South Africa

Op-Ed: Cape Town’s water future is bleak – it’s time to call in the groundwater experts

By Roger Parsons 14 August 2017

Premier Helen Zille’s Day Zero of March next year is highly credible, and without drastic action we could run out of water. The city and the province could find solutions by pulling in the experts who can play a role in helping us through the next summer. We need to plan for the worst, and hope for the best. Now. By ROGER PARSONS.

The Western Cape province in general and the City of Cape Town in particular are facing an unprecedented water crisis. Collectively we hoped good winter rains would save us – just as the good summer rains saved the northern parts of the country earlier this year. Widespread rains in January and February put a halt to large-scale inter-basin transfer of water to top up the Vaal Dam. Unfortunately we don’t have a reserve stash of water in the Western Cape as they do in Gauteng; and four months into the rainy season the winter rains have still not arrived.

With less than two months left in this hydrological year, we have only had 45% of our average annual rainfall. Cape Town’s water supply dams are still less than 30% full, instead of the 70% or more typical of this time of the year. The promise of winter rain is fast disappearing, with cold front after cold front being pushed south of the western and southern Cape by a high pressure system that seems to be glued to the southern tip of Africa. Predictions last summer regarding the number of days of water supply remaining were based on poor science, but Helen Zille’s Day Zero of March 2018 is – in my opinion – highly credible.

Cape Town is facing a summer like never before. Without drastic action we really could run out of water. The consequences of this warrants careful thought. Sure – we can buy bottled water, we can go without a shower for a week or two, our cars can stay dirty and our lawns can die. We can buy fresh produce from up north – as South Africans we know we can survive. The poor won’t be so lucky and, as usual, will be hit hardest.

Graph: Both rainfall and dam levels in Cape Town remain low, with only two months of the rainy season left and before the arrival of the hot and dry summer months. This points to the city facing a summer with little or no water.

But how can we survive? Can money buy us out of trouble? As an example, what about our urban sewerage systems? Sewerage systems are highly dependent on water to transport sewage from our homes to the treatment works. Without water, pipes will block – with a host of related health and environmental problems. If this happens, where will 3.7-million people go when they have to? The concept of running out of water is just too ghastly to bear. Can you imagine if industries have to shut down because they don’t have water – and almost all industries need water to function. The economic consequences for us, for our city, our province and our country will be disastrous. Simply put – Cape Town, we need to be afraid, very afraid.

The most obvious – and easiest – remedial action is to reduce our water use immediately, and reduce it drastically. We as the citizens of Cape Town need to act – and we need to act now. If we don’t, February, March and April are going to be hell. People who lived in Grahamstown and Pietermaritzburg in the early 1980s will remember what it was like to live on a bucket of water a day. Many South Africans already do, but that is a separate story.

Tapping into groundwater

Without rain, building dams and installing rainwater tanks is pointless. The wise and considered use of grey water can be meaningful, but we need water to generate grey water. So where can we find more water quickly? The technical solutions of desalination and re-use of wastewater (read sewage) are two options, but both are expensive, will take time to implement and suffer from a number of weaknesses. Without going into far-out options like towing icebergs into Table Bay, the only remaining option for generating new water is abstracting groundwater.

Cape Town was established here because of groundwater. Springs discharging out of Table Mountain and flowing into what is now the City Bowl provided water to the refreshment station from which Cape Town grew. The importance of these springs slowly diminished once the first water supply dams were built above the city in the late 19th century. This water still flows under the city at a rate of about 2 ML/d during summer, and even though a small fraction of what Cape Town needs, they might become important again as Cape Town’s taps run dry. Collectively many small parts make a big whole.

(Note: The current target water usage for the city is 500 ML/d, but water usage is still in the order of 630 ML/d. Summer usage is normally in the order of 1,200 ML/d).

