“What the collapsed land caused here in the community is that we need to move. The community used to be right in front of the river, and now we had to move to the back, farther away. We had to move our port, and we no longer have access to the river. We have to go via Igarapé [small water course] to get out to the Amazon River”.

The account of farmer Moisés Fernandes, a community leader from the Coadi community in Amazonas, shows the difficulties experienced by the riverine people in the region caused by the phenomena of erosion, also known as collapsed land, and the silting up of the local rivers.

Erosion is the wearing away of the land on riverbanks, which can cause landslides whereby the watercourse “swallows up” entire areas. Siltation, in turn, is the accumulation of sediment in a part of the river, forming banks of sand or beaches, hindering navigation and causing changes in the normal course of the waters.

Both are phenomena that have always existed in the Amazon, but human actions and climate change seem to be intensifying them. “In recent times, landslides have increased a lot here. My house was near the river and was hit, it is all cracked with the impact of the landslide”, says the resident of Coadi.

CONSEQUENCES

The result of these phenomena is that many riverside communities find themselves at varying levels of risk, either because of the danger of landslides or because of the high chances of isolation due to the difficulty of navigating the rivers during periods of drought.

A study carried out by the Instituto Mamirauá [Mamirauá Institute], in partnership with the University of Brasilia (UnB), the Federal University of the Southern and Southeastern Pará (Unifesspa) and the University of Toulouse, in France, has assessed 254 communities in the Mamirauá Sustainable Development Reserve, based in the state of Amazonas. Out of this total, fifty one communities were categorized in terms of their level of risk to the two phenomena. From these, four are at very high risk (Santa Domícia, Canariá, Boiador and Acapuri de Baixo); seven are at high risk (Barroso, Porto Braga, Punã, Ingá, São Raimundo do Panauã, Triunfo and Caburini); seven are at moderate risk; eleven are at low risk, and 22 are at very low risk.

To determine the levels, the researchers analyzed satellite images from 1986 to 2021, combining them with socio-economic information from the region, such as the distance of access to services and previous experiences with the studied phenomena.

Research performed active listening in the communities

Geographer Paula Silva, one of the researchers involved in the study, conducted around 60 interviews with residents of the communities at risk. She reports on what she heard from the riverine people of the Coadi community.

“In the satellite images, it was possible to see a very radical and abrupt change concerning the collapsed lands. It was not a slow process. The people interviewed said that it used to be a well-structured community, with streets, a health center, a school, an artesian well, a square and a port. It all cracked, everything collapsed. And over the years, the erosion has become much more intense, it is not a process that has stopped. On our last field visit, they had already deactivated the artesian well. And they went much farther into the forest,” says Paula.

The researcher also records the experience of Canariá community residents, a place currently undergoing recognition as an Indigenous Land. “According to their account, when the erosion started, they only heard the bang at night. They had to leave their homes, afraid that everything would fall down. 

After that incident, there has not been another more intense one, but there are large cracks, which are getting wider and wider. They were the thickness of a strand of hair and now they measure a handbreadth. The whole community is vulnerable,” warns the geographer.

The Caburini community, in turn, is experiencing the opposite problem: the heavy sedimentation in the area is causing the riverine people to move closer to the river, because the accumulation of sandbanks is making the watercourse more and more distant. For this reason, the population has already migrated four times in order to facilitate access to the river.
In addition to these changes, there are those who decide to leave the community, causing a migratory movement to other localities or to the urban area. “Some moved to the city because they had relatives there,” says Paula.

DROUGHT

With silting and the consequent difficulty of navigation, many communities suffer from lack of access to food and services during periods of drought in the region. “It is a huge distance to get around because of these beach formations. It becomes difficult to buy what you need or even to access health services if someone falls ill. Even going to other nearby communities going to school becomes a long distance,” emphasizes the geographer.

The scenario becomes worse with the intensification of drought periods in the Amazon, which reached record levels in 2023 and 2024, leaving many communities isolated.

STUDY

According to geographer André Zumak, one of the authors of the research at the Mamirauá Reserve, the risk assessment considered three main variables: danger, vulnerability and exposure. “Danger refers to the overall data of which communities are suffering erosion and sedimentation. As for exposure, it was defined based on socio-economic data collected by the Mamirauá Institute, which is precisely to know which communities have the largest population, certain infrastructure, a community center, even an ambulance. Our methodology multiplies the danger by vulnerability and exposure,” he explains.

Still according to Zumak, the study does not state with 100% certainty that the intensification of the phenomena has to do with climate change, as the period surveyed in the satellite images was until 2021.

