Module Slope Limited Flow Accumulation
Flow accumulation is calculated as upslope contributing (catchment) area using the multiple flow direction approach of Freeman (1991). For this tool the approach has been modified to limit the flow portion routed through a cell depending on the local slope. If a cell is not inclined, no flow is routed through it at all. With increasing slopes the portion of flow routed through a cell becomes higher. Cells with slopes greater than a specified slope threshold route their entire accumulated flow downhill.
References:
- Freeman, G.T. (1991): Calculating catchment area with divergent flow based on a regular grid. Computers and Geosciences, 17:413-22
- Author: O.Conrad (c) 2014
- Specification: grid
- Menu: Terrain Analysis|Hydrology|Catchment Area
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | Grid (input) | DEM | - | - |
| Weight (*) | Grid (optional input) | WEIGHT | - | - |
| Output | Flow Accumulation | Grid (output) | FLOW | - | - |
| Options | Slope Minimum | Floating point | SLOPE_MIN | Assume a given minimum slope for each cell. | Minimum: 0.000000
Default: 0.000000 |
| Slope Threshold | Floating point | SLOPE_MAX | Slope threshold, given as degree, above which flow transport is unlimited. | Minimum: 0.000000
Maximum: 90.000000
Default: 5.000000 |
| Use Flow Threshold | Boolean | B_FLOW | - | Default: 0 |
| Flow Threshold | Value range | T_FLOW | Flow threshold, given as amount of cells, above which flow transport is unlimited. Ignored if range equals zero. | - |
| (*) optional |
Command-line
Usage: saga_cmd ta_hydrology 26 -DEM <str> [-WEIGHT <str>] [-FLOW <str>] [-SLOPE_MIN <str>] [-SLOPE_MAX <str>] [-B_FLOW <str>] [-T_FLOW_MIN <str>] [-T_FLOW_MAX <str>]
-DEM:<str> Elevation
Grid (input)
-WEIGHT:<str> Weight
Grid (optional input)
-FLOW:<str> Flow Accumulation
Grid (output)
-SLOPE_MIN:<str> Slope Minimum
Floating point
Minimum: 0.000000
Default: 0.000000
-SLOPE_MAX:<str> Slope Threshold
Floating point
Minimum: 0.000000
Maximum: 90.000000
Default: 5.000000
-B_FLOW:<str> Use Flow Threshold
Boolean
Default: 0
-T_FLOW_MIN:<str> Flow Threshold
Value range
-T_FLOW_MAX:<str> Flow Threshold
Value range