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The development of groundwater as an alternative source of water in the face of inadequate municipal supplies has received a lot of attention in recent months. Photo: Dylan Blake
It would be unfortunate if all the energy and money spent on groundwater drought relief projects over the last two months does not contribute significantly to a better understanding groundwater from Cape Town.
I fully understand that Cape Town wants – and needs – to convey the message that we have been through drought and that we are returning to routine business. The city and the people who live there are in desperate need of a healthy and vibrant economy, just like the agricultural sector inside the city and in the surrounding area. Water is a key element of the equation, and the restoration of dam levels – now at 56% – gives us hope. Since the prediction of rising dam levels is much more complicated and uncertain than the prediction of depletion, my previous predictions suggest that I should not even try
. water as the dams have dried. It is likely that it will disappear again underground, as we depend on more tangible surface sources and easily crosslinked and managed. The inconsiderate plan to supply 100 ML / d for Cape Town from groundwater as an immediate emergency measure has not materialized. But this is hardly surprising. The groundwater exploration of the city has barely come out of the starting blocks. I have always believed that the absence of hydrogeological input when developing these emergency plans was to blame.
Recently, I attended a presentation on a groundwater implementation plan for the city of Cape Town. The work was undertaken as part of the international support in Cape Town. The relatively small meeting contained only three hydrogeologists. The presenter and the questions asked by the participants said that we do not know enough about our groundwater resources and that we need more data and more research. This thought is not unique to this particular gathering. As a scientist, it seems to me that we do not try to better engage with those who know – or might know – something about it. The scientific method requires it. In this case, the international hydrogeologist who undertook the work had no idea what information was and was not available.
Good leaders surround people who can provide them with the information they need. Yet who advises the City on groundwater? Who advises them as to what can be done or can not be done? What are the groundwater references that sit on these committees and make decisions that affect us all? It is really disappointing to hear the city claiming victory for 5 ML / d or 10 ML / d of Atlantis Aquifer – they pumped 14 ML / d for years before dropping the management system Atlantis water resources. from 1999.
This is not the time to take cheap pictures of those who were looking at the barrel of a rifle and who had to make some tough decisions in the face of great uncertainty. But if we want to learn something from this drought, we need to review what has been done and why. We were told that the plan was to provide up to 250 ML / d of desalination for the drought-stricken area as early as 2018; Yet, we still have only two small plants that produce about 5 ML / d. Thinking about this sort of thing is essential if we are to better manage similar situations in the future.
As soon as emergency relief operations began, the singers wondered about the impact this would have on the environment. This is as common as the claims that the uncle of my brother's sister can find underground water with the help of a stick. Such claims usually include protests that we do not have enough data and we need to do more research – invariably supported by reference to a calamitous situation overseas. This choir – which includes a group of teachers, water experts, environmentalists and others – seems to ignore the role that groundwater has played and play in the development of this country.
The first abstraction of groundwater probably took place by buckets or similar containers used to raise water from hand-dug wells. The wind pump that was erected on Brinks Farm near present-day Saldanha in 1848 was probably the first mechanical method employed for this purpose. Groundwater now accounts for about 13% of all water used by municipalities in the province, while its use by the agricultural sector is also important.
Only in the Western Cape, more than 60 towns and villages A certain degree. And it did not happen overnight. This has been going on for decades. So where are the environmental impacts of this abstraction of groundwater? What did we learn from this abstraction in our own yard? Why did Professor John Cherry – a prominent hydrogeologist from Canada who visited us in October 2017 – recognize us as leaders in the field of hydrogeology of fractured rocks? Is it because we paid for a plane ticket to attend our groundwater conference – a conference that has been held every two years since 1978 and usually attended by 300 delegates? Or is it because we have a groundwater community that is knowledgeable and experienced in this area?
Like all professions, we have good hydrogeologists and less good hydrogeologists. We seem to be particularly vulnerable to untrained individuals and scientists in related professions who claim expertise in this area. While we are trying to obtain a professional hydrogeological record, the only available remedy for those who want hydrogeological support is fact checking and due diligence. But let's leave this discussion unfinished for the moment because it's a story in itself.
