Italian to English Other Environment & Ecology research, surveys

Stumped as to how to translate this (WRef: strongholds; google: mountain complexes; corriere.it: enclose oneself in a defensive position (metaphorically); MT: defensivenesses (?))

"Complessivamente è risultato che l'attuale delta è il prodotto di azzonamenti e arroccamenti, a seconda del prevalere dell'uno o dell'altro interesse, un arcipelago di isole giustapposte, ciascuna con una forte specificità ed autonomia."

I think the text refers to the defensive positions (or perhaps even a literal defense of certain parts of the land - the Po Delta - with an accompanying equally defensive mentality): the land of the Po delta, the text claims, is partly dominated by external interests who exploit the land, and major portions of it have been recently cleared for large-scale farming, in contrast to the former "cottage industries" and smaller farms and factories present in those parts.

Azzonamenti I have translated literally as "zonings", as I think that's what's intended here.

Thanks in advance,

Peter