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How data validity may change

SEPA's live data are subject to ongoing quality control and also to periodic review

The data presented in the API archive should not be considered immutable:

  • recent observed data are subject to limited automatic quality coding, and may be revised during monthly manual quality control procedures;
  • the physical infrastructure (field sensors, loggers, telemetric hardware) is subject to technical issues that may compromise data quality or availability; all stations are equipped with back-up sensors and logging but, as these may not be connected to telemetry, missing and live data feeds may not be restored until field staff are able to visit the site;
  • river flow data may be subject to revision following annual and ad hoc reviews in response to additional calibration data, the latter typically affecting the upper - flood - portion of the calibrated range;
  • data in the duplicate API archive are subject to periodic update of aggregated data with quality-controlled data from the primary HIMS.

Quality control protocols

Recent observed hydrometric data are automatically tagged with a default _unchecked_ quality code of 254 until manual quality control is undertaken. These data are manually quality-controlled, and quality code revisions applied, on a monthly cycle, using the codes in the Table of quality codes below. The unchecked status will apply to any recent data that are available via the API and these provisional data should be used with circumspection appropriate to their end-use.

SEPA accepts no liability for any unintended or otherwise negative consequences arising from the use of the data extracted using the API, or of any subsequent legitimate revisions thereof.

Quality codes

Code number

Code name

Abbreviated code name

50 Good G
100 Estimated E
140 Provisional Prov
150 Suspect S
200 Unchecked (imported from legacy database) V
254 Unchecked U

River flow data quality

The quality codes assigned to river flow data reflect both the quality of the river level data from which they derive, and from the confidence in the rating. Flows that are based on an acceptable extrapolation beyond the highest or lowest valid gauging are considered to be extrapolated values and are coded as estimated (100). Flows beyond the acceptable extrapolation limit are coded as suspect (150).

The coding reflects a worst wins combination of the river level quality and that of the flow rating. For example, suspect quality stage data and a good rating, i.e. within the validated range, would nevertheless result in suspect flow data.

Annual review and flood flow revision

SEPA undertakes an annual review of all flow station calibrations, after which recently generated flow data are potentially subject to retrospective revision. In addition to retrospectively recalibrating relatively short periods following the annual review, SEPA occasionally improves its understanding of flood flow estimates, typically after capturing a rare flood gauging or after a hydraulic modelling exercise. In such instances, the entire flow record can be revised to reflect this improved understanding of the flow response to varying level.

Keep up with data revisions

Details of revisions following annual and ad hoc reviews are published on the News page.