Other sources of flooding

The River Thames and the lower reaches of some of the tributary rivers are affected by the tide. The River Thames has a very large tidal range, in excess of seven metres on spring tides. The tide’s influence reaches to Teddington Lock on the Thames and up several tributaries, for example as far as Lea Bridge on the River Lee.

As a result of the 1953 flood, a system of flood defences was constructed. The most iconic element of this is the Thames Barrier, which has been operational since 1982.

There are also around 400 smaller barriers and movable flood gates downstream of the Thames Barrier and over 300 km of river walls and embankments stretching into Essex and Kent that have been raised by up to two metres to give additional protection from storm surges.

Upstream of the Thames Barrier, river walls are still necessary to prevent the normal range of high tides from flooding parts of inner and central London.

This system of tidal flood defences made allowance for sea level rise and London is therefore protected to a very high level. Without the current river walls many areas of London alongside the Thames and along the tidal stretches of the tributaries would be inundated twice a day through the normal tidal cycle. River walls have been steadily built up since Roman times to give increasing levels of flood protection and to enable urban development.

However, climate change is causing sea levels to rise and impacting the tidal Thames. We are working with the Environment Agency and other partners to produce the Thames Estuary 2100 (TE2100) plan. The Plan sets a long-term adaptive pathway approach to managing tidal flood risk in London up to 2100.The plan includes the options of a new barrier or improving the current one, as well as other defence raising up and down stream along the network.

As a predominantly urban area London’s rivers are often heavily modified from their natural state. This means that rivers have been straightened, deepened, widened and constructed from materials such as concrete. These changes have often been made specifically to reduce the risk of flooding by either increasing the physical size of the river channel or increasing the rate at which it can convey water. 

The urbanised river environment also contains many bridges, tunnels and culvert structures. These culverts are often underneath roads or railways but sometimes flow under substantial areas of land. These form potential flood risks as they can become blocked or restricted through litter or more likely larger debris such as shopping trolleys, mattresses or even vehicles.

Some of the key schemes being developed across London led by the Environment Agency to reduce the risk of flooding from rivers can be found on the Environment Agency Flood and coastal erosion risk management page. 

The river catchments across London all have their own distinct characteristics, and therefore particular pressures which need to be managed, and these need to be understood. The solutions to manage flooding are closely linked within the water system to solutions needed to manage the demand for water, supply of water, and poor water quality. Opportunities for delivering green SuDS and natural flood management designed to provide multiple benefits will help London to adapt to climate change as well as improving the health and wellbeing benefits for local communities as they engage with and take ownership of their local river environment. 

Catchment Partnerships bring together and enable local communities to deliver nature-based solutions, their contact details and plans to improve their river catchment can be found on the Catchment Based Approach website (CaBA). You can also find more information on London partnerships on the Thames21 website.