Tip of the Month

One can use ISIS Mapper to create a flood map from ISIS 1-D model results, with little effort, providing the user has the following available:

• ISIS model results in the form of binary files (.zzn/.zzl files) or Tabular CSV files (.csv)
• a ground grid (e.g. DEM) for the area of interest
• a shapefile of model data (cross-section polylines or flood cell reservoir polygons) or geo-referenced ISIS model files. Creating these can also be performed in ISIS Mapper.

Step 1

Launch ISIS Mapper by clicking the ISIS Mapper icon or selecting > Tools > ISIS Mapper from the main menu of ISIS.

Step 2

Import river sections of your ISIS Model either by loading the shapefile of your model (if you have it) or by clicking on the model import icon. ISIS Mapper will then convert the sections into separate polylines within a new shapefile.

Step 3

Create a TIN (Triangulated Irregular Network) for displaying 1D model results as a water surface. From the ISIS Mapper main menu select > Modelling > 1D Flood Map > Triangulate shapefiles. When prompted select the cross section shapefile and a filename for your TIN. The TIN Creator tool will then open with your cross section shapefile pre-loaded. Create a TIN by clicking the triangulate icon . Use editing tools in TIN Creator to remove triangles linking non-adjacent points (if present). Click the ISIS Mapper icon to close TIN Creator and automatically load your TIN into the ISIS Mapper viewport.

Step 4

Add the ISIS results to a TIN. These results (binary or csv format) can be added to the TIN by selecting Modelling > 1D Flood Map> Add Binary ISIS Results to TIN or Add Tabular CSV Results to TIN respectively. Please ensure that the Tabular CSV results have been created in ISIS using the output format ’One Column per Timestep’.

Step 5

Load the ground data into ISIS Mapper by clicking Open Raster Data icon .

The user can now see the flood extent in ISIS Mapper. This can also be saved in the form of a flood depth grid or a flood extent shapefile by using the 1D Flood Calculator (select Modelling > 1D Flood Map > Generate Flood Map).

For more information about 1D Flood Calculator and other functions of ISIS Mapper, including those described above, see the ISIS Mapper manual either by selecting > Help > Open Help in ISIS Mapper.