1r.water.outlet(1)           GRASS GIS User's Manual          r.water.outlet(1)
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NAME

6       r.water.outlet   -  Creates  watershed basins from a drainage direction
7       map.
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KEYWORDS

10       raster, hydrology, watershed
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SYNOPSIS

13       r.water.outlet
14       r.water.outlet --help
15       r.water.outlet input=name output=name coordinates=east,north   [--over‐
16       write]  [--help]  [--verbose]  [--quiet]  [--ui]
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18   Flags:
19       --overwrite
20           Allow output files to overwrite existing files
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22       --help
23           Print usage summary
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25       --verbose
26           Verbose module output
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28       --quiet
29           Quiet module output
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31       --ui
32           Force launching GUI dialog
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34   Parameters:
35       input=name [required]
36           Name of input drainage direction map
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38       output=name [required]
39           Name for output watershed basin map
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41       coordinates=east,north [required]
42           Coordinates of outlet point
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DESCRIPTION

45       r.water.outlet  generates  a  watershed basin from a drainage direction
46       map and a set of coordinates representing the outlet  point  of  water‐
47       shed.
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49       Input drainage direction map indicates the "aspect" for each cell. Mul‐
50       tiplying positive values by 45 will give the direction in degrees  that
51       the  surface  runoff will travel from that cell. The value -1 indicates
52       that the cell is a depression area. Other negative values indicate that
53       surface  runoff is leaving the boundaries of the current geographic re‐
54       gion. The absolute value of these negative cells indicates  the  direc‐
55       tion of flow. This raster map is generated from r.watershed.
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57       Output  raster map values of one (1) indicate the watershed basin. Val‐
58       ues of zero (0) are not in the watershed basin.
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NOTES

61       In the context of this program, a watershed basin  is  the  region  up‐
62       stream of an outlet point. Thus, if the user chooses an outlet point on
63       a hill slope, the resulting map will be a thin silver  of  land  repre‐
64       senting the overland slope uphill of the point.
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EXAMPLE

67       A watershed in the North Carolina sample dataset region:
68       g.region raster=elev_lid792_1m -p
69       # the watershed outlet position should be placed on a stream (from
70       # accumulation map):
71       r.watershed elev_lid792_1m threshold=5000 accumulation=accum_5K drainage=draindir_5K basin=basin_5K
72       r.water.outlet input=draindir_5K output=basin_A30 coordinates=638740.423248,220271.519225
73       d.mon wx0
74       d.rast map=accum_5K
75       d.rast map=basin_A30
76       # overlay with transparency
77       r.colors map=basin_A30 color=grey
78       d.his h=accum_5K i=basin_A30
79       # report outlet size in ha
80       r.report map=basin_A30 units=h
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82       Figure: Watershed draped over flow accumulation
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SEE ALSO

85         r.wateroutlet.lessmem  (addon),  d.where, r.basins.fill, r.watershed,
86       r.topidx
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AUTHOR

89       Charles Ehlschlaeger, U.S. Army Construction Engineering Research Labo‐
90       ratory
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SOURCE CODE

93       Available at: r.water.outlet source code (history)
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95       Accessed: Saturday Jan 21 20:39:21 2023
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97       Main  index  | Raster index | Topics index | Keywords index | Graphical
98       index | Full index
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100       © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
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104GRASS 8.2.1                                                  r.water.outlet(1)