Tool Quasi-Dynamic Flow Accumulation
This tool estimates the flow distribution at a specified time after a rainfall event. It is based on a standard flow accumulation calculation (e.g. O'Callaghan & Mark 1984, Freeman 1991) that has an additional function to accumulate the flow travel time. Final flow accumulation becomes that part of the total flow through that corresponds to the portion of flow travel time that exceeds the targeted time. The travel time is estimated with the empirical Manning equation (e.g. Dingman 1994, Freeman et al. 1998, Manning 1891).
References
- Dingman, S.L. (1994): Physical Hydrology. Macmillan Publishing, 575p.
- Freeman, G. E., Copeland, R. R., Rahmeyer, W., & Derrick, D. L. (1998): Field Determination of Manning’s n Value for Shrubs and Woody Vegetation. Engineering Approaches to Ecosystem Restoration. doi:10.1061/40382(1998)7..
- Freeman, G.T. (1991): Calculating catchment area with divergent flow based on a regular grid. Computers and Geosciences, 17:413-22. ScienceDirect.
- Manning, R. (1891): On the flow of water in open channels and pipes. Transactions of the Institution of Civil Engineers of Ireland. 20: 161–207.
- 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. ScienceDirect.
- Author: O.Conrad (c) 2019
- Menu: Simulation|Hydrology
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | Grid, input | DEM | [m] | - |
| Manning-Strickler Coefficient (*) | Grid, input, optional | FLOW_K | Manning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient) | - |
| Output | Flow Accumulation | Grid, output | FLOW_ACC | [mm] | - |
| Flow Through (*) | Grid, output, optional | FLOW | - | - |
| Flow Travel Time (*) | Grid, output, optional | TIME_MEAN | - | - |
| Flow Concentration (*) | Grid, output, optional | TIME_CONC | - | - |
| Flow Velocity (*) | Grid, output, optional | VELOCITY | - | - |
| Options | Grid System | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Default | Floating point | FLOW_K_DEFAULT | default value if no grid has been selected | Minimum: 0.000000
Default: 20.000000 |
| Time | Floating point | TIME | minutes | Minimum: 0.001000
Default: 5.000000 |
| Flow Routing | Choice | ROUTING | - | Available Choices:
[0] D8
[1] MFD
Default: 1 |
| Flow Depth | Choice | FLOW_DEPTH | - | Available Choices:
[0] constant
[1] dynamic
Default: 1 |
| Constant Flow Depth | Floating point | FLOW_CONST | [mm] | Minimum: 0.000000
Default: 10.000000 |
| Reset | Boolean | RESET | Resets flow accumulation raster. | Default: 1 |
| Rain | Floating point | RAIN | The flow portion [mm] added to each raster cell before simulation starts. | Minimum: 0.000000
Default: 10.000000 |
| (*) optional |
Command-line
Usage: saga_cmd sim_hydrology 8 [-DEM <str>] [-FLOW_K <str>] [-FLOW_K_DEFAULT <double>] [-FLOW_ACC <str>] [-FLOW <str>] [-TIME_MEAN <str>] [-TIME_CONC <str>] [-VELOCITY <str>] [-TIME <double>] [-ROUTING <str>] [-FLOW_DEPTH <str>] [-FLOW_CONST <double>] [-RESET <str>] [-RAIN <double>]
-DEM:<str> Elevation
Grid, input
-FLOW_K:<str> Manning-Strickler Coefficient
Grid, input, optional
-FLOW_K_DEFAULT:<double> Default
Floating point
Minimum: 0.000000
Default: 20.000000
-FLOW_ACC:<str> Flow Accumulation
Grid, output
-FLOW:<str> Flow Through
Grid, output, optional
-TIME_MEAN:<str> Flow Travel Time
Grid, output, optional
-TIME_CONC:<str> Flow Concentration
Grid, output, optional
-VELOCITY:<str> Flow Velocity
Grid, output, optional
-TIME:<double> Time
Floating point
Minimum: 0.001000
Default: 5.000000
-ROUTING:<str> Flow Routing
Choice
Available Choices:
[0] D8
[1] MFD
Default: 1
-FLOW_DEPTH:<str> Flow Depth
Choice
Available Choices:
[0] constant
[1] dynamic
Default: 1
-FLOW_CONST:<double> Constant Flow Depth
Floating point
Minimum: 0.000000
Default: 10.000000
-RESET:<str> Reset
Boolean
Default: 1
-RAIN:<double> Rain
Floating point
Minimum: 0.000000
Default: 10.000000