I have one of these on my *to do* list, too.
I haven't found an affordable solar system for the functions I want yet, so I've run electrical power out to a three outlet junction. So far I have the lower catch basin and a small pump operational. I'll eventually add another basin to another garden bed at the crest of a slight rise and link the two together. I figure that I'll probably need a larger pump to run the entire system since my return hose will be about 20 feet longer than the one I'm running now, but time will tell.
If I'm thinking right and you run the dual basin system, you should be able to use a second pump for a waterfall. The lower pump would send water to your uphill catch basin to keep it over-filled enough to run downstream, and the other would pull water from the uphill basin specifically to feed the waterfall that recycles water in that basin. If you have two catch basins with a pump in each one and your stream bed is set to flow from right at, or at least near the top when leaving your uphill catch basin, I'd think that water loss and the possibility of pump burnout would be slight. If the pumps are off the only water lost should be the minimal amount that's actually in the stream bed at the time of power loss. The remaining water would be held in your catch basins. In order for your stream bed to flow you'd need to replace water lost from each loss of power, but it seems to me that it might work.
[Edited for redundancy;)
