Hello Yanis,
Yes, this is the classical algorithm in Telemac that allows slightly negative depths, but conserves mass. No we have a new option that keeps depths positive :
TREATMENT OF NEGATIVE DEPTHS : 2
TRAITEMENT DES HAUTEURS NEGATIVES : 2
You can refer to the new Telemac-2D manual (published very soon) or the update 6.0 already published.
The program will ask you to change a few other pamameters such as in 2D :
CONTINUITY CORRECTION : YES
and perhaps the mass-lumping on depth, just do what it asks.
You can also refer the Malpasset test-case, and look at the parameter file caspos.txt, this one is in French, there must be an equivalent in English in the case : Wesel.
With best regards,
Jean-Michel Hervouet