Brazil’s Strategy for Protecting Its Freshwater Resources

As global leaders gather in Belém for COP30, the IAEA is showcasing how nuclear techniques, including isotope hydrology, are helping Brazil protect its freshwater resources.

Brazil is home to 12% of the world’s freshwater, with rivers and wetlands stretching across the Amazon basin. Despite its abundance, water is not a given for everyone. Climate change and human activities are chipping away at this natural resource. With nearly half of Brazil’s population relying on these freshwater resources for domestic consumption, agriculture and energy production, protecting them is a national priority.

While many countries still rely on conventional hydrological tools such as measuring rainfall or river flows to monitor their water resources, the Geological Survey of Brazil (SGB), an IAEA collaborating centre since 2015, uses sophisticated hydrological and geochemical methods to better understand the country’s freshwater systems. The ultimate goal is to improve water quality, fair access, sustainable use and long-term preservation.

The IAEA’s water resources programme supported the SGB in identifying key isotope hydrology approaches that would add value to water management strategies. Through this work, the SGB set up an isotope hydrology laboratory, receiving specialized equipment, training and technical support through the IAEA’s technical cooperation programme. Until recently, SGB scientists had to send water samples to the IAEA’s Isotope Hydrology Laboratory in Vienna for analysis. Thanks to the donation of a portable gas mass spectrometer by Switzerland and the provision of training by the IAEA, SGB researchers will be able to analyse isotope data on site once the new instrument is installed. The instrument will enable them to study noble gases dissolved in groundwater, which are crucial for estimating the age, origin and flow of water sources and assessing whether they are renewable.

“This pioneering work in several fields of isotopic applications and the increase in technical and analytical capacity have had a major impact on the understanding of water dynamics and, consequently, on the management of resources,” said Roberto Kirchheim, a researcher at the SGB’s Applied Geoscience Centre.

Brazil is also sharing its knowledge and expertise to support other Latin American countries in strengthening their water management systems. The SGB is ready to play an active role in building a regional network of water laboratories through the IAEA’s Global Water Analysis Laboratory Network.

Climate change poses a serious threat to Brazil’s water resources. According to a 2024 report by Brazil’s National Water and Sanitation Agency, some parts of the country could see water resources decrease by more than 40% by 2040.

Brazilian scientists are taking part in several IAEA coordinated research projects to assess the impacts of climate change on water availability using isotope hydrology. One of these projects identified the Amazon as a key source of rainfall for Brazil and Argentina, which led both countries to strengthen their rainforest conservation efforts.

Through another IAEA coordinated research project, Brazil is studying how freshwater systems respond to the pressures of climate change and human activity to help the country prepare for future climate impacts. The data will inform discussions on groundwater management at both federal and provincial levels, enabling authorities to make evidence based decisions.

Agriculture, a vital sector for Brazil, is also taking a toll on the country’s water resources. Groundwater is often extracted for irrigation at rates that exceed its natural replenishment, threatening long-term water resource management.

To tackle this challenge, Brazil took part in an IAEA coordinated research project that applied isotope techniques to evaluate water sources in irrigation systems. With scientific guidance and coordination from the IAEA, Brazil was able to identify the sources of water used for irrigation, assess how quickly those sources were being naturally replenished, and forecast their future availability.

This knowledge has helped Brazil reduce over-extraction, optimize water allocation and promote climate-smart agricultural practices.

Spanning over 1.2 million square kilometres in Brazil, Argentina, Paraguay and Uruguay, the Guarani Aquifer is the world’s second largest transboundary aquifer system, storing over 37 000 cubic kilometres of freshwater. It is especially important for Brazil, where it supplies water for over 14 million people. 

Growing water demand, unregulated water use and pollution have raised serious concerns about the aquifer’s future. Until recently, the four countries that share it lacked the data to assess how human activity affects the aquifer and how to manage it sustainably. With support from the IAEA’s water resources programme, and technology transfer through its technical cooperation programme, scientists turned to isotope hydrology to study the aquifer’s recharge rate, quality and vulnerability to contamination. With this knowledge, the four countries developed joint strategies to manage and protect the Guarani Aquifer for future generations.

“The IAEA’s continued support has enabled Brazil to generate unprecedented isotopic datasets on rainfall, rivers, wetlands and deep aquifers, many of which are in data-scarce regions,” said Isadora Aumond Kuhn, Coordinator of the National Programme for Isotope Hydrology Applications at the SGB. “This has not only filled critical scientific gaps but also fostered stronger regional collaboration in South America.”

Brazil is hosting the 30th United Nations Climate Change Conference (COP30) in November 2025. The country is uniquely positioned to lead the conversation on the urgent need for water governance in the face of climate change and to share its experience with nuclear sciences and international cooperation to drive data-informed decision making. The IAEA, which helped put nuclear solutions on the COP agenda, is showcasing how they can contribute to mitigation and adaptation strategies at COP30. This includes building resilience in water systems using nuclear science and technology.