UV stretch to create some natural flow / rivers lines across hills and mountains

I am trying to figure out the math to create some natural flow lines using textures and texture deforming that follows the shape of a mountain like rivers flowing to the bottom.
(Much like the flowmap that comes with world machine.)
So far I tried to do this…

  1. Having a black white texture and projecting it using world align on a landscape. Much like triplanar but then only in Z.
  2. Then I have thick horizontal lines with a vertical gradient, mapped on mountains.
  3. This gradient allows me to offset the UV, so far I get some results, but when I tweak the offset and make the numbers larger and larger, the texture just stops stretching really just begor the stretch is large enough and comes back to a normal less stretchy texture.

Anyone ever tried this? Or does someone have some ideas on how to do this?
Regards! T


edit: here is an example while I try to sample a small stripe of the texture and offset it with Z. This way, the textures is getting ‘smeared’ downwards. The results looks like something I am after but this approach opens a whole other issues. If you zoom you can clearly see the tiling stripes, moire effect is way to heavy, normals and tessellation just doesn’t look right because it captures the small details and seams.