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Alba Iulia
Sunday, February 5, 2023

Understanding the Kariba Dam and Zambia’s power crisis

ColumnsUnderstanding the Kariba Dam and Zambia's power crisis
Sir Duncan with Her Majesty Queen Elizabeth the Queen Mother at the official opening of the Kariba Dam. Tuesday 17th May 1960.
Sir Duncan with Her Majesty Queen Elizabeth the Queen Mother at the official
opening of the Kariba Dam. Tuesday 17th May 1960.

Fifty years ago the Kariba Dam was the centrepiece of collaboration of the Central African Federation. Built in just four years, it was opened by the Queen Mother in 1960 in front of a crowd of 3,000 onlookers, reported by British Pathé at the time, in black and white of course, “as one of the wonders of the world”, an “£80-million masterpiece of engineering skill”. In the Queen Mother’s words, it marked “a new era in the economic life of the Rhodesias”, generating “power for the rapidly growing industries for this potentially enormously rich territory”.

Impending catastrophe
Mention the facility today, and the talk is about the potential for catastrophic failure of the 128-metre dam wall on account of the erosion of its basalt foundations. Experts have warned that without urgent repairs the dam risks collapse, unleashing a ‘tsunami’ of water through the Zambezi Valley, reaching the Mozambique border in just eight hours where it would overwhelm the Cahora Bassa wall, in so doing eliminating 40% of the region’s hydro-electric capacity. According to the Zambezi River Authority (ZRA), which operates the dam, aside from the devastation of wildlife in the valley, the lives of an estimated 3.5-million people would be at risk from this calamitous event.

Experts have warned that without urgent repairs the dam risks collapse

The Kariba Dam, the world’s largest man-made reservoir, supplies water to two hydropower stations: that on the north bank, operated since 1976 by the Zambia Electricity Supply Company (Zesco), with an installed capacity of 1,080 megawatts (MW); and the south bank, operated by the Zimbabwe Power Corporation (ZPC), with 750MW currently and projects to increase this to 1,050MW by 2018. Cahora Bassa’s installed capacity is 2,060MW, much of which is transmitted to South Africa. A further two dams, Itezhi-Tezhi and Kafue Gorge, are on the Kafue River, a tributary of the Zambezi, with a combined capacity of a little over 1,000MW once Itezhi-Tezhi is completed.

Kariba requires rehabilitation, especially to the plunge pool into which the water from the sluices is discharged at a peak of 8,000 tonnes per second. Along refurbishment to the spillway, rehabilitation is expected to cost $300-million over 10 years, seemingly cheap at the price when considering the cost of a new Kariba at around $5-billion. Emergency spilling over the years has scoured a plunge pool to a depth of about 80 metres around 50 to 75 metres downstream of the dam wall. The emergency spilling is itself a result of a lack of turbine capacity.

Many of the issues are, in the words of one specialist engineer, “fairly predictable 50-year maintenance works”. Moreover, “the growing installed turbine capacity at Kariba makes it less likely that substantial spilling will be required going forward”. There is a view that the sense of ‘crisis’ is seriously trumped up – and for good reasons: 300-million of them, in fact.

Overlooked, perhaps inevitably, amidst the hyperbole of collapse, destruction and loss of life, is the cost of the poor management of the asset, and the water resource, something that can be relatively easily fixed and where the failure to do so is less dramatic but no less costly. The answer to this crisis is, however, at least as political as it is technical, in Zambia as elsewhere.

The dam wall at the Kariba North Bank Power station
The dam wall at the Kariba North Bank Power station

Increased demand
Today there are chronic power shortages in both Zambia and Zimbabwe, attributable only in part to lower than normal reservoir levels, particularly at Kariba.

Zimbabwe’s power demand is some 2,200MW. Its supply is usually around two-thirds of this. In April 2015, for example, Harare, Bulawayo and Manyati stations were producing a combined output of 78MW against a capacity of 265MW. With problems afflicting Hwange Thermal Station, with an installed capacity of 920MW, pressure for continued production has been placed on Kariba to deliver close to its 750MW.

In Zambia, the electricity shortage is a result of some good news – an increased demand for electricity – and some bad, in the form of delays to new generation projects and overuse of newly-installed ‘peaking’ turbines at Kariba.

Demand for electricity has grown very rapidly in Zambia as new customers have been connected to the grid. These have included residential, commercial, agricultural, industrial, and mining customers. Demand has increased from around 1,600MW in 2008 to about 2,200MW in 2015. Ultimately this is a good thing as it represents economic growth and progress for the country. The challenge has been bringing in new generation projects on time to keep up with the growing demand.

This has been compounded by delays to new generation projects in Zambia.

Long before the current shortages, Zesco recognised the growing electricity demand and began to contract for new generation. Notable recent additions to Zesco’s generation capacity have included 50MW from a new Ndola-based fuel oil generation plant, and the 360MW (2x180MW) Kariba North Bank Expansion to meet peak evening demand.

Zesco has also contracted an additional 120MW of hydro power from Itezhi-Tezhi and 300MW of coal-fired power from Maamba Collieries. Delays to these two projects are a key reason for the current energy shortages in Zambia. Both were planned to be online in 2014, but have been delayed due to financing issues and the slow completion of powerlines to connect these projects to the national grid. If Itezhi-Tezhi and Maamba had been finished on time, there would be no power supply problem this year.

Zambia’s total installed generation capacity is currently just over 2,200W and will grow to over 2,600MW once these new schemes are connected by 2016. Other new projects are at various pre-development stages, but timeframes continue to drift and financing requirements cast uncertainty over further projects. For instance the 750MW Kafue Gorge lower hydro project would greatly increase power supply availability in Zambia in perhaps the 2020 timeframe, but financing for this $2-billion project is not yet secured. There is, as an illustration, a proposal for a 600MW solar power project currently, though this would, as the US Energy Administration notes in its chart, below, an expensive (and inconsistent) option, especially for a country with an abundance of hydro and coal.

Cost of Electricity for New-Build Power Plants

plant type average tariff

coal-fired 9.5
gas-fired 7.5
nuclear 9.5
biomass 10.1
wind 7.4
wind (offshore) 19.7
solar pv 12.5
solar thermal 24.0
hydroelectric 8.4
geothermal 4.8

Zesco used more water than they were supposed to
Kariba has been used to meet this growing demand, requiring more water to drive the turbines, pushing the volume of water use for generation to levels unsustainable by regular annual rainfall and inflows. Both Zesco and ZPC have been using more water than they are supposed to during 2015.

Zesco has been generating a lot more electricity at Kariba than in previous years

Following the completion of the 360MW Kariba North Bank Expansion project in 2013/2014, Zesco has been generating a lot more electricity at Kariba than in previous years. The new turbines are being run much more than they were originally intended to. It seems that Zesco has been operating the intended peaking units much more than the planned three to four hours a day. This means they’ve needed to use more water, resulting in low reservoir level.

As a result, ZRA reduced the water allocations for Zesco and ZPC by 12% in March 2015. Instead of reducing their water use, both Zesco and ZPC substantially increased the amount of water used. Between March and June 2015, Zesco overused its water allocation by 39%, while ZPC overused by 16%. If the utilities complied with the allocations from ZRA, there would have been some load-shedding required beginning in March this year, but it would have been minor in comparison with current cuts. This would also have provided more time to source electricity imports and pursue other mitigation strategies prior to the situation becoming a crisis.

Some of the additional power generated from the overuse of the new 2x180MW turbines has been used to meet the growing electricity demand within Zambia. There has been speculation that extra power generated is being exported, a situation not helped by Zesco’s unwillingness to publish daily statistics on power production, and its imports and exports.

So just how serious is the current situation?

