AllyR, Nothing so sophisticated. The whole property is capable of being irrigated, but pumping power is limited so I can only do so much at a time. The place was about half covered via underground mains and when we planted the first new olives (299) we put in more underground lines plus drip irrigation for them and above-ground take-offs for spray irrigation.
I rely mainly on the river to top-up a shallow well that has a 10hp 3 phase pump connected to most of the mains - the smaller pump on the river connects to the latest planting of 180 olives and I crop between these in summer because I use spray irrigation. The drip area can only be winter cropped or something drought tolerant like cowpeas in summer, and that is what I usually put in, with some pumpkins, melons etc between the trees along the drip line.
I also have a 70m deep borehole and after a couple odf trials will be putting in an air lift pump because I know the river is unlikely to keep flowing this summer.