My understanding of the generalization concept is that we will have a general class and other specialized classes for each departement, this is the result as the class diagram. May be i'm wrong, but concretly, will not that be reflected in the application by an Entity class for each departement ?
Which means it will be necessary to change source as many time as a new departement is added.
I see the approach you intituled database centric approach more suitable, like you sayed, a new departement would simply be a new entry binded with specifics attributes. We can also see it other way, each specialized departement is an instance of the departement class(Object diagram). Now with this, the problem is not totally resolved, it's deplaced to the attribute's part, are we assuming that all departements will have the same attributes