NRFA Peak Flow Dataset Version 10 released

The National River Flow Archive has released an update to its Peak Flow Dataset including the files for use in the WINFAP software for flood estimation.

The dataset includes Annual Maxima (AMAX) and Peaks over Threshold (POT) data for 939 gauging stations which have been updated with an additional water year of data (October 2019 to September 2020) in England, Northern Ireland and Wales. No update was available for sites in Scotland due to issues with the hydrometric archive.

New AMAX1 records were set at 39 stations during water year 2019/2020 with the majority of records being set in Wales and northern and central England as a result of successive large rainfall events, most notably in November 2019 and February 2020 (Sefton et. al., 2021).

As well as the additional water year of data, a period-of-record review was undertaken at 94 stations across England, Scotland and Northern Ireland – around 3,500 years of data! In Wales, tasks were undertaken to review AMAX/POT comments and photographs for all peak flow sites.

Download Version 10 of the NRFA peak flow dataset

The period-of-record review element provides an extensive check of the full record of data for 94 stations in the Peak Flow Dataset. It covers:

  • Flow and stage data (including the extension of the dataset with recent and where applicable, early records)
  • Gaugings and ratings
  • Missing data periods
  • FEH Indicative Suitability
  • Metadata (station descriptions, station type, datum history, POT threshold, bankfull stage)
  • Unrepresentative data periods
  • Rejected data

A list of stations that were included in this year’s period of record review can be found in the release note.

The NRFA’s Peak Flow Dataset provides flood data for 939 river flow gauging stations around the UK. The data can be used with the flood estimation methods set out in the Flood Estimation Handbook (FEH), which is the industry standard for current flood estimation in the UK. The Peak Flow Dataset has been shown to provide net economic benefits of almost £5.4 million per year in terms of costs saved by environmental consultants and regulators.

The Peak Flow data provided through this service originate from gauging stations operated by a range of UK hydrometric Measuring Authorities as is the case with other NRFA data. Maintenance of the NRFA Peak Flow Dataset, including the latest update, is carried out under a collaborative project between the UK Centre for Ecology & Hydrology, the Environment Agency, Natural Resources Wales, Northern Ireland’s Department for Infrastructure – Rivers, and the Scottish Environment Protection Agency.

The updated NRFA Peak Flow Dataset (Version 10) was released on 27th August 2021 and reflects the NRFA data holdings at this time. It is the seventh version released since the NRFA took over the stewardship of the national Peak Flows database. Updated peak flow time series and metadata are now available to view on the NRFA website and can be found using the NRFA’s gauging station search tool.

More information about the update can be found in the Version 10 release note.