It has been widely reported that water will run out at Kariba in October. In fact, this refers to the timing when Zesco is likely to reach 100% of its 2015 water allocation. This is not the moment, however, when the Kariba reservoir levels would physically reach the minimum operating level and thus force the turbines to be shut down. There will be enough water for Zesco to continue operating its power plant at Kariba beyond October; it will just have to exceed its total allocation from ZRA for the year (as it has done every month of 2015 thus far). At current generation levels, by end of 2015, Kariba would potentially reach a low point of 477 metres, which is 1.5 metres above the minimum operating level. At this level, there would still be about seven billion cubic metres of water in Kariba available for generation, or around 10% of the ‘live capacity’ of the reservoir. Assuming rains in the catchment arrive at the normal time, this would be the minimum drawdown level, and allow Zambia to make it through without more severe load-shedding.


It’s a difficult juggling act. The impact of a shortage of power on business would be devastating to Zambia’s economy. Should, for example, the power be cut by one-third (or 115MW) to the country’s largest copper producer, First Quantum, as many as 500 jobs and as much as $140-million in annual government income would be at risk. According to the Extractive Industries Transparency Initiative, in 2013 Zambia’s mining sector contributed 68% of export revenue, 30% of government revenue and 9% of gross domestic product. One mine, First Quantum’s Kansanshi, alone contributed 27% of all revenue from mining.

In the short-term this demands keeping the lights on, in spite of the risk of drawing down the level in Kariba, not ideal of course if there are delays to the seasonal rains, or if the work on the new power plants at Itezhi-Tezhi and Maamba are further delayed. But between increasing imports from the Southern African Power Pool and conservation through load-shedding, Zambia should manage to get through the worst.

In the longer-term, a solution to Zambia’s power woes stresses both the importance of water management at Kariba on the one hand; and the imperative of continuing to grow power supplies, including by soliciting private capital. The same rule applies across the region. Indeed, Zambia, like South Africa, is not alone in confronting, simultaneously, governance and growth in dealing with its electricity problems.

for all its abundant natural resources, Zambia’s potential has not been realised

The real emergency over Kariba has less to do with undermining its basalt foundations but with the destabilising of economic growth caused by cutting off its electrical supply. Zambia’s overall problem is that, in the Queen Mother’s words, for all its abundant natural resources, its potential has not been realised. Switching off Kariba would simply confirm this status and the reasons behind it.

By Dr Greg Mills
Head of the Johannesburg-based Brenthurst Foundation
Source:Daily Maverick


  1. When you read this piece, you get the impression that this drought story is fake. It’s not about drought in it’s literal sense. The possible scenario here is that the new bigger turbines require vast amounts of water to run or to produce the same amount of power as the previous ones. That explains why Zesco has almost exhausted share allocated to it by ZRA. Yes the level of water in Kariba has dropped, not because of drought, but because the power utility has used vast amounts of water. Period

    • @The Chosen One, I knew all along when the story of the dam wall problems first surfaced ahead of the rains story that has been over-hyped for political reasons. It is amazing that the incompetence and dirt surrounding the completion of other power plants was swept under a very worn out carpet that most people still failed to see through. This is a good account of the real story on the ground. I have been trying to tell bloggers this at the expense of blogging sanity (there are more abusers than bloggers on most blogosphere arenas anyway)

  2. It shows you how Kariba has been poorly managed. Zambia is importing power from Mozambique/Cabora Bassa which is downstream to Kariba. Its like you kaka & tunda & mina & shula in a river and u go to your neighbour downstream to ask for water to drink. Mxxxxm!!!!!

    News of drought/El-Nino was announced late last year. Even Kuomboka was not held this year bcoz of low waters. But Zesco continued operating at full capacity thereby draining the dam.

    • @ Malema, tekanya, yes kariba has been mismanaged by operating two extra turbines off peak BUT don’t forget that the kafue and luangwa rivers discharge into the zambezi after the kariba dam BUT BEFORE cabora bossa. So the Mozambican lake receives more water than Kariba. Check your geography or maps.

