Threewaterskloof dam in mid-September 2017 (left) and the same time of year in 2021 (right), via Planet.
  • Cape Town's dams are full, including Theewaterskloof, the most important in the water system feeding the city.
  • Satellite images show the remarkable transformation of the dam from its low point in 2017 – essentially a smallish river – to more than 100% capacity again this September.
  • This was the view from space as Cape Town's biggest dam filled up.
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The Theewaterskloof dam, which all by itself holds about 40% of the water storage available to feed the City of Cape Town, is this week slightly emptier again – at 99.3% capacity.

The parched wasteland the dam became in 2017 and 2018 was a stark illustration of the danger of what came to be known as Day Zero, the hypothetical point at which the city's dams would simply not have enough water to pump any out.

Now, thanks to satellite images earth-data company Planet provided to Business Insider South Africa, it serves as an illustration of how dramatically Cape Town's water fortunes have turned.

In early September 2017, Cape Town faced a summer with its dams at 35% capacity, just as it moved into its dry season. By the end of the 2018 rainy season, things had improved to 70% of capacity, collectively, for the six largest dams that provide the city with its water. By 2019, that number hit 80%, by 2020 it was at 95% – and this year the system overflowed again.

See also | Cape Town is heading into summer with dams literally 100% full – compared to 35% in 2017

As of Monday, both Theewaterskloof and the Berg River dam were officially more than 100% full, with the least-full dam in the system, Steenbras Upper, clocking in at 97.3%.

The country as a whole is also in pretty good shape. Data from the national water department shows national dams at 79.2% of their capacity, collectively, compared to the 65.2% recorded at the same time last year. 

At a provincial level, only the Eastern Cape still has low dam levels, at 50.2% of their capacity, and even that is up slightly from 2020.

Here is how Cape Town's Theewaterskloof dam filled up over the past 5 years from its low point in 2017...

Threewaters 2017

... to the evident, but still small, recovery of 2018...

Threewaters 2018

... while, by 2019, the view from space still showed sandy shores and some islands.

Threewaters 2019

From orbit, there is little difference to be seen between the pretty-much-full version of the dam in 2020...

Threewaters 2020

... and, finally, in 2021.

Threewaters 2021

You can see the Theewaterskloof dam fill up, and its surroundings turn green, in this time-lapse covering mid-September for each year between 2017 and 2021.

Threewaterskloof, mid-September in 2017 through 2021.

By comparison, aerial footage over the three years from 2016 showed how the dam collapsed into something more akin to a river. 

See also | Lesotho is choosing its own electricity over water for SA, engineers say – at Gauteng’s peril

(Compiled by Phillip de Wet)

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