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Drought forces Cape Town to the brink of ‘Day Zero’

Drought forces Cape Town to the brink of ‘Day Zero’
19 Jan
2018
Cape Town is edging closer to ‘Day Zero’, the long-feared time when the city will run out of fresh water, and the taps are turned off

Know for sun, surfing and tourism, three years of drought and increasing consumption by a growing population, has left the South African bay city of four million people with less than 90 days until the ominous sounding ‘Day Zero’, the colloquial shorthand for when Cape Town’s reservoirs and wells are depleted.

According to the local government, if residents and visitors don’t dramatically cut their water usage, the taps of Cape Town will run completely dry on 22 April. The specific date is recalculated every week based on current reservoir capacity and daily consumption, and was recently moved up by Mayor Patricia De Lille from 29 April.

‘We have to change our relationship with water,’ said De Lille, who according to accounts currently spends 70 per cent of her working day dealing with the crisis. ‘We have to plan for being permanently in a drought-stricken area.’

Of course, Cape Town won’t literally run dry, limited water rationing is already in place and residents are being urged to use no more than 87 litres (19 gallons) a day. But the city authorities have decided the situation is so dire that once the dams reach 13.5 per cent capacity, municipal water supply will be turned off for all but essential services, such as hospitals.

Pranav Bhatt cc flickr

On top of this drastic measure, Cape Town Municipality Water and Sanitation Department has issued an eclectic range of water saving advice, which includes: to collect shower, bath and basin water and re-use it to flush your toilet, or for garden and vehicle cleaning; only to flush when necessary; and to fit taps with aerators or restrictors to reduce flow to no more than six litres per minute.

Despite the seeming urgency of Cape Town’s water crisis, in global terms this is not an unprecedented phenomenon. In 2015 NASA’s GRACE satellites produced data showing that more than half of Earth’s 37 largest aquifers (underground stores from which groundwater can be extracted using a well) are being depleted.

graph1
Graphs showing the groundwater depletion and recharge in millimeters per year. a) shows aquifier usage/withdrawl data. b) shows the satellite estimates of aquifier depletion and recharge. Note: areas with a positive value are recharged and theoretically should not be in danger of depletion. (Image: Water Resource Research, AGU Journal 14/07/15)

The researchers used the GRACE satellites to take precise measurements of the world’s groundwater aquifers and detected subtle changes in the Earth’s gravitational pull, noting where the heavier weight of water exerted a greater pull on the orbiting spacecraft. The study ran from 2003 to 2013 and found that in 21 of the world’s largest aquifers, more water was removed than replaced during the decade.

What’s even more worrying, in the context of Cape Town’s imminent crisis, is that according to NASA data from 2015, South Africa’s largest aquifer in the Karoo Basin was not one of the 21, and Cape Town was not among the regions most in danger of freshwater depletion. Which suggests that if Cape Town does become the first major city in the world to run out of water, it might just be the beginning of a larger trend.

As Jay Famiglietti, senior water scientist at NASA’s Jet Propulsion Laboratory, told the Washington Post at the time, ‘The situation is quite critical, the water table is dropping all over the world. There’s not an infinite supply of water.’

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