LS Factor

Author(s)	O.Conrad (c) 2003
Library ID	ta_hydrology
Tool ID	22
Version	1.0
Menu	Terrain Analysis \| Hydrology \| Topographic Indices

Description

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

Böhner, J., Selige, T. (2006): Spatial Prediction of Soil Attributes Using Terrain Analysis and Climate Regionalisation. In: Böhner, J., McCloy, K.R., Strobl, J.: SAGA - Analysis and Modelling Applications. Göttinger Geographische Abhandlungen, Vol.115, p.13-27. PDF

Desmet, P.J.J. & Govers, G. (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. doi:10.1080/00224561.1996.12457102

Kinnell, P.I.A. (2005): Alternative Approaches for Determining the USLE-M Slope Length Factor for Grid Cells. Soil Sci. Soc. Am. J., 69: 674-680. doi:10.2136/sssaj2004.0047

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. doi:10.1002/hyp.3360050103

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

	Name	Type	Identifier	Description	Constraints
Input	Slope	grid, input	`SLOPE`	-	-
Input	Catchment Area	grid, input	`AREA`	-	-
Output	LS Factor	grid, output	`LS`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Unit	choice	`SLOPE_UNIT`	-	Available Choices: [0] radians [1] degree Default: 0
	Area to Length Conversion	choice	`CONV`	Derivation 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
	Feet Adjustment	boolean	`FEET`	Needed if area and lengths come from coordinates measured in feet.	Default: 0
	Method (LS)	choice	`METHOD`	-	Available Choices: [0] Moore et al. 1991 [1] Desmet & Govers 1996 [2] Böhner & Selige 2006 Default: 0
	Rill/Interrill Erosivity	floating point number	`EROSIVITY`	-	Minimum: 0.000000 Default: 1.000000
	Stability	choice	`STABILITY`	-	Available Choices: [0] stable [1] instable (thawing) Default: 0

Command Line


Usage: saga_cmd ta_hydrology 22 [-SLOPE ] [-SLOPE_UNIT ] [-AREA ] [-LS ] [-CONV ] [-FEET ] [-METHOD ] [-EROSIVITY ] [-STABILITY ]
  -SLOPE:          Slope
	grid, input
  -SLOPE_UNIT:     Unit
	choice
	Available Choices:
	[0] radians
	[1] degree
	Default: 0
  -AREA:           Catchment Area
	grid, input
  -LS:             LS Factor
	grid, output
  -CONV:
                        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
  -FEET:           Feet Adjustment
	boolean
	Default: 0
  -METHOD:
                        Method (LS)
                        	choice
                        	Available Choices:
                        	[0] Moore et al. 1991
                        	[1] Desmet & Govers 1996
                        	[2] Böhner & Selige 2006
                        	Default: 0
  -EROSIVITY:   Rill/Interrill Erosivity
	floating point number
	Minimum: 0.000000
	Default: 1.000000
  -STABILITY:      Stability
	choice
	Available Choices:
	[0] stable
	[1] instable (thawing)
	Default: 0