Hello, im currently working on a 3D model of a landmass, and i struggle with the rivers. My first idea was to just move the vertices around like you see on the left, but that doesnt look good. After that i tried to do the river mesh and then connect the topology, but it is taking forever. Does anyone have a better workflow for this?
Well I don't do much landscaping, but I bet the topology of the mesh are hardly ever quads, most likely it's all very dense triangles where you can sculpt indentations to the mesh and form riverbanks. I would approach it just forgetting about quads and just get a bunch of polygons in there so you have enough geometry to form all the ups and downs and irregularities a landmass would have. There's a good course you can get about it from the folks of Cg Boost I think:
I'm not sure the best way, but I think Sculpting or Displacement is the way to go. If you have an image of the rivers then Displacement is probably the best route. You can also paint the displacement which is a little work to setup for eevee users. Sculpting is probably the most common way to do it in blender. In the future, when you create terrain Always map out water first. Like lakes and rivers. It is easier to build land around these using face sets(Sculpting) or vertex groups(Everywhere).