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Residents near Shongweni Dam warned to steer clear of riverbanks
This is not a dam wall failure, its fusegate technology at work.
Shongweni Dam fusegates open. Picture – supplied
Two of the ten gates at the Shongweni Dam have fused, resulting in the release of water into the river.
The Department of Water and Sanitation said that news of the Shongweni Dam walls bursting was untrue.
“They are designed to fuse during extreme floods. So this is a safety measure, not dam failure,” said the department spokesperson Sputnik Ratau.
Ratau warned residents downstream that river flows are increasing since the dam gate fused.
“Residents should steer clear of the river banks while overflows pass,” he said.
.According to Geotechnical Engineering fusegate systems are an innovative solution for dam safety upgrades, flood protection and water resources efficiency.
“During flood events, when the dam is full water flows over the crest of the fusegate modules, which acts like an ungated spillway.
“As the floodwater levels rise, the fusegate modules sequentially tip, one after the other. The tipping threshold of each module is set precisely by the height adjustment of their inlet well, to ensure the units overturn progressively in order to compensate for the effect of exceptional flood levels,” said the site.
Ratau said that due to this technology, there was no need to open sluice gates.
On Tuesday, 12 April, the department said it has to open sluice gates at the Vaal and Hazelmere Dams on Tuesday, 12 April 2022, following the recent heavy downpours.
According to Ratau, the inflows were at 1065.67 cubic meters per second. The Vaal – which supplies most parts of Gauteng – was at 110,5% while Bloemhof Dam is at 106,9%.
DWS Hydrology experts then made further recommendations for more releases from the Bloemhof Dam, which is downstream from the Vaal Dam.
The department also opened sluice gates at Hazelmere Dam after water had reached critical levels with much-localised flooding.
“A decision has been reached for Umgeni Water to release water from the Hazelmere Dam, which is located to the north of Durban.”
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