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FAQs: tips and tricks

Select stations of interest

What does Subregion mean in this context?

A subregion denotes a hydrographic region, which represents a river basin in total or contributing parts of them, or land that drain in sum via coastal sections between defined subregions.The Download by Subregion displays 841 hydrographic regions, of which 520 are separate river or lake basins.

River basins are named after the main stream (in the NGA GeoNamesSearch spelling). Coastal sections are named after the ocean and separated from each other by an exclusion statement (wmo-basin codes), river basins intersecting the coastal sections are not part of the exclusion statement.

Hydrologically, subregions are both basins with exorheic drainage, wherein all waters flow to a common outlet, ultimately into an ocean, but also basins with endorheic drainage, where all waters are collected in sinks not connected to other basins.

Core reference for the definition of subregions is the “WMO Manual on Codes, Annex F: List of basin indicators (BB)”, edition 2011, updated in 2018 (WMO 2018). Defined from a geo-political perspective, WMO Basins are mainly transboundary basins or their country-specific basin-shares, or coastal sections between rivers which form country borders whereby island states are usually considered as a separate region. WMO Basins that are composed of several river basins draining into ocean, are split into individual basins; country-specific basin shares that form tributary basins are considered as separate basins; basins that drain into two oceans are divided according to the receiving ocean.

How do I select GRDC stations in several countries?

For selection of all stations in one country use the country filter in the "Download by Station" menu. Combine filters to look for stations located on a particular water body in a country for example. For multiple country selection use the table view in the "Download by Station" menu.

How do I find GRDC stations of several countries sharing a trans-boundary river basin?

Use the table view in the "Download by Subregion", order the table by river basin and mark those of interest. Otherwise, use the search field in the map view to look for a specific river, lake or region name. Examine also the GRDC Project Catalogues of project-related subsets of data for global and international projects to which GRDC has contributed.

How do I find GRDC stations that represent the freshwater intake to a specific Ocean?

Use the table view in the "Download by Subregion" menu, order the table by ocean and mark those of interest. Examine also the GRDC Project Catalogues of project-related subsets of data for global and international projects to which GRDC has contributed.

How do I find GRDC stations with data in a specific time period?

Option 1: Use the table view in the "Download by Station" menu. In the header row click on the 3 black dots on the right hand side. From the dropdown menu tick the "Latest Data" or "Earliest Data" box. Klick on column header "Latest Data" once or twice to sort incremental or decremental. Mark all stations in your selection and request download. Use also the filter for the WMO defined reference periods for the calculation of climatological normals.

Option 2: Download GRDC Station Catalogue from the top menu. Use filter and/or range functions in Excel spreadsheet to select suitable set of data. Once your selection is complete, copy and paste GRDC station IDs in Portal into search field "Station name or number". Once display shows the selected stations on the map or table, select stations for download. Should there be several hundred stations in your request you might have to split your request.

How do I create an individual list of GRDC stations for download?

Download the GRDC Station Catalogue and use offline the filter and selection tools of Microsoft Excel. Once your selection is complete, copy and paste GRDC station IDs into the "Station Name or Number" field. Once the selected stations are displayed on the map or table, select stations for download. Should there be several hundred stations in your request you might have to split your request.

Why do I not find a particular water body?

GRDC's inventory of water bodies lists rivers of which GRDC also provides discharge data for download. It grows continuously with database updates. If you miss a river name, try the alternative names tool to check if the river you are looking for is listed under a different name.

Why do I find subregions other than the one I am looking for when I search for a specific river, lake or region name?

Full text search for a specific character string also finds similar but not applicable names. Use the map tile or table view to check and deselect hits that do not match your criteria.

Download timeseries

Is there an API to get GRDC discharge data automatically?

Unfortunately, not. As an international data center working on behalf of WMO Member countries, GRDC is the custodian of discharge data from over one hundred Hydrological and Meteorological Services worldwide. This mandate obliges the GRDC to strictly implement the conditions for the data exchange of the WMO community set by the WMO Congress in order to protect the data ownership of national services. This requires an identified access to hydrological data, as well as an explicit acceptance of the general Terms of Use and Data Protection Regulations, and the GRDC Data Sharing Conditions by the user.

What kind of statistics ​​are provided in the "statistics" format?

With "statistics" format basic hydrological statistics of timeseries data of the gauging stations are offered. Annual characteristics are derived from monthly discharge data, either aggregated daily data or originally provided monthly data. Long-term statistics and long-term variability are derived from annual characteristics to:

Q_YVD - lowest, mean lowest, mean, mean highest, and highest daily discharge value in the individual calendar year, calculated from at least 10 monthly means in the year in question;
Q_YVM - lowest, mean, and highest monthly discharge value in the individual calendar year, calculated from at least 10 monthly means in the year in question;
Q_PVD - lowest, mean lowest, mean, mean highest, and highest daily discharge value in the given time series, calculated from yearly means, or the lowest and highest values of consecutive calendar years;
Q_PVM - lowest, mean, and highest monthly discharge value in the given time series, calculated from yearly means, or the lowest and highest values of consecutive calendar years;
Q_LTVD - lowest, mean, and highest daily discharge value in each calendar month in the given time series, calculated from monthly means, or the lowest and highest values in each calendar month in consecutive calendar years;
Q_LTVM - lowest, mean, and highest monthly discharge value in each calendar month in the given time series, calculated from monthly means, or the lowest and highest values of each calendar month in consecutive calendar years.

Why can't I access the requested data once I have received the download link?

Due to technical reasons, it may take a few minutes before data is available on the server. Please try again later. If the problem persists, please contact GRDC.

Request GIS layer

How can I get the "Watershed Boundaries of GRDC Stations" ?

"Watershed boundaries of GRDC Stations" are provided together with the requested discharge timeseries. By activating the tick-box in the data request form basin polygons of your selected stations will be added to the data download as GeoJSON file. Please note that some shapefiles are missing, as this feature is not available for all stations.

How do I view/use a GeoJSON file?

You can view/use the stationbasins.geojson file in QGIS, an open-source cross-platform GIS. Note: To use GeoJSON files in ArcGIS Desktop or ArcGIS Pro, the ESRI Data Interoperability extension is required (requires a license).

How can I get the "Major River Basins" polygons ?

GRDC Major River Basins of the World (MRB) is an ongoing GIS project of the Global Runoff Data Centre (GRDC). GIS data is provided for public use under the condition of full citation and reference to incorporated data from the HydroSHEDS database. Data can be downloaded as ESRI Layer Package (LPK) files for use within ESRI ArcMap, or ESRI Shape files. Please visit the "Data Product" menu at GRDC Website (grdc[at]bafg.de).

How can I get the "WMO Basins and Sub-Basins" polygons ?

WMO Basins and Sub-Basins (WMOBB, aka WMO Subregions) is an ongoing GIS project of the Global Runoff Data Centre (GRDC). GIS data is provided for public use under the condition of full citation and reference to incorporated data from the HydroSHEDS database. Data can be downloaded as ESRI Layer Package (LPK) files for use within ESRI ArcMap, or ESRI Shape files. Please visit the "Data Product" menu at GRDC Website (grdc[at]bafg.de).

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