Cape Town is located on some good aquifers, including the Atlantis Aquifer, the Cape Flats Aquifer and, to a limited extent, the Table Mountain Group Aquifer. Groundwater was used to supply the apartheid industrial township of Atlantis with 10 ML/d of water for almost two decades, becoming a world-recognised example of artificial recharge. Since installing a pipeline from Melkbosstrand in the 1990s, groundwater use has declined and parts of the system are now dysfunctional. Given the current state of affairs, it is difficult to understand why the Atlantis Water Resource Management Scheme is not being used at optimal capacity.

A systematic investigation of the Cape Flats Aquifer was carried out in the 1970s, with a view to recharging treated wastewater back into the aquifer. The project led to hydro-geological capacity development and spilt over in the Department of Water and Sanitation. They investigated the development of the Cape Flats Aquifer as a source of water for Cape Town, identifying two highly productive zones under present-day Mitchells Plain and Khayelitsha. Estimates set the yield of these zones at 55 ML/d which could be increased by 50% by artificial recharge. These water sources were never pursued, and a major waste site and poorly serviced settlement were established on top of these prime groundwater areas.

A decade and a half ago, the City of Cape Town initiated a project to investigate the Table Mountain Group (TMG) aquifer as a potential source of additional water. It was planned to develop a pilot scheme yielding 15 ML/d, with the expectation that the aquifer could yield more than 55 ML/d. The Table Mountain Group is a geological unit that occurs across much of the Western Cape, and its characteristics are best observed in Table Mountain. Most of the hydro-geological investigation was conducted outside of the boundaries of the city. Millions of rand later and after much environmental study, the outcomes of the hydro-geological investigation are still not known outside of the project team and their client. Some deep boreholes were drilled, but – as far as is known – none has been pumped.

The rates at which water can be supplied from aquifers cannot compete with that of dams. Also, because boreholes are dispersed over a large area, the management of well fields require more effort. Where groundwater will come into its own is when the chips are really down – when our dams are empty. Boreholes can be drilled at key points such as hospitals, schools and old age homes to keep us ticking over. They can be drilled on street corners or central points for citizens to collect their buckets of water each day. Water supply engineers design their storage needs around an accepted degree of assurance of supply, but an ever increasing demand and a prolonged period of little rain have resulted in our water supplies failing. Unusual times required unconventional responses, and turning to groundwater could be one such tactic.

At a recent Water Indaba, the City of Cape Town declared that they want groundwater to form 10% of their water supply. While doable, they are going to have to go about this in the right way and employ hydro-geologists to plan, explore, develop and manage groundwater if they want to achieve their objective.

Groundwater suffers from two major disadvantages. First, it is intangible – it cannot be seen or touched. One needs to have undergone specialised training to understand its occurrence and movement, and the resource has to be properly managed to promote its sustainable use. The Ground Water Division was established in 1978 to advance the science and technology of groundwater.

Ground Water Division of the Geological Society of South Africa are hosting our 15th biennial conference in Stellenbosch in October 2017, with leading international specialists as well as a host of local experts. Currently we have almost 400 members – providing a pool of professionals that can assist both the province and the city to develop groundwater supplies to help combat the crisis that we all know is coming.

Beware inaccurate reporting

The intangible nature of groundwater contributes to wildly inaccurate reporting on the resource, particularly in the media. There are many claims of the negative impacts of pumping groundwater on the environment, most of which are unfounded – particularly in our geological settings. Monitoring data shows that groundwater levels in the city have not yet been impacted on by drought, and in my 30 years of research and consulting in the area I have yet to find elevated levels of arsenic or cyanide in our groundwater. As a groundwater community we need to take it on ourselves to share accurate information and correct wrong and misleading information.

The second major drawback is that the topic of groundwater immediately conjures up a vision of water diviners. People think of somebody walking around with a forked stick or a half-filled bottle of brandy finding veins and rivers of water that flow underground. It is impossible to explain that there is no scientific basis to this age-old practice, with mysticism maintaining the upper hand. It remains amusing that the best place to drill a borehole in urban settings is in the driveway i.e. where the drill rig has easy access.

