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During Cape Town’s recent drought, residents who could afford it drilled for boreholes in the hope it would provide them water if the municipal taps ever ran dry. But what would happen if this practice continued unchecked, wonders Klaudia Schachtschneider – a question which has led to a fascinating project and borehole ‘census’.
It is late afternoon and I sit cooped up with a blanket and a hot water bottle while the last rain of the season washes against my windows. This is 2020 and I know that my dog walk tomorrow will take place in mask and gumboots.
Finally, Cape Town is at a place it has not been since 2014. The dams are 100% full. Even with average rainfall, our water-saving ways have helped us turn a corner in terms of water security.
Tadpoles and taproots
Much of the puddled-up water that I will slosh through on the Rondebosch Common will linger on the surface for days, hopefully long enough for my daughters to watch the leopard toad tadpoles mature. It is a race against time every spring – tadpoles growing in the temporary ponds that drain into the ground a little more each day, spring flowers bursting in a myriad of colours, fuelled by this draining water as it sinks through the soil… all the way to the (hopefully) rising groundwater table that sustains the larger plants with deeper roots through the dry summer.
Strange thing – underground water. Hidden, invisible, hard to grasp. Most of us learn about groundwater by looking at some two-dimensional illustration in a schoolbook, depicting a house, a garden, some soil and underneath, in blue, the groundwater table – as if we were adrift on an underground lake.
But groundwater is far more complex than that. It is water in 3D that moves through pores and cracks and past impermeable obstacles underneath us. And the rock type, sand or clay beneath us, determines how it flows and how close it gets to the surface. Every now and again it pops up in the form of a natural spring – like the Newlands spring. Sometimes there are several layers, stacked at different depths. Some places it gets replenished with the rainy season. In others it has been encapsulated for thousands of years – it is, literally, ancient water.
In dry regions, like the Northern Cape and the greater Karoo, groundwater is the only reliable water source. For us in Cape Town it is a welcome alternative. A fallback in times of drought. A diversification from our dammed surface water. An alternative to those who want to emancipate themselves from the city water supply.
This is something many residents of Cape Town, with cash to spare, strove to do in the Day Zero period. Anxious to avoid facing a day without running water, many opted for installing a backyard borehole. On my afternoon school-pickup drive, I would make a game of counting the number of drilling rigs that I would spot scuttling through the narrow leafy streets of suburbia. I began to wonder if the groundwater below Cape Town was not starting to look like a milkshake with too many straws in it.
Boreholes and beer
But just how many boreholes are there in Cape Town? How much water is being used in private yards, for pools, gardens, and toilets?
What is happening to the groundwater table over time across Cape Town? Is it still replenished every year, showing that we are not using too much, or are we sucking out too much, risking an unsustainable race to the bottom?
Digging around a little we found that there are no easy answers to these questions.
In 2018, WWF formulated these questions into a pilot project that was kindly funded by AB InBev, who ask themselves the same question because their long-standing beer production in Newlands is entirely groundwater dependent.
In a two-year study, we targeted the two Cape Town areas of Epping Industria and Newlands, where groundwater was not monitored by the city, but where we had reason to suspect a high prevalence of private boreholes.
The appointed consultant, geohydrologists GEOSS, kicked off the project with a ‘hydrocensus’ in both areas, which is another word for a door-to-door stocktake of boreholes.
Their findings confirmed our suspicions. In Newlands, 90% of boreholes were not noted on any city or government database and in the airport industrial area 14% were not noted. In short, nobody in Cape Town has a handle on borehole numbers and consequently nobody knows how much groundwater is being used. Hence the most sensible thing is to start measuring what the groundwater table does. At least then we know if we need to be worried about over abstraction or not.
Through the project and with the kind cooperation of private residents and businesses we have placed six dataloggers into each of the two pilot areas. These loggers are the first of – hopefully – many more. We hope to help build a whole network of groundwater monitoring points across the city.
And where should this information go? The city, as per their bylaw? The Department of Water Affairs as the legal guardian of all water? Should it stay with residents, seeing that they invested so much in a borehole that they should have the right to unlimited use?
Perhaps the answer lies in collective stewardship.
There might be many owners of water infrastructure (the borehole), but the water is still not ours to use without regard for the collective. Overuse will be to the detriment of us all, as we eat into our emergency water supply.
We at WWF believe that a partnership approach is the most appropriate, where many different stakeholders can contribute to the governance of groundwater, starting with monitoring and open information sharing, so that we all know how the water beneath our feet is faring.
Now that the Western Cape’s rainfall season comes to an end as we head into the summer months, and dams are full, one can literally hear a collective sigh of relief over Cape Town. We have one crisis less to deal with right now and Covid is quite enough, thank you. Our water provision can now be planned and re-visioned for the longer-term, bearing all crisis lessons in mind.
I am excited that GEOSS will go into the field this month to measure the winter and spring recharge to our monitoring boreholes. Let’s see what this rainy season did to our groundwater.
THIRSTY FOR MORE?
Read about the recent groundwater survey in Cape Town.