A few days ago a short article was published by the Lusakatimes. The level of interest has encouraged me to expand on my thoughts on this issue. Loadshedding has become normal in Zambia for some years now. Zambians have become used to it, and anyway, what can the average person do about it? The answer here is to apply some thought! SERIOUS THOUGHT. Aside from the frivolous suggestions that have been proposed such as filling the lake up with buckets or urinating in it to raise the level!

To be relevant, a basic understanding of how the current system operates is important, and once that has been achieved solutions start seeming to be obvious.
Several people commented on the idea of my last article, and in response to those comments I would like to clarify that the diversion I suggested should not be full time. As there is no large scale storage capacity beyond the point of abstraction on the Kafue river, and Kariba has massive, presently unused, storage capacity, it can profitably be used to increase overall water storage when there are exceptionally large floods! The 70% mentioned by Kasolo Lubembas comment will still be maintained by the power generation at the Kafue Gorge.

The new project at Kafue Gorge Lower will not place any extra demands on the flow of the river at that point as it is what is known as a run-of-the- river facility. The same idea as Batoka Gorge project now under consideration. These systems just use an additional drop of exactly the same water! This suggestion is not to divert the main flow, but only to use the storage capacity of Lake Kariba to capture excessive flows such as when there is flooding in very wet years.
As a fish farmer, water management and an understanding of environmental flows and the effects of diversions on aquatic life are subjects I am familiar with. The simple fact is that the days of natural flows are long gone, on both the Middle Zambezi and the Kafue rivers, as their flows are already now manipulated for power production.

Interestingly, most people seem to think a canal would have to be constructed ALL THE WAY to Kariba. This is not so. A very short one, just from the Kafue river to an area lower than the river is all that is required. After that the water will make its own way into the lake. This would probably be only 15 Km or so, but I leave that to the engineers to determine precisely.

How much would it cost?

Obviously cutting a canal (or a tunnel) through rock is an expensive business. But as a country with vast mining experience, we have the technology and the human resources readily available to complete this task. And many of those miners on the Copperbelt are currently out of work. Can we not use their skills here? Additionally, a canal like this could also be used for other purposes. This could offset much of the cost of construction and make it a very profitable investment. Water could be used for irrigation in one of the driest areas in Zambia, guaranteeing successful crops (two crops a year!). Possible irrigation areas are shown below, and it would work on gravity flow, saving Zesco power that is in such short supply, and saving costs charges for pumping water as well!

Another comment by Spaka like lilo mentioned Kariba may not be able to cope with the extra water.
But currently nearly US$ 300 million is being spent on refurbishing Kariba! Nevertheless, let us look at this problem. For those that are aware of the history of Kariba, you will know that when Kariba was designed it was planned with FOUR spill gates. Two more were added as an afterthought, due to exceptional river flows. Opening them ALL AT ONCE is the reason the erosion of the plunge pool has happened. Kariba was not designed for this.
In any case, there is a SERIOUS fundamental flaw in the design of the dam. That flaw is that the overflow control system and the dam wall are combined into one and the same structure!

Any sensible engineer would have separated these functions such as in the Unites States on the Hoover Dam, shown below, and most other dams in the world. On these, the spillway is completely divorced from the dam itself. Having a dam that eats away at its own foundations is really not a very good idea!

A separate spillway has numerous advantages, as the recent crises on the Oroville dam have demonstrated very visibly. If that dam had a spillway on the actual dam wall, a catastrophe would have been inevitable.

So is there an intelligent alternative for Kariba?

A simple glance at the map shows that there is indeed a viable alternative. An alternate spillway that can be used in an emergency is easily possible at very little cost. The terrain is highly suited to its construction.

Safety

With the spillway function completely removed from dam wall area, there will be no more erosion of the dam wall foundations – ever. The current repairs are only a temporary fix, as they will again be subjected to erosion, and that will necessitate repairs costing us millions again at some time in the future. This will be a PERMANENT SOLUTION.

Another problem with the Kariba dam wall that is not that widely known is that the wall has actually moved since it was built! This is due to a geological formation in the foundation rocks on the south side of the dam that contains mica. This acts as a lubricant and facilitates the slipping of the rock strata, hence the wall movement. The engineers are aware of this problem, and many millions have been spent trying to stop it. Tunnels and drainage shafts have been bored in the rock, and the top of the south bank has been covered with concrete so prevent water seeping into the rock.

Water is the problem. When it is dry, there is no movement. But when it gets wet, the slippage commences again. Of course it is not possible to stop rainfall, but most of the water causing the problem is not rainfall. It is the spray that is caused by spilling water from the gates!!!! And the profiling of the plunge pool will do nothing to stop that!

Solutions

So what will an alternate spillway look like and what will it cost? Water Engineers are very familiar with these. They are known as passive systems that let the water overflow automatically when the dam reaches a preset level. One of the main reasons we have load shedding today is because, to operate Kariba safely, the amount of incoming water must be assessed and water spilled out to make space for more. In 2011, a whole years supply of water was intentionally let out of the dam! That was a mistake and the loadshedding we have had since can be directly blamed on this. So an alternate spillway will solve this problem too, and make sure Lake Kariba is always as full of water as it can possibly be.