The groundwater community must take responsibility for not hearing from high level decision makers. Dr. Shafick Adams, from the Water Research Commission, recently raised a good point by asking what keeps political and economic leaders awake at night. This is certainly not things like the transmissivity of aquifers and its variability in the space. Or drilling yields and drilling interferences. Or even drilling methods and difficult drilling conditions. Most hydrogeologists are not so bady and exciting – regardless of what we can think of. We like to get lost in the details and take ages to get to the point. In simple terms, we can not communicate information that decision makers really need to know. We do not have a subject as mundane as climate change or empty dams. The stories of a flowing Venice or sinks that collapse can be interesting, but hardly striking. Critics of groundwater use like to cite examples of large-scale subsidence, dried-up rivers and plunging groundwater levels – all of which are examples of course abroad.
Environmentalists believe that the development and use of groundwater is harmful to the environment. neglect the risks posed by their efforts. Quite simply – it's insulting. The hydrogeologists I know are all environmentalists in the soul. There is no doubt that we can do better things to reduce our footprint. But a review of the use of groundwater in this country shows that it has no more than very small and insignificant environmental impacts. We spend our lives determining the safe performance of aquifers – a term that is closely related to the concept of sustainability. Although we are grappling with this certainty, we define very well the out-of-date limits.
As a group, the groundwater community needs to learn how to effectively and efficiently share relevant information with those who need it. For example, the presenter described the amount of groundwater that could be collected in aquifers in the Cape region. He expressed the abstract volume in millions of cubic meters a year. Well – how much does it cost? Unless you are aware of this unit of measure – and most listeners probably were not – the numbers presented were insignificant. I'm sure that if he presented the volumes in megalitres a day, everyone would have understood what he was saying. As a result of the drought, we have all been sensitized to the demand for Cape water at 600 ML / d or 500 ML / d or 450 ML / d, so we have an idea of what that means. Pumping 50 ML / day of the Cape Flats aquifer means much more for the Capetonians than the scientific notation of 18.25 x 10 6 m 3 / a.
From the same presentation I learned that there are approximately 3,000 wells and 5,000 wells in Cape Town – almost all clustered in the leafy suburbs where people can afford to drill and leave the network. This contrasts with the unqualified estimates of 30,000 boreholes used in the city. We have little scientific data to show how much groundwater is pumped – with the exception of some estimates from the back box. The volume of groundwater extracted can be in the range of 10 to 15% of recharge, a relatively small amount. The domestic use of groundwater can be in the order of 10 ML / d, but we know that a number of industries have turned to groundwater for keep their doors open. The absence of extensive monitoring prevents the badessment of negative impacts, a problem that neither Cape Town nor the Ministry of Water and Sanitation seem particularly interested in baduming.
While we receive weekly updates of dams across the country, the same is not true for groundwater. I regularly hear that aquifers in and around Cape Town are struck by the drought and frenzy of abstract groundwater. I never see measured data to support such claims. Here is a graph of groundwater levels regularly measured by the Ministry of Water and Sanitation in two boreholes in Bellville. While groundwater levels show slight intra- annual fluctuations in addition to an obvious seasonal trend, there is no evidence of significant dehydration due to drought.
Although the future of my current work on drought in the province is uncertain, we have installed or are in the process of 39 install more than 100 data loggers in the province. These instruments measure groundwater levels at the frequency you want. We take action on an hourly basis. There is a good chance that the money allocated to the fight against the drought will soon be moved elsewhere while we get, rightly or wrongly, comfort and safety with the increase of the levels of dams. It would be a shame if all the energy and money spent on groundwater drought relief projects in the last two months does not contribute significantly to a better understanding of groundwater. Cape Town and its surroundings. I plead for continued extensive groundwater monitoring for the next two years. This will allow us to have a real idea of how these levels respond to recharge and abstraction. This information can then be made accessible to managers, researchers and practitioners so that our knowledge can grow.
Now all I need to do is find a leader in Cape Town who will appreciate and support the investment needed to better manage the new normalcy. DM
Dr. Roger Parsons is a hydrogeologist with over 30 years of experience. He is the Director of Parsons & Associates Specialist, Groundwater Consultant cc and Past Provincial Chair of the Groundwater Division. He writes this article in his personal capacity.
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