The Thames Barrier

The Thames Barrier is one of the largest movable flood barriers in the world. The Environment Agency runs and maintains the Thames Barrier as well as London’s other flood defences. As the tide continues to come in, a higher level of water will build up downstream of the barrier and create a differential in water level on either side of the gates. Shortly after high water or high tide, the gates will be further rotated by 28 degrees (or roughly 2 metres) into what is called the ‘underspill’ position. The underspill is when the gates have been raised 90 degrees. The barrier is fully closed in the ‘defence’ position.

Underspill allows the higher downstream water level of the river to rush underneath the gates to shorten the amount of time it takes for the upstream and downstream water levels to equal. It also creates a ‘white rush’ effect of water behind each of the gates, stirring up the riverbed. The underspill continues for approximately 2.5 hours. You can follow us on Twitter @AlanBarrierEA or read our blog posts. or like our Facebook page. The Barrier is operated once a month for maintenance and test purposes. Details of the next planned closures are listed below.

Please note these times may change as a result of a particular experiment or test that engineers need to carry out or because of the weather. The closure and reopening of the gates may start up to an hour before the listed times. Occasionally closures may be cancelled at short notice due to the Thames Barrier being closed in that month for flood defence purposes or navigational reasons. If you plan to come and watch a test closure, please call us the day before to check it is going ahead.

Monday – 17 May 2021 -10:20am – 12:50pm
Monday – 14 June 2021 – 09:35am – 12:05pm
Tuesday – 13 July 2021 – 09:30am – 12:00 midday
Wednesday – 11 August 2021 – 09:30am – 12:00 midday
Sunday – 19 September 2021 – 06:25am – 4:25pm *
Monday – 25 October 2021 – 10:05am – 12:35pm

Annual full tidal test closure of the barrier

Please call us or check our website for our opening times, prices, and package and conference details.

Tel: 0208 305 4188




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