In the absence of an immediate solution to Cape Town’s water woes, groundwater can become a solution for the deepening crisis that began six months ago.
It is clear from current weather patterns that, unless there is a miracle, Cape Town residents are headed for tough times as the province’s dam levels — now averaging 30.8% — evaporate. While most of SA experiences heavy downpours that have filled dams to capacity, Capetonians are wondering whether the winter rains will save them from a natural disaster.
If winter rains don’t materialise in sufficient quantities, tankers will deliver water to residents. The Department of Water and Sanitation has done this before in drought-stricken provinces.
But this can only be a temporary measure to save lives and crops. Which raises the question: what is the long-term solution to water availability?
The Western Cape government has suggested desalination, among other ideas, to create a sustainable water resource for the province. While this is a sound solution, it is an expensive process that would hit the pockets of consumers. It also does not provide an immediate solution to the crisis.
However, it is a hydrological fact that while water is lost to the ocean and evaporation, a sufficient amount is absorbed by the soil and stored below ground.
Three years ago, a hydrology workshop heard that 420 towns and 80% of rural villages in SA depend on groundwater for survival. Yet this valuable resource is treated like a stepsister to surface water.
Water scientists argue that municipalities lack the human resources to effectively implement groundwater governance provisions and often do not allocate funding for its management.
The Water Research Commission estimates the total volume of available renewable groundwater in SA to be about 10-million cubic metres a year (7.5-million cubic metres a year under drought conditions). Current use is estimated to be between 2-million and 4-million cubic metres a year.
If managed correctly, groundwater has the potential to significantly add to the country’s water supply mix. It is therefore wrong, scientists argue, for groundwater to be treated as a stepsister to surface water as the two complement each other.
Groundwater is fairly cheap and quick to develop. Most is potable and areas in which it is below standard have been mapped. It can reduce the strain of high water demand from surface water resources, either as a sole supply or by augmenting surface resources.
In SA, about 98% of groundwater is found in fractured, hard rock aquifer systems. Primary aquifers are restricted to coastal sand deposits along the west and south coast of the Cape and along the KwaZulu-Natal coast.
Secondary aquifers, with hydrogeological properties including the weathering, fracturing and faulting of hard rock, are the most dominant. SA’s major aquifers are associated with the dolomitic rocks, quartzite and sandstone of the Table Mountain Group and the sandstone and shale of the Karoo Sequence.
— “A hydrology workshop heard that 420 towns and and 80% of rural villages depend on groundwater.”
Droughts and increased demand have triggered the search for alternative water sources. Groundwater in SA has been an integral part of the country’s water supply since ancient civilisation.
However, because of its hidden nature and the skill required in finding, exploiting and managing this resource, it is often overlooked as a reliable water source.
By volume, SA is predominantly serviced by surface water resources, but the picture changes once we consider the land areas covered by groundwater supply. Once rural areas are factored in, groundwater supplies more than half of the resource used.
The latest National Water Resource Strategy now incorporates groundwater in a meaningful way, enabled by the National Groundwater Strategy of 2010.
SA has very good policies, regulations, strategies, tools, guidelines and information. However, efficient management of groundwater relies on the effectiveness of applicable legislation and institutional arrangements, as well as a good understanding of the behaviour of an aquifer or well-field being managed.
There is a lack of skilled technicians and other operation and management specialists, particularly in small towns and remote rural areas where many groundwater schemes are found.
Water harvesting is equally important in solving scarcity. This simple method of amassing water is ignored by urban consumers.
Just like groundwater, harvested water comes in handy during dry seasons, when it is used for activities such as cooking, washing and drinking. Many rural villages in SA rely solely on harvested water and groundwater.
• Khumalo is a content producer at the Department of Water and Sanitation.
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