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) $

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                               r.water.outlet(1grass)