Module Channel Network

This module derives a channel network based on gridded digital elevation data.
Use the initiation options to determine under which conditions channels shall start.

Author: (c) 2001 by O.Conrad
Specification: grid
Menu: Terrain Analysis|Channels

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Elevation	Grid (input)	`ELEVATION`	A grid that contains elevation data.	-
	Flow Direction (*)	Grid (optional input)	`SINKROUTE`	An optional grid that provides information about flow directions. Values between 1 to 8 force the flow of a cell to be given to one its adjacent neighbor cells (1->NE, 2->E, 3->SE, 4->S, 5->SW, 6->W, 7->NW, 8->N). In case of other values the algorithm will use its own routing scheme. This option is in particular useful to supply the algorithm with routes that lead the flow through closed depression.	-
	Initiation Grid	Grid (input)	`INIT_GRID`	Dependent on the chosen 'Initiation Type' and 'Initiation Threshold' the values of this grid control where a channel is initiated.	-
	Divergence (*)	Grid (optional input)	`DIV_GRID`	Tracing: Convergence	-
	Tracing: Weight (*)	Grid (optional input)	`TRACE_WEIGHT`	Tracing: Weight	-
Output	Channel Network	Grid (output)	`CHNLNTWRK`	If a cell is part of a channel its value equals the channel order. Otherwise the cell is marked as no-data.	-
	Channel Direction	Grid (output)	`CHNLROUTE`	If a cell is part of a channel then its value shows the flow direction of the channel (1->NE, 2->E, 3->SE, 4->S, 5->SW, 6->W, 7->NW, 8->N). Otherwise the cell is marked as no-data.	-
	Channel Network	Shapes (output)	`SHAPES`	This shapes layer will contain the resulting channel network in vector format (lines).	-
Options	Initiation Type	Choice	`INIT_METHOD`	Options: - Less than - Equals - Greater than Controls under which condition a channel is initiated.	Available Choices: [0] Less than [1] Equals [2] Greater than Default: 2
	Initiation Threshold	Floating point	`INIT_VALUE`	Dependent on the chosen 'Initiation Grid' and 'Initiation Type' this value controls under which condition a channel is initiated.	Default: 0.000000
	Tracing: Max. Divergence	Integer	`DIV_CELLS`	Tracing: Stop after x cells with divergent flow	Minimum: 1 Default: 5
	Min. Segment Length	Integer	`MINLEN`	Minimum Segment Length (Cells)	Default: 10
(*) optional

Command-line

Usage: saga_cmd ta_channels 0 [-ELEVATION <str>] [-SINKROUTE <str>] [-CHNLNTWRK <str>] [-CHNLROUTE <str>] [-SHAPES <str>] [-INIT_GRID <str>] [-INIT_METHOD <str>] [-INIT_VALUE <str>] [-DIV_GRID <str>] [-DIV_CELLS <num>] [-TRACE_WEIGHT <str>] [-MINLEN <num>]
  -ELEVATION:<str>   	Elevation
	Grid (input)
  -SINKROUTE:<str>   	Flow Direction
	Grid (optional input)
  -CHNLNTWRK:<str>   	Channel Network
	Grid (output)
  -CHNLROUTE:<str>   	Channel Direction
	Grid (output)
  -SHAPES:<str>      	Channel Network
	Shapes (output)
  -INIT_GRID:<str>   	Initiation Grid
	Grid (input)
  -INIT_METHOD:<str> 	Initiation Type
	Choice
	Available Choices:
	[0] Less than
	[1] Equals
	[2] Greater than
	Default: 2
  -INIT_VALUE:<str>  	Initiation Threshold
	Floating point
	Default: 0.000000
  -DIV_GRID:<str>    	Divergence
	Grid (optional input)
  -DIV_CELLS:<num>   	Tracing: Max. Divergence
	Integer
	Minimum: 1
	Default: 5
  -TRACE_WEIGHT:<str>	Tracing: Weight
	Grid (optional input)
  -MINLEN:<num>      	Min. Segment Length
	Integer
	Default: 10