GRASS GIS manual: r.lfp

NAME

r.lfp - Calculates the longest flow path for a given outlet point using the r.stream.distance addon.

KEYWORDS

SYNOPSIS

r.lfp

r.lfp --help

r.lfp input=name output=name coordinates=east,north [--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:

input=name [required]: Name of input drainage direction raster map
output=name [required]: Name for output longest flow path raster map
coordinates=east,north [required]: Coordinates of outlet point

DESCRIPTION
NOTES
EXAMPLES
- Workflow example
- North Carolina sample dataset example
SEE ALSO
AUTHOR

DESCRIPTION

r.lfp calculates the longest flow path for a given outlet point and creates a new raster map with a thin line representing the longest flow path. This module requires the r.stream.distance addon.

r.lfp creates a longest flow path raster map using a drainage direction raster map and the coordinates of an outlet point. The module internally runs r.stream.distance twice to calculate flow length downstream and upstream raster maps, and combines them to get the longest flow path. An input drainage map can be created using r.watershed or r.stream.extract.

EXAMPLES

Workflow example

r.watershed elevation=elev drainage=drain
r.water.outlet input=drain output=basin coordinates=-888857.11,1117788.38
r.lfp input=drain output=lfp coordinates=-888857.11,1117788.38

North Carolina sample dataset example

# set computational region
g.region raster=elevation -p

# calculate drainage directions
r.watershed elevation=elevation drainage=drain_directions

# calculate outlet point related watershed
r.water.outlet input=drain_directions output=basin coordinates=642455,222614

# calculate longest flow path
r.lfp input=drain_directions output=lfp coordinates=642455,222614