Concerns around a “catastrophic” failure of the Kariba dam, between Zambia and Zimbabwe, have again been thrust into the spotlight, as Zambia’s Energy and Water Development Minister last week announced the possible shutdown of its hydroelectric plants, with the dam’s water levels dropping to below 14%.
Adding to concerns around the dam, Zambian Geological Survey Department director Chipilaika Mukofu said experts were still assessing the possible effect that a 4.6-magnitude earthquake on January 12 may have had on the dam.
He asserted in an earlier interview that the quake’s epicentre was within “sensitive reach” of Lake Kariba and that there was concern that the dam wall’s stability could be affected.
Meanwhile, a report released in September by risk management group Aon South Africa and the Institute of Risk Management cautioned that the impact of severe drought brought about by El Nino and the overuse of water for power generation, coupled with further project delays in critically needed rehabilitation work, could accelerate a failure of the dam.
The ‘Impact of the failure of the Kariba dam’ report held that the dam was in a “dangerous state”, with torrents from the spillway having eroded the bedrock and 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,” Aon warned in a statement.
The group further cautioned that a collapse of the dam would result in significant loss of life, damage to property and an economic fallout.
“This risk and its potential consequences should be viewed as part of the existing power supply and demand challenges in the region and will require a strong commitment from governments, private companies and financiers to prevent the failure from happening,” it noted.
While stating that water levels were dangerously low, which took some pressure off the failing construction of the dam, the report cautioned that climate change, high rainfall patterns and water inflows from other regions, as well as potential seismic activity, could all contribute to the likelihood of failure of the 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.
“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 on 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,” explained report researcher and writer Kay Darbourn.
Further risks identified in the report included a likely delay in the dam’s rehabilitation project, climate change, drought, flooding and project funding constraints.
“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,” Darbourn held.