  3. This is the real story – “Zesco used more water than they were supposed to” !!!!!

    Incompetence from incapable and ignorant PF appointed cardres. It is as simple as that.

    Now we can see the truth, and that it is very simple. Lungu and his Government cannot make excuses of drought any more. The FACT is that THEY have caused our load shedding due to negligence and poor planning.

    We cannot continue letting these incompetent F00LS blundering around in the DARK with NO PLAN. 2016 is too far away.

    They must RESIGN or get KICKED OUT NOW!

  4. In my earlier thread on Load shedding to worsen this is what I said,”@Chinena. When ZRA was set up the agreement was that Zimbabwe provides the CEO and Zambia houses the H/Q. Kariba House is in Lusaka within the town centre. Kariba North Bank had 4 machines producing about 600MW which was slightly increased when the machines were refurbished under the Power Rehabilitation Project. The station’s capacity was again increased with 2 additional machines bringing the total to about 1000 MW. ZESCO started using all 6 machines. Perhaps Zesco did not realise the impact on the usage of water using 6 MACHINES and was not aware of the IMPEDING DROUGHT. The water is shared equally between Zambia and Zimbabwe. The impact is less on Zimbabwe because it did not extend its Power Station (600MW) Water…

  5. This is the problem Zambian engineers face. When I said the power crisis has been caused by using 6 machines I was not believed.The additional 2 machines were to be used for only 4 hours for peaking purpose. But now the white man has said the same thing and he will be believed.

    • You were not the only one saying this I and others also made mention to this, however this Dr Mills is a real doctor not a Honorary one and has written a very well written answer to the issue so why didn’t Zesco tell us the truth in the beginning and they need real engineers like yourself to assist them, you may be retired but your country needs you, What we don’t need is this racism rant about whites and blacks, just get on with getting Zambia getting the lights back on.

  6. The proposal for a 600MW solar power project according to the US Energy Administration, will be an expensive option, especially for a country with an abundance of hydro and coal. If we want to improve our energy mix coal thermal power stations are the option. Countries that have produced the highest amount of energy-related CO2 from 1890 to 2014 are the USA and the Western World for their industrialization. Countries that will produce the highest number of energy-related CO2 from 2015 to 2040 are China, the USA and India. Africa’s contribution and Zambia’s in particular is negligible.

    • You are absolutely right regarding our low level of CO2 pollution and the need to focus on balancing our electric power energy sources with thermal power stations . You get the sense that the people in Government are looking for quick fixes and there is this misguided conception that solar energy will fix our power problems. Solar energy is good as part of the energy mix ,but for your base load and frequency control you still need hydro, thermal or nuclear power.
      This crisis required that Government with the help of EIZ should have constituted a think tank ( RTD as member) to help government navigate through it. Currently you have low ranking officers in the power utility and government making all sorts of misguided statements.

  7. And what about the same problem being experienced in South Africa, Botswana, Zimbabwe, Namibia and Angola, have their Utilities also misused the water allocation required for the generation?
    Its absolutely amazing that the article writer has deliberately ignore the issue of lower tariff and its implication on new power generation investments, does this then obviously point to the fact the that VITAL material information is withheld?
    The truth is, last year Zambia recorded low rainfall on average and of course the country is dynamic (economically) been growing hence more demand for power. Is it a surprise that investors have not come on board because of the low tariffs that prevail in Zambia and don’t make economic sense.
    All said and done, the truth is, the people to blame are the…

  8. Zambians themselves who have been resisting cost reflective tariffs especially the opposition and this is the truth. Get the right tariffs, energy sources are plenty and this temporal setback will never be experienced!

