Strong, forceful sounds:
* Crash: Imagine a waterfall crashing down
* Plunge: Something dropping heavily into water
* Rushing: The sound of a fast-moving river
* Gushing: Water flowing out quickly
* Spilling: Water overflowing from a container
* Pouring: Steady, heavy flow of water
* Thundering: Like a large waterfall
* Rumbling: A deep, resonating sound of water
Soft, gentle sounds:
* Dripping: The steady sound of water falling drop by drop
* Trickling: A small, delicate flow of water
* Pitter-patter: The sound of light rain or water droplets
* Whispering: A soft, almost inaudible sound of water
Other descriptive verbs:
* Cascade: A waterfall or similar flow
* Drench: To soak thoroughly with water
* Flood: To cover with a large amount of water
* Soak: To become saturated with water
You can also use adverbs to further enhance the sound:
* Crashing down
* Gushing forth
* Dripping softly
* Rumbling steadily
Remember, the most effective way to describe the sound of falling water is to use the words that best fit the specific situation you're describing.