The wettest drought
Cape Town is suffering from a severe water crisis with Level 4 water restrictions in place, yet the city has received steady rain over the past few months. I recorded another 19 mm overnight on 29 August, and over 70 mm during the past month. Why, then, do we have a water crisis?
The answer, of course, is that Cape Town, unlike London, Budapest and Paris, is one of the few cities in the world that was not built near a large river or lake. The city has to ‘import’ water from distant catchments over the Hottentot-Holland Mountains, in a drier part of the country. Rainfall in Cape Town does not fill our catchment dams.
Of course, we have been capturing water from Table Mountain for centuries, but the water requirements of the city exceeded the capacity of these dams as long ago as 1888. Furthermore, we don’t catch all the water running off the mountain. Recent research has revealed that underground rivers, flowing in tunnels under the city bowl, disgorge over 7 billion litres of water into the ocean every year! The city fathers (and mothers) are now trying to figure out how to catch and store this water.
Cape Town is adopting a broad strategy in order to develop a sustainable water culture in the city. This strategy is based on four pillars: tariff structures, public education, water saving technology and water restrictions. In the space of one sum- mer, Captonians have managed to reduce their water consumption by 27%, a figure that Sydney took 20 years to achieve, but this is not enough. The predictions are that, even with our current levels of saving, and with average rainfall through winter and spring, Cape Town will run out of water by December 2017. While some might argue that this is a good excuse to drink more craft beer or fynbos gin, it is a serious situation.
The reality is that, as a consequence of global climate change, the drier bio-climatic zone to the north of Cape Town will gradually move southwards (and the bio-climatic zone suitable for grape and deciduous fruit growing will settle over the Agulhas Bank in the Indian Ocean). We need to brace ourselves for a permanent water crisis, with water saving the norm rather than the exception. Water tariffs need to be high enough to discourage abuse but low enough to sustain enough demand so as to cover running costs and fund new water supply initiatives. Most importantly, people need to be aware of how much water they are using, and how they can achieve further savings. We also need to ‘name and blame’ water abusers, and praise ‘water ambassa- dors’ who have achieved significant savings.
Water-saving technologies, such as systems to re-use grey water, dual-flush toilets, lowflow shower heads and tap aerators, have their place, but they only work within a culture of water consciousness. We also need to ensure that watersaving devices should be installed in all renovations and new builds, as they have done in Florida and southern California in the US and in parts of Australia.
Cape Town is now investing in reverse-osmosis desalination plants, with the first due to come on line within the next few weeks, as the cost of producing potable water from sea water has decreased to less than three times the cost of municipally-supplied water thanks to modern technology. However, half this cost is incurred by buying electricity from Eskom, which, in turn, uses huge amounts of water to generate electricity! It seems that the only way to make the desalination solution viable is to combine it with alternative-energy projects, such as solar or wind power generation. • Mike Bruton is a retired scientist and a busy writer; mikefishesbruton@gmail.com.