HydrionisGlobal Water Intelligence
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Hydrionis for consulting and engineering

Long instrumental records assembled, validated and citable, so the first two weeks of a study are not spent reassembling public data that someone has already assembled.

Water resources, environmental and infrastructure consultancies871,326 relevant observations
871,326
Observations available
4
Relevant datasets
1836–2026
Period covered
4
Commercially reusable

What you can answer here

Where can I get a clean, citable long rainfall record?

Met Office areal series from 1836 for the UK, four nations and twelve climate districts, monthly, seasonal and annual, with a suggested citation and a version.

Go to the data →

How do I show what a drought year looked like across the water cycle?

Rainfall, river flow and groundwater for the same period, from the same platform, on the same provenance model.

Go to the data →

Relevant datasets

DatasetObservationsCoverageLicence
England River Flow Dataset255,7371879–2026Commercial use permitted
England River Water Quality Dataset252,8572000–2025Commercial use permitted
England Groundwater Level Dataset189,7201836–2026Commercial use permitted
UK Historical Rainfall Dataset173,0121836–2026Commercial use permitted

Key measures

Full dictionary →
MeasureDefinitionUnit
Annual precipitationTotal depth of precipitation falling over a defined area in a calendar or water year.
Annual totals for different countries are not comparable as a measure of water availability. A large arid country and a small wet one can have similar national average rainfall while having entirely different renewable water resources per person. Gauge networks also differ in density, and mountain precipitation is systematically under-measured.
mm
Mean river flowAverage volumetric discharge past a gauging station over a stated period.
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.
m³/s
Groundwater levelElevation of the water table or piezometric surface at a monitoring borehole.
Levels are specific to a borehole and its aquifer, and must be read against that borehole’s own historic range. Absolute elevations from different boreholes are not comparable.
m
Nitrate as nitrogenConcentration of nitrate in water expressed as the mass of nitrogen it contains, the convention used in environmental monitoring.
Reported as nitrogen, not as the nitrate ion: multiply by 4.43 to compare with a drinking-water standard written as NO₃. Concentrations are specific to the sampling point and vary strongly with river flow, so a wet year and a dry year are not directly comparable.
mg/l as N

What Hydrionis does not hold for you

Access

Everything referenced here is available through the JSON API and, where the source licence permits redistribution, as CSV extracts. Field definitions are in the data dictionary.

For bulk extracts, higher-volume API access, commercial licensing or bespoke work, see data enquiries.

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