In collaboration with the measuring authorities considerable effort is devoted to maintaining the quality of nationally archived river flow data. Data submitted to the NRFA are systematically submitted to a sequence of quality control checks. However, the ability of individual gauging stations to provide accurate and representative flows on a sensibly continuous basis, varies greatly from station to station - and, often, through time at the same site. To alert users to any particular hydrometric problems, or substantial disturbances to the natural flow regime, a summary description of the gauging station, its hydrometric characteristics and the catchment it commands is normally provided as part of the NRFA retrieval service.
The time series data posted on the website supersede those previously published and have been harmonised with the data holdings of the Measuring Authorities. Their co-operation in the routine updating and quality control of the NRFA data is gratefully acknowledged. Small differences between the NRFA and MA summary statistics for some of the selected gauging stations may be expected - reflecting, for instance, differing lengths of record or proportion of missing values. A minor proportion of the data remains under review - particularly for the pre-1970 values for which confirmatory evidence may not be readily available; validation of such historical material is an ongoing process. In addition, some reprocessing of high flows in particular may be anticipated as calibrations are revised following the major flood episodes experienced in recent years.
A table of daily gauged (or naturalised flows) for a calendar year - estimated values appear in blue. The flows are in cubic metres per second (also known as cumecs). Also given are monthly and annual summary information together with a concise description of the gauging station and the catchment it commands - click here for details of the individual data items featured on the tables.
These provide a compact representation of flow variability throughout the period of record for the selected gauging station. The hydrograph scale is adjusted to allow all years to feature on an A4 sheet. The hydrographs comprise the daily mean gauged (or naturalised) flows (black trace) together with the highest flow on record for each day (the blue envelope) and the lowest flow on record for each day (the red envelope). The flows are in cubic metres per second (also known as cumecs) and a logarithmic scale has been used - this tends to emphasise variability in the lower flow ranges.
To aid interpretation of the hydrographs it is recommended that the corresponding Summary Sheet is also downloaded.
This comprises daily flows gauged (or naturalised) flows with corresponding dates for the full period of record. The data is presented in a comma separated value format (csv) consisting of five columns:
NaN (not a number) is given.
NaN).
To aid interpretation of the downloaded flows hydrographs it is recommended that the corresponding Summary Sheet is also downloaded.