How is Cape Town running out of water?

20 February 2018


How does a city, like Cape Town, run out of water?


Chris Smith put this question to engineer Allan McRobie...

Allan - It’s a problem that many cities face, particularly in hot countries. I don't want to ascribe any blame to Cape Town people, because I’m not that familiar with the problem, but it does look like a case of bad planning; every city knows that it needs a certain amount of water. One thing you should be clear about is a distinction between the residential uses for drinking and washing and so forth, as opposed to agricultural uses, particularly in hot countries that could be irrigation, or industrial uses. Those latter ones are the big users of water in hot countries. Many, many times more than the cities there.

I don’t know what’s happened in Cape Town in that respect. I know they’ll be wineries, there’ll be farms around Cape Town, they will have taken water and I don’t know what they’re going to do about that. Obviously, you don’t want all your vineyards to die, the farms are needed but usually it’s a comparatively small amount of water that you need to keep a city going, and one thing you can do is bring it in from somewhere else. In South Africa the have the Lesotho Highlands water scheme, which is the neighbouring country Lesotho, where they bring water from the dams and the mountains there, but they take those to the industrial areas elsewhere north of South Africa. I don’t think that gets down to Cape Town, but it really shouldn’t have happened. Many cities face this, even London and Miami - there’s a big list - Perth in Western Australia. There’s lots of cities face this problem but you just plan for it.

Chris - The thing that concerns me though is if you look at the reports of South Africa, there’s a gentleman who drills boreholes, and he says he normally has five or six on his books at any one time waiting for a borehole. He’s now got 6,400 waiting for boreholes so everyone’s making their own salvation here, digging a borehole. This is going to to deplete the groundwater, we’re just kicking the can down the road aren’t we because we have not solved the underlying problem which is a very big aggregation of people and insufficient water gathering in that particular area to service them?

Allan - That’s absolutely right. The groundwater’s very rapidly depleted if you start to pump it up and, as happened in many places around the world, you really need to have a bigger approach to the problem. You see the Chinese: the South/North water transfer project where they take in vast quantities of water, I think from the Yangtze, and taking it thousands of miles North up to Beijing. There are many schemes like this around the world. There’s a proposal to run a pipeline from a river in Turkey over to northern Cyprus that’s very dry.

There are places in the world with lots of water and it can be transferred. There’s also, of course, the concept of virtual water, that you import chocolate or whisky are very intensive, so don’t make your own because there’s thousands and thousands of litres of water goes into one litre of whisky so buy the one litre of whisky rather than bringing it in. The same applies to tomatos or all the way down. You can bring in the water- intensive things rather than trying to grow it yourself. Let the people with the water grow it.


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