The iconic Thames Barrier, a cornerstone of London’s flood defence strategy, was temporarily closed by the Environment Agency today to protect the city from potential flooding. The closure was initiated at approximately 8 a.m. on Monday, January 15, 2024, and is scheduled to remain in effect until 6 p.m.
The Thames Barrier, situated on the River Thames at Woolwich Reach in East London, stands as a remarkable flood control structure with a width of 520 meters. Its primary function is to safeguard London from the perils of storm surges and the risk of increased river levels due to heavy rainfall.
This vital structure currently shields an expansive area of 125 square kilometres (48 square miles), which includes approximately 1.25 million residents, property and infrastructure valued at £200 billion, a significant portion of the London tube network, and numerous historic landmarks. Notable areas under its protection include the Houses of Parliament, the O2 arena, Tower Bridge, and neighbourhoods such as Southwark, Beckton, West Ham, and Whitechapel.
The Thames Barrier, a feat of engineering that became fully operational in 1982, plays a pivotal role in London’s flood defence strategy. It was constructed over eight years for £535 million, equivalent to £1.6 billion in today’s currency. Ranking as the second-largest flood defence barrier globally, it trails only the Oosterscheldekering Barrier in the Netherlands.
Before the Thames Barrier’s existence, flood defence strategies in London focused on constructing higher and more robust river walls and embankments. This approach, in place since the Thames Flood Act of 1879, remained prevalent until the mid-20th century. However, the devastating flood of 1953, which claimed 307 lives and caused an estimated £50 million in damages (equivalent to £5 billion today), prompted a significant shift in approach.
In response, the Thames Barrier and Flood Protection Act of 1972 empowered the construction of a flood barrier with movable gates across the Thames. The barrier’s creation was further recommended following a report by Sir Herman Bondi in 1966.
The Thames Barrier is a complex system comprising ten separate movable steel gates, each towering at a height of 20 meters and weighing approximately 3,700 tonnes. These gates can withstand an overall load of more than 9,000 tonnes of water. When closed, they form a solid steel wall that effectively seals the upper part of the river from the sea, preventing water from flowing upstream towards central London. The gates can also be partially closed in the under spill position, allowing a controlled amount of water to pass beneath them.
During a closure, individual gates can be sealed in just ten minutes, while the complete closure of the barrier takes roughly an hour and a half. When not in use, the gates remain hidden within curved recessed concrete cells in the riverbed, allowing river traffic to navigate freely.
The decision to close the Thames Barrier is triggered by a combination of high tide forecasts in the North Sea and elevated river flows at the tidal limit of Teddington weir. Closure becomes necessary when these factors indicate that water levels could surpass the critical threshold of 4.87 meters in central London.
The Thames Barrier has been closed on 174 occasions since it became operational in 1982, with half of these closures intended to protect against tidal flooding and the other half aimed at alleviating river flooding.
As the threat of flooding in London grows due to climate change and rising sea levels, the Thames Barrier continues to evolve to meet future challenges. The Thames Estuary 2100 project, initiated in 2002, seeks to develop a strategic flood risk management plan for London and the Thames Estuary through to 2100. This plan considers factors such as climate change, sea level rise, changes in land levels, ageing defence infrastructure, and new developments in the tidal floodplain.
The Thames Barrier is not the sole flood defence structure slated for improvement under the Thames Estuary 2100 Project. Other tidal flood defence structures and measures, including the Barking Barrier, King George V lock gate, Gallions Flood Gate, Dartford Barrier, Tilbury Dock, Fobbing Horse, Easthaven Barrier, and Benfleet Barrier, will also undergo enhancements. Additionally, the tidal Thames boasts 36 major industrial floodgates and 480 smaller movable structures, primarily safeguarding residential properties.
The temporary closure of the Thames Barrier serves as a poignant reminder of the critical role this engineering marvel plays in protecting London and its residents from the ever-present threat of flooding.
