Clem Sunter

Drought bulletin: we may just make it

2017-08-02 15:13
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I am writing this column after returning from a beautiful walk in the rain in Somerset West. On the way, I would like to have done my best imitation of Gene Kelly’s famous dance in the movie, but I am getting too old for that.

Anyway, it was a drizzle rather than a downpour, but anything is better than nothing.

Before I get to the latest probabilities on the scenarios I painted in the first bulletin, I would like to quote some statistics about the dams supplying Cape Town.

In the week ending 1 August, 2017 their combined level rose 0.5% to 27.9%. This compared to a level of 53.7% at the same time last year while the maximum last year was reached on 3 October at 62.3%.  

The difference between the beginning of August and October, 2016 was therefore 8.6% and if you add that to the current level of 27.9% you will get 36.5% at the beginning of October, 2017. In 2015, the difference during the same period was slightly lower at 7% which would make this year’s maximum turn out to be about 35%.

The drop from the maximum percentage to the minimum percentage in dam levels in the 2015/2016 summer period was 44.4% and in the 2016/2017 season 42.7%. You do not have to be a mathematical genius to see that we are on an unsustainable path, particularly if you take into account that the last 10% of dam capacity is considered too dirty to use. Essentially, we have an effective 17.9% in our dams right now. Recent statistics suggest this could rise to no more than 26.5% at the beginning of October.

At the rate of decline in the last summer season of around 6% per month, we would run out of potable water in under five months or by the middle of February next year. If you allow for the fact that the city’s water consumption has been cut from 800 to 600 million litres a day, this may lower the descent to say 4.5% a month which would push Day Zero out to the end of March next year.

If we achieve the present target for consumption of 500 million litres a day, we may last until the end of April, 2018 which gets us close to next year’s rainy season.

The reason I have gone through the numbers is to show clearly that more has to be done to increase supply in the short term and where possible cut demand. This will require a team effort as envisaged in the Liquid Gold scenario. But we have to start soon. Otherwise, it will be a case of too little, too late.

In light of the disappointing increase in dam levels last week, I would like to lower the probability of Nature’s Gift, a scenario in which we are rescued by abnormal rainfall in the next few months, from 20% to 15%. It cannot be ruled out but even the weather forecast for the remainder of August is not that promising.

For Liquid Gold, a scenario in which we dramatically change our attitude and behaviour about water, I will retain the odds at 40%. The flag to watch for this scenario to become the favourite to win the race is the announcement of some kind of joint initiative between the major players in Cape Town to undertake a special campaign about water scarcity being the norm, not the exception any more.

This applies to all communities, rich and poor alike but with the rider that the rich have to assist the poor in coping with extra costs involved. For once, Cape Town becomes the mother city for everyone.

The third scenario of Dire Straits, where we stumble into a crisis that necessitates extreme emergency measures and much disruption, is now given a 45% probability which puts it as the leading horse at this stage of the race. As someone who wrote to me after the first bulletin correctly observed, the direst variant of this scenario is no water at all. We would be the first major city in the history of the world to run out altogether.

Enough of pessimistic talk! I am going to do my Gene Kelly impression after all to make it rain again. 

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