Hydrionis Gauge–Water Linkage Dataset

49,588

Observations

7,887

Series

5,158

Subjects

1840–2010

Period covered

Methodology

Built by scripts/build-linkage.ts, a governed derivation run separately from ingestion and committed to the repository, so a page build performs no joins and a clone renders river pages without contacting the publishers. Four station registers are read: the Environment Agency’s riverName, SEPA’s river_name and catchment_name, Hub’Eau’s libelle_cours_eau with the Sandre watercourse code, and the USGS site service’s huc_cd, named from the Watershed Boundary Dataset. All four are Tier A — the publisher’s own statement about its own station. Two further jurisdictions state the water body on the record ingestion already reads, and those relationships arrive with the observations rather than through this derivation; the registry records which route each took and ranks neither above the other. There is deliberately no name-matching tier.

What this dataset cannot tell you

Read before relying on these figures

A United States linkage attaches a gauge to an eight-digit hydrologic subbasin, which is a drainage area and not a river. Many subbasins take the name of the largest river within them, and a gauge in one may sit on any watercourse inside it.
Nine hundred and nine river gauges remain unresolved, and are reported as unresolved rather than inferred. Most are Irish and Dutch: the Office of Public Works publishes the relationship behind a click-through agreement granting no reuse licence, and Rijkswaterstaat publishes no water body at all.
Boreholes, raingauges and water quality sampling points are not linked to water bodies and are not counted as unresolved. A borehole measures an aquifer and a raingauge measures the sky.
A publisher renaming a river changes this dataset. Because it is materialised and versioned rather than recomputed at build time, such a change appears as a reviewable diff rather than as a page that quietly says something new.
No spatial tier exists. One was prototyped against an authoritative open river-water-body layer and not shipped, because the coordinate handling could not be validated to a standard that would justify publishing a river name.

Coverage

Subjects	River gauges in jurisdictions whose publisher states the water body — 5,158 held
Period	1840–2010
Units	%, Mm³, km³/yr, m, mg/l, mg/l as N, mg/l as P, mm, m³/person/yr, m³/s, pH, °C
Update cadence	Irregularly, when the publisher releases
Identifier	`gauge-water-linkage` v1.0.0

Fields

Data dictionary →

Every metric this dataset carries, with the unit it is stored in and the geography level it is reported at. Full definitions are in the data dictionary.

Identifier	Field	Unit	Reported at
`river-flow-mean`	Mean river flow Average volumetric discharge past a gauging station over a stated period.	m³/s	river-gauge
`river-level`	River level Height of the water surface at a gauging station, measured against that station’s own zero point.	m	river-gauge

Rights and access

Licence position

Open with attribution. Derivative use true; redistribution true; commercial reuse true.

Attribution required:

Data from Eurostat, used under European Commission reuse policy (Decision 2011/833/EU).
Source: Hub’Eau / Système d’information sur l’eau, under Licence Ouverte (Etalab).
Contains public sector information licensed under the Open Government Licence v3.0.
Data from World Bank, used under CC BY 4.0.

HadUK-Grid is available under the Open Government Licence via the CEDA archive, which requires free registration. Other Met Office products, including forecast and commercial services, are separately licensed and are not open.
Applies to material authored by US federal agencies. Third-party material carried within a federal product may be separately protected.

Permitted uses

Public display
Derived analysis
API delivery
Bulk download
Commercial use

Available to: Public, Developer, Research, Professional, Enterprise. These follow from the rights of the contributing publishers, not from a Hydrionis pricing decision — no access tier can widen what a publisher withheld.

Contributing sources

Eurostat — Water statistics (European Commission reuse policy (Decision 2011/833/EU))
Office français de la biodiversité / SCHAPI — Hydrométrie — French river flow and stage (Licence Ouverte / Open Licence v2.0 (Etalab))
Bureau de recherches géologiques et minières — Piézométrie — French groundwater levels (Licence Ouverte / Open Licence v2.0 (Etalab))
Environment Agency — Hydrology Data Explorer API (Open Government Licence v3.0)
Environment Agency — Water Quality Archive (WIMS) (Open Government Licence v3.0)
Met Office — HadUK-Grid gridded climate observations (Open Government Licence v3.0)
Scottish Environment Protection Agency — SEPA water environment data (Open Government Licence v3.0)
United States Geological Survey — National Water Information System (US Government work — public domain)
World Bank — World Development Indicators (CC BY 4.0)

Suggested citation

Hydrionis (2026), Hydrionis Gauge–Water Linkage Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/gauge-water-linkage/

Cite the version. Hydrionis datasets change as publishers release and as methods are revised, and a citation without a version cannot be checked later.

Changelog

Version 1.0.0 — 2026-08-26

First release. Unresolved river gauges fall from 4,166 to 909 without a single name match.

Additions

Tier A linkage for England, Scotland, France and the United States, from four publisher station registers.
Method, method version, evidence source and derivation date recorded on every relationship.
Canonical water-body types derived from evidence, keeping a United States hydrologic unit distinct from a river.

Getting the data

Machine-readable metadata for this dataset is at /api/v1/datasets/gauge-water-linkage.json. For bulk extracts, higher-volume access or commercial licensing, see data enquiries.