Where the Rio São Francisco flows into the Atlantic, the coast of Brazil disappears.
Local residents blame huge dams. About a case that could put hydropower under pressure worldwide.
The village of Saramém could hardly be more remote: a small collection of huts, vegetable gardens and fishing boats in Brazil's north-east. White speckled guinea fowl cluck among them and domestic cats roam around. Nevertheless, the future of a gigantic industry, hydropower, could be decided here.
Sitting in one of the huts, Ademilson Victor Gomes says: "After the dams blocked the river, the sea began to encroach."
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Gomes has not always lived here, five kilometers from the mouth of the Rio São Francisco. He used to live in the village of Cabeço at the head of the delta.
In Brazil, the river is often called Velho Chico, Old Francis. After thousands of kilometers, it flows into the Atlantic here. In the delta, the river opens up and becomes kilometers wide.
Tourists love its picturesque scenery.
And people like Gomes appreciate its abundance of fish.
The Velho Chico seems unstoppable, indomitable and unchangeable, yet it is losing its shape. The ocean is eating away at the delta and the São Francisco is retreating. Since 1984, an amount of land larger than eight square kilometers has fallen to the water, as a data research by the SZ shows.
As he remembers the end of his homeland, the otherwise calm Gomes becomes animated, his voice loud: "The river began to weaken. The sea came and came and came! Closer and closer! The place disappeared. The sea sank Cabeço! It left nothing for anyone."
The riverbank at his new place of residence is already crumbling. The dams, which Gomes has never seen, are to blame. They had held back sediments so that Cabeço eroded along with Gomes' life. Satellite images show how much the land has retreated since 1984.
Gomes and other residents of the former village are therefore taking legal action against the dam operator. If the courts decide that hydropower is indeed to blame, it could shake the industry.
To find out whether this is the case, you have to travel six hundred kilometers inland from the delta: A huge structure rises out of the barren expanse of the Sertão, a hot savannah interspersed with thorny plants.
This is the Sobradinho rockfill dam, six kilometers long, 41 meters high and covered with rubble.
On the upstream side, endless masses of water wind around entire mountains and disappear behind the horizon.
The federal state of Berlin could easily be submerged four times in the Sobradinho reservoir. Man has created a sea in the middle of the desert.
And with it a problem: sedimentation. Instead of being washed into the delta, mud, sand and debris end up in the Sobradinho and in the cascade of subsequent dams — Paulo Afonso, Luiz Gonzaga and Xingó.
So do these dams have an expiry date, because at some point they will be full of mud and sand instead of water? And are they the reason why entire villages are disappearing in the river delta?
The answers to these questions lie at the bottom of the Sobradinho. On its surface, conditions sometimes resemble those in the high seas. "It's difficult to navigate in the center of the lake," says Alfredo Ribeiro Neto, an expert in water resources at the Federal University of Pernambuco. "The wind is very strong and the boat we used to take the measurements was therefore not stable. Yet it was the largest in the region."
Neto and a colleague surveyed the bottom of Lake Sobradinho in 2009. To do this, they cruised across the water for days, constantly listening for the echo of the sound waves that they transmitted from their boat using a special device. At the bottom, these reflected back towards the surface. The longer the signals took to return, the deeper the seabed. The researchers were able to create an underwater height profile from the time difference. This is called bathymetry.
The scientists compared the data obtained with old but inaccurate elevation data before the former shore areas were flooded.
Their result: 3.33 cubic kilometers of the lake had already silted up with sediment. That corresponds to the volume of Munich's Allianz Arena — times a thousand.
Since the study, five hundred more Bavarian stadiums must have ended up at the bottom of the Sobradinho. There is a tendency for even more, as the massive expansion of monoculture agriculture in Brazil's interior compared to 2009 means that significantly more sediment enters the Velho Chico today than at the time of Neto's study.
According to the study, the lake would have disappeared after 274 years at the latest. That sounds like there is still time. But it is less than half of the previous estimate, which was based on sediment concentration and current data. It is also outdated. "It would be good if Eletrobras would give us an insight into their data," says Neto. That way, the actual service life could finally be recorded. Eletrobras is the company that operates all of the hydroelectric power plants on the Rio São Francisco via a subcontractor. Neto's study was registered by the company, but its results were ignored. Nothing has changed in the management of the reservoir and sediments.
