yup even just dams can do that.. especially on flat lands... in my area we have a city called peterborough.. they installed an electric dam back in the day, and it affected rivers and lakes for up to 100km upstream... it would quadruple a lakes size, reroute, split up or even remove a river all together... it's amazing what a fairly small change can do...

I worked for a natural heritage conservancy there, and i worked on a "before and after" map, using old maps from before the dam was created and maps from now... the difference in the overall river/lake layout was quite easy to see.