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r.basin - Morphometric characterization of river basins


raster, hydrology, watershed


r.basin --help
r.basin [-ac] map=name prefix=prefix coordinates=east,north dir=name [threshold=threshold] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Use default threshold (1km^2)
No maps output
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


map=name [required]
Name of elevation raster map
prefix=prefix [required]
output prefix (must start with a letter)
coordinates=east,north [required]
coordinates of the outlet (east,north)
dir=name [required]
Directory where the output will be found

Table of contents


r.basin generates the main morphometric parameters of the basin starting from the digital elevation model and the coordinates of the basin's closing section (outlet). Important: r.basin works in projected locations, geographic or xy-locations are not supported.

The closing section's coordinates must belong to the river network generated by It is suggested to run it beforehand. In GRASS GIS 7, r.basin has been improved to take in input coordinates not exactly belonging to the river network (but not too far from it). It basically snaps to the closest point belonging to the network. This feature is experimental and might not produce the expected result. To check if the snapped outlet is acceptable, at the end of the computation, two outlet vector maps are produced: the one with the coordinates inserted by the user and the snapped one. If the user is not happy with this latter, should tweak the coordinates to match with the river network.

Morphometric parameters of basin

The main parameters are:
mean slope

where N is the topological diameter, i.e. the number of links in which the main channel can be divided on the basis of the junctions.
concentration time

where A is the area, L the length of the main channel and H the difference between the highest and the lowest elevation of the basin.



North Carolina sample dataset example:
g.region raster=elevation -p
r.basin map=elevation prefix=my_basin coord=637304.924954,218617.100523 \
 dir=/tmp/my_basin threshold=1000

# visualize some results
d.mon wx0
d.rast my_basin_elevation_hack

d.rast my_basin_elevation_dist2out

d.his i=aspect h=my_basin_elevation_dist2out

r.basin results


Known issues


r.hypso (Addon), (Addon), (Addon), (Addon),, (Addon), (Addon), (Addon), (Addon), (Addon), r.watershed, r.width.funct (Addon)
Related Wiki page


Di Leo Margherita, Di Stefano Massimo (2013) An Open-Source Approach for Catchment's Physiographic Characterization, Abstract H52E-06 presented at 2013 Fall Meeting, AGU, San Francisco, CA, USA 9-13 Dec. abstract



Margherita Di Leo (grass-dev AT lists DOT osgeo DOT org ), Massimo Di Stefano

Last changed: $Date: 2017-08-10 10:56:52 +0200 (Thu, 10 Aug 2017) $


Available at: r.basin source code (history)

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© 2003-2017 GRASS Development Team, GRASS GIS 7.2.3svn Reference Manual