{"id":"france-river-flow","slug":"france-river-flow","name":"France River Flow Dataset","description":"Monthly mean river discharge for long-record sites on the French national hydrometric network, including records opening in the 1910s and 1920s. The first non-anglophone national hydrometric network Hydrionis holds.","methodology":"Taken from the Hub’Eau hydrometry service’s own elaborated monthly mean (QmM), which the French flood forecasting service computes from its validated sub-hourly record. Hydrionis does not recompute it from daily values: the publisher knows which of its readings passed validation and Hydrionis does not. Series are indexed by hydrometric *site* rather than station, so a record continues across each rebuild of the installation at that place. Discharge is published in litres per second and converted to cubic metres per second, with the publisher’s unit recorded on every series. Sites need thirty years of monthly record, and at most ten are taken from each department so that coverage follows French geography rather than the historical density of French gauging.","domains":["river-flow"],"metricIds":["river-flow-monthly-mean"],"subjectScope":"French hydrometric sites with 30+ years of monthly record, capped at ten per department","cadence":"monthly","version":"1.0.0","released":"2026-08-25","changelog":[{"version":"1.0.0","date":"2026-08-25","summary":"First release.","additions":["Monthly mean flow for long-record sites across metropolitan and overseas France."]}],"limitations":["Flow is a property of a gauging site and its reach, never of a river as a whole. Two sites on the same river can differ by an order of magnitude.","The per-department cap means this is a representative national network, not the complete French record. Sites excluded by the cap met the record-length threshold and were dropped for coverage balance, not for quality.","Some sites sit on regulated reaches where flow reflects reservoir and hydropower operation as well as catchment runoff. The publisher’s influence flag is not currently carried through."],"observationCount":646543,"seriesCount":896,"subjectCount":896,"from":1900,"to":2026,"sourceIds":["fr-hubeau-hydrometrie"],"units":["m³/s"],"redistributable":true,"commerciallyReusable":true,"citation":"Hydrionis (2026), France River Flow Dataset, version 1.0.0. Retrieved from https://hydrionis.com/data/datasets/france-river-flow/","downloads":[{"file":"/downloads/observations-river-flow-fr-hubeau-hydrometrie.csv","format":"CSV","label":"river-flow observations from Hub'Eau (659,397 rows)"}],"apiPath":"/api/v1/datasets/france-river-flow.json","lastFetched":"2026-10-01","fields":[{"id":"river-flow-monthly-mean","name":"Mean monthly river flow","definition":"Average volumetric discharge past a gauging station over a calendar month.","unit":"m³/s","nativeGeography":["river-gauge"],"comparabilityNotes":"A gauge property, not a river property. Strongly seasonal, so compare a month against the same month in other years. Gauge records contain breaks where structures were rebuilt or ratings revised."}]}