A possible flood emergency at Standerton in Mpumalanga has not materialised after less water flowed into the Grootdraai Dam than expected, authorities said on Wednesday afternoon.
Police spokesperson Superintendent Amanda Peens said the outflow of the dam, which is 114% full, will be maintained at 850 cubic metres per second.
The outflow was increased on Wednesday morning from just more than 500 cubic metres per second to 850 after heavy rain fell overnight in the dam’s catchment area.
On Wednesday morning, the Department of Water Affairs and Forestry said it would try to maintain the dam’s outflow at 850 cubic metres per second to prevent flooding in the town.
Spokesperson Amelius Muller said the inflow into the dam can still be absorbed although the dam is more than 100% full.
”Even if the dam’s level increases to about 120% or more, we will be able to absorb it and maintain an outflow of below 1 000 cubic metres per second,” Muller said.
Once the outflow increases to 1 000 cubic metres per second and more, houses and businesses, as well as roads in Standerton, will be flooded.
The department has deployed personnel in the catchment area of the dam to monitor the situation and report sudden increases in inflow.
One of the problems at Standerton is that the whole town is built on wetlands. Many buildings have fountains in their basements, with submersible pumps controlling the water levels. The current high rainfall has saturated the ground, causing run-off water to flood the low-lying areas of the town.
On Monday, a small shop situated in a low-lying part of the town was evacuated.
Peens said the sun was shining brightly on Wednesday afternoon.
”I think we’re fine for now. It all depends on the weather and if more water will flow into the dam.”
She said the situation will again be assessed on Thursday morning.
By Wednesday morning, the Vaal Dam had shown an increase in capacity from 34% to 44%, with water from tributaries and the Grootdraai Dam reaching it. It is expected to increase to at least 55% in the next day or two.
The Bloemhof Dam’s level has also increased from 10% on Monday. It is expected to increase to at least 25% over the next few days.
The South African Weather Service said more rain is expected on Wednesday and Thursday, especially over the Highveld and Mpumalanga.
Weather forecaster Evert Scholtz said the tropical low over the eastern parts of the country will start moving away on Thursday, but drier conditions will only arrive from Monday onwards.
”With the amount of tropical air sitting over the country, you don’t need much of a trigger for it to rain. Although the sun came out this morning [Wednesday], we expect showers to again develop in the afternoon,” he said. — Sapa