Vaal Triangle Resources: Water

The task, which was a joint project between Rand Water and the then Department of Irrigation (now the Department of Water Affairs and Forestry), began in 1934 and was completed in 1937. The Water discharged from the Vaal Dam flows into the Barrage Reservoir, where the water level at the Barrage wall is maintained at a depth of 24 feet (7.3 m). During the construction of the Vaal Dam, a small village named Denysville after Deneys Reitz who was the minister of Water Affairs at the time of the Dams construction, was founded. Today it is the centre of activity for the marinas and boating facilities that hug the shores of the Dam.was still unpurified) was often contaminated with mud from the swollen rivers.

In 1942, the Rand Water Board began supplying the Pretoria Municipality with water. The post war expansion after 1945 led to further increases in water demand and in 1954, a new station, Zuikerbosch, situated a kilometre upstream of the Klip and Suikerbosrand Rivers came into commission.

Further additions to both the Vereeniging and Zuikerbosch works continued as the demand for water escalated. The importance of the Vaal Dam as the central storage reservoir for the Vaal River System Supply area (Gauteng and the surrounding provinces) could never be overemphasied as these areas generated more than 50% of South Africa’s gross geographical product (GGP), and more than 80% of the country’s electricity. Even in the early 1960’s it was recognised that Vaal DamThe Vaal Dam was precariously low during the 1970’s and the first of the interbasin transfer systems, the Tugela-Vaal scheme through which water is transferred via the

Drakensberg pumped-storage scheme to Sterkfontein dam in the Vaal River catchment. The water from KwaZulu-Natal is stored in Sterkfontein Dam and only released to Vaal Dam via the Wilge River when needed. Due to the favourable storage and climatic characteristics of Sterkfontein Dam, it is beneficial to store water in the deep cool Sterkfontein Dam and only release water to the shallow Vaal Dam when needed. The evaporation losses from Sterkfontein Dam are approximately 35 million m3/a which represent approximately 10% of the losses that would be experienced from Vaal Dam for a similar volume.

During the serious drought of 1983, the water resources in the adjacent Komati and Usutu basins were badly depleted, leading to serious concerns that the water supplies to various power stations could be affected. As 80% of the country’s electricity is dependent on water from the Komati-Usutu-Vaal system, it was estimated that the newly completed (1982) Grootdraai Dam would empty within a matter of months. An emergency scheme was initiated to pump water upstream over a distance of 202 km to Grootdraai Dam from Vaal Dam. The emergency scheme involved constructing 7 weirs, each with numerous pumps capable of pumping a total of 1 million m3/day (Ml/d). The emergency scheme was, fortunately, never used.

New schemes were continually being investigated. Even in the early 1950’s, investigations to harness water at high altitude in the mountains of Lesotho had been carried out.

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WATER