Maps with "holes"

[PantherCub]

Autogenerated maps frequently have depressions or holes in them, typically like the one here. In my experience, in real terrain there are seldom such depressions. Gullies that lead somewhere, yes, but very seldom isolated depressions. If there are depressions in real terrain, they are usually lakes or swamps. IMHO these maps are annoyingly unrealistic, though I admit they are not a problem for actual play.

Would it be possible to tune the map generator so that it avoided this?