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r.topidx(1grass) | Grass User's Manual | r.topidx(1grass) |
NAME¶
r.topidx - Creates a topographic index (wetness index) raster map from an elevation raster map.KEYWORDS¶
raster, hydrology, wetness, topographic indexSYNOPSIS¶
r.topidxr.topidx --help
r.topidx input=name output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:¶
- --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:¶
- input=name [required]
-
Name of input elevation raster map - output=name [required]
-
Name for output topographic index raster map
DESCRIPTION¶
r.topidx creates topographic index (wetness index), ln(a/tan(beta)), map from elevation mapwhere
a: the area of the hillslope per unit contour length that drains through any
point,
tan(beta): the local surface topographic slope (delta vertical) / (delta horizontal).
Input maps may have NULL values. For example, if you have a MASK
for a watershed (basin map from r.water.outlet), the following
command will create a masked elevation map (belev):
r.mapcalc "belev = if(isnull(basin), basin, elev)"
r.stats -Anc prints out averaged statistics for topographic index.
EXAMPLE¶
Running the command below will generate the topographic index map shown in the figure:g.region raster=elevation -p r.topidx input=elevation output=topidx_elevation
Figure: topographic index map derived from elevation map
SEE ALSO¶
r.topmodel, r.water.outlet, r.mapcalcKnown issues
REFERENCES¶
Cho, H., 2000. GIS Hydrological Modeling System by Using Programming Interface of GRASS. Master’s Thesis, Department of Civil Engineering, Kyungpook National University, Korea.Moore, I.D., R.B. Grayson, and A.R. Ladson, 1991. Digital Terrain Modeling: A Review of Hydrological, Geomorphological, and Biological Applications. Hydrological Processes 5:3-30.
AUTHORS¶
Huidae ChoHydro Laboratory, Kyungpook National University, South Korea
Based on GRIDATB.FOR by Keith Beven.
Last changed: $Date: 2017-12-19 23:53:50 +0100 (Tue, 19 Dec 2017) $
SOURCE CODE¶
Available at: r.topidx source code (history)Main index | Raster index | Topics index | Keywords index | Graphical index | Full index
© 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
GRASS 7.6.0 |