“Trying to better understand this relationship is precisely a development for the next study we are conducting. But what we can see is that in the last two years, when there have been extreme droughts, there has been an increase in reported cases of these phenomena,” he comments.

Amazon estuary is affected by global warming

As for the estuary areas in the Amazon, i.e. places where the river interacts with the Atlantic Ocean waters, the impact of climate change on the phenomena of erosion and siltation is clear. “These are natural phenomena that can be aggravated by climate change. Global warming results in an increase in the surface temperature of the oceans, causing the thermal expansion of water particles and greater melting of glaciers in polar regions. As a result, there is a rise in sea level, which can even harm estuarine areas,” explains Professor Leilanhe Ranieri, coordinator of the Laboratório de Oceanografia Geológica da Universidade Federal do Pará (UFPA) [Geological Oceanography Laboratory at the Federal University of Pará].

The laboratory studies coastal vulnerability to erosion, as well as sediment transport in areas such as Mosqueiro Island and Marajó Island, both in Pará. “The phenomena have different levels, depending on factors such as the intensity of currents, wave energy, rising tides, sediment input from rivers, as well as the state of degradation and human occupation of the estuarine margins,” says the oceanographer.

According to her, the higher the level of human occupation, the greater the risk of these phenomena to occur. “In addition, a considerable proportion of the populations that occupy these areas are socio-economically vulnerable and are often financially unable to cope with environmental problems. It is important that municipalities are prepared to deal with the effects of both phenomena,” she suggests.

INTENSITY

José Alberto Almeida, community leader of Vila do Pesqueiro, in Soure, on the Marajó Island, witnesses the changes perceived in the region. “Erosion in the community has been going on for several years, but since last year it has been stronger. We never imagined that an “August water” would bring down a large part of the community. It has knocked down trees, beachfront houses, and backyard plantations. We have already had to remove eight houses for another area of the community, which is quite frightened by the phenomena underway. We hope for help from the government to provide us with assistance and undertake a big project for us. There has been talk about relocating people from here, but that is difficult because people are used to living here. And move people where to?” he asks.

ASSISTANCE

For Leilanhe Ranieri, public authorities need to provide subsidies for coastal protection to mitigate the effects of erosion and siltation. “It is necessary to implement passive structures that allow for the natural restoration of the environment. It is also important to monitor the signs of erosion, the degree of siltation and the risks associated with them in rural areas, where many coastal communities are located, especially extractivist ones, as many individuals depend heavily on the stability of the soil in their subsistence activities,” she points out.

André Zumak, in turn, points out that the reality studied in the Mamirauá Reserve is recurrent in other Amazonian regions. “This dynamic of constant change in the landscape, with erosion and sedimentation in the rivers, occurs throughout the Pan-Amazon. Within the Brazilian Geological Service (SGB), there is a sector responsible for this mapping. Civil Defense agencies, likewise,  also carry out this type of work. However, it is still very incipient,” laments the researcher.

For Zumak, more studies are needed and, above all, better communication with the communities. “We take, for example, reports from the SGB, the analyses they make by municipality, and we realize that most of these reports are only done in the municipal seats. And the notifications also fail to reach the public managers, or the Civil Defenses. As a result, the communities are left at the mercy of any information reaching them, informing them that they are exposed to danger. Certainly, that collapsed land in Manacapuru [in Amazonas, where a landslide left two victims] evidenced several signs that it was going to happen. And at no time were the people there warned of this danger. So, I would very much like our study to be expanded, for this methodology to be appropriated by public managers and other bodies that deal with this issue, in order to prevent lives from being lost”, concludes the researcher.

IMPACTS

Yodji Jamesson Kanamari, an indigenous Kanamari, born and raised in Canariá, says that what his community feels is insecurity. “The geographical structure in front of the community has been shrinking more and more and this has impacted directly on people's lives, on the space, on the residents, especially on the issue of fear. Lately, the phenomena have become more intense. According to the survey, the houses closest to the river were, years ago, between 50 meters and 70 meters away. Today, some houses are no more than 20 meters away. A ravine has already collapsed and there is a crack in our school. If another piece slides, we will need to find another place. No one knows what lies ahead”.
 

INSTITUTIONAL PARTNERSHIP
The production of Liberal Amazon is one of the initiatives of the Technical Cooperation Agreement between the Liberal Group and the Federal University of Pará. The articles involving research from UFPA are revised by professionals from the academy. The translation of the content is also provided by the agreement, through the research project ET-Multi: Translation Studies: multifaces and multisemiotics.