{"id":"hydrionis-derived-climatology","slug":"hydrionis-derived-climatology","name":"Hydrionis Derived Climatology Dataset","description":"Everything Hydrionis computes rather than collects, in one place: reference normals and decadal means, the rainfall totals added up from daily station records, and the flow duration curves and annual maxima read off daily discharge records. The umbrella over the whole calculated layer, with the full input chain recorded for every value. The two families that are products in their own right are also catalogued separately, as the Station Rainfall Totals and River Flow Regime datasets.","methodology":"Computed through the Hydrionis derivation engine. Reference normals are arithmetic means over the complete WMO 1991–2020 period, produced only where all thirty years are held. Decadal means are produced only where at least eight of a decade’s ten years are held, and for compositional metrics such as the withdrawal sector shares, only over the years every member of the composition holds — averaging shares independently produces components that no longer sum to their total. Every value carries its method, method version, formula, input observation identifiers, input source identifiers and the limitations of the method that produced it.","domains":["precipitation","temperature","river-flow","groundwater","withdrawal"],"metricIds":[],"subjectScope":"Every subject for which Hydrionis holds a sufficiently complete record","cadence":"irregular","version":"1.1.0","released":"2026-08-31","derived":true,"changelog":[{"version":"1.1.0","date":"2026-08-31","summary":"The families calculated from daily records join the derivation layer.","methodVersion":"total-over-period 1.0.0, flow-duration-percentile 1.0.0, annual-maximum-of-daily 1.0.0","additions":["Annual and seasonal rainfall totals, and station reference averages, added up from daily station records. Catalogued in their own right as the Station Rainfall Totals dataset.","Flow duration curve percentiles and annual maximum daily flow, read off daily discharge records. Catalogued in their own right as the River Flow Regime dataset.","Where a calculation reads more inputs than can usefully be listed, the value now records the stretch of the series it was taken from and how many of those periods carried a number, in place of naming every reading individually."]},{"version":"1.0.0","date":"2026-08-24","summary":"First release of the governed derivation layer.","methodVersion":"mean-over-period 1.0.0","additions":["Reference normals and decadal means with full input provenance."]}],"limitations":["These are computed figures, not measurements. Each carries the limitations of its method, and those limitations are part of the value rather than a footnote to it.","Rights are inherited from the observations that fed each calculation. A derived value is no more freely usable than its most restrictive input.","A recomputation with a changed method produces different numbers. The method version is recorded so that a figure cited previously can still be explained."],"observationCount":468089,"seriesCount":28140,"subjectCount":8715,"from":1827,"to":2026,"sourceIds":["eurostat-water","fao-faostat","fi-syke-hydrologia","fr-hubeau-hydrometrie","fr-hubeau-piezometrie","nifc-fire-perimeter-history","noaa-ghcn-daily","se-smhi-hydro","uk-defra-wild-birds","uk-ea-hydrology","uk-ea-wims","uk-metoffice-haduk","uk-sepa","us-bureau-reclamation","us-nrcs-snotel","usgs-nwis","worldbank-wdi"],"units":["%","Mm³","NTU","ha","index","kg/ha","km³/yr","m","mg/l","mg/l as C","mg/l as CaCO₃","mg/l as N","mg/l as P","mg/l as SO₄","mm","months","m³/person/yr","m³/s","pH","t","°C","µS/cm","µg/l"],"redistributable":true,"commerciallyReusable":false,"rightsNote":"Redistribution is permitted by every contributing source.","citation":"Hydrionis (2026), Hydrionis Derived Climatology Dataset, version 1.1.0. Retrieved from https://hydrionis.com/data/datasets/hydrionis-derived-climatology/","downloads":[],"apiPath":"/api/v1/datasets/hydrionis-derived-climatology.json","inputsLastRead":"2026-10-05","fields":[]}