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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:

CEFA point estimate (beta)

The CEFA point estimate (map click panel, the cefa_point_estimate MCP tool, and its CSV/JSON downloads) is a storm-response simulation built from several open datasets, listed here individually because none of them is the NRFA Peak Flow Dataset above:

  • Rainfall — CEH-GEAR daily 1 km rainfall. © Database Right/Copyright UK Centre for Ecology & Hydrology. All rights reserved. Contains material based on Met Éireann data © Met Éireann and Met Office data © Crown copyright. Made available under the Open Government Licence v3.0 (OGL v3) (DOI 10.5285/dbf13dd5-90cd-457a-a986-f2f9dd97e93c).
  • Storm-response training data — UK-Flow15, 15-minute flow records. Rights holders: Newcastle University, UK Centre for Ecology & Hydrology, Environment Agency and Scottish Environment Protection Agency, OGL v3 (DOI 10.5285/211710ac-f01b-4b52-807f-373babb1c368), and NRFA Peak Flow Dataset descriptors: “Data from the UK National River Flow Archive” (version 14.0.1, as above, used under the NRFA data terms).
  • Terrain, catchment delineation and urban extent — a blend of the Environment Agency 2 m LiDAR Composite DTM and OS Terrain 50, and OS Open Zoomstack (urban areas). Contains OS data © Crown copyright and database right. © Environment Agency copyright and/or database right 2022. All rights reserved. Made available under OGL v3.
  • SAAR9120 and PROPWET — the served raster reconstructs byte-for-byte from HadUK-Grid v1.3.0.0 1 km annual 30-year rainfall (1991–2020). Contains Met Office data © Crown copyright and database right, OGL v3 (DOI 10.5285/b963ead70580451aa7455782224479d5).
  • Soil (HOST classification) — Data originated from the Cranfield University, Land Information System LandIS® Portal (National Soil Map; Calculating SPRHOST and BFIHOST from soil assoc maps, May 2026) as Public Data 2026, subject to the Open Licence (LandIS Portal EULA).

CEFA is a beta research feature: sharper than FEH SM2025 up to 1-in-20 on 456 unseen catchments, and not certified for design use.

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.

EA flood-risk map overlays

The optional Flood zones (2 & 3) and Surface water risk map overlays are drawn live from Environment Agency web map services published on the Defra Data Services Platform: the Flood Map for Planning (Rivers and Sea) - Flood Zones and the Risk of Flooding from Surface Water (NaFRA2) datasets. © Environment Agency copyright and/or database right, made available under the Open Government Licence v3.0 (OGL v3).

Both overlays are off by default and are map context only - they are indicative published extents, not a site-specific flood risk assessment, and no hydrology calculation in Hydrometric reads them. The EA publishes both services above 1:50,000 only, so they appear once the map is zoomed in. Coverage is England.

Questions

For questions about data licensing or to report an attribution issue, contact the Hydrometric team at community@hydrometric.io.