| Riet | |
| Name Other: | Gmaap |
| Name Etymology: | Native name Gama-!ab meaning 'muddy' in !Kora language |
| Pushpin Map: | South Africa |
| Pushpin Map Caption: | Location of the Riet River mouth |
| Subdivision Type1: | Country |
| Subdivision Name1: | South Africa |
| Subdivision Type3: | Region |
| Subdivision Name3: | Free State, Northern Cape |
| Length: | 300km (200miles) |
| Source1 Location: | Near Smithfield |
| Mouth: | Vaal River |
| Mouth Location: | Confluence |
| Mouth Coordinates: | -28.9994°N 23.8881°W |
| Mouth Elevation: | 1001m (3,284feet) |
| Tributaries Right: | Modder River |
The Riet River is a westward-flowing tributary of the Vaal River in central South Africa. In precolonial times the Riet was known as the Gama-!ab (or Gmaap), a name meaning 'muddy'. Its main tributary is the Modder River and after the confluence the Riet River flows westwards to meet the Vaal.[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.[2] It flows through the Kalkfontein Dam.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. When Vanderkloof Dam is spilling excess water from Vanderkloof Dam is transferred to the Kalkfontein Dam.
