HARARE - Concerns surrounding the structural health of the Kariba Dam have risen following an announcement that the region could be facing a shutdown of its hydroelectric plants, as water levels drop “dangerously” low.
Zambian Energy minister Dora Siliya raised the alarm last week when she announced that water levels in the dam had dropped to below 14 percent, prompting the shutdown of the dam’s hydroelectric plants.
The situation was exacerbated by a 4,6 magnitude earthquake, which hit the Kariba area and parts of Zambia on January 12.
The incident raised fears about the vulnerability of the dam wall, although no damages were recorded.
Lake Kariba, which straddles the border between Zambia and Zimbabwe, generates up to 40 percent of hydropower to the southern African region and could have catastrophic effects should its walls fail.
According to a statement, Chipilaika Mukofu, director at the Geological Survey Department in Zambia, said that the possible
effects of the earthquake were being investigated.
Mukofu also said that the epicentre of the quake was within sensitive reach of Lake Kariba and that the stability of the dam wall could be affected as a result.
A recent report by the Institute of Risk Management SA (IRMSA) detailed the implications of a failure at the Kariba Dam.
The report, titled Impact of the failure of the Kariba Dam, said the dam was in a dangerous state, with a gaping crater of eroded bedrock undercutting its foundation.
“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,” wrote Kay Darbourn, researcher and writer of the report.
“In December 2014, the critical period was defined as ‘the next three years’, while the rehabilitation project is only due for completion in 2025.”
The latest development comes after Zambia and Zimbabwe last year signed a deal worth $294 million to repair the dam, but efforts seemed to have been delayed by the Zambezi River Authority as tender processes continued.
With some countries in the southern region relying mainly on hydropower from the Zambezi, several economies would be severely affected should the dam collapse. South Africa alone will lose 1 500 megawatts (MW) of imported power, the report said.
Meanwhile, Energy minister Samuel Undenge last week said the country was working on a number of power projects to hedge itself against acute power shortages that might emanate from low water levels in Kariba Dam.
“There are plans to build the Batoka Dam and that one will also produce relatively cheap power. The feasibility studies will be completed by mid-year then the tenders for contractors will be floated,” he said.
“Beginning of next year, work at Batoka will start,” he added. Undenge said construction of the Batoka Dam would take five years.
“Construction work starts in 2017. We expect it to be completed by 2023,” he said.
The Batoka project was initially stalled by a dispute over the payment of the Central African Power Corporation debt, incurred at the construction of the Kariba Dam in the Rhodesian era. Zimbabwe paid off its share of the debt to pave way for the $3 billion project.
The Batoka hydro-electricity project is a three-phased project, which involves construction of the dam, construction of the power station and construction of the transmission lines.
Upon completion, Batoka power station will generate
2 400 megawatts of electricity, to be shared equally between Zimbabwe and Zambia.
The two countries are presently experiencing serious power deficits following the drop in water levels at the Kariba Dam where the two countries share a hydro-electricity generating plant.
As of last week, Kariba was generating about 470 megawatts of electricity from about 750 MW last August when the Zambezi River Authority introduced water rationing to maintain acceptable water level.
Other projects in the pipeline include the Hwange Expansion Project, to produce an additional 600MW of power, installation of two units at Kariba to generate an additional 300MW, work at the Bulawayo thermal power station and at Munyati power station.