Appendix F — TRFC Commands

The TUFLOW Rainfall Control File (.trfc) contains commands used to generate rainfall grids based on point rainfall gauges, it is read into the .tcf using the Rainfall Control File command. For more information on the .trfc see Section 4.1.12. Generating and using rainfall grids is discussed in Section 8.4.3.1.4. The TUFLOW Wiki Rainfall Control File Examples page also includes some useful discussion on this subject. The available TRFC commands are listed below. For an explanation of the command syntax, see Commands.

F.1 TRFC Commands

IDW Exponent == <p> | {2}

If using the RF Interpolation Method == IDW the exponent in the IDW equation can be changed from the default value of 2. Refer to Section 8.4.3.1.4 for more details.

IDW Maximum Distance == <max_dist>

If using the RF Interpolation Method == IDW the maximum distance for a point to be considered in the IDW interpolation can be set using this command. If not specified, no maximum distance is considered. Using metric units (default), the distance is in metres. Using Units == US Customary, the units are feet. Refer to Section 8.4.3.1.4 for more details.

IDW Maximum Points == <max_points>

If using the RF Interpolation Method == IDW the maximum number of points considered in the interpolation can be specified. This may reduce memory usage if a very large number of rainfall points are used. Refer to Section 8.4.3.1.4 for more details.

If Event == <e1> | <e2> | <e3> | …

Controls which commands to process for different events (see Appendix A).

If Scenario == <s1> | <s2> | <s3> | …

Controls which commands to process for different scenarios (see Appendix A).

Maximum Hyetograph Points == <max_pts> | {1,000}

Legacy command - expand to find out more

From the 2026.0.0 TUFLOW release onwards, this command is no longer required as the maximum number of hyetograph points is allocated dynamically based on the input files. As such, if this command is specified, it is ignored and CHECK 2624 is issued.

For releases prior to 2026.0.0:

Controls the temporary memory allocated for reading / storing the rainfall data. If more the 1,000 points occur in the rainfall hyetograph, this can be increased. Can also be reduced to decrease temporary memory allocation.

Maximum RF Locations == <max_rf_gauges> | {1,000}

Legacy command - expand to find out more

From the 2026.0.0 TUFLOW release onwards, this command is no longer required as the maximum number of rainfall locations is allocated dynamically based on the input files. As such, if this command is specified, it is ignored and CHECK 2624 is issued.

For releases prior to 2026.0.0:

Controls the temporary memory allocated for reading / storing the rainfall data. If more the 1,000 point rainfall locations are used, this can be increased. Can also be reduced to decrease temporary memory allocation.

Read GIS RF Point == <gis_layer>

Read the point rainfall locations in the 2d_rf file format (see Table 8.12) in a rainfall control file. Refer to Section 8.4.3.1.4 for more details.

This command is optional if the RF Interpolation Method is set to POLYGON. See Read GIS RF Polygons.

Read GIS RF Polygons == <gis_layer>

The GIS layer contains a series of polygons or regions in the 2d_rf format (see Table 8.12). This command is mandatory with the RF Interpolation Method == POLYGON approach. Refer to Section 8.4.3.1.4 for more details.

When all rainfall polygons have a populated “Name” attribute, the polygon attributes are used. Rainfall points (Read GIS RF Point) are not required, however if they are also specified, they are ignored and WARNING 2627 is issued.

When all rainfall polygons have a blank “Name” attribute, then a 2d_rf rainfall points layer with one point in each polygon is required. f1/f2 attributes (see Table 8.12) are applied from the rainfall points and the rainfall polygon attributes are ignored. CHECK 2626 is issued if all rainfall polygons have a blank “Name” attribute and ERROR 2619 occurs if the polygon does not contain a rainfall point. If rainfall polygons include a mix of blank and populated “Name” attributes, ERROR 2628 occurs.

If there are overlapping polygons, WARNING 2623 is issued and the later polygon overwrites the earlier polygon(s), whether they have the same or different names.

Read GIS RF Triangles == <gis_layer>

Reads in a GIS layer containing the triangulation of the rainfall points. The GIS objects should be polygons or regions with three vertices, with each vertex snapped to a rainfall point location as specified by Read GIS RF Point. The layer is typically produced by other software specialising in the interpolation of rainfall, but can be manually created when only a small number of rainfall locations exist. The attributes of the GIS layer are not used. For each grid cell in the rainfall output grids, the rainfall depth is based on the planar (linear) interpolation of the three rainfall depths at the vertices of the bounding triangle. Refer to Section 8.4.3.1.4 for more details.

