In precolonial times the Riet was known as the Gama-!ab (or Gmaap), a !Kora name meaning 'muddy'.

[1] The Riet flows about 300 km from the vicinity of the eastern Free State town of Smithfield and has a confluence with the Vaal River upstream from the Northern Cape town of Douglas.

Water from the Orange River at Vanderkloof Dam is fed into the Riet River at Jacobsdal to provide water for irrigation.

This has the combined effect of adding water to the river and lowering the salinity.

This article related to a river in South Africa is a stub.