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NAME
r.ros - 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, fire
SYNOPSIS
r.ros
r.ros help
r.ros [-vs] model=string [moisture_1h=string] [moisture_10h=string] [moisture_100h=string] moisture_live=string [velocity=string] [direction=string] [slope=string] [aspect=string] [elevation=string] output=string [--overwrite] [--verbose] [--quiet]
Flags:
- -v
- Run verbosely
- -s
- Also produce maximum SPOTTING distance
- --overwrite
- Allow output files to overwrite existing files
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- model=string
- Name of raster map containing fuel MODELs
- moisture_1h=string
- Name of raster map containing the 1-HOUR fuel MOISTURE (%)
- moisture_10h=string
- Name of raster map containing the 10-HOUR fuel MOISTURE (%)
- moisture_100h=string
- Name of raster map containing the 100-HOUR fuel MOISTURE (%)
- moisture_live=string
- Name of raster map containing LIVE fuel MOISTURE (%)
- velocity=string
- Name of raster map containing midflame wind VELOCITYs (ft/min)
- direction=string
- Name of raster map containing wind DIRECTIONs (degree)
- slope=string
- Name of raster map containing SLOPE (degree)
- aspect=string
- Name of raster map containing ASPECT (degree, anti-clockwise from E)
- elevation=string
- Name of raster map containing ELEVATION (m) (required w/ -s)
- output=string
- Name of raster map to contain results (several new layers)
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
- 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
- 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
- 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
- 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
- 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
- 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
- Name of an existing raster map
layer in the user's current mapset search path containing wind direction,
clockwise from north (degree).
- slope=name
- Name of
an existing raster map layer in the user's current mapset search path containing
topographic slope (degree).
- aspect=name
- 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
- Name of an existing raster map
layer in the user's current mapset search path containing elevation (meters).
- output=name
- 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
r.ros can be run either non-interactively or interactively. The program
is run interactively if the user types r.ros without specifying flag settings
and parameter values on the command line. In this case, the user will be
prompted for input. The program will be run non-interactively if the user
specifies the names of raster map layers and any desired options on the
command line, using the form:
r.ros [-vs] 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
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 using the formula:
moisture_100h = moisture_10h + 1 = moisture_1h + 2.
However at least one of them should be given. Options velocity=name
and direction=name must be in pair, whether given or not. If none
is given, the program will assume a no-wind condition. Options slope=name
and aspect=name must be in pair, whether given or not. If none is
given, the program will assume a topographically flat condition. Option
elevation=name must be given if -s option is used.
EXAMPLE
Assume we have inputs, the following generates ROSes and spotting distances:
r.ros -vs 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.
SEE ALSO
g.region,
r.slope.aspect,
r.spread
REFERENCES
Albini, F. A., 1976, Computer-based models of wildland fire behavior:
a user's manual, USDA Forest Service, Intermountain Forest and Range Experiment
Station, Ogden, Utah.
Andrews, P. L., 1986, BEHAVE: fire behavior prediction and fuel
modeling system -- BURN subsystem, Part 1, USDA Forest Service, Intermountain
Research Station, Gen. Tech. Rep. INT-194, Ogden, Utah.
Chase, Carolyn, H., 1984, Spotting distance from wind-driven
surface fires -- extensions of equations for pocket calculators, US Forest
Service, Res. Note INT-346, Ogden, Utah.
Lathrop, Richard G. and Jianping Xu, A geographic information
system-based approach for calculating spotting distance. (in preparation)
Rothermel, R. E., 1972, A mathematical model for predicting
fire spread in wildland fuels, USDA Forest Service, Intermountain Forest
and Range Experiment Station, Res. Pap. INT-115, Ogden, Utah.
Rothermel, Richard, 1991, Predicting behavior and size of crown
fires in the northern Rocky Mountains, US Forest Service, Res. Paper INT-438,
Ogden, Utah.
Xu, Jianping, 1994, Simulating the spread of wildfires using
a geographic information system and remote sensing, Ph. D. Dissertation,
Rutgers University, New Brunswick, New Jersey.
AUTHOR
Jianping Xu, Center for Remote Sensing and Spatial Analysis, Rutgers University.
Last changed: $Date: 2009-05-23 01:12:36 -0700 (Sat, 23 May 2009) $
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