I've never had to do falling water for a project before. But when I was learning AC I did this castle experiment pictured below. There are two meshes intersecting each other. One is earth and the other is water. Mold the earth one to how it suppose to be. Then drop the water mesh into place and mold it so it makes the water surface as you can see in the next two pics. And for good measure I threw in a pick of an island I did experimenting with more with water. I made it so each water layer was 10' and I thought it turned out pretty neat.
Hopefully one day AC will include actual "water" in the model with real physics so water (and air) can be visually modeled how it will interact with the model.