    • Twenty years ago there were a lot less people on the grid in southern Africa, the gov’ts of these countries never bothered to build more generating plants now we have a crisis, in our own country Zesco has been mandated to generate power for the nation if they can’t let the private sector step in just like we have done with the cell phone operators. the other big issue is the road system now we have thousand of cars on our roads compared to 20 years ago or the water shortage in Lusaka

  9. In case Lungu and his PF have failed to read this the first time around, PLEASE RE-READ this here!

    COST of Electricity for New-Build Power Plants

    plant type – average tariff UScents/kwh
    coal-fired 9.5
    gas-fired 7.5
    nuclear 9.5
    biomass 10.1
    wind 7.4
    wind (offshore) 19.7
    solar photo voltaic 12.5
    solar thermal 24.0
    hydroelectric 8.4
    geothermal 4.8

    Out of the options that Zambia has (coal-fired, solar photo voltaic, solar thermal and hydroelectric) Lungu is now advocating THE MOST EXPENSIVE OPTIONS!!!!

    This Eurobond money has deranged this man. The kaloba will HAVE TO BE PAID BACK! WITH INTEREST!

    Just complete Batoka Gorge and do not throw away Zambias future just to get elected in 2016!

    • Just build nuclear power stations like the in Capetown then no water shortages will stop power production, USA, CANADA, INDIA, Japan ,KOREA , EUROPE to name a few all have them, only 3 have leaked in 50 yrs and those were because of being built in a earth quake zone, or poor maintenance . if SA can do it so can Zambia . Namibia has the Uranium .

    • realist the article does not indicate how long it will take to build each of those power supply options. My guess is that you can put up a solar plant in the quickest possible time. Since you are based out side Zambia I am sure you can wait for a Hydro project to be completed in 5 years but for us running small companies in Zambia we want the problems sorted out within the next six months.

    • Ken there have been more than three serious nuclear accidents, I will name a few; Fukushima (Japan) which cast doubt on whether even an advanced economy like Japan can master nuclear safety. in 1979 there was a nuclear disaster at Three Mile Island (USA) total cost US$ 2.4 billion. 1986 Chernobyl (Russia). 21/01/2002 Mache(France) total cost US$ 102M. 27/12/1999 Blayais (France) total cost US$ 55 M. 4/05/1987 Kalpakkam(India) total cost US$300 M. 02/02/1995 Kota, Rajasthan(India) total cost US$280 M. 22/04/1975 Browns Ferry Alabama(USA) total cost US$ 240 M. 02/09/1996 Crystal River, Florida(USA) total cost US$ 384 M. Could give you more.

  10. We have been saying that this load shedding is nothing to do with draughts, other wise Vic falls which poures into kariba dam should be dry and caborabasa down stream should be cutting supplies which it is not. It is either PF are ignorant to keep repeating the rainfall story or they think Zambians are all dull.

    • These machines use a lot of water and hence the decision to construct the kariba dam to store water to run these machines. The water you are seeing at Victoria Falls is not sufficient to run these machines. Because the water that is coming into the lake is less than the water these machines are using this has resulted in the lake being depleted and eventually if this not controlled the Lake will be completely drained.. The Victoria Falls Power Station at the foot of the Falls uses the water that is in the river and is called a run-of-the-river plant and the disadvantage is that power generated is affected by the available water flow.

  11. Good write up. Solar plants are initially very expensive but very cheap later. At no time are going to experience solar shortage. After all there is global warming.
    Depending only on Southern Province for HEP is illogical. Explore other areas without enough perennial water flows.
    Zambia is endowed with so much natural resources including human. Stop politicking and channel the resources where they are most needed not in few people’s pockets.

    • solar does not use heat, it uses light waves in particular infra red to excite the electron from their valence band into the conduction band. in so doing free electrons are generated in the conduction line of the material and hence can move in any particular direction depending on the electric field. So olo kupye bwanji, it does not matter. what we need are particular wavelengths of light capable of knocking those electrons into the conduction band. Global warming has no direct influence on the efficiency of PVCs.

