The role of groundwater in the Thames river basin

Superficial deposits of the Thames basin

The Thames river basin is a battleground for environmental change and the water environment is no exception. With a population of over 13 million people and with London at its heart, population increases, land-use pressures and water resources are already delicately balanced with climate change bringing even more uncertainty. In the space of just a couple of years, water levels have swung from record lows to record highs bringing extreme drought and devastating floods. To manage the pressures on our water environment and to make informed policy decisions we need sound scientific understanding and evidence.

The Thames catchment is rich in groundwater resources with the Chalk, Cotswold limestone and Lower Greensand forming principal aquifer units which support 40 per cent of public water supplies and sustain our rivers. As experts in groundwater science BGS is involved in a number of research projects that provide a basin-scale assessment of groundwater resources as well as local-scale groundwater issues such as contaminant attenuation in floodplains.

Characterising the hydraulic properties of superficial deposits

There is an extensive covering of superficial deposits within the Thames basin. These are primarily river terrace deposits associated with the River Thames itself and the Rivers Kennet, Ock and Lea. Using a combination of data from the minerals industry and statistical modelling approaches, permeability of superficial deposits across the basin has been mapped. These approaches show systematic variations in aquifer characteristics across the Thames basin that can be related to depositional and post-depositional history.

Integrated surface-water groundwater modelling of the Thames catchment

Floodplains and their role in contaminant attenuation.

Modelling the water resources of the Thames catchment is challenging because we are reliant on both surface water from our rivers and groundwater from several aquifers. To assess this complex water system we are developing a series of linked hydrological and groundwater models, which will be used to assess water availability under a landscape of multiple pressures such as climate change and land use change.

River Thames floodplain near Oxford

Floodplains are dynamic systems in which water is exchanged between the river and adjacent meadow and often forms a boundary between urban and rural areas. The floodplains potentially play a key role in attenuating contaminants, particularly from urban environments. Using Port Meadow near Oxford we are investigating how the biogeochemical processes operating in floodplain environments might affect the concentrations of urban contaminants reaching surface water courses.


More about groundwater in the Thames basin:

Reference

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