Hydrometric
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Data & attributions

Hydrometric combines several third-party and open datasets. This page lists each source, its licence, and the attribution required to reuse it. Where a dataset has a version (e.g. the NRFA Peak Flow Dataset), the currently deployed version is stated below and is recorded against every analysis in its audit record.

Hydrological data

NRFA Peak Flow Dataset

Annual maximum flow (AMAX), peaks-over-threshold (POT), and catchment descriptor records are sourced from the National River Flow Archive (NRFA) Peak Flow Dataset, published by the UK Centre for Ecology & Hydrology (UKCEH). Hydrometric's production database is built from NRFA Peak Flow Dataset version 14.0.1.

© UK Centre for Ecology & Hydrology. Used under the NRFA data terms (see the NRFA data download terms and conditions). Live station browsing (map viewer only) additionally uses the NRFA public API.

EA Hydrology Data Explorer & SEPA data

River level, flow, and rainfall gauge data referenced from the Environment Agency (EA) Hydrology Data Explorer are made available under the Open Government Licence v3.0 (OGL v3). © Environment Agency copyright and/or database right.

Equivalent Scottish gauge data is © Scottish Environment Protection Agency (SEPA) copyright and/or database right, used in accordance with SEPA's data terms.

UKCP18-derived climate change allowances

Climate change allowance factors for peak river flow are derived from UK Climate Projections 2018 (UKCP18) and published as Environment Agency flood risk assessment climate change allowance guidance. © Met Office / © Environment Agency. Guidance reproduced under OGL v3. Coverage is limited to the 11 EA river basin districts (England only) — Scotland (SEPA) and Wales (NRW) guidance is not currently implemented.

FEH statistical & ReFH method citations

The FEH statistical method (SM2008/SM2025), pooling group formation, and ReFH rainfall-runoff model implemented in Hydrometric are based on published Flood Estimation Handbook (FEH) and UKFE methodology. The ReFH rainfall-runoff output is a research preview computed with the published ReFH1 (Kjeldsen, 2007) coefficients; the production ReFH2 coefficients are licensed to Wallingford HydroSolutions (WHS) and are not used here. Full bibliographic citations are listed in the references section of every generated report, and the underlying methodology is documented in:

Map data

Basemaps

The interactive catchment map offers a choice of basemap styles:

Terrain & LiDAR

The 2 m LiDAR, hillshade, and slope terrain layers are derived from the Environment Agency 2 m LiDAR composite, processed and served by Aegaea's terrain tile infrastructure. Coverage is limited to locations present in the source composite. © Aegaea / © Environment Agency copyright and/or database right. EA LiDAR source data is made available under OGL v3.

Current-view PNG exports reproduce the layers selected in the interactive map. Standard catchment/project map exports and Flood Estimation Reports use a fixed, auditable 2 m LiDAR recipe. Where LiDAR has no coverage or the terrain service is unavailable, the output is explicitly captioned as a topographic or neutral fallback; its recipe, boundary version, renderer version, and fallback reason are recorded in report provenance.

Questions

For questions about data licensing or to report an attribution issue, contact the Hydrometric team.