Tool Overland Flow Distance to Channel Network

This tool calculates overland flow distances to a channel network based on gridded digital elevation data and channel network information. The flow algorithm may be either Deterministic 8 (O'Callaghan & Mark 1984) or Multiple Flow Direction (Freeman 1991). Sediment Delivery Rates (SDR) according to Ali & De Boer (2010) can be computed optionally.

References

Ali, K. F., De Boer, D. H. (2010): Spatially distributed erosion and sediment yield modeling in the upper Indus River basin. Water Resources Research, 46(8), W08504 doi:10.1029/2009WR008762.
Freeman, G.T. (1991): Calculating catchment area with divergent flow based on a regular grid. Computers and Geosciences, 17:413-22. doi:10.1016/0098-3004(91)90048-I.
Nobre, A.D., Cuartas, L.A., Hodnett, M., Renno, C.D., Rodrigues, G., Silveira, A., Waterloo, M., Saleska S. (2011): Height Above the Nearest Drainage - a hydrologically relevant new terrain model. Journal of Hydrology, Vol. 404, Issues 1-2, pp. 13-29, ISSN 0022-1694, 10.1016/j.jhydrol.2011.03.051. doi:10.1016/j.jhydrol.2011.03.051.
O'Callaghan, J.F. & Mark, D.M. (1984): The extraction of drainage networks from digital elevation data. Computer Vision, Graphics and Image Processing, 28:323-344. doi:10.1016/S0734-189X(84)80011-0.

Author: O.Conrad (c) 2001-14
Menu: Terrain Analysis|Channels

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Elevation	grid, input	`ELEVATION`	A grid that contains elevation data.	-
	Channel Network	grid, input	`CHANNELS`	A grid providing information about the channel network. It is assumed that no-data cells are not part of the channel network. Vice versa all others cells are recognised as channel network members.	-
	Preferred Routing (*)	grid, input, optional	`ROUTE`	Downhill flow is bound to preferred routing cells, where these are not no-data. Helps to model e.g. small ditches, that are not well represented in the elevation data.	-
	Fields (*)	grid, input, optional	`FIELDS`	If set, output is given about the number of fields a flow path visits downhill. For D8 only.	-
	Manning-Strickler Coefficient (*)	grid, input, optional	`FLOW_K`	Manning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient)	-
	Flow Depth (*)	grid, input, optional	`FLOW_R`	flow depth [m] for flow travel time estimation	-
Output	Overland Flow Distance	grid, output	`DISTANCE`	The overland flow distance in map units. It is assumed that the (vertical) elevation data use the same units as the (horizontal) grid coordinates.	-
	Vertical Overland Flow Distance	grid, output	`DISTVERT`	This is the vertical component of the overland flow	-
	Horizontal Overland Flow Distance	grid, output	`DISTHORZ`	This is the horizontal component of the overland flow	-
	Flow Travel Time (*)	grid, output, optional	`TIME`	flow travel time to channel expressed in hours based on Manning's Equation	-
	Sediment Yield Delivery Ratio (*)	grid, output, optional	`SDR`	This is the horizontal component of the overland flow	-
	Fields Visited	grid, output	`PASSES`	Number of fields a flow path visits downhill starting at a cell. For D8 only.	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Flow Algorithm	choice	`METHOD`	Choose a flow routing algorithm that shall be used for the overland flow distance calculation: - D8 - MFD	Available Choices: [0] D8 [1] MFD Default: 1
	Boundary Cells	boolean	`BOUNDARY`	Take cells at the boundary of the DEM as channel.	Default: 0
	Beta	floating point number	`FLOW_B`	catchment specific parameter for sediment delivery ratio calculation	Minimum: 0.000000 Default: 1.000000
	Default	floating point number	`FLOW_K_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 20.000000
	Default	floating point number	`FLOW_R_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 0.050000
(*) optional

Command-line

Usage: saga_cmd ta_channels 4 [-ELEVATION <str>] [-CHANNELS <str>] [-ROUTE <str>] [-DISTANCE <str>] [-DISTVERT <str>] [-DISTHORZ <str>] [-TIME <str>] [-SDR <str>] [-FIELDS <str>] [-PASSES <str>] [-METHOD <str>] [-BOUNDARY <str>] [-FLOW_B <double>] [-FLOW_K <str>] [-FLOW_K_DEFAULT <double>] [-FLOW_R <str>] [-FLOW_R_DEFAULT <double>]
  -ELEVATION:<str>        	Elevation
	grid, input
  -CHANNELS:<str>         	Channel Network
	grid, input
  -ROUTE:<str>            	Preferred Routing
	grid, input, optional
  -DISTANCE:<str>         	Overland Flow Distance
	grid, output
  -DISTVERT:<str>         	Vertical Overland Flow Distance
	grid, output
  -DISTHORZ:<str>         	Horizontal Overland Flow Distance
	grid, output
  -TIME:<str>             	Flow Travel Time
	grid, output, optional
  -SDR:<str>              	Sediment Yield Delivery Ratio
	grid, output, optional
  -FIELDS:<str>           	Fields
	grid, input, optional
  -PASSES:<str>           	Fields Visited
	grid, output
  -METHOD:<str>           	Flow Algorithm
	choice
	Available Choices:
	[0] D8
	[1] MFD
	Default: 1
  -BOUNDARY:<str>         	Boundary Cells
	boolean
	Default: 0
  -FLOW_B:<double>        	Beta
	floating point number
	Minimum: 0.000000
	Default: 1.000000
  -FLOW_K:<str>           	Manning-Strickler Coefficient
	grid, input, optional
  -FLOW_K_DEFAULT:<double>	Default
	floating point number
	Minimum: 0.000000
	Default: 20.000000
  -FLOW_R:<str>           	Flow Depth
	grid, input, optional
  -FLOW_R_DEFAULT:<double>	Default
	floating point number
	Minimum: 0.000000
	Default: 0.050000