Groundwater flooding can occur where there has been a decrease in abstraction from large aquifers underlying major urban centres, due to a reduction in industrial activities. Previously depressed groundwater levels recover, causing the risk of flooding to subsurface infrastructure such as tunnels and the basements of buildings. It can also cause changes in the geotechnical and geochemical properties of the subsurface that could result in settlement and corrosion of deeply founded structures.
Schematic representation of the bedrock geology of the London Basin and Chalk groundwater levels. This does not include the overlying superficial deposits (Thames Water © 2007.)
Groundwater rebound in UK cities
Groundwater rebound has occurred in some of the UK’s major conurbations including London, Birmingham, Nottingham and Liverpool.
In London in the late 1990s, a group of stakeholders including Thames Water, the Environment Agency and London Underground developed a strategy to address this risk by increasing groundwater abstraction from the confined Chalk aquifer underlying central London by around 50 million litres per day, using this water for public and private supply. This has resulted in the stabilisation of groundwater levels.
Contact
Please contact BGS Enquiries (enquiries@bgs.ac.uk) for further information.