Control Continuous Stream Water Flow

I making a continuous stream on a small hill to my walkout along my deck and into my firepit area. I need a way of varying how much water is pumped and therefore comes down the stream. I am not sure there are pumps that can be varied or if you just vary the ball valve, but I want to control it with my Zwave devices and be able to increase it or slow it down depending on the moment.

Any ideas on how best to do this would be appreciated. I am kind of new to Zwave, but now have 25 devices and growing.