Module SAFETYFACTOR

This module computes a slope stability (expressed as a factor-of-safety) raster according to the traditional infinite slope model theory (see cf Selby, 1993) The resulting raster represents the ratio of resisting forces/driving forces (fs) on a potential shear plane with fs lesser 1 unstable, fs greater 1 stable. Except for a slope raster (in radians), all input variables can be specified either globally or distributed (through grids). The module creates a continuous fs raster (values above 10 are truncated), and a binary stability grid with nodata = stable, 1 = unstable (optional).

Author: A. Günther (c) 2012
Specification: grid
Menu: Terrain Analysis|Slope Stability

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Slope grid (rad)	Grid (input)	`A`	-	-
	Min thickness grid (m) (*)	Grid (optional input)	`Bmin`	A grid representing minimum cell layer thicknesses to potential shear plane (in meters)	-
	Max thickness grid (m) (*)	Grid (optional input)	`Bmax`	A grid representing maximum cell layer thicknesses to potential shear plane (in meters)	-
	Min saturation grid (-) (*)	Grid (optional input)	`Cmin`	A grid representing minimum cell relative water saturation of layer (dimensionless)	-
	Max saturation grid (-) (*)	Grid (optional input)	`Cmax`	A grid representing maximum cell relative water saturation of layer (dimensionless)	-
	Min friction grid (degree) (*)	Grid (optional input)	`Dmin`	A grid representing minimum cell frictional shear strength of layer (in degrees)	-
	Max friction grid (degree) (*)	Grid (optional input)	`Dmax`	A grid representing maximum cell frictional shear strength of layer (in degrees)	-
	Min density grid (g/cm3) (*)	Grid (optional input)	`Emin`	A grid representing minimum cell bulk density of layer (in grams per cubiccentimeters)	-
	Max density grid (g/cm3) (*)	Grid (optional input)	`Emax`	A grid representing maximum cell bulk density of layer (in grams per cubiccentimeters)	-
	Min cohesion grid (MPa) (*)	Grid (optional input)	`Fmin`	A grid representing minimum cell layer cohesion (in Megapascals)	-
	Max cohesion grid (MPa) (*)	Grid (optional input)	`Fmax`	A grid representing maximum cell layer cohesion (in Megapascals)	-
Output	FS values	Grid (output)	`G`	Resulting factor-of-safety (-) grid	-
Output	FS classes (*)	Grid (optional output)	`H`	Resulting stability (0/1) grid	-
Options	Min global thickness (m)	Floating point	`fBmin`	Constant value if no raster set	Default: 1.000000
	Max global thickness (m)	Floating point	`fBmax`	Constant value if no raster set	Default: 1.000000
	Min global saturation (-)	Floating point	`fCmin`	Constant value if no raster set	Default: 0.000000
	Max global saturation (-)	Floating point	`fCmax`	Constant value if no raster set	Default: 0.000000
	Min global friction (degree)	Floating point	`fDmin`	Constant value if no raster set	Default: 33.000000
	Max global friction (degree)	Floating point	`fDmax`	Constant value if no raster set	Default: 33.000000
	Min global density (g/cm3)	Floating point	`fEmin`	Constant value if no raster set	Default: 1.600000
	Max global density (g/cm3)	Floating point	`fEmax`	Constant value if no raster set	Default: 1.600000
	Min global cohesion (MPa)	Floating point	`fFmin`	Constant value if no raster set	Default: 0.000000
	Max global cohesion (MPa)	Floating point	`fFmax`	Constant value if no raster set	Default: 0.000000
	Parameter sampling runs	Integer	`fI`	Number of sampling cycles	Default: 1
(*) optional

Command-line

Usage: saga_cmd ta_slope_stability 0 -A <str> [-Bmin <str>] [-Bmax <str>] [-Cmin <str>] [-Cmax <str>] [-Dmin <str>] [-Dmax <str>] [-Emin <str>] [-Emax <str>] [-Fmin <str>] [-Fmax <str>] [-fBmin <str>] [-fBmax <str>] [-fCmin <str>] [-fCmax <str>] [-fDmin <str>] [-fDmax <str>] [-fEmin <str>] [-fEmax <str>] [-fFmin <str>] [-fFmax <str>] [-fI <num>] [-G <str>] [-H <str>]
  -A:<str>    	Slope grid (rad)
	Grid (input)
  -Bmin:<str> 	Min thickness grid (m) 
	Grid (optional input)
  -Bmax:<str> 	Max thickness grid (m) 
	Grid (optional input)
  -Cmin:<str> 	Min saturation grid (-) 
	Grid (optional input)
  -Cmax:<str> 	Max saturation grid (-) 
	Grid (optional input)
  -Dmin:<str> 	Min friction grid (degree) 
	Grid (optional input)
  -Dmax:<str> 	Max friction grid (degree) 
	Grid (optional input)
  -Emin:<str> 	Min density grid (g/cm3)
	Grid (optional input)
  -Emax:<str> 	Max density grid (g/cm3)
	Grid (optional input)
  -Fmin:<str> 	Min cohesion grid (MPa) 
	Grid (optional input)
  -Fmax:<str> 	Max cohesion grid (MPa) 
	Grid (optional input)
  -fBmin:<str>	Min global thickness (m)
	Floating point
	Default: 1.000000
  -fBmax:<str>	Max global thickness (m)
	Floating point
	Default: 1.000000
  -fCmin:<str>	Min global saturation (-)
	Floating point
	Default: 0.000000
  -fCmax:<str>	Max global saturation (-)
	Floating point
	Default: 0.000000
  -fDmin:<str>	Min global friction (degree)
	Floating point
	Default: 33.000000
  -fDmax:<str>	Max global friction (degree)
	Floating point
	Default: 33.000000
  -fEmin:<str>	Min global density (g/cm3)
	Floating point
	Default: 1.600000
  -fEmax:<str>	Max global density (g/cm3)
	Floating point
	Default: 1.600000
  -fFmin:<str>	Min global cohesion (MPa)
	Floating point
	Default: 0.000000
  -fFmax:<str>	Max global cohesion (MPa)
	Floating point
	Default: 0.000000
  -fI:<num>   	Parameter sampling runs
	Integer
	Default: 1
  -G:<str>    	FS values
	Grid (output)
  -H:<str>    	FS classes
	Grid (optional output)