Mining on Indigenous reservations in the Brazilian Amazon has increased 1,217% in the last 35 years

Wildcat prospecting has expanded faster since 2017 and occurs mainly on the Kayapó, Munduruku and Yanomami reservations, according to a study by scientists at Brazil’s National Space Research Institute.

By Elton Alisson  |  Agência FAPESP – The last 35 years at the Brazilian Legal Amazon (an area spanning nine Brazilian states defined by federal law for environmental protection and developmental purposes) saw wildcat mining activities on Indigenous reservations expand from 7.45 square kilometers (km²) of occupied area in 1985 to 102.16 km² in 2020, a 1,217% increase. All mining in these reservations is illegal. Wildcat prospecting in the Kayapó, Munduruku, and Yanomami reservations accounts for 95% of the total.

These are some of the key findings of a study conducted by researchers at Brazil’s National Space Research Institute (INPE) and the University of South Alabama (USA) in the United States. An article on the study is published in the journal Remote Sensing.

“We observed steady expansion of mining on Indigenous reservations between 1985 and 2020, with particularly fast growth from 2017 on. In that year, illegal mining activities occupied 35 km² of Indigenous land. By 2020, they had expanded to almost 103 km²,” Guilherme Augusto Verola Mataveli, first author of the article, told Agência FAPESP. Mataveli is currently a postdoctoral researcher in INPE’s Earth Observation and Geoinformatics Division and has a scholarship from FAPESP. 

The other authors of the article include Michel Eustáquio Dantas Chaves, also a researcher at INPE, and Elton Vicente Escobar Silva, a PhD candidate at INPE.

To locate mining activities on Indigenous reservations, the researchers analyzed a dataset for the period 1985-2020 from MapBiomas, a collaborative network of NGOs, universities and tech startups that maps land use and land cover across Brazil.

MapBiomas provides annual land use and land cover maps for the entire Brazilian territory at a spatial resolution of 30 meters, based on automatic classification of Landsat images using the Random Forest machine learning algorithm.

“The system classifies images automatically and can distinguish between areas of forest with or without mining activities, especially areas where the soil is bare and the visible characteristics are quite different from areas with plant cover,” Mataveli said.

However, the system has some limitations when it comes to detecting mining activities on Indigenous reservations, such as the impossibility of classifying gold panning and similar activities carried out using equipment on boats anchored in rivers and smaller areas where the forest cover has not been cleared even though wildcat prospecting goes on there.

“The growth in mining on Indigenous reservations in the Brazilian Legal Amazon as detected by our study was alarming enough, but it was probably an underestimate given these limitations in the dataset we used,” Mataveli said.

Growing encroachment by illegal miners 

The researchers found that gold is produced by 99.5% of the illegal mining operations on Indigenous reservations in the Amazon. The remaining 0.5% produces cassiterite, the ore from which tin is derived.

The growth of mining in the period was most intense on the Kayapó reservation, where it occupied an area of 77.1 km² in 2020, or almost 1,000% more than in 1985 (7.2 km²).

On the Munduruku reservation, it expanded from 4.6 km² in 2016 to 15.6 km² in 2020. On the Yanomami reservation, it expanded from 0.1 km² to 4.2 km² in the period.

“The government must intensify oversight, monitoring and law enforcement in these areas in order to halt the advance of illegal mining,” Mataveli said.

The Yanomami, living on a reservation demarcated in 1992, are the most isolated of the three communities, he added. For a long time, this isolation hindered encroachment by wildcat prospectors, but rising international gold prices and weakening protection of the Amazon in recent years have boosted investment in infrastructure for access to the area, which is protected by law. “The Yanomami reservation became the new frontier for illegal mining because of this combination of factors,” he said.

The area occupied by the activity on this reservation exceeded 2 km² for the first time in 2018, according to the study. Since then, encroachment and human rights violations have multiplied as illegal mining has advanced.

In 2022, the Federal Police (an agency of the Ministry of Justice in Brazil) observed a 505% increase in illegal mining along the Uraricoera River, a major artery for the Yanomami. Their leaders estimate that more than 20,000 wildcat prospectors have invaded the reservation. The Yanomami population is believed to total about 30,000. Malaria and other infectious diseases have spread swiftly in step with all this encroachment.

“The tragedy and humanitarian crisis we’re seeing now in the Yanomami community was perfectly predictable,” Mataveli said.

To reverse the trend, the first step should be to identify and monitor the Indigenous areas where illegal mining has increased most in recent years. It is also necessary to curb deforestation. Mining in the Amazon, including the Indigenous reservations there, occurs after the forest has been cleared, Mataveli noted.

“Illegal mining in the Amazon is very closely associated with deforestation because the forest has to be cleared before mining can begin,” he said.

The article “Mining is a growing threat within Indigenous lands of the Brazilian Amazon” is at: www.mdpi.com/2072-4292/14/16/4092.