- Extreme droughts, human interventions and growing boat traffic are contributing to riverbank collapses that endanger riverside communities in the Brazilian Amazon.
- Four public river ports in Amazonas state have been damaged by riverbank collapses in the past decade, prompting concerns about the safety of Amazon port infrastructure.
- Brazil’s Federal Public Ministry is investigating alleged failures to prevent collapses at regional ports that connect riverside communities and provide access to essential services.
On the afternoon of Oct. 7, 2024, a section of banks along the Solimões River abruptly collapsed at the port of Manacapuru in Brazil’s Amazonas state. The resulting crater was the size of two soccer fields and as deep as 20 meters (65 feet). The collapse killed two people and shut down the port, a regional hub for moving goods and passengers about 160 kilometers (100 miles) upstream from the state capital, Manaus.
Investigations later identified an erosion process known as terras caídas — literally “fallen lands” — a natural phenomenon observed along fast-flowing rivers across the Amazon Basin. During the dry season, when water levels drop sharply, riverbanks become tall, exposed walls, particularly vulnerable at river bends, where the waters can more easily dig their base and destabilize the terrain.
At Manacapuru, however, human interventions on the riverbank contributed to the collapse. A report by Brazil’s federal geological agency, SGB, obtained by Mongabay shows that the river port was built directly on a bend of the Solimões (the name used in Brazil for the upper stretch of the Amazon River). The document states that walls and embankments further weakened the riverbank, which could no longer support its own weight amid the river’s low water level.
“We need to be more careful when choosing where to build ports along Amazonian rivers,” Elton Andretta, a geoscience researcher at SGB, told Mongabay by phone. “Brazil already has satellite imagery and other technologies to monitor Amazonian rivers and identify risks. More conscious use of riverbanks helps prevent disasters.”
Manacapuru isn’t an isolated case. Over the past 10 years, three other public river ports in Amazonas state — in the municipalities of São Paulo de Olivença, Manicoré and Itacoatiara — have also experienced structural damage from riverbank collapses, raising concerns about the safety of port infrastructure across the Brazilian Amazon.
At the end of 2024, the Federal Prosecutor’s Office, MPF, launched an investigation into alleged omissions by the National Department of Transport Infrastructure (DNIT), requesting information about inspections and preventive measures against collapses at Amazonian river ports. In an email to Mongabay, MPF said it has already received an overview of river port conditions and is reviewing the material to determine what measures and referrals are needed.
In an emailed statement to Mongabay, DNIT said it manages 48 small public river ports in the Brazilian Amazon. Known by the acronym IP4, these ports are crucial for connecting riverside communities and ensuring access to health care, education, commerce, banking services and other basic needs available in regional urban centers. In a biome where rivers remain the primary transportation routes for people and cargo, IP4 ports function much like bus stations in the rest of the country.
President Luiz Inácio Lula da Silva’s administration has allocated more than 770 million reais ($140 million) for the construction, maintenance and revitalization of Amazonian river ports, with about 390 million reais ($72 million) spent from 2023 to date. According to the DNIT, most ports remain fully operational, but budget constraints have limited efforts to repair and maintain infrastructure affected by river erosion. The agency said it is prioritizing IP4 ports classified as critical, “with a risk to safety or operational continuity.”
Waterways raise erosion risks
The collapse of an IP4 port in Itacoatiara, also in Amazonas state, on Oct. 11, 2023, highlighted another risk factor for riverbank erosion: boat traffic. According to news outlet G1, witnesses reported that a bank of the Amazon River gave way after a ship passed through the port. The vessel’s passage had generated a wave that struck the riverbank exposed by low water levels. The port remains closed, and DNIT told Mongabay it is still awaiting a technical report on the causes of the collapse.
The impact of ship waves on the banks of Amazonian rivers is concerning in light of Brazil’s plan to develop waterways as priority export corridors, aiming to create new export routes to China through the Pacific. These infrastructure projects are meant to improve logistical efficiency in northern Brazil. On Aug. 28, President Lula signed a decree adding the Madeira, Tapajós and Tocantins rivers — the first two of which are tributaries of the Amazon — to Brazil’s privatization program, paving the way for private companies to manage the waterways and carry out regular dredging and other works aimed at boosting cargo capacity and reducing transport costs.
“It’s very worrying to think about large waterways on Amazonian rivers,” Ayan Fleischmann, a geoscience researcher at the Mamirauá Institute, a research organization supported and overseen by Brazil’s Ministry of Science, Technology and Innovation, told Mongabay by phone. “The Amazon’s history with large infrastructure projects is not good for local populations. It will be necessary to ensure river management and clear rules to deal with the increase in boat traffic.”
Andretta, from SGB, said boat traffic can contribute to river erosion during the dry season and increase the risk of bank collapse. But the waves they generate can be even more harmful during floods, when the water reaches the homes of riverine communities and destabilizes their foundations, knocking over furniture and damaging appliances. “There are measures to reduce these impacts, such as signage to reduce the speed of boats,” he said.
DNIT told Mongabay it is monitoring the increase in large-vessel traffic on Amazonian rivers and has already adopted monitoring and prevention measures. “This growth brings opportunities for national logistics, but also requires care with navigation safety and port preservation,” the agency said in an email.
Threats to riverine communities
The terras caídas phenomenon also threatens riverside communities in the Brazilian Amazon, with several incidents in recent years in which houses, schools, churches and public squares were swept away by rivers. In 2023, an SGB report identified 119 areas at risk from river erosion in the state of Amazonas, threatening 29,000 people.
A study published in February 2025 assessed the risks related to river erosion in 238 riverine communities in the Mamirauá Sustainable Development Reserve, along the Solimões. The analysis showed that 26% of these communities are subject to riverbank collapses and another 18% suffer from sediment deposition, a problem that spawns kilometer-long sandbars in front of communities and can isolate them.
“We need to rethink how we respond to disasters and manage risks in the Brazilian Amazon,” said Fleischmann, from the Mamirauá Institute. “Public debate often centers on droughts and floods, which have grown more extreme and carry enormous consequences for local communities. But the Amazon region faces many other risks, including riverbank erosion.”
Disasters are surging across the Amazon, yet their impacts remain widely undercounted, according to an analysis by researchers from Brazil, Ecuador, Bolivia, Colombia and the United States. Reviewing more than 12,500 reports of storms, floods, landslides, droughts and wildfires recorded between 2013 and 2023, the team found that in a single year more than 3 million people were affected and more than 100,000 public infrastructure facilities were damaged.
“The Amazon is undergoing a process of disaster synergy, with overlapping risks that amplify one another,” Fleischmann said. “We need coordinated action across institutions to rethink how we approach the issue and to recognize these events as compound disasters.”
Banner image: The Manacapuru terminal was built on an erosion-prone riverbank along a bend of the Solimões River, where the risk of land collapse is higher, especially when human interventions alter the terrain. Image courtesy of SGB.
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Citations:
Zumak, A., Fassoni-Andrade, A. C., Pereira, H. C., Papa, F., Dos Santos Silva, P., Do Nascimento, A. C., & Fleischmann, A. S. (2025). Riverine communities in the central Amazon are largely subject to erosion and sedimentation risk. Communications Earth & Environment, 6(1). doi:10.1038/s43247-025-02058-x
Pacheco, R., Iñamagua-Uyaguari, J. P., Selaya, G., Ribeiro, S. C., Alencar, A. A., & Dávalos, L. M. (2025). Weather disasters and their underreported transboundary impacts on Amazonian communities. Environmental Research Letters, 20(12), 121005. doi:10.1088/1748-9326/ae20a7
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