Global Network of Isotopes in Precipitation (GNIP)

Global Network of Isotopes in Precipitation/Rivers

The Global Network of Isotopes in Precipitation was initiated in 1958 by IAEA and WMO, and became operational in 1961. The objective was a systematic collection of basic spatial data on the isotope content of precipitation across global scales to determine temporal and spatial variations of both environmental stable isotopes and tritium in precipitation. The initial driver was to monitor atmospheric thermonuclear test fallout through the determination of the radioactive hydrogen isotope tritium. However, the focus has changed to become an observation network of stable hydrogen and oxygen isotope data for hydrological studies since the 1970s.

For over 50 years, GNIP has provided global isotope data for the use in hydrological investigations, i.a. water resources investigation, planning, conservation and development. Although these primary objectives remain important, other scientific disciplines have increasingly used this invaluable and unparalleled isotope database over the past decade, including:

  1. verifying and improving atmospheric circulation models,
  2. studying regional, global and temporal climate,
  3. studying the interactions of water between atmosphere and biosphere, and
  4. providing baseline information for the authentication of commodities, such as food, plants, and for tracking migratory species (birds, fish, butterflies etc.), and for forensic purposes.

The GNIP database encompasses more than 100,000 isotope records of monthly and event-based precipitation samples from more than 1,000 stations globally (note that not all stations were active at the same time).

Global Network of Isotopes in Rivers (GNIR)

GNIR functions in a similar way to GNIP, relying on voluntary international partnerships between the IAEA and organisations, institutions, as well as researchers for sample collections, isotopic analyses, and contribution of published or unpublished data for global rivers and streams.

Presently, the GNIR database contains around 21,000 stable water isotope records from 750 sites in 35 countries. In addition, 12,200 tritium records were collected from 170 stations in 28 countries (not all stations being active at the same time). Further information is available via the GNIR web and FAQ pages ( and

GNIP and GNIR data are available via Detailed information on sampling methods are available from the IAEA Isotope Hydrology Network (Login required)

Contact details

International Atomic Energy Agency
Water Resources Programme
Vienna International Centre, PO Box 100
A-1400 Vienna, Austria

Contact Person

Stefan Terzer-Wassmuth