Appendix B Parameters
Following are parameters that can be specified within TUFLOW CATCH via user commands.
Tips for use:
- Use the search box to dynamically filter the table
- Sort the filtered (or unfiltered) table by clicking the arrows at the top of each column
- Use “s” on your keyboard to toggle the contents pane on and off to provide more screen width if needed
- UD = user defined
- N/A = not applicable
- For each parameter, use the links in the final column to navigate to either:
- A description of the corresponding control file command that includes the parameter (these links are all suffixed with ‘==’)
- The section containing the relevant descriptions (these links are all called ‘science’)
| Parameter | Notation | Units | Description | Links |
|---|---|---|---|---|
| Water depth threshold | \(d\) | m | The minimum cell water depth for which pollutant export is permitted for a given pollutant within a given material. Below this depth, no pollutant export occurs. Applies equally to all pollutant export models. Evaluated on a cell by cell basis |
Depth Threshold == science |
| Accumulation limit | \(L_{acc}\) | kg/ha | The maximum dry store areal mass of a given pollutant allowed to accumulate within a given material. Used with the Washoff1 pollutant export model. Above this value, no further mass is added to a cell’s dry store. Must be a positive number |
Limit == science |
| Erosion limit | \(L_{shr}\) | kg/ha | The maximum erosion or deposition allowed within a material for a given pollutant. The number is specified only as a positive number, but is applied equally to erosion and deposition. For example, if a number of 100 is specified, and erosion is occurring in a given cell, then erosion will stop when the areal mass reaches -100 kg/ha. Equally, if deposition is occurring in the same cell, it will cease when the areal mass reaches 100 kg/ha. These areal masses can be converted to eroded depth or accretion height by assuming a bulk density and applying a conversion from hectares to square metres |
Limit == science |
| Dry store accumulation rate | \(R_a\) | kg/ha/yr | The rate at which a pollutant accumuates mass to its dry store. Used only in accumulation pollutant export models. Set to zero to suppress pollutant export or a large value to rapidly populate pollutant dry stores. This might be useful in setting initial conditions |
Rate == science |
| Washoff time constant | \(T_c\) | s | A time constant that controls the rate at which a pollutant is washed off (out of its dry store) when both minimum cell water depth and rainfall conditions are met. Used only in accumulation pollutant export models. Set to a large (small) number for slow (rapid) pollutant dry store release |
Time Constant == science |
| Rainrate threshold | \(R_r\) | mm/hr | The minimum instantaneous cell rain rate above which pollutant is exported from its dry store. Used only in accumulation pollutant export models. Set to a large (small) number for reduced (enhanced) pollutant washoff. Evaluated on a cell by cell basis |
Rain Threshold == science |
| Critical shear stress for deposition | \(\tau_{cd}\) | N/m\(^2\) | The maximum bed shear stress at which deposition can occur from a pollutant’s wet to dry store. The rate at which this deposition occurs is then set by the specified settling velocity. Used only in shear stress pollutant export models. Set to a small (large) number for reduced (enhanced) pollutant settling. Evaluated on a cell by cell basis. Should be less than the corresponding critical shear stress for erosion |
Deposition Stress == science |
| Critical shear stress for erosion | \(\tau_{ce}\) | N/m\(^2\) | The minimum bed shear stress at which erosion can occur from a pollutant’s dry to wet store. Used only in shear stress pollutant export models. Set to a large (small) number for reduced (enhanced) pollutant erosion. Evaluated on a cell by cell basis. Should be greater than the corresponding critical shear stress for deposition |
Erosion Stress == science |
| Deposition velocity | \(w_s\) | m/d | The still water velocity at which a pollutant settles from the wet to dry store. Set to a small (large) number for reduced (enhanced) pollutant settling. Evaluated on a cell by cell basis |
Deposition Velocity == science |
| Erosion rate | \(E_r\) | g/m\(^2\)/s | The rate at which a pollutant is eroded from its dry store. Used only in shear stress pollutant export models. Set to a small (large) number for reduced (enhanced) pollutant erosion. Evaluated on a cell by cell basis |
Erosion Rate == science |
| Nodestring boundary timestep | \(dT_{ns}\) | s | The timestep at which lines within a nodestring (Q) boundary condition file for TUFLOW FV (created from TUFLOW HPC predictions) are separated. This is not the timestep at which boundary data is written from memory to file |
Catch BC Output Interval Nodestring == science |
| Lateral boundary timestep | \(dT_{lat}\) | s | The timestep at which lines within a lateral (element, QC) boundary condition file for TUFLOW FV (created from TUFLOW HPC predictions) are separated. This is not the timestep at which boundary data is written from memory to file |
Catch BC Output Interval Lateral == science |
| CSV write timestep | \(dT_{csv}\) | d | The timestep (in simulation time) at which boundary condition data in memory is written to boundary condition files for TUFLOW FV (created from TUFLOW HPC predictions). This is not the timestep separating individual lines in a boundary condition file |
CSV Write Frequency Day == science |
