How Viet Nam Uses Isotope Hydrology to Protect Water and Share Expertise Across Asia

More than four decades of support from the International Atomic Energy Agency (IAEA) have helped Viet Nam build expertise that now informs water management at home and supports other countries across Asia and the Pacific.

Water beneath the ground can be difficult to understand: where it comes from, how quickly it is replenished and how pollution reaches it are questions that directly affect the people who depend on it. From the Mekong River Delta to the Red River Delta, Vietnamese scientists are finding answers through isotope hydrology, a nuclear-derived technique that helps trace water through the environment.

More than four decades of support from the International Atomic Energy Agency (IAEA) have helped Viet Nam build expertise that now informs water management at home and supports other countries across Asia and the Pacific. Isotope hydrology uses naturally occurring stable and radioactive isotopes to investigate the origin, movement and age of water, as well as sources of contamination.

Vietnamese researchers use stable isotopes such as deuterium and oxygen-18 alongside radioactive isotopes including tritium and carbon-14 to understand how rivers and aquifers connect, how groundwater moves and how quickly supplies are replenished.

Scientists also use isotopic techniques to trace groundwater pollutants, including arsenic and nitrogen. These investigations give policymakers evidence to guide water use and protect supplies from contamination and excessive extraction.

Helping Ha Noi Manage Groundwater Extraction

In Ha Noi, understanding the connection between the Red River and underground water supplies has practical consequences for the city's drinking water. Isotopic analysis has helped researchers assess how much river water contributes to groundwater, giving authorities a clearer basis for deciding how much can be extracted.

Nguyen Chi Nghia, Principal Manager of the Center for Planning and Investigation of Water Resources in Northern Viet Nam, explained that this knowledge supports licensing an appropriate extraction volume for the Ha Noi Urban Clean Water Supply Company, helping meet residents' needs and avoid adverse impacts on regional geology.

Building Laboratories People Can Trust

Over the past 25 years, Viet Nam has established and strengthened 18 facilities for isotope hydrology studies, and 50 Vietnamese scientists have received training in the techniques.

IAEA technical cooperation has supported the Centre for Nuclear Techniques and the Institute for Nuclear Science and Technology (INST), providing equipment and training that cover field sampling, sample preparation and laboratory analysis.

At INST, equipment includes a tritium enrichment system, water filtration equipment, a submersible groundwater sampling pump and a liquid scintillation counter for measuring tritium and carbon-14 activity. Scientists have also trained at advanced laboratories abroad.

Reliable measurements require regular checks, so Vietnamese laboratories participate in IAEA intercomparison exercises and proficiency tests coordinated by its Isotope Hydrology Section and Vienna laboratory. Research published in international scientific journals reflects the country's growing expertise.

INST scientist Dinh Thi Bich Lieu credited IAEA-supported training in measuring low tritium concentrations with helping the laboratory produce reliable results and participate in these exercises. IAEA expert Melanie Vital highlighted another essential skill: interpreting the measurements to answer real water management questions.

Sharing Experience Across the Region

Through the Regional Cooperative Agreement for Research, Development and Training Related to Nuclear Science and Technology for Asia and the Pacific (RCA), Viet Nam supported 15 countries between 2022 and 2025.

In Lao PDR, Vietnamese experts trained scientists in groundwater sampling for chemical and isotopic analysis. Testing surface water and groundwater from the Vientiane Basin helped clarify connections between the Nam Ngum River and groundwater, improving understanding of groundwater quality.

IAEA Section Head Kaori Kawarabayashi described this regional cooperation as a practical outcome of decades of investment in Vietnamese scientific capacity.

What Comes Next for Water Research

The RCA publication Social and Economic Impact Assessment of Hydrology and Groundwater Projects, launched at the 70th IAEA General Conference, highlights progress from 2000 to 2025 across Asia and the Pacific, including Viet Nam.

The 17th International Symposium on Isotope Hydrology, scheduled for May 2027 at IAEA Headquarters in Vienna, will examine analytical advances, water management applications, and research and training needs linked to the United Nations Water Action Decade. Participants can also learn how to join the IAEA's Global Water Analysis Laboratory (GloWAL) Network.