In the same vein, it was with embarrassment that we had to listen to the then Minister of Water Affairs and Forestry, Ronnie Kasrils, tell a packed hall during the opening of the International Association of Hydro-geologists conference in Cape Town in 2000 that there is an underground dam that extends from Cape Town to Port Elizabeth. Groundwater just doesn’t work like that.

Groundwater follows scientific laws and principles – first developed by Henri Darcy in Dijon, France, in the 1850s. It is well known that some rocks have better potential than others and that some rocks produce better quality water than others. In places, we are surprised with better results than expected. This is the nature of secondary aquifer systems that occur across 95% of South Africa. Through research and experience our knowledge of these systems has grown significantly over the past 40 years. Yet it remains that hydro-geologists are mostly excluded from the highest levels of planning and decision-making. As an individual active in the field, I don’t know of any groundwater specialists that have been pulled into provincial or city meetings to properly consider the role that groundwater can play in helping us through the next summer.

The development of groundwater resources to combat drought is nothing new. In the early 1980s a large groundwater exploration programme was initiated to abstract groundwater from the dolomites in Gauteng. This source was going to supplement the fast dwindling surface water supplies, but timeous rains and concerns about sinkhole formation brought the initiative to a grinding halt. Groundwater resources were developed to support towns along the Garden Route during the drought of 2009-2010; but they too weren’t followed to completion.

Let us join the global village

If it is felt that our South African experience isn’t enough, let us join the global village. California experienced devastating droughts during the past five years, with surface water supplies drying up and groundwater levels plummeting. Following drought ending rains in 2017, their water experts are now reviewing what went wrong and what they did right to get through their crisis. Not everything can be blamed on climate change. The cost of sending a small panel of experts to California to learn their lessons will surely be a very sound investment.

It is going to take time to drill and equip enough boreholes across the city. We only have so many drillers in the region, and drilling companies are already in high demand in the agricultural sector. The industrial sector is also entering the fray. We need to plan in which areas we are likely to have the best chance of success – and of course modern procurement protocols are a major handbrake in moving forward. The accountants and financial offices are going to have to find better means of fighting corruption and ensuring that public funds are optimally spent. We need to plan for the worst, and hope for the best. Now.

As happened in Pretoria in the drought of the mid-1980s, everybody drilled boreholes when the municipal supplies were at risk. In one suburb two out of three houses had boreholes. This sort of boom in business – an emerging water economy I am told – brings out the chancers, and we are already hearing about individuals claiming that they can find water using instruments that sound very impressive. Terms like induced polarisation and electromagnetic fields roll off their tongues. There is no protection against this lot, but it is required that people who consult in the natural sciences are registered with the South African Council for Natural Scientific Professions. This body has some challenges when it comes to groundwater and it cannot differentiate the good from the bad, but it is a start.

The drilling of boreholes by private landowners may provide a part solution to the city’s water supply woes, particularly if well managed. In a city context, groundwater could be used for non-potable uses – particularly flushing of toilets and washing. It would be both unwise and irresponsible to drink groundwater abstracted in an urban setting because of the threat posed by leaking sewage pipes. Groundwater samples should be subjected to chemical and microbiological analysis before thinking of using borehole or well point water for domestic supply and “disconnecting from the grid”. We are really dealing with a resource more intimate to us and our families than a solar geyser system.

The hydro-geological community is of the considered opinion that groundwater has an important role to play in helping both the Western Cape and the City of Cape Town through the current drought. Boreholes won’t solve the problem by themselves, but they can help us through this crisis. However, if this is to be realised, decision-making at the highest levels of planning has to include hydro-geological expertise and we have to act now – not tomorrow, but today.

Dr Roger Parsons is a hydro-geologist with more than 30 years’ experience. He is Chair of the Western Cape branch of the Ground Water Division of the Geological Society of South Africa. He writes in his private capacity.

Photo: Cape Town is facing a summer like never before. Without drastic action we really could run dry. Photo: Dan Gold/(Unsplash)

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