FMA Challenge 2: Difference between revisions

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To test the effect of completely removing the embankments in the images above, the 15m and 30m TUFLOW models were used. Initially the 30m model was run as this is a quick running model so good for an initial sensitivity tests.
 
The embankments were removed by digitizing the polygons shown in grey in the images below, and using TUFLOW’s Z Shape functionality that creates TINs within the polygons whose perimeters are merged with the surrounding ground levels to erase the embankments. ThisWithin isthe ademo verymodel, quickthe processembankment toremoval docan andbe setuprun (aboutusing 5the minutesscenario in''EMB''. With this case)scenario applied, andTUFLOW therewill ismodify nothe needtopography toby reworkcalling the layer ''2d_zsh_remove_ridges_001_R.shp'' as shown in the originaltgc DEMfile.
 
Within the demo model, the embankment removal can be run using the scenario ''EMB''. With this scenario applied, TUFLOW will modify the topography by calling the layer ''2d_zsh_remove_ridges_001_R.shp''
 
The images below for the initial 30m grid run show the levels at the high water marks with and without the embankments at the two locations previously discussed. The red values are the 1964 HWMs, the blue values the without embankments scenario and the black values in brackets for the with embankments case previously discussed. An improvement in the calibration results tends to result.
 
The 15m simulation provided an even better calibration, and gives the best overall performance of all simulations carried out. The maximum flood extent layer is provided in the ftp download for this simulation.
 
In conclusion, we would summarise that some of the key embankments within the study area either did not exist at the time of the 1964 event or were of a lower height or configuration.