Hi @JBPLee ,Welcome to the forums!
I would approach it the following way.
First, let’s clarify that the Water Body River system, if I’m not mistaken, is mainly designed for horizontal surfaces, so I wouldn’t use it for the vertical part of the waterfall because it’s not built to simulate free fall. I would leave it only for the water at the top and, if you want, also for the area at the bottom where the water becomes stable again.
I would handle the falling section as a separate visual effect. I would create a vertical static mesh with a slightly irregular shape, not completely straight, and apply a material that simulates the downward movement of the water.
At the base of the waterfall, I would add a Niagara system for the impact, with splash particles and maybe some mist to give it more volume. You could also add an additional material to simulate the foam accumulated in the area where the water hits.
I think the key is to think of the waterfall as three distinct parts: the upper water, the fall, and the impact. If you treat them as independent elements and then integrate them visually with materials and particles, it’s usually easier to control and the result ends up being much more convincing.
In this video, it is explained a bit better how to create a waterfall.
As mentioned in this post
the ideal approach is not to rely entirely on the Water System to solve the whole effect.
Then, to make the waterfall look more like the one you’re trying to create (Alves Waterfall, Jacobina, Bahia, Brazil), I would take a clear reference image and analyze its structure. I would first try to replicate it with the terrain and rock meshes, without placing any water yet. Once the overall shape is well achieved, only then would I place the water in the areas where it would naturally flow and fall. That helps the result feel much more believable, because the water follows the logic of the environment and not the other way around.
In this video it is explained better how to create a waterfall (using Water Particles), and it can serve as a guide for the impact and flow.
Also in this one Creating Stunning Waterfalls
if it were a smaller waterfall, you could consider using Niagara Fluids to simulate it, since it allows you to work with a more physical and dynamic water simulation.
However, for a larger waterfall like the one you mentioned, it’s usually more practical to separate it into pieces: use Water Body for the upper and lower water, a mesh with a material for the falling section, and traditional Niagara for the impact and mist.
Additionally, on the Learning site there is also an explanation on how to create a waterfall for a cinematic.
Hope it helps!