Groundwater Flood Risk

Flooded road and gate

Flooding from groundwater can happen when the level of water within underlying rock or soil (known as the water table) rises. When the water table rises and reaches the ground level, water can seep through the surface and flooding can occur.

Groundwater flooding usually occurs following heavy or prolonged rainfall and can last weeks or even months causing significant damage and disruption.

What is the risk in Southampton?

Our current understanding of groundwater flood risk is limited due to the complexities of mapping flows and understanding where groundwater is likely to emerge. There are believed to be a number of perched water tables within the city which increases the likelihood of groundwater flooding, with issues usually arising following periods of persistent rainfall.

Who is responsible for managing the risk?

Southampton City Council as the Lead Local Flood Authority are responsible for overseeing management of the risk of flooding from groundwater.

As the LLFA we continuously aim to improve our knowledge of groundwater flood risk in the city through data collection and analysis. As part of this we ask that if you believe you have experienced groundwater flooding please report it to us to improve our understanding of the issue.

As it is a complex matter there are many studies being conducted nationally with the aim to improve the understanding of groundwater, however one of the many challenges of groundwater flooding is that many traditional methods of managing flood risk may not be effective against groundwater flooding.

How can you prepare?

Knowing the risk of groundwater flooding in your area is a good first step to understanding your flood risk and determining any measures you could take to reduce you risk. Use the Environment Agency’s Groundwater Vulnerability Map by finding your location on the map and clicking the Landscape tab and searching the Geology and Soils layer.

Managing groundwater flooding is complex however there are many steps you can take to both reduce your risk of flooding and to keep yourself safe in the event of a flood, these are explained on the following webpages: