Flowing rivers?

Anyone knows how to create flowing rivers and falls like in this scenery ? I saw one from a developer also in Switzerland. I would love to create some like this.

They may be rolling barrels with alpha materials (so 3d objects…it shouldn’t be difficult to find them in the scenery editor)
Or effects
Or 3d object with animated materials

Yea maybe. I would need to install the scenery and dig.

Nice innovation in scenery making I think