Additional details on 2D results

2D results data are saved in a specific raster format. This is compatible directly with Flood Modeller.

2D results data can also be loaded by selecting the standard load data option, Add GIS Data, and browsing to the required 2D data management file (extension is .2dm or .sup or xmdf.sup). Depending upon which file type is selected the loading procedure is slightly different, as described below:

• .sup file selected - The associated data files for the available output parameters (e.g. flow, depth, etc) are automatically loaded into a new window. The window displays the available timesteps in the selected results (for information only). It enables you to select the parameters they require and then click OK to load them into the viewport.
• .2dm file selected - User is then prompted to browse to and select which associated .dat files to load (one for each output parameter, i.e. flow, velocity, depth and water level). The selected files are then displayed in the 2D data selection window.

If all available time steps are loaded from your 2D model results then you can select any time step to display in the map view from the list of available time steps which is displayed in the Time Steps tab in the right hand side panel of the interface. It should be noted that in addition to the real time steps, some pseudo time steps will also likely be present within your dataset. These are all signified by time flags that begin with “9999” and are defined as follows:

• 9999 - Every cell contains the maximum value that occurred there throughout the simulation period. This is provided in all 2D parameter output files.
• 9999.1 - Represents the velocity/flow at the time of maximum depth, i.e. present in flow and velocity outputs only.
• 9999.1 - Represents the time (in hours) at which each cell first gets wet. This is present in the water level output only.
• 9999.2 - Represents the time (in hours) at which the maximum depth is occurring. This is present in the water level output only.
• These extra time steps will be ignored by Flood Modeller when you animate your data (as they are not “real” time steps). They are available to visualise in the map view and can be output as separate ascii grid layers using the 2D Flood Calculator tool.

Other layers (for example map tiles, aerial photographs and topography grids) can then be loaded using the Add GIS Data command, to facilitate greater understanding of the results.

The Properties menu (accessed by right clicking the layer in the Layers panel) can be used to change the colour scheme used for the results. Predefined colour schemes can be loaded in, and result grids can be further manipulated to increase the clarity of the results, e.g. make partially translucent, edit colours to highlight particular data ranges (such as threshold exceedance), etc. These can be found under the Symbology tab.

The Flood Modeller 2D Flood Calculator tool can be used to extract flood extents grids from the 2D Model / TUFLOW results data. These grids will be an alternative format to the 2D output grid: Format options available are ASCII (.asc) or Binary (.flt) grids, contour shapefile (.shp polygon), and Google earth format (.kml)

It should be noted that it is also possible to post-process ASCII grids with the trace outline to shapefile function (Layer Convertor in either the Grid Tools or Shapefile Tools sections of the Toolbox). This automatically draws an outline over only the outer edge of a flood extent grid. Thus, a much smaller file is produced; however the depth data of the grid is not retained. Furthermore, the Layer Convertor tool (Toolbox > Grid Tools or Shapefile Tools) can also be used to convert grid or shapefile format files into Google Earth format (kml).

Details of the operation of the 2D Flood Calculator tool are provided in Section How to use the 2D Flood Calculator.