By Adrian Piers

[Read 110 times, 1 reads today]
Loading...

26 COMMENTS

  1. Hey! Why are crying about water???? One of the effects of global warming is extreme heat,, so go solar side by side with your hydro and other small supporting power generators

    0

    0
    • This is a great article. I particularly like the idea of using a bypass that passes through what appears as very arid part of Chirundu through Simamba. With better design, this could be used for irrigation as this land is relatively flat. However, I don’t agree with a diversionary canal linking Kafue to a tributary going to Gwembe. The Munali Hills and the land behind Mazabuka are not a mere 15km or thereabouts. The real cure for Zambia’s power base load shortfall is to make more coal power stations like Maamba.

      0

      0
    • The real cure for Zambia’s power base load shortfall is to make more coal power stations like Maamba. Zambia’s carbon footprint is almost zero. We provide oxygen to the world due to lack of Industrialisation and having a very small population. Zambian coal from Gwembe Valley is excellent for thermal. We should aim for 3 or more coal power stations to provide base load power as an alternative to Hydro power. Solar power is great – during the day when they are no clouds. Power storage systems for solar are very expensive or nonexistent. Solar is great for mini grids or single households, and not for industrial customers – so far. Let’s look to coal for power source diversification.

      0

      0
    • ZAMBIA CAN NEVER BE SHORT OF WATER FOR HYDRO POWER. ZAMBIA HAS EVER BEEN LACKING ENGINEERING BRAINS AND THE POLITICAL WILL TO GO INTO SERIOUS ENGINEERING VENTURES SUCH AS EG DESIGNING THE TURBINES FOR THE HYDRO POWER STATIONS AND YET TURBINES ARE JUST A HEEP OF COPPER WIRE MINED IN ZAMBIA. PROF. CLIVE CHIRWA WANTED TO START THE BALL ROLLING ON THE ENGINEERING PATH, BUT, HE WAS FRUSTRATED BY ZAMBIAN ENGINEERS TO SAVE THEMSELVES FROM SHAME ONCE THE RAIL SYSTEM ELECTRIFICATION BECAME A REALITY. THE IDEA OF MAAKING TRAINS IN ZAMBIA WAS TOO CHALLENGING FOR ZAMBIAN ENGINEERS- HENCE, THEY HAD NO OPTION BUT TO MAKE SURE CHIRWA’S PLANS NEVER TOOK OFF.

      0

      0
  2. Good article. A large solar farm could pump spilled water back into the dam during the day and reuse it at night when solar does not produce power.

    This coukd be a form of power storage that could assist during evening peak time. I know Cabora Bassa Dam downstream would not like this..

    0

    0
    • Instead of Mickey Mouse solutions of pumped storage, Zambia should look at having more coal power stations. South Africa thrives on coal and we are even ready to import power from them. Why not use our coal along Gwembe Valley to generate more base load power supply like Maamba will be doing soon?

      0

      0
    • Maamba coal too low quality for steel production but excellent for thermal use. You are literally burning the coal to heat water in boilers when producing power. This is the best use for Zambia’s coal, nothing else.

      0

      0
  3. Adrian, this is another excellent piece to resolve national problems. Your articles have been copied and will be presented to government as ideas by one John CHANDA or Peter CHISALA or Jacob MUSENGE or Simon CHISANGA or Chishala CHUNGU or Moses MWILA!

    0

    0
    • @3 Sakala J, let those you have mentioned COPY THE IDEAS AND TAKE THEM TO GOVT. I believe NO ONE HAS PREVENTED ADRIAN PIERS FROM PUTTING THIS BRILLIANT IDEAS OPENLY TO GOVERNMENT! Even at INTERNATIONAL SYMPOSIA ORGANIZED BY RENOWNED INTERNATIONAL BODIES HIS IDEAS CAN BE PRESENTED INCLUDING TO THE AFRICAN DEVELOPMENT BANK (AfDB)WHO ARE FUNDING THE REHABILITATION OF THE DAM! Let him also SEEK AUDIENCE WITH MINISTRIES Responsible for ENERGY and WATER and as @5 Kambe has suggested HE CAN EVEN GO TO ZDA and tell THEM HE HAS A PROJECT HE WISHES TO PACKAGE ON A PPP BASIS!! A BRILLIANT IDEA CAN NOT ALWAYS FAIL TO FIND SUPPORTERS IN ALL THESE CIRCLES I HAVE MENTIONED,EVEN BEYOND!

      0

      0
    • @Bwaafya, The issue is plagiarism. Those guys must learn to acknowledge the source of the ideas. They present them as if it was their own ideas and pretend to be brilliant. May be the author needs to patent his ideas.

      0

      0
  4. Jeez! and all this time we have never thought of this? We are a disaster! What is the education for? Is it for pushing over-priced GRZ contracts?

