Module SHALSTAB

This module is a realization of the SHALSTAB (Shallow Slope Stability) model from Montgomery & Dietrich (1994). The model computes grid cell critical shallow groundwater recharge values (CR in mm/day) as a measure for relative shallow slope stability, utilizing a simple model that combines a steady-state hydrologic model (a topographic wetness index) to predict groundwater pressures with an infinite slope stability model. For computation, a slope (in radians) and a catchment area (in m2) grid are required. Additionally, information on material density (g/cm3), material friction angle (°), material hydraulic conductivity (m/hr), bulk cohesion (MPa) and depth to potential shear plane (m) are required that can be specified either globally or through grids. The module produces a continuous CR (mm/day) raster with unconditionally stable cells blanked, and unconditionally unstable cells as CR = 0. Optionally, a classified CR grid can be calculated representing seven stability classes.

Reference: Montgomery D. R., Dietrich, W. E. (1994) A physically based model for the topographic control on shallow landsliding. Water Resources Research, 30, 1153-1171..

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

Parameters

Command-line

Usage: saga_cmd ta_slope_stability 2 [-A <str>] [-B <str>] [-Cmin <str>] [-Cmax <str>] [-Dmin <str>] [-Dmax <str>] [-Emin <str>] [-Emax <str>] [-Fmin <str>] [-Fmax <str>] [-Jmin <str>] [-Jmax <str>] [-fCmin <str>] [-fCmax <str>] [-fDmin <str>] [-fDmax <str>] [-fEmin <str>] [-fEmax <str>] [-fFmin <str>] [-fFmax <str>] [-fJmin <str>] [-fJmax <str>] [-fK <num>] [-G <str>] [-H <str>]
  -A:<str>    	Slope grid (rad)
	Grid (input)
  -B:<str>    	Catchment area grid (m2)
	Grid (input)
  -Cmin:<str> 	Min Density grid (g/cm3)
	Grid (optional input)
  -Cmax:<str> 	Max Density grid (g/cm3)
	Grid (optional input)
  -Dmin:<str> 	Min Hydraulic conductivity grid (m/hr) 
	Grid (optional input)
  -Dmax:<str> 	Max Hydraulic conductivity grid (m/hr) 
	Grid (optional input)
  -Emin:<str> 	Min Thickness grid (m)
	Grid (optional input)
  -Emax:<str> 	Max Thickness grid (m)
	Grid (optional input)
  -Fmin:<str> 	Min Friction angle grid (degree) 
	Grid (optional input)
  -Fmax:<str> 	Max Friction angle grid (degree) 
	Grid (optional input)
  -Jmin:<str> 	Min Bulk cohesion grid (MPa) 
	Grid (optional input)
  -Jmax:<str> 	Max Bulk cohesion grid (MPa) 
	Grid (optional input)
  -fCmin:<str>	Global minimum density (g/cm3)
	Floating point
	Default: 1.600000
  -fCmax:<str>	Global maximum density (g/cm3)
	Floating point
	Default: 1.600000
  -fDmin:<str>	Global minimum conductivity (m/hr)
	Floating point
	Default: 2.700000
  -fDmax:<str>	Global maximum conductivity (m/hr)
	Floating point
	Default: 2.700000
  -fEmin:<str>	Global minimum thickness (m)
	Floating point
	Default: 1.000000
  -fEmax:<str>	Global maximum thickness (m)
	Floating point
	Default: 1.000000
  -fFmin:<str>	Global minimum friction angle (degree)
	Floating point
	Default: 33.000000
  -fFmax:<str>	Global maximum friction angle (degree)
	Floating point
	Default: 33.000000
  -fJmin:<str>	Global minimum bulk cohesion (MPa)
	Floating point
	Default: 0.000000
  -fJmax:<str>	Global maximum bulk cohesion (MPa)
	Floating point
	Default: 0.000000
  -fK:<num>   	Parameter sampling runs
	Integer
	Default: 1
  -G:<str>    	CR values
	Grid (output)
  -H:<str>    	CR classes
	Grid (optional output)