1r.uslek(1) GRASS GIS User's Manual r.uslek(1)
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6 r.uslek - Computes USLE Soil Erodibility Factor (K).
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9 raster, hydrology, soil, erosion
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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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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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60 r.watershed provides for USLE L, S, LS factors.
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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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94 r.usler, r.watershed
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97 Yann Chemin, SIC-ISDC, Turkmenistan
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100 Available at: r.uslek source code (history)
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102 Accessed: Saturday Oct 28 18:18:09 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 8.3.1 Reference Manual
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111GRASS 8.3.1 r.uslek(1)