The collection and dissemination of long-term hydrological data and information on a global scale is the principal reason for the operation of the GRDC. The primary objective consists in supporting the water and climate related programmes and projects of the United Nations, its specialised agencies, and the scientific research community on global and climate change, and integrated water resources management. The modelling of the global water balance, the analysis of long-term trends or circulation patterns, and the estimation of fluxes of freshwater and pollutants into the oceans, are only some examples of application of reliable and consistent global data sets.
To extend and maintain this global dataset, the main functions of GRDC are the acquisition and management of historical river discharge data and associated metadata. Key partners for the provision of river discharge data are National Hydrological Services of all WMO member states. Acting as an international data centre, GRDC coordinates and disseminates the information about national data holdings and data access. This also includes the collection of metadata and the contribution to standardised hydrologic metadata profiles.
According to its data policy, GRDC data and associated data products are freely available for non-commercial use. GRDC acts as a facilitator between the producers of hydrological data and the research community and is key partner in a number of data collection and data management projects. This includes the World Climate Research Programme (WCRP), the Global Climate Observing System (GCOS), the Intergovernmental Hydrological Programme (IHP) of UNESCO, and other international programmes and initiatives focused on Earth observation towards sustainable development. GRDC is a member of the Global Terrestrial Network for Hydrology (GTN-H), supporting the development and use of integrated products on global scale and is linked to the Global Earth Observation System of Systems (GEOSS).
For the execution of its tasks and international recognition, GRDC is mandated by the World Meteorological Organization (WMO) in several resolutions. Through this multilateral and bilateral collaboration, the hydrological and meteorological services of WMO member states directly contribute to the successful operation of GRDC.
Relevant WMO resolutions:
Resolution 24 (Cg-19 2023) “Hydrological Data Management in the WMO Information System 2.0” recognises GRDC, as a major centre for supporting the implementation of the WMO Hydrological Observing System (WHOS), the Global Hydrological Status and Outlook System (HydroSOS), and serving also the other major initiatives of the Organization, especially in the framework of the WMO Plan of Action for Hydrology 2022 - 2030.
Under the Topic “Climate and Hydrology Data Management within the WMO Information System 2.0” the Congress encourages Members:
- To support the GRDC, through the provision of the hydrological data and related information that they need;
- To consider also providing support to the Centre in the form of staff, funding, and other resources.
Resolution 21 (Cg- XII) – Global Runoff Data Centre (GRDC) has been recalled.
Resolution 1 (Cg-Ext 2021) “Unified Data Policy” agrees to have one unified data policy for all WMO domains and disciplines. It also lists a minimum set of core data that Members shall exchange on a free and unrestricted basis to underpin the services they provide for the protection of life and property and for the well-being of all nations.
The list includes core and recommended data for the following Earth system disciplines/domains:
- Weather
- Climate
- Hydrology
- Atmospheric Composition
- Cryosphere
- Oceans
- Space Weather
Resolution 24 (Cg-XVIII-2019) “Vision, Strategy and Organizational Arrangements for Hydrology and Water Resources in WMO” calls for a better Plan of Action to strengthen operational National Hydrological Services and the capabilities of national service providers that will support Member states’ efforts to fulfil the following Long-term Ambitions:
- No one is surprised by a flood;
- Everyone is prepared for drought;
- Hydro-climate and meteorological data support the food security agenda;
- High-quality data supports science;
- Science provides a sound basis for operational hydrology;
- We have a thorough knowledge of the water resources of our world;
- Sustainable development is supported by information covering the full hydrological cycle;
- Water quality is known;
Resolution 25 (Cg-XIII-1999) “Exchange of Hydrological Data and Products” extends and specifies the commitment of Resolution 40 (Cg-XII-1995) as follows:
“… those data and products which are necessary for the provision of services in support of the protection of life and property and for the well-being of all peoples.”
“… additional data and products … which are required to sustain (international) programmes and projects related to operational hydrology and water resources research”
“…all hydrological data and products exchanged under the auspices of WMO … to the research and education communities, for their non-commercial activities.”
Resolution 40 (Cg-XII) “WMO Policy and practice for the exchange of meteorological and related data and products including guidelines on relationships in commercial meteorological activities” addresses the fundamental principle of broadening and enhancing the free and unrestricted international exchange of meteorological and related data and products in the sense of non-discriminatory provision of data and data products exempt from charges.
Resolution 21 (Cg-XII) “Global Runoff Data Centre (GRDC)” encourages all member countries to support GRDC through the provision of hydrological data and related information that it needs. The Congress adopted also the practice that countries should provide free and unrestricted access to all data and products to the research and education community under the auspices of WMO, with the understanding that the commercial use of these data may be subject to conditions.
Support letters from the WMO Secretary-General:
| Year | Titel | Language |
|---|---|---|
| 2015 | German support for WMO’s water-related programs | English (PDF, 94KB) |
| 2004 | Supply of historical hydrological data | English, French, Spanish, Russian, Arabic (PDF, 363KB) |
| 1996 | Support the GRDC | English, French, Spanish, Russian (PDF, 609KB) |
| 1990 | Surface water runoff data for the GRDC | English (PDF, 370 KB) |
| 1982 | Surface water runoff data set | English (PDF, 296 KB) |