Kariba Dam is falling down

2014-03-31 08:00

A large pool carved out by opening the sluice gates has eroded the integrity of the wall, which may collapse within the next three years.

The foundation of the Kariba Dam wall is eroding and has to be repaired urgently to avert a massive disaster.

If the wall collapses, it will affect 3.5?million people living downstream from the dam.

Power supplies to large parts of southern Africa will also be disrupted because a flood will affect two hydroelectric schemes?–?one at Kariba and another at Cahora Bassa, which supply a combined 1?500?megawatts of power to South Africa.

The restoration of the dam, which was completed in 1958, will cost approximately R2.7?billion and is considered to be one of the largest and most challenging operations of its kind.

Chris Herold, the vice-president of the SA Institute of Civil Engineering, says the biggest problem is the more than 50 years of water erosion in the immersion pool at the foot of the dam’s 128m-high wall.

“This is the deep pool where the lake’s huge volumes of water fall when the sluice gates are opened. Erosion takes place where the water hits the bottom of the pool?–?and the pool has been carved out deeper and deeper over the decades,” he adds.

“The pool is already 9m deep in certain places. As the erosion cuts the pool walls wider, it cuts back into the foundation of the wall.”

As this happens, the structure of the wall becomes increasingly unstable, which could lead to it eventually collapsing, says Herold.

According to him, the problem is aggravated because the erosion hazard means no more than three of the dam’s six sluice gates can be opened at any one time.

This halves the dam’s release capacity and if there’s a flood, only half of the water can be released.

This will place additional pressure on the wall.

Elizabeth Karonga, the communications manager of the Zambezi River Authority, confirms the damage.

She says a team of French engineers inspects the wall every five years.

According to her, engineers are building models for the restoration of the wall and the repairs could take at least six years?–?one for each sluice gate.

José Matola, a specialist hydrologist at Cahora Bassa, told City Press’ sister paper, Rapport, an emergency meeting with all “relevant authorities” in Malawi, Mozambique, Zimbabwe and Zambia is set for tomorrow.

“We are very worried. If action is not taken quickly, the wall will break in three years’ time and we at Cahora Bassa will be hit by a huge wave against which we stand no chance at all,” he says.

Looming Kariba catastrophe

Join the conversation!

24.com encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
Comments have been closed for this article.

Inside News24

Traffic Alerts
There are new stories on the homepage. Click here to see them.


Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.

Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.


Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.

Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.