RF Grid Cell Size == <value>

Sets the cell size for the generated rainfall grids. If omitted, a value 10 times the 2D domain cell size (or the Base Cell Size for Quadtree models) is used. Typically the rainfall can be satisfactorily represented on a much coarser resolution than that required for the hydraulic calculations, and using high resolution rainfall grids is not required and unnecessarily consumes memory and disk space, and may slow down the simulation. Refer to Section 8.4.3.1.4 for more details.

RF Grid Format == ASC | FLT | NC | TIF

This mandatory command sets the output grid format. Options are TIF (GeoTIFF - extension .tif) , FLT (ESRI binary grid – extension .flt), ASC (ESRI asc grid – extension .asc), or NC (NetCDF extension .nc). Refer to Section 8.4.3.1.4 for more details.

The rainfall grids are output to a separate folder (RFG\<rainfall_grid>) in the location of the .trfc file. If the .trfc file is in the bc_dbase\ folder, a new folder bc_dbase\RFG\ is created containing the output grids.

The output formats from the rainfall interpolation are compatible with the formats used by the .tcf Read Grid RF, and once the rainfall grids have been generated this command can be used to apply the rainfall, rather than regenerate the rainfall grids using the .trfc file (should the .trfc input files remain unchanged).

NC: If NetCDF output is specified a single output file (.nc) containing all timesteps in a single file is created. This is given the simulation name: TUFLOW\bc_dbase\RFG\<simulation_name>.nc ensuring that the dataset is not accidentally overwritten as the simulation is running. There is no limit to the number of rainfall timesteps that are included in the NetCDF format.

A total rainfall depth is also output, however, this is not used by TUFLOW during the simulation, and it can be used for checking purposes. For more information see TUFLOW NetCDF Rainfall Format Wiki Page.

TIF, FLT and ASC: A series of grids are written (one for each hyetograph timestep) in the specified formats. Due to the large number of grids that may be written, these are separated into a sub-folder under the RFG\ folder, for example:

\bc_dbase\RFG\<simulation_name>\<simulation_name>_<time>.tif

An index file containing a list of the times and rainfall grid filenames is written in .csv file format in the same folder, for example:

\bc_dbase\RFG\<simulation_name>\<simulation_name>_rf_index.csv

A limit of 1,000 grids exists if using the TIF, FLT or ASC format, if more than 1,000 grids are required the NetCDF format should be used.

RF Grid Origin == <OX>, <OY>

Sets the origin for the output rainfall grid. If this command is omitted the rainfall grid origin is based on the origin of the TUFLOW 2D domain(s). Refer to Section 8.4.3.1.4 for more details.

RF Grid Size (N,M) == <rows>, <columns>

Sets the size of the output rainfall grids. Similar to the .tgc Grid Size (N,M) command. If omitted the rainfall grid size is based on the dimensions in the TUFLOW 2D domain(s). Refer to Section 8.4.3.1.4 for more details.

RF Grid Size (X,Y) == <X_length>, <Y_length>

Sets the size of the output rainfall grids. Similar to the .tgc Grid Size (X,Y) command. If omitted the rainfall grid size is based on the dimensions in the TUFLOW 2D domain(s). Refer to Section 8.4.3.1.4 for more details.

RF Interpolation Method == IDW | POLYGON | TIN

This is a mandatory command (for direct rainfall models) that sets the interpolation approach between rainfall locations. Refer to Section 8.4.3.1.4 for details.

IDW: An inverse distance weighting (IDW) approach is used to calculate the rainfall depth based on the distance to the surrounding rainfall points (specified by Read GIS RF Point).

POLYGON: A series of GIS polygons in 2d_rf format are specified by Read GIS RF Polygons to apply spatially uniform rainfall within each polygon.

This method is similar to using a series of rainfall polygons read in via the .tbc Read GIS RF command. However, pre-processing using a .trfc file is significantly more memory efficienct, particularly if a large number of rainfall boundaries is used.

TIN: A TIN (Triangulated Irregular Network) is specified via Read GIS RF Triangles which connects the rainfall point locations.