Groundwater use potential for South Africa
Groundwater’s role in South Africa is often underestimated, whereas two thirds of our population depend on groundwater for their domestic needs. Although a large volume of water users rely on surface water, the majority of small water supplies, which are critical to livelihoods, health and dignity, depend on groundwater.
Groundwater is essential to the water supply of towns such as Beaufort West, Prince Albert, Graaf Reinet, Atlantis and Mussina. Even large cities like Pretoria and Johannesburg are partly dependent on groundwater supplies. There is therefore a need to raise the status of groundwater to equal that of surface water in meeting the country’s growing water demand.
Dr Shafick Adams, Research Manager at the Water Research Commission says: “The total estimated volume of available, renewable groundwater in South Africa is 10 343 million m3/a or 7 500 million m3/a under drought conditions. South Africa is currently using between 2 000 and 4 000 million m3/a of this groundwater. Therefore there is the potential to considerably increase groundwater supplies in South Africa”.
The Department of Water Affairs with support from the Water Research Commission (WRC) has produced a detailed Strategy on artificial recharge to encourage the optimum usage of the country’s aquifers. Artificial recharge is the process whereby surface water is transferred underground to be stored in an aquifer. The most common methods used involve injecting water into boreholes and transferring water into spreading basins where it infiltrates the subsurface. Underground water storage is an efficient way to store water because it is not vulnerable to evaporation losses and it is relatively safe from contamination.
Mr Fanus Fourie, Hydrogeological Resource Analyst at the Department Water Affairs, says “Artificial recharge can be implemented virtually everywhere where groundwater is being used or being planned for use. It can augment water supplies on a large scale such as in Atlantis near Cape Town, or Windhoek in Namibia, or it can be used to boost single borehole schemes like at Kharkhams in Namaqualand, or for irrigation supplies for individual households such as in Hermanus in the Southern Cape. Areas potentially suitable for artificial recharge in South Africa have been identified using a GIS (Geographic Information System) process and are presented on WMA (Watershed Management Area) scale maps”.
The best advice given to anyone who is considering artificial recharge is to start monitoring groundwater levels immediately. This will give a good indication of the aquifer’s potential to accept water. Electronic data loggers are easy to use and affordable – start collecting data! Other time-series data to start collecting are the quality, reliability and volume of water available for recharge, and groundwater abstraction from the aquifer.
Artificial recharge is working and can be used to ensure water availability for later use. It is much cheaper than most new resource developments like desalination. In Plettenberg Bay the cost is one fifth, and in Sedgefield one fourth, of the desalination capital cost.
For more details contact:
Dr Shafick Adams
Research Manager: Water Resource Management
Tel: 012 330 0340