Description:
Using the Donjon World generator (http://donjon.bin.sh/scifi/world/index.cgi) I came up with this basic image for a planet that has 10 percent of its water in ice caps and 30 percent free flowing water. Maybe that's too much, but I am trying to envision Volturnus as a "post garden" world following the Sathar attack from 900 years before.

The planet may have already been moving into a post-garden phase before the Eorna were destroyed.