SAGA-GIS Module Library Documentation (v2.1.3)

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

Parameters

 NameTypeIdentifierDescriptionConstraints
InputElevationGrid (input)DEM--
Weight (*)Grid (optional input)WEIGHT--
OutputFlow AccumulationGrid (output)FLOW--
OptionsSlope MinimumFloating pointSLOPE_MINAssume a given minimum slope for each cell.Minimum: 0.000000
Default: 0.000000
Slope ThresholdFloating pointSLOPE_MAXSlope threshold, given as degree, above which flow transport is unlimited.Minimum: 0.000000
Maximum: 90.000000
Default: 5.000000
Use Flow ThresholdBooleanB_FLOW-Default: 0
Flow ThresholdValue rangeT_FLOWFlow 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