Kariba Dam and Zambezi River catchment problems. Is it Global warming or mismanagement of the environment?

Lake Kariba - another damned manmade disaster

By Rodger Savory - 

Kariba is a dam which is in failing to meet it’s designed parameters for hydro power generation as originally envisaged by my grandfather when he first did the calculations for the dam and surveyed the locations for the dam wall.

Jimmy Savory as he was known was later the head of the Irrigation Department for the Southern Rhodesian government however during WW11 he was hired by Jeffares and Co. to do the “backbone traverse” which was basically 130 miles upstream from Kariba gorge near Binga. He and a crew of workers made all their own roads and basically had to explore the entire area and as he says in his book it became obvious, “and showed for the first time that an immense lake would be created with an excessively high wall” he goes on to state that during the 4 months he spent doing this job he, “traversed, check levelled and chained some 164 miles of county. It had become clear that a dam built at Kariba would create an immense lake, and in fact when Kariba was built later on, the lake created the largest artificial body of water in the world.”

He goes on to say, “nothing much happened with the Kariba dam scheme until about 1953-4” 

He goes on to say, “there was a considerable body of opinion in the Northern territory in favour of a scheme on the Kafue river and it was being pushed vigorously. Gradually a real battle between the two schemes developed” He goes on to say and this is very important, “We were of course in favour of the Kariba scheme, and fortunately we were in a very strong position because our department, i.e., the Irrigation Department of the Southern Rhodesia Government, had for many years taken all available recordings both on the Zambezi river and the Kafue river.” He goes on to say, “So every time the Kafue protagonists came up with their scheme we had all the information on availability of water, etc., and could shoot it down.”

Based on my grandfather along with 3 other engineers had crunched the numbers and when he told Prime Minister, Mr. Garfield Todd the results Mr. Todd then took the matter up with the Federal Prime Minister and that is why Kariba was built.

Now during the 10 years between when grandpa figured out how big Kariba would be and the conversation with the Prime Minister he had been keeping very accurate figures and measuring the water. So let me describe what the lands in the catchment looked like in those days.

Firstly they were wild and populated by small groups of villagers mainly along the river systems. Gardens were grown with the water from the rivers, fish were caught and drums were beaten at night to keep elephants out the gardens and lions away from villages.

The policy of burning grass in the dry season had not started to be implemented yet. That started in 1954.

The catchment had huge populations of buffalo and elephant and all the rest of the game species. The ground was always covered with grass and leaves. Always, there just was never any bare soil except for at salt licks. Every photo in my grandfathers album the camps are always on land with trampled grass on the ground.

So based on the 10 years of actual water flowing in the rivers the decision was made to build the lake. No one could ever imaging how the land management would change over the next 70 years. No one could imagine just how different the rivers would flow.

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Ok now let us jump forward several decades.

In 1995 – 6 I was hired by MANO Consulting to do research in Western Province on the impact of borehole on rural women. We traveled all over the catchment. I had 3 young research students from UNZA with me. While we were traveling to the boreholes each time we were 10 km from a borehole I would say, “ok guys 10 km to go” the students could not understand how I always knew. Finally I explained that we had been traveling through thick forest and suddenly we ran out of trees. I explained that the furthest from water someone will walk to gather firewood is 10 km out and 10 km home, also the furthest cattle and goats will graze away from the kraal is 10 km out and 10 km home. So after 17 years of boreholes being put all over Western Province to create clean drinking water for people who used to migrate out from the Zambezi and then back to the Zambezi as their dambos dried up these people how lived all the time at the boreholes and the land could no longer support them. The trees and the grass were gone in perfect 10 km radius deserts around each borehole. The people had had more children, so basically there were more mouths to feed on less resources, a sad state of affairs.

Then in 2001 - 2 I returned to the area and did forest straight line transects and did over 6400 km of straight line transects to measure the larger trees still left. What I found was truly shocking. Well known watering holes which used to be deep enough for buffalo and elephant to wallow in were now completely silted up and dry. The annual burning had decimated the huge wildlife populations which once roamed the area. There were gaps of meters between grass plants with 99% bare soil. There was no mulch under the trees and worst of all in the entire survey not 1 single newly germinated mukwa or rosewood tree was found to have germinated, not 1. So the entire forest is dying out.

