Types of flooding
Due to its location, Lambeth is at risk of several different types of flooding. Find out what these are, how they are managed and what you can do about preventing it or seeking advice.
Highway flooding
Highway authorities provide and manage highway drainage and roadside ditches. They are responsible for managing surface water flood risk on roads through maintenance of the highway drainage system.
Responsibility for managing the flood risk from highways in Lambeth falls to Lambeth Council and Transport for London red routes.
Flooding from rivers, seas and tides
Flooding from rivers, such as the River Thames, is referred to as fluvial flooding and is managed by the Environment Agency. Fluvial flooding occurs when the river level rises above its banks or flood defences and overflows onto land. Tidal flooding is where the river is influenced by a high tide that occurs during severe winds or storms (i.e., a storm surge).
Flood Zones mark the area susceptible to these sources and are defined for every river. These outline the different flood risks and where defences are in place to protect communities from fluvial or tidal flooding.
See the flood risk map on GOV.UK.
Surface water flooding
Surface water flooding occurs when rainwater does not drain away through the normal drainage systems or soak into the ground but lies on or flows over the ground instead. This is one of the most common types of flooding in Lambeth due to its very urban landscape and reliance on the sewer network for drainage.
See how to reduce the risk of flooding in your home.
Groundwater flooding
Groundwater flooding happens when levels of water in the ground rise above the surface. It can affect property and structures above and below the ground, with basements being particularly susceptible. It is most likely to happen in areas where the ground contains aquifers. These are permeable rock or porous substrate that water can soak into or pass through.
Lead Local Flood Authorities have a remit to manage the risk of groundwater flooding. Further information on the groundwater flood risk in Lambeth can be found in the Lambeth Surface Water Management Plan
The risk of flooding from groundwater in Lambeth is extremely low due to the depth of the water table. There are frequent occurrences in the borough of sub-surface water entering basements and cellars. This is typically due to seasonal variations in perched water (a lens of water above the natural ground water table) that flows through more porous soils found typically 1m to 2m below the surface. If the water flow lacks fluctuations (daily or even seasonally) it is likely to be from an unnaturally occurring source.
Should you experience flooding and suspect it to be from groundwater, please contact sustainability@lambeth.gov.uk
Sewer flooding
Sewer flooding happens when sewers are overwhelmed by heavy rainfall or when they become blocked. The chance of flooding depends on the capacity of the local sewerage system and the amount of rain that falls.
The water and sewerage undertaker responsible for managing the flood risk from public sewers in Lambeth is Thames Water Utilities Ltd.