SAGA-GIS Module Library Documentation (v2.1.3)

Module LS Factor

Calculation of slope length (LS) factor as used by the Universal Soil Loss Equation (USLE), based on slope and specific catchment area (SCA, as substitute for slope length).
References:

Boehner, J., Selige, T. (2006):
Spatial Prediction of Soil Attributes Using Terrain Analysis and Climate Regionalisation'
In: Boehner, J., McCloy, K.R., Strobl, J.: 'SAGA - Analysis and Modelling Applications', Goettinger Geographische Abhandlungen, Vol.115, p.13-27

Desmet & Govers (1996):
'A GIS Procedure for Automatically Calculating the USLE LS Factor on Topographically Complex Landscape Units'
Journal of Soil and Water Conservation, 51(5):427.433

Kinnell, P.I.A. (2005):
'Alternative Approaches for Determining the USLE-M Slope Length Factor for Grid Cells.'
http://soil.scijournals.org/cgi/content/full/69/3/674

Moore, I.D., Grayson, R.B., Ladson, A.R. (1991):
'Digital terrain modelling: a review of hydrogical, geomorphological, and biological applications'
Hydrological Processes, Vol.5, No.1

Wischmeier, W.H., Smith, D.D. (1978):
'Predicting rainfall erosion losses - A guide to conservation planning'
Agriculture Handbook No. 537: US Department of Agriculture, Washington DC.

Parameters

 NameTypeIdentifierDescriptionConstraints
InputSlopeGrid (input)SLOPE--
Catchment AreaGrid (input)AREA--
OutputLS FactorGrid (output)LS--
OptionsArea to Length ConversionChoiceCONVDerivation of slope lengths from catchment areas. These are rough approximations! Applies not to Desmet & Govers' method.Available Choices:
[0] no conversion (areas already given as specific catchment area)
[1] 1 / cell size (specific catchment area)
[2] square root (catchment length)
Default: 0
Method (LS)ChoiceMETHOD-Available Choices:
[0] Moore et al. 1991
[1] Desmet & Govers 1996
[2] Boehner & Selige 2006
Default: 0
Rill/Interrill ErosivityFloating pointEROSIVITY-Minimum: 0.000000
Default: 1.000000
StabilityChoiceSTABILITY-Available Choices:
[0] stable
[1] instable (thawing)
Default: 0

Command-line

Usage: saga_cmd ta_hydrology 22 -SLOPE <str> -AREA <str> [-LS <str>] [-CONV <str>] [-METHOD <str>] [-EROSIVITY <str>] [-STABILITY <str>]
  -SLOPE:<str>    	Slope
	Grid (input)
  -AREA:<str>     	Catchment Area
	Grid (input)
  -LS:<str>       	LS Factor
	Grid (output)
  -CONV:<str>     	Area to Length Conversion
	Choice
	Available Choices:
	[0] no conversion (areas already given as specific catchment area)
	[1] 1 / cell size (specific catchment area)
	[2] square root (catchment length)
	Default: 0
  -METHOD:<str>   	Method (LS)
	Choice
	Available Choices:
	[0] Moore et al. 1991
	[1] Desmet & Govers 1996
	[2] Boehner & Selige 2006
	Default: 0
  -EROSIVITY:<str>	Rill/Interrill Erosivity
	Floating point
	Minimum: 0.000000
	Default: 1.000000
  -STABILITY:<str>	Stability
	Choice
	Available Choices:
	[0] stable
	[1] instable (thawing)
	Default: 0