{"id":"gauge-water-linkage","slug":"gauge-water-linkage","name":"Hydrionis Gauge–Water Linkage Dataset","description":"Which water body each monitoring gauge sits on, and the evidence for it. A versioned, materialised derivation covering the jurisdictions whose publishers state the relationship, with the method, the method version, the evidence source and the date of derivation recorded on every linkage.","methodology":"A governed derivation, worked out once and stored rather than recalculated when a page is shown, so river pages render 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 Hydrionis 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.","domains":["river-flow"],"metricIds":["river-flow-mean","river-level"],"subjectScope":"River gauges in jurisdictions whose publisher states the water body","cadence":"irregular","version":"1.0.0","released":"2026-08-26","derived":true,"changelog":[{"version":"1.0.0","date":"2026-08-26","summary":"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."]}],"limitations":["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 stored and versioned rather than recalculated each time, such a change appears as a reviewable difference 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."],"observationCount":14277,"seriesCount":2086,"subjectCount":2086,"from":1880,"to":2010,"sourceIds":["uk-ea-hydrology","usgs-nwis"],"units":["m³/s"],"redistributable":true,"commerciallyReusable":true,"citation":"Hydrionis (2026), Hydrionis Gauge–Water Linkage Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/gauge-water-linkage/","downloads":[{"file":"/downloads/observations-river-flow-usgs-nwis.csv","format":"CSV","label":"river-flow observations from USGS (646,106 rows)"},{"file":"/downloads/observations-river-flow-uk-ea-hydrology.csv","format":"CSV","label":"river-flow observations from EA (261,070 rows)"}],"apiPath":"/api/v1/datasets/gauge-water-linkage.json","inputsLastRead":"2026-10-01","fields":[{"id":"river-flow-mean","name":"Mean river flow","definition":"Average volumetric discharge past a gauging station over a stated period.","unit":"m³/s","nativeGeography":["river-gauge"],"comparabilityNotes":"Flow is a property of a specific gauge on a specific reach, and cannot be attributed to a river as a whole. Two gauges on the same river can differ by an order of magnitude. Where a station measures flow through a sluice, lock or pumping station — much of the Dutch network does — discharge is signed and a negative value means water moving in the reverse direction, which is a real operating state and not an error. Managed flow of that kind is not comparable with discharge at a natural gauging station, because it reflects operational decisions as well as hydrology."},{"id":"river-level","name":"River level","definition":"Height of the water surface at a gauging station, measured against that station’s own zero point.","unit":"m","nativeGeography":["river-gauge"],"comparabilityNotes":"Level is measured against each station’s own zero point, which is set locally and is not a common datum. Two gauges reading 3 m are not at the same height, and a level is not a depth of water: it says where the surface sits relative to a reference, not how deep the river is. Read a level against that gauge’s own record, never against another gauge’s."}]}