London flood risk

A Greater London Assembly report in 2011 stated that there was a `serious risk` of flooding if London faces severe rainfall. Regardless of the Thames Barrier – which is there to protect against flooding from the sea, the London Assembly’s Environment Committee claim that some streets could flood from rain within minutes. Rainfall equal to what other parts of the country experienced in 2007 could flood roads within minutes and cause river flooding soon thereafter. According to the report, ‘lives could be lost’ and damage to property could amount to ‘tens of billions of pounds’. The report concludes that it is ‘just chance’ that London has so far escaped rainfall severe enough to cause widespread flooding.

According to the Environment Agency, there are about 534,000 properties in London on the Thames floodplain (about 1 in 4 properties).

Flooding is one of London’s highest risks with up to 680,000 properties at risk of flooding across the capital. Three types of flooding may affect the capital:

Surface Water flooding when the drainage network becomes overloaded in heavy rainfall.

• Tidal Flooding from River Thames Flood Surges – this is what the Thames Barrier protects against.
• River Flooding from the River Thames and tributaries. This would result from heavy rainfall upstream of London, similar to the rainfall upstream of Tewkesbury in the 2007 floods.