Move it, guys, this has nothing to do with the river carving of the old days
And to be clear, this setup doesn't carve a river in a mountain! It masks out a valley in which a river flows, though you can always add some gradient if really needed.
Quotedo you test them on units that the general public have, old stuff like a few of us still have, to see how they function
I tested this on the latest TG4 version, but there's nothing in it that wouldn't work in an earlier version, no fancy stuff (and only one or two blue nodes).
Here's some screendumps from the pdf.
It's a very basic but versatile, masked setup, and you'd have to fill in the blancs using the masks to get the terrain you want. If you want a grassy plain in the valley, add grass colors and displacement or pops; if you want strata in the high country, add strata; if you want rocks and gravel or sand in the river, add some fake stone setup and color it. If you want a tarmac road, add tarmac (which it almost is now); if you want a gravel road, add a fake stone mix.
If you want another layout of the river, reseed, and the other components will move with it, if you don't want the mudflats; slide the stream itself wider; if you don't want the road, disable it. If you want just a path or a highway, adjust the width. It's pretty self-explanatory (I labeled all nodes, added some notes, and there's a pdf), and actually not very difficult to understand (no internal nodes either, so easy to follow lines).