Tool SHALSTAB
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..
- Author: A. Günther (c) 2012
- Menu: Terrain Analysis|Slope Stability
Parameters
| Name | Type | Identifier | Description | Constraints | |
|---|---|---|---|---|---|
| Input | Slope grid (rad) | Grid, input | A | A slope angle grid (in radíans) | - |
| Catchment area grid (m2) | Grid, input | B | A catchment area grid (in square meters) | - | |
| Min Density grid (g/cm3) (*) | Grid, input, optional | Cmin | A grid representing minimum material density (in g/cm3) | - | |
| Max Density grid (g/cm3) (*) | Grid, input, optional | Cmax | A grid representing maximum material density (in g/cm3) | - | |
| Min Hydraulic conductivity grid (m/hr) (*) | Grid, input, optional | Dmin | A grid representing minimum material hydraulic conductivity (in m/hr) | - | |
| Max Hydraulic conductivity grid (m/hr) (*) | Grid, input, optional | Dmax | A grid representing maximum material hydraulic conductivity (in m/hr) | - | |
| Min Thickness grid (m) (*) | Grid, input, optional | Emin | A grid representing minimum material thickness (in m) | - | |
| Max Thickness grid (m) (*) | Grid, input, optional | Emax | A grid representing maximum material thickness (in m) | - | |
| Min Friction angle grid (degree) (*) | Grid, input, optional | Fmin | A grid representing minimum material friction angle (in degrees) | - | |
| Max Friction angle grid (degree) (*) | Grid, input, optional | Fmax | A grid representing maximum material friction angle (in degrees) | - | |
| Min Bulk cohesion grid (MPa) (*) | Grid, input, optional | Jmin | A grid representing minimum bulk cohesion | - | |
| Max Bulk cohesion grid (MPa) (*) | Grid, input, optional | Jmax | A grid representing maximum bulk cohesion | - | |
| Output | CR values | Grid, output | G | Resulting critical recharge (m/day) grid | - |
| CR classes (*) | Grid, output, optional | H | Classified critical recharge (-) grid | - | |
| Options | Grid System | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Global minimum density (g/cm3) | Floating point | fCmin | Constant value if no raster set | Default: 1.600000 | |
| Global maximum density (g/cm3) | Floating point | fCmax | Constant value if no raster set | Default: 1.600000 | |
| Global minimum conductivity (m/hr) | Floating point | fDmin | Constant value if no raster set | Default: 2.700000 | |
| Global maximum conductivity (m/hr) | Floating point | fDmax | Constant value if no raster set | Default: 2.700000 | |
| Global minimum thickness (m) | Floating point | fEmin | Constant value if no raster set | Default: 1.000000 | |
| Global maximum thickness (m) | Floating point | fEmax | Constant value if no raster set | Default: 1.000000 | |
| Global minimum friction angle (degree) | Floating point | fFmin | Constant value if no raster set | Default: 33.000000 | |
| Global maximum friction angle (degree) | Floating point | fFmax | Constant value if no raster set | Default: 33.000000 | |
| Global minimum bulk cohesion (MPa) | Floating point | fJmin | Constant value if no raster set | Default: 0.000000 | |
| Global maximum bulk cohesion (MPa) | Floating point | fJmax | Constant value if no raster set | Default: 0.000000 | |
| Parameter sampling runs | Integer | fK | Number of sampling cycles | Default: 1 | |
| (*) optional | |||||
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 <double>] [-fCmax <double>] [-fDmin <double>] [-fDmax <double>] [-fEmin <double>] [-fEmax <double>] [-fFmin <double>] [-fFmax <double>] [-fJmin <double>] [-fJmax <double>] [-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, input, optional -Cmax:<str> Max Density grid (g/cm3) Grid, input, optional -Dmin:<str> Min Hydraulic conductivity grid (m/hr) Grid, input, optional -Dmax:<str> Max Hydraulic conductivity grid (m/hr) Grid, input, optional -Emin:<str> Min Thickness grid (m) Grid, input, optional -Emax:<str> Max Thickness grid (m) Grid, input, optional -Fmin:<str> Min Friction angle grid (degree) Grid, input, optional -Fmax:<str> Max Friction angle grid (degree) Grid, input, optional -Jmin:<str> Min Bulk cohesion grid (MPa) Grid, input, optional -Jmax:<str> Max Bulk cohesion grid (MPa) Grid, input, optional -fCmin:<double> Global minimum density (g/cm3) Floating point Default: 1.600000 -fCmax:<double> Global maximum density (g/cm3) Floating point Default: 1.600000 -fDmin:<double> Global minimum conductivity (m/hr) Floating point Default: 2.700000 -fDmax:<double> Global maximum conductivity (m/hr) Floating point Default: 2.700000 -fEmin:<double> Global minimum thickness (m) Floating point Default: 1.000000 -fEmax:<double> Global maximum thickness (m) Floating point Default: 1.000000 -fFmin:<double> Global minimum friction angle (degree) Floating point Default: 33.000000 -fFmax:<double> Global maximum friction angle (degree) Floating point Default: 33.000000 -fJmin:<double> Global minimum bulk cohesion (MPa) Floating point Default: 0.000000 -fJmax:<double> 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, output, optional