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Why boreholes may be a really bad idea

Oct 22 2017 14:51
Mandi Smallhorne

I ONCE got bitten by a miniature Schnauzer – she went straight for my calf as I walked past, ripping my yoga pants and slashing my leg impressively. When I complained to the resident of the house, less than a block from my home, his response was: “So what?”

Oddly enough, I’ve not felt particularly warm about this man since then.

So when I saw that he had parked some enormous industrial vehicle on the sidewalk outside his home (when he drove it off, the sidewalk was damaged) and put up signs reading “Boreholes/boorgatte”, I didn’t think admiringly: “What an enterprising businessman!”

It is rather enterprising, of course; he’s taking advantage of the panic among residents of the ‘burbs, worried that the flow of water to their taps might be disastrously interrupted. But even if I didn’t carry a grudge, I would still have had the same thoughts around this:

Recharge. Recharge is the word you need to think about when you drill down to harvest water from the aquifers.

The system that you’re tapping into up here in Gauteng is enormous. It stretches from Springs, swooping south under Lenasia and west to Carltonville. It probably has the capacity of Lake Kariba, according to water scientist Dr Anthony Turton.

Lake Kariba took five years to fill, and contains about 185 cubic kilometres of water, a pretty impressive number; but it’s still a finite number. If you started to tap our Highveld groundwater more heavily than the rate of recharge, you’d soon see a reduction in those cubic kilometres.

In India, as anyone who’s read Fred Pearce’s book When the Rivers Run Dry will know, the water table has been extensively tapped for agriculture: “In some areas, government data show groundwater levels have dropped by an average of more than 30 feet since 2005.”

This means that boreholes need to go deeper and deeper to reach the water, a cost to farmers. “The major declines in India’s aquifers are part of an alarming trend across much of the world. Water is being pumped out much faster than it can naturally be replenished in parts of Asia, Africa, the Middle East and the Americas […] In most places where aquifers are overstressed, similar trends are colliding: heavy pumping for farming, growing demands on limited water supplies, and a failure to adequately manage or regulate the groundwater that’s left. Droughts have added to the pressures on groundwater, and climate change is projected to intensify droughts in many of the same regions where aquifers are in decline.”

NASA has been using satellite technology to map and track water in earth’s aquifers, and reckons that more than half of the world’s 37 largest aquifers are declining. This is water that has accumulated over thousands, even millions of years (some of the aquifers originated in meltwater from glaciers at the end of the last Ice Age, for example).

Yet the Table Mountain aquifer is a pillar of Patricia de Lille’s strategy for the Western Cape’s water crisis. In a Facebook post focused on the Western Cape, Dr Turton asks “…on what technical basis has the sustainable yield of the Table Mountain Aquifer and other local groundwater resources been estimated? […] as demand grows and more water is abstracted, while at the same time rainfall trends show a distinct declining trend, then recharge is going to decrease and with that sustainable yield severely impacted. […]

"Are these politicians merely ignorant and clutching at straws by the allure of the Cinderella resource beneath their feet? […] Has anyone in power even asked the question about aquifer recharge?”

Very good question. Our rainfall may well be in decline, not just in the Western Cape, but across the country. Even those areas that continue to have the same volume of water may get it in huge storms like the one that struck eThekwini earlier this month – I suspect that that kind of storm may not lead to satisfactory recharge of groundwater.

In addition, of course, we have damaged the land’s ability to retain water to soak down into the water table, through stripping topsoil and reducing vegetation cover, through paving and tarring and building, through damage to our rivers and wetlands.

But then you see something like this: “Johannesburg Water has entered into a partnership with Borehole Water Association (BWA) to encourage the city’s residents to switch to borehole water to mitigate the crippling drought.”

Apparently about ten ‘affluent areas’ have been identified that are just perfect for boreholes. (My neighbour must be delighted with that trigger word, “affluent”.)

Do you need permission to sink a borehole? No, says the Department of Water and Sanitation’s website – unless you’re going over a “certain volume” which, one gathers, is unlikely to be reached by a residential borehole.

Why not? That resource should not be tapped lightly, willy-nilly, at the whim of an affluent homeowner served by a local entrepreneur. “We are mining water now that should be the birthright of future generations,” writes Pearce. We should be strictly accounting for all water abstracted.

Yes, it will be harder to manage our water crises without relying significantly on groundwater. But before we go ahead and drill into such precious resources, I for one would like to see all the facts, figures, projections and sustainability.  If we act without great care and precautions, Peak Groundwater may come a lot quicker than we imagine.

  • Mandi Smallhorne is a versatile journalist and editor. Views expressed are her own. Follow her on Twitter.

mandi smallhorne  |  opinion
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