- General - definitions of the quality flags
- General - how accurate is the data?
- General - how can I download the data?
- General - how often is the Hydrometric data updated?
- General - I have an abstraction licence. Can I use this information?
- General - is all the Hydrological data recorded in Greenwich Mean Time (GMT)?
- General - what is a water day?
- General - what is sub-daily data?
- General - what is the difference between checked and unchecked data?
- Groundwater - what does MAOD mean?
- Groundwater - what is borehole depth?
- Groundwater - what is the difference between dipped, logged and telemetered data?
- Groundwater - why are there sometimes differences between dipped and groundwater telemetered data at the same site?
- Rainfall - how do I download historic rainfall data?
- Rivers - is river flow always a function of river level?
- 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 - what is the difference between river level and river flow?
- Rivers - why do river levels or flow sometimes increase or decrease unexpectedly?
- Rivers - why is 15 minute (instantaneous) flow data only available for a small number of stations?
- Rivers - why is Real-Time Flow data only available for a small number of stations?
- Water Quality - how accurate is the data?
- Water Quality - how are the Water Quality sites selected?
- Water Quality - how do I analyse the data?
- Water Quality - how is the data different to the Water Quality Archive data?
- Water Quality - how often do we take readings?
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?
Created: 20 November 2018 Updated: 30 March 2023
We work closely with the National Flow Archive to ensure the daily flow data we provide them with is the same as we hold in our archive. Over time there is a risk that there may be small differences for a small percentage of records at a few sites. The Environment Agency will regard its daily flow data as correct unless there is evidence to prove otherwise.
Note that the NRFA Peak River Flow dataset is to be used as the primary source for flood peak data. The stations selected for the NRFA have been subject to further analysis for peak flow quality assessment including additional peak flow data that pre-dates the Environment Agency’s digital the EA’s hydrometric archive (WISKI database), consequently, some stations in the Hydrology Data Explorer have peak flow data that currently differ from that in the NRFA.