Suddenly: August

It’s nearly the end of July, and that means that it’ll soon be August. After that… [double checks] yes, September.

So what? This happens every year, right?

Well, yes it does, but September 1st is unofficially known as Spring Day in South Africa, bringing with it… well… Spring. Not really Spring, but unofficially Spring. Springy enough not to be Winter anymore. Unofficially, at least.

That also happens every year, but given that we’re basically 5 weeks away from it (and therefore 5 weeks away from what is unofficially the end of the rainy season), and our dams are still looking emptier than an ANC promise, we really should be well into full panic mode by now. Especially given that the medium term forecast for the next fortnight (making up, as it does, 40% of that 5 week period) shows no sign of significant rainfall for the Western Cape.

Look, tomorrow is not going to be dry, but with a forecast of just 5.2mm of precipitation over 24 hours, it’s not going to be particularly wet either.

With the Cape Town dams sitting at 27.4% of capacity (as per this morning’s city figures) – and with the last 10% of that infamously “unusable” – things are looking every bit as precarious as ever. Add to that the fact that Cape Town’s residents are using 643,000,000 litres a day (that’s 143,000,000 litres or almost 30% more than we should be) and you (actually “we”) have a recipe for disaster.

There’s enough publicity about this situation on the TV, the internet (not least this damned blog), the radio and everywhere else for everyone in Cape Town to understand the gravity of the situation. But given that we’re apparently still paying no attention and not saving nearly enough of the wet stuff, I’ve now come to the conclusion that a lot of the locals simply don’t care.

I wonder how they’ll feel in 6 months time?

Good news, bad news

GOOD NEWS!
As of 0600 this morning (it’s Friday today, for those wondering), the Theewaterskloof dam has 5,476,628,400,000 more litres of water in it than its low point on Tuesday at 1200.

BAD NEWS!
That only equates to its volume being 1.14% up on earlier in the week.
Current level = 14.05%*.

 

And therein lies the message that there’s a long, LONG way to go yet till we’re out of this mess, folks. Keep saving water!

* Obviously, there will still be inflows that haven’t reached the dam yet, so this figure will rise a bit.

Damn

Dam level figures released today for Cape Town’s ‘Big 6’ indicate that we’re 0.4% worse off than we were this time last week, teetering once again just above the magical 30% ‘CRITICAL‘ level, below which nothing actually changes.

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Oh then, to be in Sheffield (as I was a couple of weeks ago) where the dams are just about as full as they can be:

That total of 10,410,000,000 gallons is equal to 47,324,796,900 litres, in case you were wondering.

And what does a dam that’s 98% full look like? Like this.
And what does the other side of the wall look like when the dam is 100.1% full? Like this.

Going critical

Nothing good comes from things going critical. Nuclear power plants are probably highest up the list of things which are bad when they go critical, with toddler tantrums pretty close behind.
Critical isn’t good situation to be in. Critical is… well… critical.

Unless something rather remarkable occurs very shortly, when their capacities are measured again on Monday, Cape Town’s dams will have fallen below the “critical” level of 30%.

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It’s obviously an arbitrary level that they’ve chosen to call “critical”, and quite what happens when we cross that threshold is unclear, although we have been told that we shouldn’t panic. But then, that begs the question, why bother having a “critical” level in the first place if nothing changes once you find yourself below it?

After all, very little happened when we crossed the legendary “careful now” 70% margin, nor the distinctly worrying “er… guys…?” 50% line.

I do hope that the city council have got this all in hand…

Barry Wood, the city’s manager of bulk water supply, told the council’s portfolio committee “We don’t have to be too concerned, provided that it starts to rain.”

Ah. That’s all ok then.
Colour me completely reassured.

Water lot we got…

Right. The general consensus seems to be that we’re done with winter now and the good news is that Cape Town’s dams are full to bursting. Not literally though, I hope.

dams

Yes, you read right: our dams are 104.5% full right now, with just Wemmershoek letting the side down with its paltry 99.9%. “Big Boy” Theewaterskloof is looking especially resplendent on 107.5%, no less.
How can this be? Well, it’s not like the water rises above the dam wall and is held there by a giant meniscus or anything (although that would be really cool to see). The extra 7.5% is due to the difference between the intended capacity of the dam and the actual amount of water it can safely hold, as described here:

Man-made dams are artificial catchment areas and, by definition, are storage areas for water. When the dammed water reaches a level that indicates the maximum water that that dam can hold (before being put under stress by additional water pressure), a drum gate opens automatically to prevent over-pressure. The drum gate is designed to keep the dam at the maximum of the storage level – the so-called ‘full’ level – but often the ‘full’ level is well below the dam walls max capacity, for safety. So, as the water level begins to rise, the water level above the ‘full’ level is marked, and typically ends at 10% (or 110% if you like) above ‘full’. At this point, the water pressure is considered to be dangerous and sluices are opened to let water out. These sluices are carefully controlled to make sure that the river below the dam wall does not breach it banks and ruin expensive weekend homes! I think that saying the dam is 107% full is meaningless, and misleading, even though it an engineering necessity.

Either way, despite the fact that we are closing in on 1,000,000,000,000 litres of stored water, it’s still sensible to use it carefully, as the City points out:

It is important to bear in mind that the time to save water is when there is water to save, and we should therefore not become complacent about our water saving efforts. Cape Town will never be in the position of having sufficient water to waste, and we must continue to be vigilant.

Right you are. Not that my garden will need any more watering for about a month given the last couple of weeks.