Data Access Form

Dataset Title:	GRDC MEAN MONTHLY DISCHARGE (MQ)
Institution:	GRDC (Dataset ID: GRDC_MEAN_MONTHLY_DISCHARGE)
Information:	Summary \| License \| Metadata \| Background \| Subset \| Files \| Make a graph

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Variable

Optional
Constraint #1

Optional
Constraint #2

Minimum

or a List of Values

Maximum

GRDCno (GRDC number)

time (YYYY-MM-DD, UTC)

1806-01-01

2019-04-01

Original (original (provided) data)

0.0

39400.0

Calculated

0.0

30163.33

Flag

100

Server-side Functions

distinct()

Hover here to see a list of options. Click on an option to select it.

File type: (more information)

(Documentation / Bypass this form )

(Please be patient. It may take a while to get the data.)

The Dataset Attribute Structure (.das) for this Dataset

Attributes {
 s {
  GRDCno {
    String long_name "GRDC number";
  }
  time {
    String _CoordinateAxisType "Time";
    Float64 actual_range -5.17536e+9, 1.5540768e+9;
    String axis "T";
    String ioos_category "Time";
    String long_name "YYYY-MM-DD";
    String source_name "YYYY-MM-DD";
    String standard_name "time";
    String time_origin "01-JAN-1970 00:00:00";
    String time_precision "1970-01-01";
    String units "seconds since 1970-01-01T00:00:00Z";
  }
  Original {
    Float32 _FillValue -999.0;
    Float32 actual_range 0.0, 39400.0;
    String long_name "original (provided) data";
  }
  Calculated {
    Float32 _FillValue -999.0;
    Float32 actual_range 0.0, 30163.33;
    String long_name "GRDC calculated from daily data";
  }
  Flag {
    String _Unsigned "false";
    Byte actual_range 0, 100;
    String long_name "percentage of valid values used for calculation from daily data";
  }
 }
  NC_GLOBAL {
    String cdm_data_type "Other";
    String Conventions "COARDS, CF-1.6, ACDD-1.3";
    String creator_name "GRDC";
    String creator_type "institution";
    String creator_url "https://www.bafg.de/GRDC/EN/01_GRDC/grdc_node.html";
    String history 
"2025-07-14T19:52:09Z (local files)
2025-07-14T19:52:09Z http://erddap.emodnet-physics.eu/erddap/tabledap/GRDC_MEAN_MONTHLY_DISCHARGE.html";
    String infoUrl "https://www.bafg.de/GRDC/EN/01_GRDC/grdc_node.html";
    String institution "GRDC";
    String keywords "calculated, data, discharge, flag, grdc, grdcno, hh_mm, identifier, mean, month, monthly, original, time, yyyy, yyyy-mm-dd";
    String license "Creative Commons Attribution Share-Alike http://www.opendefinition.org/licenses/cc-by-sa";
    String sourceUrl "(local files)";
    String standard_name_vocabulary "CF Standard Name Table v55";
    String subsetVariables "GRDCno";
    String summary "GRDC Mean Monthly Discharge (mq). GRDC data from a local source.";
    String time_coverage_end "2019-04-01";
    String time_coverage_start "1806-01-01";
    String title "GRDC MEAN MONTHLY DISCHARGE (MQ)";
  }
}

Using tabledap to Request Data and Graphs from Tabular Datasets

tabledap lets you request a data subset, a graph, or a map from a tabular dataset (for example, buoy data), via a specially formed URL. tabledap uses the OPeNDAP (external link)

Data Access Protocol (DAP) (external link)

and its selection constraints (external link)

The URL specifies what you want: the dataset, a description of the graph or the subset of the data, and the file type for the response.

(easy) You can get data by using the dataset's Data Access Form or Subset form. They make the URL for you.
(easy) You can make a graph or map by using the dataset's Make A Graph form. It makes the URL for you.
(not hard) You can bypass the forms and get the data or make a graph or map by generating the URL by hand or with a computer program or script.

Tabledap request URLs must be in the form
https://coastwatch.pfeg.noaa.gov/erddap/tabledap/datasetID.fileType{?query}
For example,
https://coastwatch.pfeg.noaa.gov/erddap/tabledap/pmelTaoDySst.htmlTable?longitude,latitude,time,station,wmo_platform_code,T_25&time>=2015-05-23T12:00:00Z&time<=2015-05-31T12:00:00Z
Thus, the query is often a comma-separated list of desired variable names, followed by a collection of constraints (e.g., variable<value), each preceded by '&' (which is interpreted as "AND").

For details, see the tabledap Documentation.