  12. Suggestion on saving money.
    1. Stop all bye-elections up to 2016 general elections forthwith
    2. Stop funding some Ministerial Hq for three months
    3. Reduce VIP trips locally and abroad
    4. Tighten forex controls- our country is very vulnerable to monetary controls.
    5. Stop externalising funds (shoprite, Sugar, mines) for 6 months
    6. Build nation from local resources.
    Given for free

  13. Good piece of work submitted here. The level of intellect among some bloggers is great…really amazing and one would surely think if all these brains were brought together their carriers motivated well, we would find solutions to the challenges our ‘great country with enormous potential’ is confronting. The problem is with our engineers at ZESCO. Senior Engineer RTD uli mukali mudala, you were well educated not these engineers at ZESCO balenyanga chabe ama hule ba fi coulour.

  14. Bwalya Chileshe
    If we stop VIP travels what will our self proclaimed “Mother of the nation” be doing as a hobby?Dont forget Tasila and her fashion parades.Namashina fye.Wishy ati “Chagwa” umwana ati “Tasila”.My Eastern brothers also.

  15. I think we will find that all the money spent on the new generators $500 million plus will have been a waeste unless we have climate changes oposite to what scientists are predicting ie increased rainfalls. You mean the whole of Zesco did not know that the capacity of the new turbines does not match the region’s rainfall patterns?? It is that they knew but corruption won the day in form of 10% inducement to pipo in PF. They were hoping the other projects will have kicked in by now and no one will notice the unsuitable order. Same thing at how they are over charging the country with the most expensive roads in the world. No one is accoutable in PF and they all have to be worried, alot of them will be camping outside the courts when we have a change of GRZ.

  16. What I got from this. The Kariba was completed in four years and officially opened in 1960. In “FOUR” years. Modern day green friendly hydro power plants can be completed in that time and have a higher production low maintenance bill. Shaking my head in disbelief at our Zambian engineers.

  17. According to the information,why not drilling some boreholes and start drawing some water from underground to keep the dam maybe somewhere around 10 meters above the operating level? The report says,by the end of this year water level would fall to about 477 meters and this will leave a space of about 1.5 meters above the operating level. The suggestion is,let us drill boreholes and start refilling the dam for our own good.

  18. Mwanza
    That is the thickest comment yet.
    1. Boreholes use electricity.
    2. Pipe it to Kariba?
    3. All the boreholes combined would provide only enough water for a day.
    Etc etc.
    The mind boggles. Go to school.

  19. Very interesting blog…some comments are very intelligent and inspiring while others are….dumb, not inspiring!
    Maybe if the issue of tariffs is sorted out, even the issue of PPAs(power Purchase Agreements),which Zesco is unwilling to offer. For example, my company is sitting on over USD300billion for such projects (energy/power generation) since 2012, but the government and Zesco have regularly refused to budge.
    This money is available even now!as long as Tariffs and issue us PPAs we will do it!

  20. My first time i have found well meaning Zambians who are able to reason and tabulate issues without insults and shallow minds. Am honoured and looking forward to learn more. Keep it up gentlemenp. We need people like you if we’re to develop our mother Zambia.

  21. In the far future, it will be possible to reuse the water coming down from the turbines, and pumping it back on to the dam above, using the very power generated by the falling water. Dream, but this is what the future should be.

  22. There is no excuse to the power crisis in that region…just root out all the stupidity to maintain the lights on…There are countries without massive water resources but yhey have power throughout the year….

  23. Just be all careful when you issue some offending comments. There is no water mismanagement per se, but the demand for electricity is such that ZRA must turbine water as much as possible, both countries having not much of other reserves. It is also a fact that climate change has drastically decreased the rainfall in the catchment basin resulting in low level of water in the Kariba reservoir. Below a certain level, the hydropower plants cannot be efficiently operated and must be switched of. this is a pure technical constraint and not mismanagement.
    Being involved in the Kariba Dam Rehabilitation Project as a technical advisor to one of the international funders of the project since 2013, I realise how much wrong information is disseminated by incompetent people and adventurous media on…

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