The development of water resources in the Mokopane, Polokwane, Lebowakgomo and the Burgersfort/Steelpoort areas is a response to additional water for proposed extensive platinum-mining developments on the Platreef, in the Mokopane area, and on the Eastern Limb of the Bushveld Igneous Complex. Certain smaller-scale mining developments are also proposed as far south as the Groblersdal area.
The Dwaf study provides information on the quantities of water required and the spatial distribution, and a model was developed as part of this investigation to assess various scenarios of future water requirements, in order to prepare a flexible layout of bulk infrastructure to distribute water to the different users over this wide region.
Projections of water needs show an increase from the present 197-million cubic metres a year to between 280-million and 380-million cubic metres a year in 2020.
There is little potential for further water-resource development in the Sand and Mogalakwena river catchments, as water resources in the region are largely developed, the Dwaf said.
“Although the Olifants river is also well-developed, there is some potential to increase the yield of that system by providing additional storage,” OJS van den Berg, chief engineer: Options Analysis North, Dwaf said.
This development, however, will be expensive, limiting the additional yield to high-value uses. As the Olifants river is part of the international Limpopo river system, negotiations are required with the other basin states – Botswana, Zimbabwe and Mozambique.
“These can be complex and time-consuming. Environmental requirements are also of great importance. The Olifants river system is one of the main rivers feeding the Kruger National Park. Ecotourism plays a major role in the economies of the Limpopo and Mpumalanga provinces,” Van den Berg explained.
During the first phase of development, announced by Minister of Water Affairs and Forestry Ronnie Kasrils, the Flag Boshielo dam, situated on the Olifants river near Marble Hall, in Mpumalanga, will be raised by five metres at an estimated cost of R212-million.
This will increase its storage capacity from 100-million cubic metres to 188-million cubic metres, allowing 72-million cubic metres of water to be used each year as compared to the present 56-million cubic metres.
Core drilling on the foundations and dam wall has been completed and the design is well advanced.
Construction will begin by the end of this year, pending environmental authorisation and successful consultations with the co-Limpopo basin states. Completion of the project is scheduled for October 2005.
During the second phase, a large dam will be built either at Rooipoort on the Olifants river, 80 km south-east of Polokwane, or 50 km south of Burgersfort, at De Hoop on the Steelpoort river tributary of the Olifants.
“The best option will be chosen on the basis of confirmation of the future growth in water requirements and investigations regarding supply infrastructure to the demand centres. A decision is targeted for mid-2004,” Van den Berg said, adding that foundation drilling at the De Hoop site has been completed.
At the Rooipoort site, drilling is currently being undertaken, preliminary designs for both sites are available and more detailed designs are now being undertaken.
Hydrological analyses showed that a dam at Rooipoort would yield between 50-million and 80-million cubic metres, depending on the final design.
A dam at Steelpoort would yield between 60-million and 90-million cubic metres.
Detailed environmental-impact assessments are to start early next year. At this stage, the cost of the project is estimated at between R700-million and R900-million.