Hydrionis for consulting and engineering

1,367,476

Observations available

Relevant datasets

1836–2026

Period covered

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

Dataset	Observations	Coverage	Licence
England River Water Quality Dataset	748,160	2000–2025	Commercial use permitted
England River Flow Dataset	255,739	1879–2026	Commercial use permitted
England Groundwater Level Dataset	189,904	1836–2026	Commercial use permitted
UK Historical Rainfall Dataset	173,673	1836–2026	Commercial use permitted

Key measures

Full dictionary →

Measure	Definition	Unit
Annual precipitation	Total 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 flow	Average 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 level	Elevation 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 nitrogen	Concentration 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

Use this data

No bulk download is offered here, which is a licence position rather than a product one: at least one contributing publisher does not permit redistribution. The values can be read on the page, cited, and pointed to at source.

The bulk extract archive is at downloads, and the datasets above each carry their own file where the licence permits one.

Field definitions are in the data dictionary. What Hydrionis withholds and why is on why some values are missing. What exists today for organisations, and what does not, is on Hydrionis Professional.