Future Flows and Groundwater Levels: projections for the 21st century

Climate change will increase temperatures and change rainfall across England, Scotland and Wales. In turn, this will modify patterns of river flow and groundwater recharge, affecting the availability of water and changing the aquatic environment.

There have been many studies of the impact of climate change on river flows in different parts of the UK, but coverage has been uneven and methods have varied. This has meant that it has been very difficult to compare between different locations and hard to identify appropriate adaptation responses.

The Future Flows and Groundwater Levels project has addressed these issues by carrying out a consistent assessment of the impact of climate change on river flows and groundwater levels across England, Wales and Scotland. We used the latest probabilistic climate projections from the Met Office Hadley Centre (UKCP09).

The project has been co-funded by the Environment Agency, Defra, UKWIR, the British Geological Survey, the Centre for Ecology and Hydrology (CEH), and Wallingford HydroSolutions.

Projections of changes in groundwater levels

Projections of changes in groundwater level, simulated using the project's climate projections, have been made using two types of groundwater models:

lumped catchment groundwater models (R-Groundwater) of groundwater level time-series at 24 observation boreholes in the main aquifers across Great Britain
a ZOOMQ3D distributed groundwater model of the Chalk aquifer of the Marlborough and Berkshire Downs and south-west Chilterns

Climate projections

The project has used the following information from UKCP09 to assess changes in river flows and groundwater levels across England, Scotland and Wales:

projections from the ensemble of 11 variants of the Met Office Regional Climate Model (HadRM3) as continuous time-series of climate variables from 1950 to 2099
probabilistic projections of changes in climate variables as an ensemble of 10 000 monthly change factors for the following three time-slice and greenhouse gas emission scenario combinations:

2050s under a medium emissions scenario (A1B)
2080s under a medium emissions scenario (A1B)
2050s under a high emissions scenario (A1FI)

Downscaled climate products

Based on these projections the project has generated the following climate datasets:

1 km gridded time-series (1950–2098) of precipitation and potential evapotranspiration for Great Britain for each of the 11-member ensemble of HadRM3 climate simulations
Catchment average time-series (1950–2098) of precipitation and potential evapotranspiration for 283 river sites and 24 groundwater observation boreholes, for each of the 11-member ensemble of HadRM3 climate simulations

These data are available through the Future Flows and Groundwater Levels official website operated by the Centre for Ecology and Hydrology (CEH).

Projections of changes in river flows

The climate projections have been used to simulate changes in river flows at 283 river sites across Great Britain using both the 11-member ensemble of regional climate model projections and for 30 selected rivers the ensembles of 10 000 monthly change factors. These outputs are accessible at Future Flows and Groundwater Levels official website operated by CEH.