Provided by: grass-doc_8.3.0-1_all 
NAME
r.ros - Generates rate of spread raster maps.
Generates three, or four raster map layers showing the base (perpendicular) rate of spread
(ROS), the maximum (forward) ROS, the direction of the maximum ROS, and optionally the
maximum potential spotting distance for fire spread simulation.
KEYWORDS
raster, fire, spread, rate of spread, hazard, model
SYNOPSIS
r.ros
r.ros --help
r.ros model=name [moisture_1h=name] [moisture_10h=name] [moisture_100h=name]
moisture_live=name [velocity=name] [direction=name] [slope=name] [aspect=name]
[elevation=name] base_ros=name max_ros=name direction_ros=name [spotting_distance=name]
[--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
model=name [required]
Raster map containing fuel models
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
Raster map containing the 1-hour fuel moisture (%)
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
Raster map containing the 10-hour fuel moisture (%)
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
Raster map containing the 100-hour fuel moisture (%)
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 [required]
Raster map containing live fuel moisture (%)
Name of an existing raster map layer in the user’s current mapset search path
containing live (herbaceous) fuel moisture (percentage content multiplied by 100).
velocity=name
Raster map containing midflame wind velocities (ft/min)
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 raster map containing wind directions (degree)
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 raster map containing slope (degree)
Name of an existing raster map layer in the user’s current mapset search path
containing topographic slope (degree).
aspect=name
Raster map containing aspect (degree, CCW from E)
Name of an existing raster map layer in the user’s current mapset search path
containing topographic aspect, counterclockwise from east (GRASS convention) in
degrees.
elevation=name
Raster map containing elevation (m, required for spotting)
Name of an existing raster map layer in the user’s current mapset search path
containing elevation (meters). Option is required from spotting distance computation
(when spotting_distance option is provided)
base_ros=name [required]
Output raster map containing base ROS (cm/min)
Base (perpendicular) rate of spread (ROS)
max_ros=name [required]
Output raster map containing maximal ROS (cm/min)
The maximum (forward) rate of spread (ROS)
direction_ros=name [required]
Output raster map containing directions of maximal ROS (degree)
The direction of the maximal (forward) rate of spread (ROS)
spotting_distance=name
Output raster map containing maximal spotting distance (m)
The maximal potential spotting distance (requires elevation raster map to be
provided).
DESCRIPTION
r.ros is part of the wildfire simulation toolset. Preparational steps for the fire
simulation are the calculation of the rate of spread (ROS) with r.ros, and the creating of
spread map with r.spread. Eventually, the fire path(s) based on starting point(s) are
calculated with r.spreadpath.
r.ros is used for fire (wildfire) modeling. The input is fuel model and moisture and the
outputs are rate of spread (ROS) values. The module generates the base ROS value, maximum
ROS value, direction of the maximum ROS, and optionally the maximum potential spotting
distance of wildfire for each raster cell in the current geographic region. These three
or four raster map layers serve as inputs for the r.spread module which is the next step
in fire simulation.
The r.ros module and two related modules r.spread, and r.spreadpath can be used not only
for wildfire modeling but also generally to simulate other events where spread of
something is involved and elliptical spread is appropriate.
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). More information on r.ros and r.spread
can be found in Xu (1994).
The output parameter is a basename (prefix) for all generated raster maps and each map
gets a unique suffix:
• .base for the base (perpendicular) ROS (cm/minute)
• .max for the maximum (forward) ROS (cm/minute),
• .maxdir for the direction of the maximum ROS, clockwise from north (degree), and
optionally
• .spotdist for the maximum potential spotting distance (meters).
So, if the output parameter is blackforest_ros, r.ros creates blackforest_ros.base,
blackforest_ros.max, blackforest_ros.maxdir, and (optionally) blackforest_ros.spotdist
raster maps.
If only one or two of the options moisture_1h, moisture_10h, and moisture_100h are given,
the module 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 both given or both omitted. If none is given, the
module will assume a no-wind condition.
Options slope and aspect must be also given together. If none is given, the module will
assume a topographically flat condition. Option elevation must be given if -s (spotting)
flag 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=ros
NOTES
1 r.ros is supposed to be run before running r.spread module. The combination of
these two modules forms a simulation of the spread of wildfires.
2 The user should be sure that the inputs to r.ros are 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 module. As far as the user just use r.ros together with r.spread, there
is no need to concern about these output units.
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, Jersey (ref).
SEE ALSO
g.region, r.slope.aspect, r.spread, r.spreadpath Sample data download: firedemo.sh (run
this script within the "Fire simulation data set" location).
AUTHOR
Jianping Xu, Center for Remote Sensing and Spatial Analysis, Rutgers University.
SOURCE CODE
Available at: r.ros source code (history)
Accessed: Tuesday Jun 27 11:13:09 2023
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