The rivers don't meander in the way that real rivers do- real rivers meander because of differences in flow velocity across the width of the river, but the simulation doesn't run at that sort of resolution. If it did, the area covered would be far smaller.
I really liked From Dust. It seemed impressive what could be done on the 360 at the time, and I'd really like to see it with a higher-res, larger scale simulation on some more modern hardware.
The rivers don't meander in the way that real rivers do- real rivers meander because of differences in flow velocity across the width of the river, but the simulation doesn't run at that sort of resolution. If it did, the area covered would be far smaller.