I can’t come up with a better solution for river arrays at the top of my head, but I’ll think about it. Something else I’ve though about is that you might want to alter some of your algorithms a bit to make the terrain more realistic. For instance, rivers tend to originate from mountains in the real world, mountain ranges tend to somewhat follow coastlines etc. For the most part it’s probably unneccessary to worry too much about this, but it might be something to keep in mind. You are already doing some of this this by having cool poles and a hotter equator, for instance. For me personally, the rivers appearing out of nothing is a bit jarring, but I might be in a small minority. I think rivers in CIV V usually begin Next to hills or mountains.