The history and future of the Thames Barrier

The North Sea Flood of 1953 was caused by a combination of a high spring tide and severe windstorms, and in some areas led to the sea level being more than 5.6 meters above its normal height. It was one of the most devastating natural disasters ever to be recorded in the UK with 1,600 km of coastline damaged; 30,000 people evacuated, 24,000 homes affected with a consequent death toll of 307. This incident prompted calls for a mechanism to protect the capital from similar events. This led to the construction of the Thames Barrier

Construction began in 1974, and in addition to the barrier, the flood defences for 11 miles downriver were raised and strengthened. The barrier was officially opened by the Queen on the 8th May 1984, with a total coast reaching £1.5 billion (in 2014 prices). It is built across a 520-metre wide stretch of the Thames, and divides the river into 6 navigable spans.

By holding back the tide, the barrier creates more space in the river for excess water from upstream to flow down. At low tide, the Thames Barrier is then opened and the floodwaters flow to the sea. Last winter the UK had the stormiest and wettest period of weather for a century with the barrier closed a record 50 times over the winter period – compared to just 35 times between 1990 and the end of 1999.

In terms of the future of the Thames Barrier, a project entitled TE2100 aims to develop a tidal flood risk management plan for the Thames Estuary through to 2100. This strategy takes into account a changing climate, changes within the estuary and the problem of ageing flood defences. The project has a 40 year vision, producing recommendations for the first 25 years for 8 geographical areas. Public consultation has played an important part in the development of the TE2100 Plan.

The Environment Agency funded extensive research on changes in fluvial flows, sea storm surges and sea level rise. This research also featured 300 investigations into how tidal flood risk is increasing in the Thames Estuary due to ageing flood defences and the increase in people living and working within the floodplain. The conclusions drawn from these studies are that it is unlikely that major changes will be needed to be made to the existing flood defence systems and structures for the next 25 years. From 2035 the plans for the barrier are to focus on renewal and reshaping of the riverside and the upgrading of existing defences.

The Thames Barrier, with some modification, has the potential to continue to protect London though this century (based on current climate guidance). It may prove more cost effective, as a future strategy, to build further defences downstream in around 2070 to support the Thames Barrier towards the end of its lifespan.

 

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