r.uslek(1grass)

1r.uslek(1)                    Grass User's Manual                   r.uslek(1)
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NAME

6       r.uslek  - Computes USLE Soil Erodibility Factor (K).
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KEYWORDS

9       raster, hydrology, soil, erosion
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SYNOPSIS

12       r.uslek
13       r.uslek --help
14       r.uslek   psand=name   pclay=name   psilt=name  pomat=name  output=name
15       [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]
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17   Flags:
18       --overwrite
19           Allow output files to overwrite existing files
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21       --help
22           Print usage summary
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24       --verbose
25           Verbose module output
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27       --quiet
28           Quiet module output
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30       --ui
31           Force launching GUI dialog
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33   Parameters:
34       psand=name [required]
35           Name of soil sand fraction raster map [0.0-1.0]
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37       pclay=name [required]
38           Name of soil clay fraction raster map [0.0-1.0]
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40       psilt=name [required]
41           Name of soil silt fraction raster map [0.0-1.0]
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43       pomat=name [required]
44           Name of soil organic matter raster map [0.0-1.0]
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46       output=name [required]
47           Name for output USLE K factor raster map [t.ha.hr/ha.MJ.mm]
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DESCRIPTION

50       r.uslek calculates the USLE K factor, that is the Soil Erodibility Fac‐
51       tor.  It  takes  input  of  soil texture classes (sand, clay, silt) and
52       organic matter, all in range of [0.0-1.0]. The FAO World Soil CD  docu‐
53       mentation  was  used to produce the conversion system between soil tex‐
54       tures and soil classes. The soil classes are in number of 12 and appar‐
55       ently  come  from  a  USDA  publication  of 1951 (p.209). Once the soil
56       classes have been identified (by vector cross-products tests),  a  gen‐
57       eral  conversion table was applied for transforming soil classes into K
58       factor.
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NOTES

61       r.watershed provides for USLE L, S, LS factors.
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EXAMPLE

64       Calculate the USLE K factor (synthetic values,  North  Carolina  sample
65       dataset):
66       # NC data: simulation
67       g.region rural_1m -p
68       r.mapcalc "sand  = 0.11"
69       r.mapcalc "clay  = 0.47"
70       r.mapcalc "silt  = 0.42"
71       r.mapcalc "organ = 0.0136"
72       r.uslek psand=sand pclay=clay psilt=silt pomat=organ output=usle_k
73       r.univar usle_k
74       # Result: uslek = 0.25
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76       Example  with  small variations (condition: d_sand + d_clay + d_silt =>
77       1.0)
78       # NC data: simulation
79       r.mapcalc -s "sand_r = rand(0.09,0.13)"
80       r.mapcalc -s "clay_r = rand(0.45,0.49)"
81       r.mapcalc -s "silt_r = rand(0.40,0.44)"
82       r.mapcalc -s "organ  = rand(0.01,0.70)"
83       r.mapcalc "temp_sum = sand_r + clay_r + silt_r"
84       r.mapcalc "sand = sand_r / temp_sum"
85       r.mapcalc "clay = clay_r / temp_sum"
86       r.mapcalc "silt = silt_r / temp_sum"
87       r.mapcalc "test = sand + clay + silt"
88       r.info -r test
89       g.remove -f rast name=sand_r,clay_r,silt_r,temp_sum,test
90       r.uslek psand=sand pclay=clay psilt=silt pomat=organ output=usle_k
91       r.univar usle_k
92       # Result: uslek =  variable values
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AUTHORS

98       Yann Chemin, SIC-ISDC, Turkmenistan
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100       Last changed: $Date: 2014-11-24 18:15:23 +0100 (Mon, 24 Nov 2014) $
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SOURCE CODE

103       Available at: r.uslek source code (history)
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105       Main index | Raster index | Topics index | Keywords index  |  Graphical
106       index | Full index
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108       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
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112GRASS 7.6.0                                                         r.uslek(1)