The 1D Flood Calculator controls

Within Flood Calculator a number of options exist allowing you to tailor the flood map calculation to your specific needs. These options are:

• Select TIN - Choose the TIN containing water surface elevation details. All compatible TIN datasets present in the Layers panel automatically populate this list box. A TIN with loaded 1D model results has to be specified for all 1D flood map calculations. However, it is not necessary to specify a TIN for the Static Flood Extent from Grid option (this calculation does not require it) and so the Select TIN window is disabled if this option is chosen.
• Select Ground Surface - Choose the surface raster. All compatible grid datasets present in the Layers panel automatically populate this list box. If the user would like to obtain the map of water elevations only they can select NAN from this list, which means no ground elevation data will be used in the subsequent calculations.
• Select Time Step - Select time step result from to use in flood map calculation from list of time steps associated to selected TIN. If you would like to have output files for more than one time step or all the time steps, then you have to carry out a separate flood calculation for each. Multi-time step calculations can be automated using the batch run option, see section Batching Multiple Calculations below.
• Run - After specifying the required flood map calculations click the Run button to start the calculation process. If performing a single calculation (i.e. not defined in the batch run table) Flood Modeller will prompt for a filename and location for the new flood map that will be generated (the file will also be then added to the batch table).
• Output Type - Selection of the output grid format or shapefile format is done when specifying the filename for the new flood map.
• Add - Allows the user to add a defined flood map calculation and associated parameters as a new task in the 1D flood calculator batch run table. If only one calculation is needed, then the task will be added automatically to the task list when you click on the Run button. After the task has been added to the list, you can define further calculations as additional tasks or edit the parameters of existing tasks in the table.
• Delete - Allows you to delete the selected task from the list of tasks in the batch run table.
• Save - Allows you to save a list of flood map calculation tasks with all the parameters into a special .cbt file. This file can be loaded later and all the flood map calculations can be repeated again without having to specify all parameters again.
• Load - Allows you to load the special .cbt file containing a predefined set of flood map calculations.
• Load to View - This tick box (ticked by default) enables the output files generated by the flood calculator to be loaded into viewport automatically.
• Calculate event duration grid - Allows you to define an event duration grid from your 1D model results, i.e. grids where the vertical scale is a duration that a flood threshold is exceeded within the underlying ground cell over a specified modelled period. If the event duration box is ticked the main display remains unchanged except that now it is possible to select multiple time steps from the list of available time steps. By default all time steps shown are initially selected. The selected time steps specify the time interval which will be used when calculating values within the event duration grid.
• Calculation of a grid of water levels - It is possible to generate a grid of water levels without using any ground grid. With the 1D flood calculator set to 'Flood extent from TIN' select option 'NaN' from the ground grid list (i.e. export TIN only). You specify the other required parameters as normal, i.e. output filename, TIN file and model time step, etc. In addition, since no ground grid is set, you must also specify a grid cell size for the output data (add task to batch table and use Edit button to change cell size, as described above). The default cell size is 10m. Once all settings are completed click the Run button to proceed with the calculations.
• Calculation of a Static Flood Extent from Grid - Allows you to create flood extent map without using a TIN. Select the Static Flood Extent from Grid option in the upper right of the 1D Flood Calculator window. Then you specify the (constant) water level for which the static flood extent is to be calculated, as shown in the figure below. As no TIN is specified the output map will not be dependent on any model data, instead it will represent a horizontal water surface spread over the source ground grid.

Calculations can take time if large datasets are selected. The calculation progress is shown on the status bar below the viewport of the main interface. Flood Calculator runs separately from Flood Modeller thus other functions can be accessed while the depth grid(s) are being generated.