SAGA 9.4.2 | Tool Library Documentation

SHALSTAB


Description

This tool 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 tool 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..


Parameters

 NameTypeIdentifierDescriptionConstraints
InputSlope grid (rad)grid, inputAA slope angle grid (in rad__ans)-
Catchment area grid (m2)grid, inputBA catchment area grid (in square meters)-
Min Density grid (g/cm3)grid, input, optionalCminA grid representing minimum material density (in g/cm3)-
Max Density grid (g/cm3)grid, input, optionalCmaxA grid representing maximum material density (in g/cm3)-
Min Hydraulic conductivity grid (m/hr) grid, input, optionalDminA grid representing minimum material hydraulic conductivity (in m/hr)-
Max Hydraulic conductivity grid (m/hr) grid, input, optionalDmaxA grid representing maximum material hydraulic conductivity (in m/hr)-
Min Thickness grid (m)grid, input, optionalEminA grid representing minimum material thickness (in m)-
Max Thickness grid (m)grid, input, optionalEmaxA grid representing maximum material thickness (in m)-
Min Friction angle grid (degree) grid, input, optionalFminA grid representing minimum material friction angle (in degrees)-
Max Friction angle grid (degree) grid, input, optionalFmaxA grid representing maximum material friction angle (in degrees)-
Min Bulk cohesion grid (MPa) grid, input, optionalJminA grid representing minimum bulk cohesion-
Max Bulk cohesion grid (MPa) grid, input, optionalJmaxA grid representing maximum bulk cohesion-
OutputCR valuesgrid, outputGResulting critical recharge (m/day) grid-
CR classesgrid, output, optionalHClassified critical recharge (-) grid-
OptionsGrid Systemgrid systemPARAMETERS_GRID_SYSTEM--
Global minimum density (g/cm3)floating point numberfCminConstant value if no raster setDefault: 1.600000
Global maximum density (g/cm3)floating point numberfCmaxConstant value if no raster setDefault: 1.600000
Global minimum conductivity (m/hr)floating point numberfDminConstant value if no raster setDefault: 2.700000
Global maximum conductivity (m/hr)floating point numberfDmaxConstant value if no raster setDefault: 2.700000
Global minimum thickness (m)floating point numberfEminConstant value if no raster setDefault: 1.000000
Global maximum thickness (m)floating point numberfEmaxConstant value if no raster setDefault: 1.000000
Global minimum friction angle (degree)floating point numberfFminConstant value if no raster setDefault: 33.000000
Global maximum friction angle (degree)floating point numberfFmaxConstant value if no raster setDefault: 33.000000
Global minimum bulk cohesion (MPa)floating point numberfJminConstant value if no raster setDefault: 0.000000
Global maximum bulk cohesion (MPa)floating point numberfJmaxConstant value if no raster setDefault: 0.000000
Parameter sampling runsinteger numberfKNumber of sampling cyclesDefault: 1

Command Line


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