    0

    0
  5. I honestly feel you, Adrian should arrange to personally present your obviously well researched scientifically sound solutions to state house, to the president himself. you just might be pleasantly surprised and serve your country and the rest of the citizens a big service. Maybe also try Mr Patrick Chisanga of ZDA. Im sure he will be of assistance. If you go other routes, your ideas will be rubbished. You can tell by most of the commentators IQ on this site. I await the feed back from Sakala J eagerly. Well done Adrian.

    0

    0
    • State House is the problem….there is no proactive allocated personnel to look at what other professionals advise on management of resources, policy, economy, education and now power shortages rather reactive approach….in SA there is even a presidential hotline where people are employed just to get suggestive advise from the public. In every budget speech you even hear some suggestion used sited from such a forum. Secondly is the high learning institutions pa Zed, there are a laughing stock……when do we ever hear any intellectual suggestion or discussion on media regarding problems Zambia is facing…..there existence is not such educate but help government with solutions

      0

      0
  6. Only a Qaddafi -type of President have spines to go for such grand schemes. For some reason, democrats grumble all day about the impossibilities of bringing about such an eighth wonder of the wonder. That’s democracy for you – play ground arguments that would have prevented Columbus from discovering the world. If Super Ken had lived in an era of the social media, Tazara and Tazama would not have seen day light. Discouraging postings would have stung KK’s nerves. You’re one in a million Adrian, the world needs your kind to move forward. Please do post pdf formats of your visions of Zambia’s Hydro Schemes. Zikomo.

    0

    0
  7. I have a copy of Gadaffi’s Green Book. It is an excellent masterpiece which if read by anyone with a brain would understand that none of Zambia’s problems requires nuclear energy or foreigners to manhandle us into development.
    Adrian, what is your private email address? You have a great mind and sadly, our leadership is so dull that none of them apprecate anything other than bribes. Wait and see what ideas Lungu will bring from his dodgy trip to Israel! Do not hold your breath for anything better than dodgy solutions !

    0

    0
  8. Nice article Adrian and thanks for acknowledging comments from bloggers.

    Also to be considered is the multi billion dollar dam being proposed to be built in Congo that will have enough energy to supply the whole southern africa.

    Not saying we should not be energy sufficient but if other uses the the cannel can be built into it like a series of dams for irrigation, fisheries and leisure then the costs can be justified.

    0

    0
    • ”Nice article Adrian and thanks for acknowledging comments from bloggers”

      How does it feel to be acknowledged for making a positive and thought provoking idea for once? See, some of you people are intelligent and can make such meaningful contributions but instead you would rather waste time and vent your anger on useless political issues!

      For once just try hard not to be like NEZ the cadre, I know how you feel about the loss in 2016! It’s gone!

      To Adrian, please engage the Minister Hon. Lloyd Mulenga Kaziya, MP, the Minister of Water Development Sanitation and Environmental Protection. He is a very good man with alot of humility and has time for all who go to him with brilliant ideas..
      I admire your brilliant brains, I must admit! Another well researched article!

      0

      0
    • Yes you are right, since Sata died (MHSRIP), Zambia is only short of a leader in OPPOSITION!

      0

      0
  9. Is it possible to have divergence gates on the Kafue, close to Kafue town which can help diverge controlled amounts of water to the Kariba dam accordingly?

    0

    0
  10. This is a very educative and interesting article by Adrian Piers. My only hope is that our Minister of Energy and his Permanent Secretary are also reading these articles and then eventually use this valuable data to initiate the feasibility studies and then implement these innovative ideas that will benefit Zambia for many years to come. By the way this knowledge is being provided by Adrian Piers FREE OF CHARGE – IN THE DEVELOPED WORLD YOU WOULD NEED TO HIRE A CONSULTANT AT VERY HIGH PRICE TO COME UP WITH SIMILAR DATA BEING GIVEN HERE ON A SILVER PLATTER. I hope the Permanent Secretary is a technocrat who can digest this article and start moving forward; as for the Minister of energy we can forgive him because he is just a political appointee and operates as a rubber stamp at the helm of…

    0

    0
  11. Interesting and mind provoking article. Some of the ideas which sound ingenious have inherent flaws.

    1. The article states that kafue gorge lower and upper are run of the river power stations. This is not true. Kafue gorge power station has a capacity of 990(6 x 165MW machines).Its main reseivoir is itezhi dam and it hassmaler reseivoir at kafue ten times smaller than Itezhi tezhi. Kafue gorge lower which is currently being constructed has a reseivoir which will be about 4 km upstream of the power plant. Station yield is expected to be 750MW. Besides the kafue river basin provides water to zambia sugar and theurban population of lusaka. The canal idea is might affect supply to all these competing needs.

    2. The idea of constructing a new spill way canal or gates or system is…

    0

    0
  12. This is a very good article. Thank you for sharing and i wish this option could be explored. In addition there are quite a number of hydro stations like Chishimba, Lusiwasi which could also contribute to power generation if upgraded. There is also Lumangwe falls which upto now you can’t understand why it is still undeveloped.

    0

    0

Comments are closed.