Brazil has lost 15% of its surface water since the early 1990s

Posted on 26 August 2021

New MapBiomas platform details alarming declines in surface water in the Pantanal and Amazon
Brazil is drying up!

The country has lost 15 per cent of its surface water in the past 30 years, according to an alarming analysis published on the new MapBiomas Water Platform. Overall, Brazil’s surface water plunged from 19.7 million hectares in 1991 to 16.6 million hectares in 2020. It’s a decline that’s been recorded across all biomes, with some particularly shocking findings:
  • Take the Negro river. One of the largest tributaries of the Amazon and one of the world's ten largest rivers by average discharge - it has lost 22% of its surface water.
  • Or the Pantanal, the world’s largest tropical wetland – the Brazilian section has lost 74% of its surface water
Some of the greatest losses are close to agricultural zones, which suggests that increased consumption and the construction of small farm dams that fragment the drainage network, are contributing to the loss of natural surface water in Brazil – along with deforestation and rising temperatures due to climate change.

“Changes in land use and coverage, construction of dams and hydroelectric plants, excessive use of water resources for the production of goods and services have altered the quality and availability of water in all Brazilian biomes,” said Carlos Souza, coordinator of the Water Working Group at the MapBiomas project - a network of researchers, NGOs, universities and companies.

The loss of nearly three-quarters of the Brazilian Pantanal’s natural surface water is bound to have a major impact on river flows and water dynamics – and on all the people and over 4000 species that depend on them. Hydropower plants have certainly contributed to the losses and yet there are still dozens of other hydropower dams on the drawing board for this region – dams that will generate negligible amounts of power, while having significant social and environmental impacts.

“These dams are adding to an agricultural model that already alters the water drainage regime and intensifies the deposition of sediments, reducing the flow of water. If this development model is not revised, the future Pantanal is compromised,” said Cássio Bernardino, WWF-Brazil, which has partnered with MapBiomas network and the Imazon NGO on the analysis.

Unsurprisingly, there seems to be a link between wildfires and the reduction in surface water in some areas. Such as in the municipality of Corumba in Mato Grosso do Sul, which boasts two unwanted records – it’s seen the most fires and lost the most surface water between 1985 and 2021.

“The fire and water cycles are interconnected. Less water makes the earth and the organic matter that settle on it more vulnerable to fire. More fire suppresses the vegetation, which plays a crucial role in perpetuating springs,” explained Tasso Azevedo, Coordinator of MapBiomas.

Another example is the São Francisco River. One of the largest rivers in the country, it has lost 10% of its surface water over the past 15 years, which coincides with a period of agricultural expansion in Matopiba region. At its mouth, communities are already feeling the effects, with salt water intruding further up the river and inland.

And then there is the vast Cerrado savanna, which is critical for Brazil's agricultural production and home to incredible biodiversity. But its water system is being transformed. Natural surface water has fallen from 864,000 hectares to just 490,000 hectares. Much more surface water is now governed by hydropower, changing water flows and impacting people and nature.

This new data is a clear warning sign. Brazil needs to take urgent action to safeguard its priceless water resources. Other countries should also take note. They need to sustainably conserve and manage their freshwater ecosystems in the face of growing pressures, including the worsening impacts of our warming world.


About MapBiomas Water: This is an unprecedented initiative for territorial mapping of the dynamics of surface water and water bodies for the entire national territory since 1985. The Water series processed more than 150 thousand images generated by the Landsat 5, 7 and 8 from 1985 to 2020. With the help of artificial intelligence, the area covered by water in each pixel of 30 m X 30 m of the more than 8.5 million square kilometers of Brazilian territory was analyzed over the 36 years between 1985 and 2020, distinguishing natural and anthropic water bodies. In all, 108 terabytes of images were processed, revealing areas, years and months of greater and lesser water coverage. The method also allows you to identify the area with water each month throughout the period, as well as transitions and trends. Data can be found in annual, monthly and accumulated maps and statistics for any period between 1985 and 2020 on the platform , open to all.
About MapBiomas: Multi-institutional initiative, involving universities, NGOs and technology companies, focused on monitoring changes in land cover and land use in Brazil. This platform is today the most complete, up-to-date and detailed spatial database of land use in a country available in the world. All data, maps, methods and codes of MapBiomas are made available publicly and free of charge on the initiative's website:

The Pantanal wetland has lost 74% of its surface water since 1985
© Andre Dib/WWF

Related links

Fires in Ladario, in the state of Mato Grosso do Sul, Brazil. August 2020.
© Silas Ismael / WWF-Brasil
New MapBiomas Water tool shows alarming loss of surface water in Brazil
© MapBiomas Water
Rio Negro has lost 22% of its surface water in 30 years
© Michel Roggo / WWF
© Lidia Nuñez / WWF-Paraguay