Government Briefing Highlights: Addressing Uncertainties Around Rufiji Floods

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The government spokesman for the United Republic of Tanzania, Mr Mobhare Matinyi, held a press conference on Friday, April 12, 2024, to discuss the recent Rufiji floods, which affected two towns and displaced approximately 88,000 residents. During the meeting, it was highlighted that the Julius Nyerere Hydropower Plant played a role in managing the water levels and mitigating the extent of the flooding experienced in October last year.

The government would want us to believe the Julius Nyerere Hydropower Plant has spared and deferred the submersion of those swathes of land affected by the floods in October last year.

This is a distraction from the real problems the Nyerere dam has unleashed on our people and the environment. I acknowledge that the Rufiji basin is infamous for seasonal floods. Still, the dam has worsened the regularity, frequency, and intensity of the floods, reducing the affected areas to unsuitable areas for human settlement.

This discourse disputes the government’s position on the Rufiji floods, which has intentionally sidestepped the real causes while pitching a tent on the symptoms of a gigantic problem rather than addressing the real causes. This discussion will differentiate causes from effects, concluding that the construction of the Nyerere dam was a poorly designed, unsustainable project and was not a smart idea at all.

The damming of the Stiegler’s Gorge within the Selous Game Reserve was met with stiff opposition both locally and internationally, but policymakers and decision-makers opted to plug their ears with cotton and descended to erect this white elephant that has been erroneously hailed as a missing link to our energy hunger! Well, the gospel truth ought to come now out; it is not!

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Those who opposed the project raised concerns over environmental degradation, technical deficiencies, alternative viable and optimal options, and sustainability. Still, our beloved government parlayed honouring Nyerere’s earlier aspirations as the main reason to move forward to implement the much-criticised project! The decision-makers should have considered current variables before dumping more than a trillion into a project unlikely to generate the anticipated power over the long haul.

Nyerere Connection to the Project Doubted

While I concede that Nyerere toyed with erecting the then-known Stiegler’s Gorge in the same locale, Nyerere’s effort was doomed by many factors. While environmental factors were not at the top of the menu, development partners conspicuously avoided the loop.

No donor would want to be associated with a mammoth project that wiped out major towns, impoverishing the residents there and, on top of that, having a project that fails to realize her project objectives.

Construction Challenges Underestimated

The biggest killer underlying assumption in damming waters for hydroelectric power generation is silt. Soil erosion as a result of terracing cultivation bares the soil, leaving any damming of water projects in a dire situation.

As water flows to the dam, it is heavily silted. Over time, sedimentation settles on the ground, culminating in the reduction of the effective depth of the dam, rendering power generation below the design capacity.

Both Mtera and Kidatu suffered from silt, and within six years, their design’s effective depth was dangerously compromised. Their life spans outlived them, and power production was reduced. Over time, both dams have failed to live up to the hype, generating less power than projected during design.

Nyerere dam is even more precarious than the other two dams. When the volumes of water and the load of silting are taken into account, Nyerere’s dam carrying capacity is much lower than the two dams, meaning overflows of the excess water and silt will be a perennial concern as we advance to protect the facilities against structural demise. Since the dam’s functionality has temporarily wobbled, albeit still structurally sound, the costs of rectifying the problem of regular overflows will be astronomical and possibly uneconomical.

For beginners, to change tack, the dam needs to be drained and water rechanneled as it was before its filling to excavate it and deepen its effective depth. That herculean commitment will make initial project costs look like child play. Without increasing the depth to cover most of the dam area, the increased precipitation due to global warming will lead to even more devastating floods with grave damage downstream.

Also, read The Julius Nyerere Hydropower Project is Now 90% Complete While Conserving the Environment – What Should We Expect Next?

Curiously, the government spokesman alludes to one of the purposes of the Nyerere dam was to prevent floods such as those that appeared at Rufiji, and raised a specious claim that had the dam not been erected, the Rufiji floods would have begun last October. The government mouthpiece failed to grasp that the timeliness of the flood occurrence was never a major concern, but the extent of the floods was. Since he did not address the volumes of the floods between the two epochs, the whole exercise lacked substance for circumventing comparative reasoning.

Even if we allot him the benefit of the doubt that the dam has prevented the floods from hitting the affected area, he failed to comprehend that the dam brimming with water was a more serious threat for all communities downstream than the perennial rivers ever were.

The dam is storing water while the river is not. So, claiming the dam has deterred future Rufiji floods makes no sense. At the same time, in every essence, it has increased the chances of devastating floods because it stores large volumes of water carrying a higher probability of overflooding. As the precipitation increases, the dam is easily filled with vast amounts of stored water and rainwater that prompts regular gates opening to contain the situation.

Suppose this happened a few months after the dam’s inauguration. In that case, when siltation is incorporated into the equation three to four years down the road, we should expect the water-carrying capacity to be emphatically reduced. That has grave consequences for downstream human and non-human activities. It means more frequent dam draining to save it from potential structural failures. And that translates into more flooding of intensity never witnessed before!

The Designed Power Output is Just Another Pipe Dream

Every day, we are bombarded with power output to the tune of 2.15 gigawatts that may be sustained possibly within two or three years. Still, the electricity generation capacity will constrict as silt sediments the dam floor. As the silt sediments continue to wipe out the dam’s designed effective depth, power production will systematically dwindle.

By my conservative estimate, power generated at Nyerere dam will taper down to a mere third of the installed capacity within six years of water flowing into it. So, overall, from the installed capacity of 2.15 gigawatts, we should expect only a third of the total to be generated by January 2030.

This rough estimate conforms with past experiences of how the two dams of Mtera and Kidatu fared during the same duration. This Nyerere calamity is likely to fare even worse, but for estimating purposes, I shall cordon off the figure to 717 megawatts as a power supply by January 2030.

Concluding Remarks

Water damming in Tanzania has performed poorly, and future power generation efforts should digress away from these money-guzzling white elephants, which promise a lot but fall short in delivery. We need to recalibrate our energy policy to focus on natural gas and coal as the mainstay of power supply.

Let us stop to tie our power generation future to the vagaries of weather, soil erosion, under-investment and poor maintenance culture. The bad news about projects of this magnitude is that sporadic lies can carry us that far, but once you have hit the iceberg, it is difficult to parade the same lies and get away with them.

We ought to concede that the Nyerere dam is an ecological disaster waiting to happen. If we continue to bury our heads in the sand, hoping the problems will disappear, we are fooling nobody but ourselves.

We need independent assessors to piece together the issues raised in this article and let them arrive at their own independent conclusions. If these postulates are established as facts, we may need to invest more in excavations to deepen the dam depth so it may carry more water and sediments to upend overflows, prompting the opening of the gates to free the dam from man-made disasters, leading to structural collapse.

The dam is useful for water supply and will ease the water shortage in Dar es Salaam, which is a bonus in itself. However, power generation will not last long as mud will wipe out all the effective depth of the dam needed for power generation in years to come.

If there is any disservice we have done to Nyerere, it was to roil his legacy with this dam. This is the Magufuli brainchild, not Nyerere’s. Since the project is an ecological calamity waiting to unfold, tying the Magufuli legacy to it is the most sensible thing we should do. Nyerere did not build this dam, which will fail in due season.

I think we should let Magufuli own this ecological disruption since he couldn’t listen to contrarian advice against creating an ecological disaster where there was none. It is fair and sensible to call it the MAGUFULI DAM. Let’s stop from eviscerating Nyerere’s good name with the damming project gone extremely awry.

The author is a Development Administration specialist in Tanzania with over 30 years of practical experience, and has been penning down a number of articles in local printing and digital newspapers for some time now.

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