I. What is the GRDC?
The Global Runoff Data Centre (GRDC), managed by the World Meteorological Organization (WMO), is an international hub established in 1988. Its primary goal is to support global climate change research and integrated water resource management. GRDC hosts the world’s most comprehensive, quality-assured river discharge data repository.
The center’s mission is to collect, manage, and share long-term hydrological data to support the United Nations and its specialized agencies in water resource and climate-related projects. Collaborating with national hydrological services worldwide, GRDC ensures the collection of historical river flow data and associated metadata, enabling coordinated data sharing and access.
GRDC’s data and products, available free for non-commercial use, support a wide range of activities, including water balance modeling, long-term trend analysis, and freshwater and pollutant transport studies. GRDC also serves as a core partner in several international initiatives, including the World Climate Research Programme (WCRP) and the Global Climate Observing System (GCOS).
As a member of the Global Terrestrial Network for Hydrology (GTN-H), GRDC promotes Earth observation and the achievement of sustainable development goals. Through WMO-led collaborations, GRDC maintains international recognition as a trusted bridge between hydrological data providers and the research community, offering reliable support for global water resource management.
II. What Data Can We Get from GRDC?
The GRDC offers a wide array of data and products to facilitate hydrological research, including:
- Observed River Discharge Data: Data from stations worldwide, useful for hydrological model calibration, model result evaluation, and remote sensing data validation.
- Geospatial Products:
- Major River Basins of the World.
- Watershed boundaries of GRDC stations.
- WMO-defined basins and sub-basins.
- Freshwater Fluxes into the World’s Oceans.
- Global composite runoff fields.
These resources support applications such as water resource planning and climate impact assessments.
Figure 1: An Overview of Global River Discharge and Hydrological Research Support Products Provided by GRDC.
III. How to Download Data from GRDC?
Access GRDC data via the GRDC River Discharge Data Download Page.
Figure 2: GRDC Discharge Data Download Page.
The GRDC discharge data offers three download options: download by subregion, download by station, and download GRDC station catalogue. Below is an introduction to each method:
3.1 Download by Subregion:
This method allows you to download data based on a specific geographic region. Use the table or tiles interface to select your target research area, which includes key information such as the subregion name, the number of stations, and the region’s name.
Figure 3: Illustrating the subregion download process through table.
Figure 4: Illustrating the subregion download process through tiles.
3.2 Download by Station:
Select data for specific stations using filters such as station name/number, water body, region, sub-region, country, or time period. Interactive maps and tables simplify the selection process, while detailed metadata is available by clicking on specific station markers.
Figure 5: Illustrating the station download process through map.
Figure 6: Illustrating the station download process through table.
3.3 Download GRDC Station Catalogue:
The GRDC station catalogue provides metadata for all stations with river discharge data. Available in Excel format, it enables users to select stations and time series of interest. Enter station numbers into the “Station Name or Number” field on the Download by Station page to retrieve data, or submit a direct data request to GRDC.
Figure 7: GRDC Station Catalogue.
Figure 8: GRDC Project Station Catalogues.
IV. How to Read and Process GRDC Data?
GRDC data is available in multiple output formats to suit diverse research needs:
- GRDC Export Format: Daily or monthly data (or both).
- GRDC Statistics Format: Statistical summaries only.
- NetCDF: Daily or monthly data.
- WaterML2: Monthly data only.
- ZRXP: Daily or monthly data (or both).
Example Data Processing Workflow
Using the DOS-ASCII format as an example involves the following steps:
- Extract Essential Attributes: Retain key details such as GRDC-NO, River, Station, Country, Latitude, Longitude, Date, and Value.
- Filter data: Remove irrelevant entries, such as records prior to 2000, to focus on the study’s timeframe.
- Aggregate Data: Convert daily discharge values into monthly cumulative discharge for easier analysis of trends.
Briefly describe the data processing workflow, as shown in Figure 9. Processed data can then be used for various applications, such as evaluating the performance of hydrological models. The processed results are shown in Figure 10. As shown in Figure 11, the processed data can be used to evaluate the performance of hydrological models.
The pre-processed data (Figure 9) can support various applications, including evaluating the performance of hydrological models. The processed results are presented in Figure 10, showcasing the aggregated discharge values. Furthermore, Figure 11 illustrates the use of processed data to compare simulated discharge with observed in situ measurements for rivers such as the Danube and Rhine, across different models and resolutions.
Figure 9: Pre-processed Data.
Figure 10: Post-processed Data.
Figure 11: Time series comparison of simulated (red dashed line) and in situ discharge (black solid line) for the Danube River and Rhine River across different models and resolutions.
This article is developed by Mingze Sun.
ALICE-LAB: Asian Land Information for Climate and Environmental Research Laboratory
The Community Water Model (CWatM) is an open-source hydrology tool that models the water cycle, incorporating both natural processes and human water demands. Used in ALICE-LAB, it supports sustainable water management by distinguishing climate impacts from human activities.
The Noah-MP LSM, developed by NCAR, simulates complex land surface processes like soil moisture, snowpack, and evapotranspiration, vital for hydrology and climate studies. With customizable modules, it supports diverse scales and applications, enabling ALICE-LAB to conduct high-resolution simulations on global water dynamics and long-term climate impacts.