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Dear forum,

Today a coworker asked me if within Bluekenue or any other post-processor tool (or script) there is a way of extracting the "maximum" value of water depth and the correspondant velocity vector (U,V, and magnitude) of each node from a simulation (a transient flood model) and export it as a raster, which then will be used for a "flood risk" map.

The "exporting results to raster" part I believe can be achieved with post-telemac or even with the crayfish plugin which I haven't fully tested yet...but really don't know where to start for extracting procedure.

Has anyone tackled a similar requirement?.

Regards.

José Díaz.

Hello José,

in Bluekenue you can do it.
Open your simulation result (Results.slf) - select WATER DEPTH (or VELOCITY UV) - then select Tools - Exctract Surface - Temporal Maximum - choose the frames to take into account - press ok.

Now you can save the result as .xyz file: select the file that has the default name "WATER DEPTH(Max)" - File - Save Copy as - select the format.

I use this procedure to excract the maximum values. Then, because QGIS gives problem to open the resulting .xyz file I use a short matlab script to convert the .xyz file in .tiff. But probably you use another GIS that opens it without problems.

Hope this helps,

Daniele

Dear Daniele,

Thank you for your response. A quick question regarding this procedure, does the velocities extracted correspond to the maximum temporal of the water depth or are "independent" outputs of the maximum values alone?

Thank you,

José Díaz.

it is indepenent.
the algorithm just take the maximum values of the variable you selected.

In fact, if you have only the variable "VELOCITY UV",so no WATER DEPTH and BOTTOM in your results file, you would get the same results.

You are welcome,

Daniele

Hi José,

With Blue Kenue or other postprocessor, it just reads the maximum of your graphical printout. If your GRAPHIC PRINTOUT PERIOD is scarce, you may miss the maximum.

You can also directly get it from Telemac with the “VARIABLES FOR 2D GRAPHIC PRINTOUTS” :

• MAXZ = MAXIMUM ELEVATIONS
• TMXZ = CORRESPONDING TIMES FOR MAXIMUM ELEVATIONS
• MAXV = MAXIMUM VELOCITIES
• TMXV = CORRESPONDING TIMES FOR MAXIMUM VELOCITIES

Alexis

Hello

Telemac allows you to have directly the maximum of elevation, velocity and their accuring times. To do that, you need to add MAXZ, TMXZ, MAXV,TMXV to the VARIABLES FOR GRAPHIC PRINTOUTS.

I hope that this helps

with my best regards

Riadh ATA

Hello José,

enclosed you will find a short Python script which extracts "the "maximum" value of water depth and the corresponding velocity vector".
Here in Austria we need exactly that especially for governmental projects.
It writes the results back to BlueKenue files, so this is the biggest part of the script.
You should mainly modify the first 14 lines. Python 2.7.x and numpy is required and it uses some fancy indexing methods from numpy. It uses the selafin parser which you can find in the telemac directory, therefore you have to change also this

P.S. In BlueKenue you can create ascii grid files which can be read by QGIS. Or you use the QGIS Artelia Telemac plugin.


Hope this helps,
Clemens

Dear Clemens, Riadh and Alexis

Both the graphic printout and the script are exactly what I needed, pretty straightforward!

Thank you!