Furthermore my camp was on the banks of the Zambezi near Mazeba Bay and whilst fishing one day an very polite old gentleman came across the river and we had a long chat. He told me he used to be the Superintendent of Schools in Livingstone (Zambia) and that when in this position he was the one who stopped the town of Livingstone having it’s name changed. I cannot remember his name. Anyway while speaking to him he said something which really shocked me. He stated that when he was a boy the river in the gorge below the Ngonye Falls near Sioma had always stayed high for 6 months after the rains ended but that now only 1 month after the rains ended the river returned to the low position.

This got me thinking and connecting the dots as to why Kariba in no longer filling up.

So here is my explanation.

Research from the University of Namibia clearly shows that bare soils have 84% evaporation of precipitation whilst covered soils only have 10% evaporation of precipitation. This original study have been repeated in numerous trials.

So even if the rainfall has stayed exactly the same between 1944 and today let us do the mathematics.

Let us take the rainfall at Mongu Zambia at 939 mm per year. That is 939 litres per square meter of land. But for illustration purposes to make a point I am going to use this same figure over the entire catchment. 815,000 square kilometers or 815,000,000,000 meters squared. So we multiply the amount of precipitation which falls by the area of land and we know the total amount of rain which makes it to the ground, in this case 815,000,000,000 x 939 = 765,285,000,000,000 litres of water each year.

HOWEVER in 1944 the amount of rain that then soaked into the ground and stayed there was 765,285,000,000,000 less 10% = 688,756,500,000,000 litres this due to the totally covered soils which were maintained by vast herds of animals and saw little to no fire.

TODAY the same rainfall 765,285,000,000,000 that falls in the catchment now instead has the 84% evaporation which did not exist in 1944 – 54 when my grandfather took his measurements of the actual flow into the rivers. So the new figure is now 765,285,000,000,000 less 84% = 122,445,600,000 litres of water available from the exact same rainfall now available to flow down the rivers and into the dam.

To make this more clear 688,756,500,000,000 - 122,445,600,000 = 688,634,054,400,000 litres LESS of water now flowing into Lake Kariba today than did when the measurements and calculations were originally performed. Basically we now get 5 times less water into the lake than we are supposed to do. This would explain why the old schools Superintendent noticed the water level in the river dropping 5 months earlier than it used to drop.

Sadly the Okavango Delta is firmly in the grip of a severe drought and the annual flood waters from Angola, which bring life to the delta, have not arrived. This, combined with wide spread fires, make these some of the toughest times we have seen here in the Okavango. Courtesy Rhino Conservation Botswana

Translate this into we could get 5 more lakes for free if we worked with ALL people living in the entire catchment and taught them the importance of stopping fires 100% and learning to graze their cattle to mimic the herds of wildlife which used to exist, by planning the grazing holistically whilst making decisions to increase our forests again.

Current thought models are to tax the people of Zambia forever into the future to pay for a new lake at #Batoka this makes zero sense at all. The root cause of the problem as to why Kariba doesn’t have enough water to generate power like it used to has not been addressed so it will not go away. Why not instead use a fraction of the money to build an unneeded dam. The new dam will just end up being a silt trap dam as the bare soils and erosion get worse and worse over time. Look at the massive sand dams in Yemen if you don’t believe me. When Yemen turned to desert their dams filled with sand and are still there in the desert to learn from. We need to teach our people how to manage their lands to regenerate them to be able to feed our growing populations and turn the circles of desert back into vibrant grass and forest ecosystems which support all life, human, livestock and wildlife and the plants and fungus we all depend on.

How a very few people will benefit from the building of a new dam but millions of people will benefit from a program to fill the current dam, by creating policy and programs to encourage national uptake of regenerative agriculture in the entire catchment basin.

I suspect all politicians will be scared of what I have written and none will have the courage to make this the most important political aspect for the nation, however a true leader will understand just how vital what I am sharing is and will get his nation behind him to make the changes necessary to improve both rural and urban lives. By changing how we manage the catchment we will not need to build more dams and we will not need to have power cuts as Kariba could have water flowing into it strongly for 5 months longer than is the current status. We will see who is brave enough to adopt this into the national dialogue. The people in the Copperbelt, Harare and Johannesburg are actually dependent on the people in Southern, Western and Matabeland Provinces who they currently look at as their backwards rural cousins, and yet these cousins through their collective actions hold the solutions to all their urban sophisticated cousins in their hands.

The choice is clear the city cousins have to support their rural cousins with education, grants and outreach to change how they manage the catchments.