What are facts about the Thames Barrier?

- The Thames Barrier is a flood defence system built across the River Thames in London, England.

- It is designed to prevent flooding of central London from tidal surges and high river flows.

- The Thames Barrier is the second-largest movable flood barrier in the world, after the Maeslantkering in the Netherlands.

- It is managed by the Environment Agency, an executive non-departmental public body of the UK Government.

- The barrier is 520 meters(1,706 ft) long and stands 18.3 metres (60 ft) tall.

- It consists of ten steel gates that can be raised to block the flow of water into the Thames.

- Each gate is 61 metres (200 ft) wide and weighs 4,500 tonnes.

- The gates are operated by a hydraulic system that uses water pumped from the river.

- The Thames Barrier was built between 1974 and 1982, at a cost of around £534 million.

- It was opened by Queen Elizabeth II on 8 May 1984.

- The Thames Barrier has been raised over 190 times since it became operational, preventing flooding of central London on several occasions.

- In 2014, the Thames Barrier was closed for a record-breaking 40 days during the winter floods.

- The barrier is expected to remain operational until at least 2070, but it may be upgraded or replaced in the future.