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
- Author: O.Conrad (c) 2001-14
- Specification: grid
- 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 (optional input) | 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 (optional input) | FIELDS | If set, output is given about the number of fields a flow path visits downhill. For D8 only. | - |
| Manning-Strickler Coefficient (*) | Grid (optional input) | FLOW_K | Manning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient) | - |
| Flow Depth (*) | Grid (optional input) | 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 (optional output) | TIME | flow travel time to channel expressed in hours based on Manning's Equation | - |
| Sediment Yield Delivery Ratio (*) | Grid (optional output) | 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 | 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 |
| Beta | Floating point | FLOW_B | catchment specific parameter for sediment delivery ratio calculation | Minimum: 0.000000
Default: 1.000000 |
| Default | Floating point | FLOW_K_DEFAULT | default value if no grid has been selected | Minimum: 0.000000
Default: 20.000000 |
| Default | Floating point | 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>] [-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