A flooded street in Centurion on December 9 2019. Picture: NDAMULELO THOMOLI VIA REUTERS
A flooded street in Centurion on December 9 2019. Picture: NDAMULELO THOMOLI VIA REUTERS

Despite potentially record-breaking rainfall that resulted in floods in parts of Gauteng, the water levels of the main dams in the northern parts of the country have hardly moved.

Continuous rain fell for almost seven days in parts of the highveld, after starting last week. However, the rain seems to have fed into river systems downstream from the Vaal Dam, which dropped to below 40% full over the past two weeks.

“The recent rains in Gauteng and parts of Mpumalanga and south of Limpopo have had little impact on the country’s water situation, with dam levels still dropping by [one percentage point] weekly,” the department of water said in a statement on Friday. Hydrologists, the statement read, attributed this to the recent rain mainly occurring in areas with “little or no catchments at all”, only affecting smaller dams.

This comes despite parts of Pretoria recording, according to preliminary data, potentially record-breaking rainfall. Areas such as Bronkhorstspruit, Irene and Pretoria central each recorded more than 200mm of rain, said Wayne Venter, a forecaster at the SA Weather Service. Meanwhile, the weather station at Unisa’s main campus recorded 312mm of rainfall, which Venter said could be a new record.

Johannesburg, on the other hand, received only 120mm over the weeklong rain and Springs, in the East Rand, recorded 144mm for the same period. The Hartbeespoort Dam got 220mm with videos of the dam’s wall overflowing surfacing online this week. According to data from the department of water, the Hartbeespoort Dam stood at over 96% full this week. Some dams in Limpopo also saw minor increases.

*Select the fullscreen button on the top right corner of the graphic to enlarge it.

Venter explained that the Vaal Dam is more dependent on rainfall in the eastern parts of the highveld. Despite some of these areas, such as Standerton and Ermelo, recording good rainfall during the past week, little appears to have made it to the Vaal.

Venter said some thundershowers are expected in these areas later on Friday, and then more again closet to Christmas. It remains uncertain at this stage, Venter said but “rainfall for midsummer is forecast ... [to] be below-normal rainfall for Limpopo, Gauteng, and Mpumalanga”.

The water department said both Tshwane and Johannesburg will keep their water restrictions in place. “Dams are still at a lower average level and still falling slightly despite a few increases,” the department said.

vandermerwep@businesslive.co.za