[Image: Wikimedia Commons]
The Vaal Dam is surging toward full capacity at an astonishing pace, leaving many wondering: Will it overflow? And if so, what does that mean for those downstream?
Over the past week, the dam’s water levels have climbed relentlessly, reaching 89.2% by Thursday—a dramatic rebound from earlier this year when it languished below 30%.
According to the Water Resource Information Centre for the Catchment Management Forums of the Upper Vaal Water Management Area, the dam had been gaining over two percentage points per day, though this slowed slightly to one point between Wednesday and Thursday, reports The Citizen.
If this trajectory holds, the dam could hit 100% by early to mid-March.
Despite these rapid gains, Midvaal councillor Pieter Swart and the Department of Water and Sanitation have reassured the public that the dam is equipped to handle such surges. Swart noted that the inflows will likely slow as rainfall decreases and contributions from upstream sources like the Grootdraai Dam diminish. Meanwhile, the department has moved to quell fears of an uncontrolled overflow.
“The Vaal Dam operates with a full supply level of 100%, but it has a flood absorption capacity of up to 126%, meaning it can handle significant excess water before structural risks arise,” the department explained to The Citizen.
However, officials aim to keep levels below 103% as a precaution, allowing for better control over peak inflows. If necessary, controlled releases will be implemented, and affected downstream communities will be informed well in advance.
Unlike some dams that spill over when full, the Vaal Dam employs a strategic sluice gate system.
“It doesn’t ‘overflow’ in the way that, say, the Gariep Dam does,” Swart clarified. “Once it reaches capacity, the sluices are opened to release water in a controlled manner. If we expect heavy rains, the gates are strategically managed to prevent sudden surges.”
Water expert Carin Bosman reinforced this, dismissing the notion of an “overflow risk.”
“The dam is designed to release excess water—this is not a failure or a danger; it’s part of the system’s function,” she stated. Overflow events typically occur in mid to late March or early April, as the dam absorbs seasonal rainfall.
What About Flooding? For residents along the Vaal River, the real risk isn’t the dam overflowing—it’s development within designated flood zones.
“The closest major suburb, Three Rivers, occasionally experiences flooding when multiple sluices are open and heavy rainfall continues,” Swart acknowledged. However, flood management protocols are in place.
The Department of Water and Sanitation collaborates with the National and Provincial Disaster Management Centres, municipalities, and Rand Water to track water levels and mitigate potential flood risks. Key measures include:
- Issuing early warnings to downstream communities.
- Activating evacuation plans if conditions escalate.
- Adjusting sluice releases strategically to manage flood peaks.
- Coordinating emergency response efforts with local authorities.
“The department continuously monitors the dam using real-time gauging stations, SAWS rainfall forecasts, and advanced hydrological models,” officials stated. In an emergency, notifications will be issued through media statements, social media updates, direct coordination with municipalities, and SMS alerts.
Swart, too, keeps a close eye on conditions.
“I provide daily updates on my social media platforms, especially when the level fluctuates significantly. When we near capacity, official notifications from Rand Water and other authorities will also be sent out.”
Despite the dam’s high levels, experts urge continued water conservation.
“We’ve seen the Vaal Dam drop to critical levels before—down to 25%—and that would be catastrophic for water security, agriculture, and communities reliant on its supply,” Swart warned.
“Using water wisely now ensures resilience against drier periods and protects this vital resource for the future.”
For now, the Vaal Dam is rising, but there’s no cause for panic—just careful management and a watchful eye on the skies.
[Source: The Citizen]
