Upslope Area
- Author: O.Conrad (c) 2001
- Menu: Terrain Analysis | Hydrology | Flow Accumulation
Description
This tool allows you to specify target cells, for which the upslope contributing area shall be identified. The result will give for each cell the percentage of its flow that reaches the target cell(s).
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This version uses all valid cells (not 'no data' values) of a given target grid to determine the contributing area. In case no target grid is provided as input, the specified x/y coordinates are used as target point.
References
- 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.
- Qin, C. Z., Zhu, A. X., Pei, T., Li, B. L., Scholten, T., Behrens, T. & Zhou, C. H. (2011): An approach to computing topographic wetness index based on maximum downslope gradient. Precision Agriculture, 12(1), 32-43. ResearchGate.
- Quinn, P.F., Beven, K.J., Chevallier, P. & Planchon, O. (1991): The prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models. Hydrological Processes, 5:59-79. ResearchGate.
- Seibert, J. & McGlynn, B. (2007): A new triangular multiple flow direction algorithm for computing upslope areas from gridded digital elevation models. Water Resources Research, Vol. 43, W04501,
C++ implementation in SAGA by Thomas Grabs (c) 2007, contact: thomas.grabs@natgeo.su.se, jan.seibert@natgeo.su.se. Wiley. - Tarboton, D.G. (1997): A new method for the determination of flow directions and upslope areas in grid digital elevation models. Water Resources Research, Vol.33, No.2, p.309-319. Wiley.
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Target Area | grid, input, optional | TARGET | - | - |
| Elevation | grid, input | ELEVATION | - | - |
| Sink Routes | grid, input, optional | SINKROUTE | - | - |
| Output | Upslope Area | grid, output | AREA | - | - |
| Options | Grid System | grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Target X coordinate | floating point number | TARGET_PT_X | The x-coordinate of the target point in world coordinates [map units] | Default: 0.000000 |
| Target Y coordinate | floating point number | TARGET_PT_Y | The y-coordinate of the target point in world coordinates [map units] | Default: 0.000000 |
| Method | choice | METHOD | - | Available Choices:
[0] Deterministic 8
[1] Deterministic Infinity
[2] Multiple Flow Direction
[3] Multiple Triangular Flow Directon
[4] Multiple Maximum Downslope Gradient Based Flow Directon
Default: 2 |
| Convergence | floating point number | CONVERGE | Convergence factor for Multiple Flow Direction algorithm | Minimum: 0.001000
Default: 1.100000 |
| Contour Length | boolean | MFD_CONTOUR | Include (pseudo) contour length as additional weighting factor in multiple flow direction routing, reduces flow to diagonal neighbour cells by a factor of 0.71 (s. Quinn et al. 1991 for details). | Default: 0 |
Command Line
Usage: saga_cmd ta_hydrology 4 [-TARGET ] [-TARGET_PT_X ] [-TARGET_PT_Y ] [-ELEVATION ] [-SINKROUTE ] [-AREA ] [-METHOD ] [-CONVERGE ] [-MFD_CONTOUR ]
-TARGET: Target Area
grid, input, optional
-TARGET_PT_X: Target X coordinate
floating point number
Default: 0.000000
-TARGET_PT_Y: Target Y coordinate
floating point number
Default: 0.000000
-ELEVATION: Elevation
grid, input
-SINKROUTE: Sink Routes
grid, input, optional
-AREA: Upslope Area
grid, output
-METHOD: Method
choice
Available Choices:
[0] Deterministic 8
[1] Deterministic Infinity
[2] Multiple Flow Direction
[3] Multiple Triangular Flow Directon
[4] Multiple Maximum Downslope Gradient Based Flow Directon
Default: 2
-CONVERGE: Convergence
floating point number
Minimum: 0.001000
Default: 1.100000
-MFD_CONTOUR: Contour Length
boolean
Default: 0