HomeNewsMounting concerns about failure of Kariba Dam as El Nino bites

Mounting concerns about failure of Kariba Dam as El Nino bites

Kay Picture
Kay Darbourn, author of the “Impact of the failure of the Kariba Dam” report.

Kay Darbourn, author of the “Impact of the failure of the Kariba Dam” report, which was finalised in June 2015 and is sponsored by Aon South Africa, unpacks her findings.

Region faces shutdown of hydro-electric plants and collapse of mining industry. 

Concerns regarding a catastrophic failure of the Kariba Dam have been thrust into the spotlight again as Zambia’s energy minister announced last week the possible shutdown of its hydroelectric plants with water levels in Kariba Dam dropping to below 14%. Adding to concerns about Kariba dam, the Geological Survey Department director Chipilaika Mukofu said experts were still assessing the possible effect of a 4.6 magnitude earthquake on the Kariba Dam in Siavonga on 12 Jan 2016.  In an interview, Mukofu said the quake’s epicentre was within sensitive reach of Lake Kariba and there was concern that the dam wall’s stability could be affected.

In a report released in September 2015 by Aon South Africa and the Institute of Risk Management (IRMSA), the risks and challenges for the region were detailed relating to the current state of the Kariba Dam and the proposed rehabilitation project. The “Impact of the failure of the Kariba Dam” report was finalised in June 2015 and is sponsored by Aon South Africa and researched and written by Kay Darbourn.  Now with the impact of severe drought brought about by El Nino and overuse of water for power generation, coupled with further project delays in critically needed rehabilitation work, the risks that could accelerate a failure of the dam may be increasing

The Kariba Dam is in a dangerous state

Built on a seemingly solid bed of basalt in 1959, the torrents from the spillway have eroded the bedrock leaving a gaping crater, undercutting the dam’s foundations. Engineers have been warning for some years now that without urgent repairs, the whole dam will collapse, knocking out Mozambique’s Cahora Bassa Dam and 40% of southern Africa’s hydroelectric capacity. Along with the devastation of wildlife in the valley, the lives of 3.5 million people are at risk.

“While water levels are dangerously low which takes some pressure off the failing construction of the dam for now, the bigger picture of the state of Kariba dam is critical.  Climate change, high rainfall patterns impacting future dam levels and water inflows from other regions, and potential seismic activity, could all contribute to the likelihood of failure of the Kariba Dam. In December 2014, the critical period was defined as “the next three years”, while the rehabilitation project is only due for completion in 2025,” explains Kay Darbourn, researcher and writer of the report.

On the flipside of Kariba’s pummelling water that has compromised its bedrock, current water levels continue to drop, and electricity supply within Zambia and Zimbabwe is already reduced by more than half. Mining companies have borne the brunt of having to import electricity supply at huge cost, triggering the closure of some mines and over 10 000 job losses.  Businesses and homes experience power cuts for up to 14 hours a day.

“But when water levels do improve and Kariba starts filling up again, there is no telling what the pressure could do to the retaining structures. The dependency of the region to Kariba Dam is massive, but while our original report focused on the failure of the dam, the impact of the drought shows similar consequences for countries in the region,” adds Darbourn.

Some of the further risks noted since the release of the original report include:

Project Delay

  • Feedback from the Zambezi River Authority (ZRA) in September 2015 confirmed that the procurement of the Supervision Consultant was being finalised and that this would be followed by a tendering process for the contractor that will carry out the Plunge Pool Rehabilitation works. Thus far there have been no details of any tender or the work commencing on the floodgates.
  • An ESIA report, which was one of the requirements before work could commence on the Kariba Dam wall, was published 10 November 2015 and notes that the Kariba Dam Emergency Preparedness Plan, completed in 2013, is still to be updated. This is an essential part of any disaster management operations if the dam fails before or during the project.

Climate Change, Drought or Flooding

  • NewsDay Zimbabwe reported on 13 November 2015 that there was just 1% usable water left in Kariba. Both Zambia and Zimbabwe rely heavily on power generation from Kariba, and both are experiencing severe power constraints impacting industry and the population.
  • It was agreed that the ZRA will prepare a Climate Change Action Plan during Project Implementation that focuses on water management. Monitoring and evaluation systems are an essential element of this strategy and would help the Zambezi River Basin communities and dam operators to understand clearly whether current water management practices are climate smart

Funding and Debt Repayment

  • While funding was secured in December 2014; delays, economic constraints and currency challenges will undoubtedly lead to an increase in the cost of the entire

“Whether you are a shareholder, stakeholder, board member, business executive, risk manager or even a private individual, if you live, work, own property or have investments in South Africa, Zambia, Zimbabwe, Botswana, Mozambique or Malawi, the chances are that if the Kariba Dam fails you will be affected. This will just be the start of years of economic, social, environmental, humanitarian and technological fallout that will devastate the region’s economies,” explains Darbourn.

Some countries rely mainly on hydropower from the Zambezi and their economies will be severely impacted, both for industries that rely on electricity to operate and in terms of revenue generated from the sale of electricity.  South Africa, already in a precarious energy supply shortage, will lose 1,500MW of imported power as the Cahora Bassa Dam fails.

Access to water for people in the Kariba and Cahora Bassa catchment areas for drinking, food and agriculture will be restricted. Transportation and access to the areas affected will be curtailed. New projects and investment in the region will be severely compromised, as the ongoing lack of electricity and water will make these uneconomical, potentially for up to eight years while the dams are rebuilt.

Ashley Theron
Ashley Theron-Ord is based in Cape Town, South Africa at Clarion Events-Africa. She is the Senior Content Producer across media brands including ESI Africa, Smart Energy International, Power Engineering International and Mining Review Africa.