This is a canal paralleling the Gariep (aka Orange) River in the Northern Cape of South Africa. Around the turn of the 19th century missionaries moved into this area and developed water irrigation systems that supported the development of an orchard industry which is still going strong, with an increasing focus on table grapes. The dry conditions facilitated drying fruit, so this is essentially the tried apricot and raisin capital of the world. Or at least, southern Africa.
This water wheel turns with the force of the water in the canal, and with the wheel rotates a cup which picks up a small amount of water with each rotation, dumping that into a sluice that feeds to an irrigation pipe or ditch.