1r.uslek(1)                  GRASS GIS 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 or‐
52       ganic matter, all in range of [0.0-1.0]. The FAO World Soil CD documen‐
53       tation  was used to produce the conversion system between soil textures
54       and soil classes. The soil classes are in number of 12  and  apparently
55       come  from  a  USDA  publication of 1951 (p.209). Once the soil classes
56       have been identified (by vector cross-products tests), a  general  con‐
57       version table was applied for transforming soil classes into K factor.
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NOTES

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

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

94        r.usler, r.watershed
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AUTHOR

97       Yann Chemin, SIC-ISDC, Turkmenistan
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SOURCE CODE

100       Available at: r.uslek source code (history)
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102       Accessed: Saturday Jan 21 21:15:21 2023
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104       Main  index  | Raster index | Topics index | Keywords index | Graphical
105       index | Full index
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107       © 2003-2023 GRASS Development Team, GRASS GIS 8.2.1 Reference Manual
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111GRASS 8.2.1                                                         r.uslek(1)
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