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hi everyone..

wishing you a great and beautiful day.

I had a bit confusing to understand the result for evolution and rugosite totale. for the evolution, is it the -ve data means erosion and +ve deposition or else? and can somebody explain about the rugosite totale? I have try search in forum and in manual but could not found it.

thank you in advance for your attention and reply.


regards,
Shahirah

Yes, evolution is the change in bed level positive upwards.

Rugosite totale (total bed roughness) is the roughness height calculated from the friction coefficient or the results of the roughness and ripple predictors if you are using these.

AHA.. now it's more clear. thank You.

Hello,

I attached the result from the bed after running with sisyphe. You can see the initial and final steps of evolution. It shows a crisscross pattern of evolution which doesn't look like a real thing. Does anyone have any idea what things could be responsible for changing the bed evolution this way?

Hi Michiel,

Just to be clear, is the TOTAL ROUGHNESS value used by TELEMAC-2D and does it override the given roughness coefficient in hydrodynamic calculations?

Thanks,
André Renault

Hello André,

I am not a sediment transport nor a GAIA specialist, but looking at the calling graph, I would answer yes, see:
- TELEMAC2D (calling GAIA_STEP with variable CHESTR),
- GAIA_STEP (calling GAIA_PREPARE_STEP with variable KS_TEL),
- GAIA_PREPARE_STEP (calling TOB_GAIA with variable KS_TEL),
- TOB_GAIA computing KS_TEL possibly from KS (computed by KS_GAIA) with sediment at the bottom.

A GAIA specialist may also confirm if it is right or not.

Chi-Tuan

Hi Chi-Tuan,

Thank you for your reply. I've looked into it a bit based on your comments, and found this:

• As far as I understand, the keyword KSCALC (compute bed roughness at sediment scale) has to be activated in order for TOB to be calculated using sediment roughness.
• In the GAIA reference manual, it is written "This roughness could be sent to Telemac but it is not supported yet." This may have changed, but based on my reading of TOB_GAIA, I think this is still the case.

So my conclusion is that bed roughness is used in the sediment shear stress calculation if KSCALC is selected, but not anywhere else or otherwise.
Please correct me if I am wrong!

Thanks,
André

Hello André,

You seem to be right. Sorry, I read subroutines quite quickly and not line by line, in particular the condition with KSCAL .

Chi-Tuan