The Current Status of Dams in South Africa
By the end of March 2016, Western Cape dams were 32% full. This is a year-on-year decrease of 13%, with dam capacity having reached 45% by the end of March, 2015. Generally, South Africa’s water storage infrastructure was only 53% full, with 1 711 8106m³ water in storage of a possible 3 224 6106m³. In July 2015, dam storage was at 75% full.

City of Cape Town

The City of Cape Town is perpetually affected by water shortages, with options to increase storage decreasing, extremely costly to construct and damaging to the environment.

Cape Town is supplied by 14 dams with a collective capacity of approximately 900 000 Ml (900 000 000 000 litres). Most of this capacity is provided by five large dams: the Theewaterskloof, Voëlvlei, Berg River, Wemmershoek and the Steenbras Upper and Lower dams. The remaining dams are much smaller and only contribute 0.4% to total capacity.

In future, the City will need to find other means of meeting its increasing water requirements. As there is no more suitable land on which to build dams in the Cape Town area, no further dams will be built.

The option to apply Hexagon-WEP® on dams where evaporation levels are high, such as Voëlvlei, will add to the percentage of water available to the City without having to invest in any further construction.

Voëlvlei Dam

Voelvlei Dam in Cape TownVoëlvlei Dam is Cape Town’s second largest supply dam, even though it is not built on any major river. Instead, it is supplied with water from two canals that divert water from the Klein Berg, Leeu and Twenty-Four rivers, which have catchment areas in the Porterville and Tulbagh mountains.

Voëlvlei Dam was built by the Department of Water and Sanitation and was completed in 1971. However, the infrastructure required for the city to use this water, including the water treatment works, pumping stations and the 80 km of 1 500 mm pipeline connecting the dam to the city were constructed by the City of Cape Town.

Oudtshoorn

Oudtshoorn is supplied with water from the Melville Dam (built in 1942) and Koos Raubenheimer Dam (built in 1971) both of which are owned and operated by the Oudtshoorn Municipality. These dams, together with the Rust en Vrede stream, supply water to the urban and industrial consumers in Oudtshoorn as well as to rural users along the pipeline route.

The extensive development of new houses for the historically disadvantaged communities of Oudtshoorn and the Klein Karoo has resulted in a significant increase in the demand for water in Oudtshoorn. This demand growth is threatening the long-term sustainability of Oudtshoorn’s existing sources of supply.

Knysna

“Knysna, being a water scarce area, is extremely vulnerable to long periods of no rain since it relies largely on water from its rivers.” That was what was stated in a report to the Knysna Municipality’s Section 80 Governance meeting held February 24. Water security must be considered when there’s a holding dam containing a minimum of a 6-month water supply. It was stated that Knysna has never had that capacity, and the problem has been amplified by the recent increase in houses. Currently, there’s only 71 days water storage and this is at risk of dropping.

  • The Akkerkloof Dam, Knysna’s main reserve, is down to 37%, constituting 28 days water at the average of 12ml/day.
  • The Glebe Dam is at a shocking 5%, containing only poor quality water which in resulted in the stopping of pumping on Feb 16 so as to avoid damage to the system.
  • The Sedgefield Desalination Plant and the Knysna Reverse Osmosis Plant requires R4.15-million to carry out more repairs.
  • The Gouna, Karatara and Knysna river flows are so low (only 2mm over the weir) that if it drops further, water supply will only be able to run every second or third day.
  • The situation in Buffalo Bay is critical as there is no flow of water over the Goukamma weir.

Vaal Dam

eNCA 17 August 2016 – Water levels in Vaal Dam are running dangerously low. DENEYSVILLE, Free State – The Water and Sanitation Department has warned South Africans to use water sparingly.
The department says one of the country’s main water supplies, the Vaal Dam, is about 34-percent full. That’s the lowest it’s been in years. Boats have been removed because the water is so shallow. Officials say they haven’t declared a water crisis, but they’re hoping for a good rainy season.

For further assistance please contact

Cobus Meiring from SCLI at cobus@naturalbridge.co.za

Written by Cobus Meiring