Tool Upslope and Downslope Curvature
This tool first calculates the local curvature of a cell as sum of the gradients (i.e. tangens of slope) to its neighbour cells. This is a simple estimation of the general curvature and is strongly correlated with general curvatures calculated with other methods (e.g. Zevenbergen & Thorne 1987). Then upslope curvature is calculated as the distance and flow proportional weighted average local curvature over a cell's upslope contributing area following the multiple flow direction algorithm after Freeman (1991). In a similar way the downslope curvature is calculated by summarizing the curvatures of all hydrologically downslope connected cells. The local upslope/downslope curvatures just take the immediately neighboured cells into account.
References
- Freeman, G.T. (1991): Calculating catchment area with divergent flow based on a regular grid. Computers and Geosciences, 17:413-22. ScienceDirect.
- Zevenbergen, L.W., Thorne, C.R. (1987): Quantitative analysis of land surface topography. Earth Surface Processes and Landforms, 12: 47-56. Wiley Online Library.
- Author: P.Gandelli, O.Conrad (c) 2015
- Menu: Terrain Analysis|Morphometry
Parameters
| Name | Type | Identifier | Description | Constraints |
Input | Elevation | Grid, input | DEM | - | - |
Output | Local Curvature | Grid, output | C_LOCAL | - | - |
Upslope Curvature | Grid, output | C_UP | - | - |
Local Upslope Curvature | Grid, output | C_UP_LOCAL | - | - |
Downslope Curvature | Grid, output | C_DOWN | - | - |
Local Downslope Curvature | Grid, output | C_DOWN_LOCAL | - | - |
Options | Grid System | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
Upslope Weighting | Floating point | WEIGHTING | - | Minimum: 0.000000 Maximum: 1.000000 Default: 0.500000 |
Command-line
Usage: saga_cmd ta_morphometry 26 [-DEM <str>] [-C_LOCAL <str>] [-C_UP <str>] [-C_UP_LOCAL <str>] [-C_DOWN <str>] [-C_DOWN_LOCAL <str>] [-WEIGHTING <double>]
-DEM:<str> Elevation
Grid, input
-C_LOCAL:<str> Local Curvature
Grid, output
-C_UP:<str> Upslope Curvature
Grid, output
-C_UP_LOCAL:<str> Local Upslope Curvature
Grid, output
-C_DOWN:<str> Downslope Curvature
Grid, output
-C_DOWN_LOCAL:<str> Local Downslope Curvature
Grid, output
-WEIGHTING:<double> Upslope Weighting
Floating point
Minimum: 0.000000
Maximum: 1.000000
Default: 0.500000