In fact, operators in Brazil have had to measure the accumulation of sediment in their lakes since 2010. The results must be publicly available — Eletrobras should therefore be able to provide information. But spokespeople refer sometimes to internal, sometimes to external bodies, dozens of emails and countless phone calls are not answered.
Behind closed doors, an external consultant from Eletrobras explains that the company will never disclose the lifespan of its lakes due to the ongoing privatization process:
This is because the lifetime of the lakes defines the lifetime of the hydropower plants and thus the market value of the company.
In short, if too much sand falls to the bottom of the reservoirs, Eletrobras' share price will also fall.
In an office of the national electricity agency in the capital Brasilía, advice is finally available. Oswaldo Acosta is a specialist in energy services and was able to view bathymetries from Eletrobras — not historical ones, but fairly recent ones that the company had to create thanks to new legislation. "In some cases, we have already been able to identify that the amount of sediment is extremely high," says Acosta.
However, Acosta still needs more measurements to derive trends for sedimentation. Old bathymetries do not exist or, like Neto's, are ignored for apparently methodological reasons. Acosta and his small team are therefore unable to say how drastically the space in Brazil's lakes is shrinking.
Acosta has also carried out research on the Velho Chico delta. "A colleague identified sediment movements using radioactive tracers. In a joint study, he showed that these are deposited in the São Francisco reservoirs in particular." That was in 2008, and there were regular follow-up studies. This did nothing to change the management of the reservoirs or the advance of the sea in the delta.
Gomes' son Benito loads into his wooden boat. His mother, Valdeci, is also there. The senior citizen helps push the boat.
After a bit of driving, she sets down on the last sandbank of the delta, between tree skeletons that have withered in the salt water and sun. The view from afar is enough for her.
On the open sea, it juts out of the ocean at an angle: the lighthouse. Three meters below the boat now lie the remains of Cabeço's green palm trees, the church and dozens of houses.
Benito skillfully manoeuvres around the lighthouse, which has now been eaten away by rust and lies in the middle of the sea.
Soon, all visible remnants of Cabeço will have disappeared along with the lighthouse. However, the legal memory of Cabeço could change the whole of Brazil. "It takes time, it's hard work, it's complicated. But in the end, we are confident that we will obtain compensation for the environment, the people or their heirs," says José Luiz Jaborandy Rodrigues Filho. He is a lawyer specializing in environmental proceedings and is representing the villagers who are taking legal action against a subcontractor of Eletrobras.
Negotiations have been going on since 2002. But it was not until 2017 that a commission of experts presented a report of more than 1,500 pages. Two verdicts in the tripartite proceedings were handed down in Cabeço's favor at the lowest level in 2022. "The judge recognized what the experts recognized: The causal link between the dams and the reduction in sediment flow to the estuary," says Filho. And thus the downfall of Cabeço.
Around 20 million euros in damages have been awarded to the plaintiff residents of Cabeço, but the amount can still change in all directions. This is because the verdicts so far mean nothing. "Cases of this importance and complexity end up in the Supreme Court," says Filho. Gomes and Valdeci may never know the final verdict. Eletrobras' subcontractor does not want to comment on the events, citing the ongoing proceedings.
"What is happening here is an important precedent," says Filho. With more than 110 gigawatts and myriad reservoirs, Brazil is the world's second-largest hydropower producer after China. A ruling could have repercussions not only domestically, but also in international jurisdiction: Will operators have to pay for damage that builds up over decades? The answer to this question will probably not help Gomes. "Cabeço," he sighs, "was a good place."
Text, photos and videos: Tobias Landwehr. Infographics: Jonas Jetzig. Editing: Christoph von Eichhorn. Digital storytelling: Elisa von Grafenstein. Video editing: Luca Maria Riedel, Elisa von Grafenstein. Digital design, teaser image: Isabel Kronenberger. Art direction: Lina Moreno.