This tool 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.
| 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, input, optional | 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, input, optional | FIELDS | If set, output is given about the number of fields a flow path visits downhill. For D8 only. | - |
Manning-Strickler Coefficient (*) | Grid, input, optional | FLOW_K | Manning-Strickler coefficient for flow travel time estimation (reciprocal of Manning's Roughness Coefficient) | - |
Flow Depth (*) | Grid, input, optional | 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, output, optional | TIME | flow travel time to channel expressed in hours based on Manning's Equation | - |
Sediment Yield Delivery Ratio (*) | Grid, output, optional | 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 | Grid System | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
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 |
Boundary Cells | Boolean | BOUNDARY | Take cells at the boundary of the DEM as channel. | Default: 0 |
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 |