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NAMEr.topidx - Creates a topographic index (wetness index) raster map from an elevation raster map.KEYWORDSraster, hydrology, wetness, topographic indexSYNOPSISr.topidxr.topidx --help r.topidx input=name output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui] Flags:
Parameters:
DESCRIPTIONr.topidx creates topographic index (wetness index), ln(a/tan(beta)), map from elevation mapwhere
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. EXAMPLERunning 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 ALSOr.topmodel, r.water.outlet, r.mapcalcKnown issues REFERENCESCho, 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. AUTHORSHuidae ChoHydro Laboratory, Kyungpook National University, South Korea Based on GRIDATB.FOR by Keith Beven. SOURCE CODEAvailable at: r.topidx source code (history)Main index | Raster index | Topics index | Keywords index | Graphical index | Full index © 2003-2021 GRASS Development Team, GRASS GIS 7.8.6 Reference Manual
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