- General - definitions of the quality flags
- General - how often is the Hydrometric data updated?
- General - what is the difference between checked and unchecked data?
- General - how can I download the data?
- General - how accurate is the data?
- General - what is sub-daily data?
- General - what is a water day?
- General - is all the Hydrological data recorded in Greenwich Mean Time (GMT)?
- General - I have an abstraction licence. Can I use this information?
- Rivers - why is Real-Time Flow data only available for a small number of stations?
- Rivers - there are differences between the data available on the Environment Agency’s website and the National River Flow Archive, which time series should I use?
- Rivers - why do river levels or flow sometimes increase or decrease unexpectedly?
- Rivers - what is the difference between river level and river flow?
- Rivers - is river flow always a function of river level?
- Rivers - why is 15 minute (instantaneous) flow data only available for a small number of stations?
- Groundwater - why are there sometimes differences between dipped and groundwater telemetered data at the same site?
- Groundwater - what is borehole depth?
- Groundwater - what does MAOD mean?
- Groundwater - what is the difference between dipped, logged and telemetered data?
- Water Quality - why do the Water Quality sites record different variables?
- Water Quality - how are the Water Quality sites selected?
- Water Quality - how is the data different to the Water Quality Archive data?
- Water Quality - what Water Quality Data is available?
- Water Quality - how often do we take readings?
- Water Quality - why are some sites closed?
General - what is a water day?
Created: 30 March 2023 Updated: 30 March 2023
All our daily data (mean, max, min and total) are calculated over a water day. This is from 9am GMT one morning through to 8.59am GMT the following day. For example, the day mean on the 1st January is the average of all the 15 min values from 09:00 1st January to 08.59 2nd January.