Cape Town - The imminent drilling of boreholes into aquifers on Table Mountain and on the Philippi Horticultural Area (PHA) could have a disastrous impact on the environment in the long run, University of Cape Town (UCT) professor Dr Kevin Winter has cautioned.
The City of Cape Town said it would commence the drilling of boreholes as part of an emergency measure amid a devastating dry spell which has left dams with critically low quantities of usable water.
The first phase - which would take place on the Table Mountain Group Aquifer (TMGA) and which was hoped would yield in excess of 2 million litres of water per day - was due to start at the end of the month, mayoral committee member for water services Xanthea Limberg said.
She said additional boreholes would be added on the mountain if the drought persisted.
Winter, from UCT’s environmental and geographical sciences department, warned against the “over-abstraction” of groundwater. In an article, “When taps run dry”, Winter said it could have a huge impact on the environment.
“Tall trees (would start) withering, dying and falling over, as well as lakes and rivers ceasing to flow are the first signs of the over-abstraction of groundwater,” he said.
“Domestic gardens would be abandoned and become increasingly covered by hardened surfaces resulting in elevated urban temperatures. Levels of dust particles rise and so do lower levels of atmospheric temperature.
“With an increase of contaminants in confined bodies of water, surface water quality deteriorates,” Winter said.
Limberg said the costs of the emergency schemes, which would include a small-scale desalination plant, were estimated at R315 million over three financial years.
“The city’s Water and Sanitation Department will be funding these projects primarily via internal re-prioritisation,” she explained.
Limberg said the desalination plant, which is located along Cape Town’s north-western coastline, was also expected to contribute an additional 2million litres a day.
“In the event that there is another winter of below average rainfall, the city will be expanding the emergency schemes and accelerating further schemes,” Limberg said.
She said this would be done as Phase Two and would include the drilling and expanding of a well-field into the Cape Flats Aquifer, which was expected to contribute a combined yield of 5million litres per day.
Limberg said an additional yield of 10 million litres per day would also be extracted from the TMGA.
Winter said: “It is going to rain, but perhaps not significantly enough. So, what is likely to happen is the city will reduce the pressure greatly, slowing tap water to a mere trickle. If the taps do run dry, however, there will be chaos.”