The JIA irrigation scheme comprises a weir in the Orange River that diverts water into main and sub-canals linked with siphons through the river, delivering the water to the farms through a number of sluice gates. There are also a number of pumps that augment water from the river into the canal system. A layout of the infrastructure can be seen here.
The system comprises 42 km of canals of different shapes and sizes. The scheme starts with the Vioolsdrift canal on the South African side at a weir in the Orange River, approximately 13 km upstream of the N7 road bridge across the river. The Naupoort siphon is used to transfer water across the border into the Bennie vd Hoven branch canal, which runs for a distance of 1.5 km on the Namibian side.
The main canal crosses the river at the bridge with the Vioolsdrift siphon, and from there it remains on the Namibian side for 7.9 km (Noordoewer canal). Where the Noordoewer canal ends, part of the flow continues on the Namibian side as the Duifieloop canal (4 km), while the balance of the water is discharged into the Rooiwal siphon. This siphon then transfers the water across the border, back into the Rooiwal canal in South Africa.The length of this canal is 1.7 km before it divides into two canals – the Swartbas- and the Duin.
The latter is a branch canal, while the Swartbas discharges its water into the Swartbas siphon, which then crosses the river into Namibia. The lengths of the Swartbas and Duin canals are 3.7 km and 2.5 km respectively.
At the bifurcation of the Swartbas and Duin canals, the Swartbas pump station discharges its water into the system. Downstream of the Swartbas siphon (on the Namibian side), the Modderdrift main canal feeds the water over a distance of 2.3 km. The Modderdrift pump station’s water is discharged into the canal at its start. This canal discharges some of its water into the 2.3 km Modderdrift North branch canal, which remains on the Namibian side, while the balance of the water is discharged into the Modderdrift siphon back across the border into the Modderdrift South canal.
The length of this last section of canal is 3.1 km. Approximately halfway along the Modderdrift South canal, the Modderdrift South pump station pumps water into the canal. Farmers withdraw water all along the canal system by means of sluice gates according to the size of their land listed with the JIA. In a few cases, farmers have their own pump stations on the river from where they abstract their own irrigation water.
Water is drawn directly from the canal for household purposes. In most cases this is done with a small centrifugal pump pumping directly from the canal. Other uses of the canal water are dust control, and providing drinking water to the informal settlement at Rooiwal.
The map below provides the spatial distribution of the JIA canals, pumping stations, sluices and the diversion weir. The canal names and sluice numbers are shown by selecting the respective individual elements. The pumping station names and some pictures are also shown by selecting the pumping station markers. The canal names (and in some cases pictures of the canals) are indicated by selecting the canal section name markers. Detailed information on fields are also shown by selecting individual fields. The Department of Water Affairs of South Africa’s flow data for the weir can be accessed by selecting the weir’s marker and then the appropriate link to the required data.
Legend: Sluices; Pump Stations; Diversion Weir; Canal Section Names; Canals; Irrigated Fields