BGS operates the National Groundwater Level Archive (NGLA). The NGLA, along with the National River Flow Archive, is run in partnership with the UK Centre for Ecology & Hydrology and other measuring authorities:
- Environment Agency in England
- Department of the Environment in Northern Ireland
- Scottish Environment Protection Agency in Scotland
- Natural Resources Wales/Cyfoeth Naturiol Cymru in Wales
Where does the groundwater level data come from?
The NGLA collects and archives groundwater level time-series data from both the current observation borehole network (operated by the various measuring authorities) and from historical sites that were previously monitored but have since been decommissioned.
How are groundwater levels measured?
Groundwater levels are now measured manually using a dipper or automatically by a pressure transducer. Automatic readings may be stored in a datalogger that is visited periodically and downloaded by field staff, or sent automatically over the phone network to a database in a data centre (telemetry).
The observation borehole network
The groundwater observation borehole network in the UK has grown over the years and now comprises thousands of boreholes, many of which are telemetered. This network development, operation and maintenance is carried out by the various measuring authorities.
Since before the 1980s, subsets of the observation borehole network have been selected as ‘index wells’ to monitor aquifer response to meteorological drought as well as factors such as climate or land-use change. Of particular importance are the 40 boreholes from the archive used for the Hydrological Summary for the UK.
Data for these boreholes is compiled monthly to provide a continually updated picture of national and regional trends and variations in groundwater resources. Boreholes have been chosen to represent all major UK aquifers and, as far as possible, the boreholes were selected as being in zones least affected by substantial abstraction. This allows the archive to provide a summary of the natural groundwater situation, although the network does include boreholes in the London Basin and some other areas affected by pumping.
Data storage
The groundwater level data in the NGLA is held within a corporate database and is linked to the associated well record from our WellMaster database. WellMaster holds important information such as borehole construction, aquifer information and geology for around 60 000 boreholes. WellMaster data comes from logs of boreholes that were drilled for water supply; many also contain a single historical reading of the water level taken after drilling or when the borehole was surveyed.