NAME

       r.water.outlet  - Watershed basin creation program.

KEYWORDS

       raster, hydrology

SYNOPSIS

       r.water.outlet
       r.water.outlet help
       r.water.outlet    drainage=string   basin=string   easting=x   northing=y    [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       drainage=string
           Name of input raster map

       basin=string
           Name of raster map to contain results

       easting=x
           The map E grid coordinates

       northing=y
           The map N grid coordinates

DESCRIPTION

       r.water.outlet  generates  a  watershed  basin  from  a  drainage  direction   map   (from
       r.watershed) and a set of coordinates representing the outlet point of watershed.

   Selected Parameters
       drainage=name
              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 r.watershed.

       basin=name
              Output map: Values of one (1) indicate the watershed basin. Values of zero are  not
              in the watershed basin.

       easting=value
              Input value: Easting value of outlet point.

       northing=value
              Input value: Northing value of outlet point.

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.

EXAMPLE

       A watershed in the North Carolina sample dataset region:
       g.region rast=elev_lid792_1m -p
       # the watershed outlet position should be placed on a stream (from
       # accumulation map):
       r.watershed elev_lid792_1m thresh=5000 accum=accum_5K \
         drain=draindir_5K basin=basin_5K
       r.water.outlet drainage=draindir_5K basin=basin_A30 \
         east=638741.43125 north=220269.7
       d.mon x0
       d.rast accum_5K
       d.rast -o basin_A30
       # overlay with transparency
       r.colors basin_A30 color=grey
       d.his h=accum_5K i=basin_A30

       Watershed draped over flow accumulation

SEE ALSO

        d.where, r.watershed, r.topidx

AUTHOR

       Charles Ehlschlaeger, U.S. Army Construction Engineering Research Laboratory

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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       © 2003-2013 GRASS Development Team