What is 'Yoruba'? It is hard to see the land under the water in these samples. I mean that the land under water should have the same displacement as the waterfall itself, otherwise it would be 'a wall of water'. I worked with a lake with the same underlying displacements as the world (before cutting a river), for my studies into a cascading river, smoothing the water plane in a compute terrain. But it's hard to get 'flat' water perpendicular to the streambed.
I imagine this is a lake with a mask-like blendshader, fed through a displaced surface shader? Will you tell us how you achieved this?