A throw up post to see if it piques anyone interest. I first read about this being implemented in Cascadia Pacific Northwest of America
Bioregionalism is a political, cultural, and environmental system and set of views based on naturally-defined areas called bioregions, or ecoregions. Bioregions are defined through physical and environmental features, including watershed boundaries and soil and terrain characteristics. Bioregionalism stresses that the determination of a bioregion is also a cultural phenomenon, and emphasizes local populations, knowledge, and solutions.
Instead use the River Basin Districts to determine regions.
Obviously this crosses the Northern Irish Border in the UK, but it wouldn't work without this, a lot of the time rivers divide regions or countries but actually people on either side of river would have more in common.
I started to try and outline Liffey bioregions and potential new Dublin electoral constituencies down to local councils areas.
Bioregions is is based on watersheds and many other commons areas flora, fauna, weather and people defined and overlayed together.
This is on my Todo List... Irish River Basin districts