I remember some people mentioned the map now in factorio is logically flat. It is actually the same everywhere. It does need difference between places and places. I think this is a good start. Pollution affect a set of things, heavily on solar, a little bit on assemblers, very slightly on furnaces, visually on water bump.
Btw, I even tried to purpose that the water should have a value to point out the depth, or the volume it remains. After been comsumed, the water should fall. And you could even script source of water. And this mechanism could even affect the shore line. Means land blocks also need a value to points out its height.
That's it.