SAGA-GIS Module Library Documentation (v2.1.3)

Module Overland Flow Distance to Channel Network

This module 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.
- 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.
- 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. online

Parameters

 NameTypeIdentifierDescriptionConstraints
InputElevationGrid (input)ELEVATIONA grid that contains elevation data.-
Channel NetworkGrid (input)CHANNELSA 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 (optional input)ROUTEDownhill 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 (optional input)FIELDSIf set, output is given about the number of fields a flow path visits downhill. For D8 only.-
Manning-Strickler Coefficient (*)Grid (optional input)FLOW_KManning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient)-
Flow Depth (*)Grid (optional input)FLOW_Rflow depth [m] for flow travel time estimation-
OutputOverland Flow DistanceGrid (output)DISTANCEThe 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 DistanceGrid (output)DISTVERTThis is the vertical component of the overland flow-
Horizontal Overland Flow DistanceGrid (output)DISTHORZThis is the horizontal component of the overland flow-
Flow Travel Time (*)Grid (optional output)TIMEflow travel time to channel expressed in hours based on Manning's Equation-
Sediment Yield Delivery Ratio (*)Grid (optional output)SDRThis is the horizontal component of the overland flow-
Fields VisitedGrid (output)PASSESNumber of fields a flow path visits downhill starting at a cell. For D8 only.-
OptionsFlow AlgorithmChoiceMETHODChoose a flow routing algorithm that shall be used for the overland flow distance calculation: - D8 - MFDAvailable Choices:
[0] D8
[1] MFD
Default: 1
BetaFloating pointFLOW_Bcatchment specific parameter for sediment delivery ratio calculationMinimum: 0.000000
Default: 1.000000
DefaultFloating pointFLOW_K_DEFAULTdefault value if no grid has been selectedMinimum: 0.000000
Default: 20.000000
DefaultFloating pointFLOW_R_DEFAULTdefault value if no grid has been selectedMinimum: 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>] [-FLOW_B <str>] [-FLOW_K <str>] [-FLOW_K_DEFAULT <str>] [-FLOW_R <str>] [-FLOW_R_DEFAULT <str>]
  -ELEVATION:<str>     	Elevation
	Grid (input)
  -CHANNELS:<str>      	Channel Network
	Grid (input)
  -ROUTE:<str>         	Preferred Routing
	Grid (optional input)
  -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 (optional output)
  -SDR:<str>           	Sediment Yield Delivery Ratio
	Grid (optional output)
  -FIELDS:<str>        	Fields
	Grid (optional input)
  -PASSES:<str>        	Fields Visited
	Grid (output)
  -METHOD:<str>        	Flow Algorithm
	Choice
	Available Choices:
	[0] D8
	[1] MFD
	Default: 1
  -FLOW_B:<str>        	Beta
	Floating point
	Minimum: 0.000000
	Default: 1.000000
  -FLOW_K:<str>        	Manning-Strickler Coefficient
	Grid (optional input)
  -FLOW_K_DEFAULT:<str>	Default
	Floating point
	Minimum: 0.000000
	Default: 20.000000
  -FLOW_R:<str>        	Flow Depth
	Grid (optional input)
  -FLOW_R_DEFAULT:<str>	Default
	Floating point
	Minimum: 0.000000
	Default: 0.050000