Power crisis looms in Zambia as world’s largest man-made dam dries up

Severe climate change and unpredictable weather events have caused the world’s largest man-made lake to lose more than 98% of its water.

Lake Kariba, formed by the Kariba Dam, is the largest man-made lake in the world. The double-curvature concrete dam has an estimated height of 128m with a crest length of 617m and has the capacity to hold back 181 billion cubic metres of water. The Kariba Dam was constructed across the Zambezi River between 1956 and 1959; it was commissioned in 1960 and opened by the late Queen Elizabeth II. Kariba generates an estimated 1,080 megawatts of electricity output for Zambia and 1,050 megawatts for Zimbabwe. Unfortunately, water levels have dwindled sharply in recent years, raising fears that the two nations’ hydropower turbines may have to switch off completely if water levels continue to decline.

According to data from the Zambezi River Authority (ZRA), the agency jointly controlled by the two nations’ governments, the dam had 2.34% of usable storage water, compared with 20.86% a year ago. The current water levels are close to those reached in the 1995/96 season, the lowest recorded since the 62-year-old giant dam was completed.

Energy crisis looms

Zambia’s state-owned power utility company, ZESCO, which supplies energy to over 80 per cent of the country, recently announced that it would immediately increase the length of blackouts from six hours to 12 hours. Meanwhile, Zimbabweans have been forced to endure 19 hours of power outages a day. “The current water levels are extremely low at the moment. We are literally breaking new records in terms of low levels in the reservoir because the levels are lower than any recorded level in the history of a generation a the dam and this is threatening our continued electricity generation at the power station,” said Wesley Lwiindi, ZESCO Kariba North Bank Station director, in an interview.

Mr Wesley Lwiindi of ZESCO Kariba North Bank Station said the current water levels are extremely low © Zambezi River Authority

“If the delay in rainfall were to continue much further, it could lead us to shift away from our current load management strategy, where we are managing our stakeholders, especially our high power consumers to minimise utilisation of electricity. We might be forced to move to the next level, which is load shedding in the country,” Lwiindi continued.

Investing in renewable energy

Meanwhile, Zambia’s President, Hakainde Hichilema, has condemned the 12-hour blackouts, saying the current load shedding had the potential to erode the economic gains Zambia has made after the Covid-19 pandemic. “I am directing ZESCO to consider splitting the 12 hours of load shedding per area into a six-hourly schedule to help maintain economic operations. We shall not shy away from taking responsibility where challenges are being faced, as that is key to addressing them. And in addressing these problems, we shall not take politically convenient, populist routes; our decisions shall be based on building sound foundations that will last for generations to come.”

President Hakainde Hichilema said that he will not use political convenience in addressing the energy crisis that has rocked the copper-rich southern African state © Zambezi River Authority

Mr Hichilema said the lack of sufficient investment in the energy sector by previous governments has contributed to the perilous power deficit in the country.

Zambians are nervous

“The ongoing blackouts have negatively affected my stationery business operations. I run a small business and I can’t afford alternative electricity supplies because my business solely depends on hydroelectric power for my daily operations. I don’t even know when this problem will be solved. I am extremely worried about the 12hr load shedding implemented by ZESCO. I just hope I won’t be forced to go out of business. How long I can hold on, only God knows,” said Joseph Mwenda, a businessman based in Isoka, Zambia.

Joseph Mwenda, a small businessman from Isoka, Zambia, struggling to turn on a Genset after electricity was cut off © Mwanjo enterprise

“My life depends on this business, but now it is just a shadow of its former self. No one comes to access printing and cyber services because I do not have electricity. I think the weeks ahead will be rough,” said Mwenda.

Refurbishing the dam

Meanwhile, after more than 50 years of generating power for the Southern African region, the Kariba Dam is currently going through rehabilitation works for its continued safe operation. The renovation works involve reshaping the plunge pool to limit scouring and erosion coupled with the refurbishment of the spillway and associated infrastructure to improve the dam’s stability and future operations.

A cross-section of the Kariba Dam’s plunge pool. The natural river bed downstream of the dam has eroded over time as a result of heavy spillage of flood waters © Zambezi River Authority

For nearly a decade, experts have raised concerns regarding the dam’s lack of structural maintenance and negligence. Unfortunately, the dam’s torrent spillage has excavated a giant cavern in the Zambezi river bed, now the cavern has grown to more than 10 times bigger and deeper than the original design dimensions and it is threatening the stability of the foundations of the dam structure.

Digging a canal

Some energy experts have suggested that the Congo River in the Democratic Republic of Congo (DRC), the continent’s second longest, could hold the solution for the Zambezi River’s water scarcity. “We are strongly advising the Zambian government to consider digging a canal that can direct water from the Congo River to the source of the Zambezi. This development will improve electricity generation for both countries.”

But Arthur Chapman, an independent consultant in climate change adaptation and disaster risk assessment remains pessimistic. “Even if the heads of state of Zambia, DRC and Zimbabwe agree to the canal idea, the plan will never be achieved, due to the fact that the Zambezi’s source lies in the far north-west corner of Zambia, more than 100km from the Congo River.”

Considering the current electricity deficit the two drought-stricken countries are experiencing, they should look to renewable energy for a reliable, efficient and sustainable energy supply.

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