Rainy spell increases Vaal Dam levels

Recent rains falling in the right catchment areas have resulted in a signifiant uptick in Vaal Dam levels. 

The Vaal Dam is currently at 60.6%. The Sterkfontein Dam is at 95.8%, and the Grootdraai and Bloemhof dams are at over 100%. 

The flow of water into the Vaal Barrage Dam as of 7am on Thursday morning was 89.718m³/s, just short of the maximum flow of water recorded on Wednesday, at 90.087m³/s, according to Rand Water. 

24.5mm of rain fell on Wednesday, with an evaporation rate of 11.5mm of water. 

ALSO READ: Why the Vaal Dam doesn’t fill up after every thunderstorm

It is incredibly difficult to fill the dam, which has a storage capacity of 2.57 billion m³. This is because the dam’s shoreline stretches 880km through three provinces – Gauteng, the Free State and Mpumalanga. 

Its catchment area, which is the area where rainfall needs to hit in order to make a difference to the dam’s capacity, is 38,500km². 

The latest spell of rain this week is significant, because the difference made to its fullness means rains lasted long enough to produce run off to the dam. 

Good rainfall could be partly attributed to the effects of the current La Niña phenomenon, where cool waters build up in the eastern Pacific.

For some regions in the world, this means extended dry spells, but in southern Africa, it means cooler temperatures and more regular rainy spells. 

Last year, Storm Report SA predicted a moderate-to-strong La Niña, which was expected to peak between November 2020 and January 2021. It is expected to weaken as the country approaches autumn.  

Compiled by Nica Richards. 

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