NAME

       r.carve  - Generates stream channels.
       Takes vector stream data, transforms it to raster and subtracts depth from the output DEM.

KEYWORDS

       raster, hydrology

SYNOPSIS

       r.carve
       r.carve --help
       r.carve   [-n]   raster=name   vector=name   output=name    [points=name]    [width=float]
       [depth=float]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -n
           No flat areas allowed in flow direction

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       raster=name [required]
           Name of input raster elevation map

       vector=name [required]
           Name of input vector map containing stream(s)
           Or data source for direct OGR access

       output=name [required]
           Name for output raster map

       points=name
           Name for output vector map for adjusted stream points

       width=float
           Stream width (in meters)
           Default is raster cell width

       depth=float
           Additional stream depth (in meters)

DESCRIPTION

       r.carve accepts vector stream data as input, transforms them to raster,  and  subtracts  a
       default-depth  +  additional-depth  from a DEM. If the given width is more than 1 cell, it
       will carve the stream with the given width. With the -n flag it should eliminate all  flat
       cells  within  the stream, so when and if the water gets into the stream it will flow. The
       points option generates x,y,z for points which define the stream with the z-value  of  the
       bottom  of  the  carved-in  stream.  These  points  can  then be combined with contours to
       interpolate a new DEM with better representation of valleys.

NOTES

       r.carve does not create a depressionless DEM because many depressions are  in  flat  areas
       and not in the streams.

EXAMPLE

       North Carolina sample dataset:
       # set computational region
       g.region raster=elev_lid792_1m -p
       # digitize a ditch for the farm pond
       echo "L  3 1
        638692.93595422 220198.90026383
        638737.42270627 220149.74706926
        638984.43306379 220148.19158842
        1     1" | v.in.ascii -n input=- output=ditch format=standard
       # visualize original data
       d.mon wx0
       d.rast elev_lid792_1m
       d.vect ditch
       # carve
       r.carve raster=elev_lid792_1m vector=ditch output=carved_dem width=3 depth=0.5
       # visualize resulting carved DEM map
       d.rast carved_dem
       # visualize
       r.relief input=elev_lid792_1m output=elev_lid792_1m_shaded
       r.relief input=carved_dem output=carved_dem_shaded
       d.rast elev_lid792_1m_shaded
       d.erase
       d.rast carved_dem_shaded
       # flow accumulation
       r.watershed elevation=elev_lid792_1m accumulation=elev_lid792_1m_accum
       r.watershed elevation=carved_dem accumulation=carved_dem_accum
       d.rast elev_lid792_1m_accum
       d.erase
       d.rast carved_dem_accum
       # differences
       r.mapcalc "accum_diff = elev_lid792_1m_accum - carved_dem_accum"
       r.colors accum_diff color=differences
       d.erase
       d.rast accum_diff

       Fig:  Original 1m LiDAR based DEM with vector streams map on Fig: Original 1m LiDAR based DEM shown as shaded terrain
       top

       Fig: Carved 1m LiDAR based DEM                               Fig: Carved 1m LiDAR based DEM shown as shaded terrain

       Fig: Flow accumulation in original 1m LiDAR based DEM        Fig: Flow accumulation in carved 1m LiDAR based DEM

KNOWN ISSUES

       The module does not operate yet in latitude-longitude coordinate reference system.  It has
       not  been  thoroughly  tested,  so  not  all  options may work properly - but this was the
       intention.

REFERENCES

       Terrain modeling and Soil Erosion Simulations for Fort Hood and Fort Polk test  areas,  by
       Helena  Mitasova,  Lubos  Mitas,  William M. Brown, Douglas M.  Johnston, GMSL (Report for
       CERL 1999)

SEE ALSO

        r.flow, r.fill.dir, r.watershed

AUTHORS

       Bill Brown (GMSL)
       GRASS 6 update: Brad Douglas

SOURCE CODE

       Available at: r.carve source code (history)

       Accessed: Thursday Aug 01 11:29:50 2024

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       © 2003-2024 GRASS Development Team, GRASS GIS 8.4.0 Reference Manual