Cape Town's taps can still run dry despite possible Day Zero scrapping - experts

Cape Town – The politicians may have given us hope that Day Zero could be avoided this year – but water experts say this does not mean Cape Town's taps won't run dry.

It is still as likely to happen as it was a week ago.

And the weather services say their latest long-term predictions for rainfall in the south-western Cape, which suggest Cape Town may get above normal rains this winter, are hardly any better than guess work.

The most significant happening in the world of the water crisis this week was the announcement by DA leader Mmusi Maimane that Day Zero would possibly not happen in 2018.

- Read: Cape Town may avoid Day Zero this year - Maimane

It left many people gobsmacked.

Dam levels were still dropping, consumers had not reached the 450 million litres a day water-saving target, none of the water augmentation schemes had come on line and there had been no rain. So why?

High risk of forecast being wrong

There was a flurry of responses on social media groups with people expressing anger, suspicion and puzzlement. Some saw it as politicians using the drought as a political football. Others queried if Day Zero had been a reality. Many, however, believed there was still a crisis and urged people to carry on saving water.

In his announcement, Maimane did add the caveat that scrapping Day Zero for this year was based on the premise that Capetonians would continue saving water and that the region got "decent rainfall" this winter.

But even the weather scientists will not say that.

Cobus Olivier, a scientist at the South African Weather Service, said on Friday the long-term rainfall forecast for May, June and July, released this week, did indicate above normal rainfall for the south-western parts of the country.

"But we always give out this information with the caveat that there is a high risk of this forecast being wrong. You have to take this into account, but the public don't usually do that," Olivier said.

The reason was that the computer models used for the country's winter rainfall area did not work well for the weather systems that brought winter rainfall. They did, however, work well for the summer rainfall region.

Day Zero 'as likely to happen as it was a week ago'

"Globally there has been a lot of work trying to understand why these models fail, but even if they do find out, it doesn't mean they will know what to do about it. So the long-term forecasts for our winter rainfall areas are only just a bit better than guessing," Olivier said.

He said he had been "a bit surprised" that Day Zero had been scrapped, and had expected the City to take a more conservative approach.

Christine Colvin, head of World Wide Fund for Nature's Fresh Water Programme, said it appeared that it was the DA rather than the City that wanted to claim a victory over Day Zero.

"We have definitely not defeated Day Zero. It is still as likely to happen as it was a week ago."

The reallocation by agriculture of water to urban areas, plus the huge consumer water savings, had made it possible to push back Day Zero from April to August, but Colvin said that was just short-term relief.

"All the science tells us that we have a drier future in the Western Cape. It is a pity Day Zero has been taken away. It was a blunt, but very useful indicator and people have got used to it. I urge them not to take their eye off the ball. We're in this for the long haul," Colvin said.

'The red lights are flashing'

Kevin Winter, head of the University of Cape Town's (UCT) Future Water Institute, said while scrapping Day Zero may have a calming effect on the public, the prospect of the taps running dry was "still sitting there".

"There is no reason that Day Zero won't come back at us. No one can say with any confidence that we will get more rainfall than last year. While the city officials have been sweating blood, there has been political point scoring. I think it was a move to save face."

Winter said the UCT institute had been doing its own modelling and "the red lights are flashing".

The City's response to the question why Day Zero had been scrapped did not provide a clear answer.

In a written response Deputy Mayor Ian Neilson said that the City had taken a conservative approach in calculating Day Zero, which meant that the date could shift further away under more favourable conditions – as it had done progressively when water was released from agriculture, with donations by farmers, pressure management and consumers cutting consumption.

But nothing in that response explains why Day Zero had been scrapped altogether, particularly as Neilson stressed that Day Zero was "not some scare campaign".

"The water crisis is real. People can go to the dams and see for themselves," he said.

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