.TH r.water.outlet 1grass "" "GRASS 6.4.4" "Grass User's Manual"
.SH NAME
\fI\fBr.water.outlet\fR\fR  - Watershed basin creation program.
.SH KEYWORDS
raster, hydrology
.SH SYNOPSIS
\fBr.water.outlet\fR
.br
\fBr.water.outlet help\fR
.br
\fBr.water.outlet drainage\fR=\fIstring\fR \fBbasin\fR=\fIstring\fR \fBeasting\fR=\fIx\fR \fBnorthing\fR=\fIy\fR  [\-\-\fBoverwrite\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR] 
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.PP
.SS Parameters:
.IP "\fBdrainage\fR=\fIstring\fR" 4m
.br
Name of input raster map
.IP "\fBbasin\fR=\fIstring\fR" 4m
.br
Name of raster map to contain results
.IP "\fBeasting\fR=\fIx\fR" 4m
.br
The map E grid coordinates
.IP "\fBnorthing\fR=\fIy\fR" 4m
.br
The map N grid coordinates
.PP
.SH DESCRIPTION
\fIr.water.outlet\fR generates a watershed basin from a drainage
direction map (from \fIr.watershed\fR) and
a set of coordinates representing the outlet point of watershed.
.SS Selected Parameters
.IP "\fBdrainage=\fR\fIname\fR 
.br
Input map: drainage direction. Indicates the "aspect" for each 
cell. Multiplying positive values by 45 will give the direction in 
degrees that the surface runoff will travel from that cell. The 
value -1 indicates that the cell is a depression area. 
Other negative values indicate that 
surface runoff is leaving the boundaries of the current geographic 
region. The absolute value of these negative cells indicates the 
direction of flow. This map is generated from 
\fIr.watershed\fR.
.IP "\fBbasin=\fR\fIname\fR 
.br
Output map: Values of one (1) indicate the watershed
basin. Values of zero are not in the watershed basin.
.IP "\fBeasting=\fR\fIvalue\fR 
.br
Input value: Easting value of outlet point. 
.IP "\fBnorthing=\fR\fIvalue\fR 
.br
Input value: Northing value of outlet point. 
.PP
.SH NOTES
In the context of this program, a watershed basin is the
region upstream of an outlet point. Thus, if the user
chooses an outlet point on a hill slope, the resulting map
will be a thin silver of land representing the overland
slope uphill of the point.
.SH EXAMPLE
A watershed in the North Carolina sample dataset region:
\fC
.DS
.br
g.region rast=elev_lid792_1m \-p
.br
# the watershed outlet position should be placed on a stream (from
.br
# accumulation map):
.br
r.watershed elev_lid792_1m thresh=5000 accum=accum_5K \(rs
.br
  drain=draindir_5K basin=basin_5K
.br
r.water.outlet drainage=draindir_5K basin=basin_A30 \(rs
.br
  east=638741.43125 north=220269.7
.br
d.mon x0
.br
d.rast accum_5K
.br
d.rast \-o basin_A30
.br
.br
# overlay with transparency
.br
r.colors basin_A30 color=grey
.br
d.his h=accum_5K i=basin_A30
.br
.DE
\fR
.PP
\fIWatershed draped over flow accumulation\fR
.SH SEE ALSO
\fI
d.where,
r.watershed,
r.topidx
\fR
.SH AUTHOR
Charles Ehlschlaeger, U.S. Army Construction Engineering Research Laboratory
.PP
\fILast changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $\fR
.PP
Full index
.PP
© 2003-2014 GRASS Development Team