A flood emergency might be declared at Standerton in Mpumalanga as more water flows into the already over-full Grootdraai Dam, authorities said on Wednesday.
Police spokesperson Superintendent Amanda Peens said a joint meeting would be held with officials from the Department of Water Affairs and Forestry and emergency services in the town on Wednesday afternoon to discuss the situation.
”At the moment, we are still fine,” she said. ”The water level actually dropped a bit. But a lot of rain fell in the Amersfoort area and that water is still on its way to the dam.”
She said 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.
The flood water from the dam is not a huge rush of water, but a steady increase of the level of the slowly flowing stream. The town is situated in an oxbow of the Vaal River, which causes flood water to take the shortest route — mostly through a part of the town, Peens said.
On Monday, a small shop situated in a low-lying part of Standerton was voluntarily evacuated.
”The shop owner always evacuates his shop when it rains a lot and he only goes back once the rain has stopped.”
The Department of Water Affairs and Forestry said the inflow into the Grootdraai Dam was at 700 cubic metres per second at 7am on Wednesday. It was expected to increase to about 1 200 cubic metres per second during the day. The outflow being released from the dam was 540 cubic metres per second at 7am.
Departmental spokesperson Amelius Muller said it would be increased to 850 cubic metres per second as the inflow increased.
”The dam is 114% full at the moment, but it still has a lot of capacity to absorb a higher inflow,” Muller said. ”Even if the dam’s level increases to about 120% of more, we will be able to absorb it and maintain an outflow of below 1 000 cubic metres per second.”
Once the outflow increases to 1 000 cubic metres per second and more, it would become necessary to evacuate houses in Standerton and close roads.
The department has deployed personnel in the catchment area of the dam to monitor the situation and to report sudden increases in inflow.
He said the Vaal Dam has shown an increase in level over the past two days 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