Quasi-Dynamic Flow Accumulation
- Author: O.Conrad (c) 2019
- Menu: Simulation | Hydrology
Description
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.
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 number | FLOW_K_DEFAULT | default value if no grid has been selected | Minimum: 0.000000 Default: 20.000000 | |
| Time | floating point number | 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 number | FLOW_CONST | [mm] | Minimum: 0.000000 Default: 10.000000 | |
| Reset | boolean | RESET | Resets flow accumulation raster. | Default: 1 | |
| Rain | floating point number | RAIN | The flow portion [mm] added to each raster cell before simulation starts. | Minimum: 0.000000 Default: 10.000000 |
Command Line
Usage: saga_cmd sim_hydrology 8 [-DEM] [-FLOW_K ] [-FLOW_K_DEFAULT ] [-FLOW_ACC ] [-FLOW ] [-TIME_MEAN ] [-TIME_CONC ] [-VELOCITY ] [-TIME ] [-ROUTING ] [-FLOW_DEPTH ] [-FLOW_CONST ] [-RESET ] [-RAIN ] -DEM: Elevation grid, input -FLOW_K: Manning-Strickler Coefficient grid, input, optional -FLOW_K_DEFAULT: Default floating point number Minimum: 0.000000 Default: 20.000000 -FLOW_ACC: Flow Accumulation grid, output -FLOW: Flow Through grid, output, optional -TIME_MEAN: Flow Travel Time grid, output, optional -TIME_CONC: Flow Concentration grid, output, optional -VELOCITY: Flow Velocity grid, output, optional -TIME: Time floating point number Minimum: 0.001000 Default: 5.000000 -ROUTING: Flow Routing choice Available Choices: [0] D8 [1] MFD Default: 1 -FLOW_DEPTH: Flow Depth choice Available Choices: [0] constant [1] dynamic Default: 1 -FLOW_CONST: Constant Flow Depth floating point number Minimum: 0.000000 Default: 10.000000 -RESET: Reset boolean Default: 1 -RAIN: Rain floating point number Minimum: 0.000000 Default: 10.000000