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NAME

r.ros - Generates rate of spread raster map layers.
Generates three, or four raster map layers showing 1) the base (perpendicular) rate of spread (ROS), 2) the maximum (forward) ROS, 3) the direction of the maximum ROS, and optionally 4) the maximum potential spotting distance.

KEYWORDS

raster, rate of spread

SYNOPSIS

r.ros
r.ros help
r.ros [-s] model=name [moisture_1h=name] [moisture_10h=name] [moisture_100h=name] moisture_live=name [velocity=name] [direction=name] [slope=name] [aspect=name] [elevation=name] output=name [--overwrite] [--verbose] [--quiet]

Flags:

-s
Also produce maximum SPOTTING distance
--overwrite
Allow output files to overwrite existing files
--verbose
Verbose module output
--quiet
Quiet module output

Parameters:

model=name
Name of raster map containing fuel MODELs
moisture_1h=name
Name of raster map containing the 1-HOUR fuel MOISTURE (%)
moisture_10h=name
Name of raster map containing the 10-HOUR fuel MOISTURE (%)
moisture_100h=name
Name of raster map containing the 100-HOUR fuel MOISTURE (%)
moisture_live=name
Name of raster map containing LIVE fuel MOISTURE (%)
velocity=name
Name of raster map containing midflame wind VELOCITYs (ft/min)
direction=name
Name of raster map containing wind DIRECTIONs (degree)
slope=name
Name of raster map containing SLOPE (degree)
aspect=name
Name of raster map containing ASPECT (degree, anti-clockwise from E)
elevation=name
Name of raster map containing ELEVATION (m) (required w/ -s)
output=name
Name prefix for output raster maps (.base, .max, .maxdir)

DESCRIPTION

r.ros generates the base ROS value, maximum ROS value, direction of the maximum ROS, and optionally the maximum potential spotting distance of a wildfire for each raster cell in the current geographic region. The calculation of the two ROS values for each raster cell is based on the Fortran code by Pat Andrews (1983) of the Northern Forest Fire Laboratory, USDA Forest Service. The direction of the maximum ROS results from the vector addition of the forward ROS in wind direction and that in upslope direction. The spotting distance, if required, will be calculated by a separate function, spot_dist(), which is based on Lathrop and Xu (in preparation), Chase (1984) and Rothermel (1991). These three or four raster map layers serve as inputs for another GRASS raster program r.spread. More information on r.ros and r.spread can be found in Xu (1994).

Parameters

model
Name of an existing raster map layer in the user's current mapset search path containing the standard fuel models defined by the USDA Forest Service. Valid values are 1-13; other numbers are recognized as barriers by r.ros.
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).
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).
velocity
Name of an existing raster map layer in the user's current mapset search path containing wind velocities at half of the average flame height (feet/minute).
direction
Name of an existing raster map layer in the user's current mapset search path containing wind direction, clockwise from north (degree).
slope
Name of an existing raster map layer in the user's current mapset search path containing topographic slope (degree).
aspect
Name of an existing raster map layer in the user's current mapset search path containing topographic aspect, counter-clockwise from east (GRASS convention) (degree).
elevation
Name of an existing raster map layer in the user's current mapset search path containing elevation (meters).
output
Prefix of new raster map layers in the user's current mapset to contain
1) the base (perpendicular) ROS (cm/minute);
2) the maximum (forward) ROS (cm/minute),
3) the direction of the maximum ROS, clockwise from north (degree), and optionally
4) the maximum potential spotting distance (meters).
If 'my_ros' is given as the output name, then r.ros automatically assigns 'my_ros.base', 'my_ros.max', 'my_ros.maxdir', and optionally, 'my_ros.spotdist' as the names for the actual output map layers.

OPTIONS

If the options moisture_1h, moisture_10h, and moisture_100h are partially given, the program will assign values to the missing option using the formula:

moisture_100h = moisture_10h + 1 = moisture_1h + 2.
However at least one of them should be given. Options velocity and direction must be in pair, whether given or not. If none is given, the program will assume a no-wind condition. Options slope and aspect must be in pair, whether given or not. If none is given, the program will assume a topographically flat condition. Option elevation must be given if -s option is used.

EXAMPLES

Assume we have inputs, the following generates ROSes and spotting distances:
r.ros -s model=fire_model moisture_1h=1hour_moisture moisture_live=live_moisture
velocity=wind_speed direction=wind_direction
slope=slope aspect=aspect elevation=elevation output=my_ros

NOTES

  1. r.ros is supposed to be run before running another GRASS program r.spread. The combination of the two forms a simulation of the spread of wildfires.
  2. The inputs to r.ros should be in proper units.
  3. The output units for the base and maximum ROSes are in cm/minute rather than ft/minute, which is due to that a possible zero ft/minute base ROS value and a positive integer ft/minute maximum ROS would result in calculation failure in the r.spread program.
  4. The user needs to provide only ONE output name even the program actually generates THREE or FOUR map layers.
  5. The rules for optional parameters must be followed.

REFERENCES

SEE ALSO

g.region, r.slope.aspect, r.spread

AUTHOR

Jianping Xu, Center for Remote Sensing and Spatial Analysis, Rutgers University.

Last changed: $Date: 2009-07-15 02:13:03 -0700 (Wed, 15 Jul 2009) $


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