Explore the flood protection system of treasure walls in the world's No. 1 country

Normally, they are hidden beneath the road surface but when there is a flood, the flood water will push this barrier upwards, preventing the flow of water from outside from overflowing into the building.

Norman Hughes was sitting at the technical control room in the basement of the US National Archives , and the computer screen beside him suddenly signaled the building's flood control barriers were activated.

Outside, long hours of heavy rain, overloading Washington DC's flood drainage system, many roads and structures were flooded, water was even absorbed into the White House basement.

Heavy rains flooded the intersection of Route 15 and Constitution Avenue in Washington DC on July 8.

Many cars were stalled on Canal Street in Washington, while drivers climbed onto the roof of the car and called for help.

Part of the basement at the West Wing of the White House was also soaked with water due to heavy rain.

13 years ago, a big storm caused huge amounts of water from many places to go to the National Archives building on Pennsylvania Avenue, which holds countless valuable documents and documents of the United States, causing the situation. unprecedented chaos.

On the night of June 25 and 26, 2006, a big storm hit nearly 18cm of rain on Washington for 6 hours. The rain poured down the slopes around the National Archives, flooding the tunnel and causing power outages. Water rises across the stage of Theater William G. McGowan on campus, the process of cleaning up the mess takes three weeks.

US National Archives Headquarters.

Hughes still remembered the storm of the past and when the warning signal flashed on the computer screen, he thought in his mind: 'My God! Big trouble. ' He quickly left the control room, ran to inspect the flooded areas of the building. When he saw the activated glass-fiber flood barrier , he was relieved.

'I returned to the control room when the power went out,' Hughes said.

The history of heavy rain in the morning of July 8, has brought real worry moments for the US National Archives management team, the massive stone building, where many treasures are kept. country ' as the original declaration of independence, the US constitution or the declaration of human rights.

The agency was then evacuated and closed for two days, but it avoided the disaster, when the flood barrier had well performed its function, said Timothy Edwards, the building manager.

The US National Archives was built in the 1940s in a low-lying area. As a precaution, engineers built a giant concrete building reinforced by thousands of stakes.

'It's like a boat,' Edwards describes. 'It's not like we can float, but it's almost like that'.

By 2009, to prevent recurring flood risks, the Federal Archives installed two fiberglass flood prevention ports, capable of activating themselves . This is a system developed and deployed by the Netherlands in flood prone roads.

Tim Edwards, the building manager of the US National Archives, on the flood control system helped them avoid flooding during the heavy rain on July 8.

Normally, they are hidden beneath the road surface but when there is a flood, the flood water will push this barrier upwards, preventing the flow of water from outside from overflowing into the building. When fully activated inside the metal frame, the walls will have a height of nearly 2.5 meters, effectively preventing flood water. After that, the pump can be deployed to accelerate the drainage rate to the outside.

In the rain on July 8, flood-proofing walls have risen completely and this is the third time they have operated at full capacity, since the time of installation.

'It was a heavy rain , ' said Edwards. 'But everything works well. We are not affected too much. '

• The world's longest automatic flood protection system