing the NFFL standard fuel models defined by the USDA Forest Service. Valid values are 1-13; other numbers are recognized as barriers by r.ros

If you don't dispose of a fuel map, you can try to define the fuel by your expert judgement, with the help of this publication. Another useful reference is the conversion table here.

  • moisture_1h Name of an existing raster map layer in the user's current mapset search path containing the 1-hour (<.25") fuel moisture (percentage content multiplied by 100)
  • moisture_10h Name of an existing raster map layer in the user's current mapset search path containing the 10-hour (.25-1") fuel moisture (percentage content multiplied by 100)
  • moisture_100h Name of an existing raster map layer in the user's current mapset search path containing the 100-hour (1-3") fuel moisture (percentage content multiplied by 100)

This is an estimation of moisture content in dead fuel. Small dead fuels are defined as “those dead fuels that take ten hours to lose 63% of the difference between their initial moisture content and equilibrium moisture content in atmosphere of constant temperature and humidity”. This quantity gives the ten hours lag fuel (moisture_10h). The quantities moisture_1h and moisture_100h, respectively referring to 1 hour and 100 hours, are expressed likewise. The relationship among these quantities is expressed by the empirical equation:

moisture_100h = moisture_10h + 1 = moisture_1h + 2

If the options moisture_1h=name, moisture_10h=name, and moisture_100h=name are partially given, the program will assign values to the missing option.

These parameters are either estimated in laboratory or deduced by empirical correlations, such as for example:

moisture_1h [%] = 147.2 ( 101 - FFMC ) / ( 59.5 + FFMC )

where FFMC is the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System, and is expression of the water content of litter and fine dead fuels. It provides a direct indication of the ignition and flammability of fine dead fuels. See for example this and this.

  • moisture_live Name of an existing raster map layer in the user's current mapset search path containing live (herbaceous) fuel fuel moisture (percentage content multiplied by 100)

This parameter refers to the moisture content in live fuel, and depends on the state of vegetation, which has a seasonal trend. It may vary from 50 in dry season, up to 500 in wet season. It should be calibrated on the basis of the vegetation present in the area and the climatic region.

Fire simulation data

You may want to check with the "Fire simulation data" set from http://grass.osgeo.org/download/sample-data

Example

Here is a synthetic example using the North Carolina dataset. The sample "Fire simulation data" linked above will be more realistic, this is provided for quick testing and visualization.

# Start GRASS 6 X-monintor
d.mon x0
d.resize w=800 h=802
d.font Arial

g.region rast=elevation

#prepare colored shaded relief backdrop image
r.his h=elevation i=elevation_shade r=ele.r g=ele.g b=ele.b
r.composite r=ele.r g=ele.g b=ele.b out=elevation.his

# prep synthetic inputs
r.mapcalc cent=100
r.mapcalc twenty=20
r.mapcalc winddirn=45
r.mapcalc windspeed=1519   # 15 knots

r.in.poly in=- out=source << EOF
P
   634292  217561
= 1
EOF

# Rough class matching
r.reclass in=landuse96_28m out=USDA.model << EOF
2 = 1
3 = 2
4 = 1
6 = 3
7 = 4
8 9 = 5
10 11 = 9
15 = 8
18 = 10
EOF

r.ros -s model=USDA.model moisture_1h=twenty moisture_live=cent \
  velocity=windspeed direction=winddirn \
  slope=slope aspect=aspect elevation=elevation \
  output=ros

r.spread -sd max=ros.max dir=ros.maxdir base=ros.base \
  spot_dist=ros.spotdist w_speed=windspeed f_mois=twenty \
  start=source backdrop=elevation.his output=tmp.rspread \
  x_output=tmp.rspread.x  y_output=tmp.rspread.y

r.null tmp.rspread.x setnull=0
r.null tmp.rspread.y setnull=0

See also