Start with a row of water jets, each one of which can be turned on or off independently.
Adjust the jets, so that when they're all on, the streams of water that they produce are all parallel to one another, and arc gracefully through the air from the jets, to the basin which catches the water.
Have
a computer control the jets of water, in the same manner as a graphical waterfall.
For an especially "clean" appearance, the jets used would be laminar flow nozzles.