Planet Care

159: Flood barriers


In 2020, 150 million people were now living on land that will be below the high-tide line by 2050, threatening to all but erase some of the world’s great coastal cities. As one example, the River Thames in London is liable to serious flooding. As sea levels continue to rise, the Houses of Parliament, the O2 arena, Tower Bridge, and areas including Southwark, the Isle of Dogs, Whitechapel and West Ham would be flooded unless a barrier was built which could protect 48 mi² (125 km²) of central London from flooding caused by tidal surges.


Flood barriers.

In the early 1970s, such a barrier was designed by Rendel, Palmer and Tritton for the Greater London Council and tested at the Hydraulics Research Station, Wallingford.

The site at New Charlton was chosen because of the relative straightness of the banks, and because the underlying river chalk was strong enough to support the barrier.

Work began at the barrier site in 1974 and construction, which had been undertaken by a Costain/Hollandsche Beton Maatschappij/Tarmac Construction consortium, was largely complete by 1982. The barrier was officially opened on 8 May 1984 by Queen Elizabeth II.

The Maeslantkering is a storm surge barrier on the Nieuwe Waterweg, in South Holland, Netherlands. Controlled by a supercomputer, it automatically closes when Rotterdam is threatened by floods.

Part of the Delta Works, it is one of largest moving structures on Earth, On May 10, 1997, after six years of construction, Queen Beatrix opened the Maeslantkering. The barrier is connected to a computer system which is linked to weather and sea level data. It is expected to be closed once every ten years due to a storm surge.

With the rise in sea levels, the storm surge barrier will need to close more frequently in 50 years time, namely once every five years.

Sjoerd Groeskamp and ​​​​Joakim Kjellsson, oceanographers from the Royal Netherlands Institute for Oceanography and the Oceanographic Research Center in Kiel, Germany, respectively, have presented a plan to build two giant dams, to close the North Sea and thereby protect 25 million Europeans from rising sea levels. One, measuring 295 mi (475 km) would be built between the north of Scotland and Norway, while the other 100 mi (160 km) between France and the south-west of England.

Over in northern Italy, in 2003, work began on a massive flood barrier designed to isolate Italy’s Venetian Lagoon, the enclosed bay where Venice is located. The project, known as Mose, (MOdulo Sperimentale Elettromeccanico = Experimental Electromechanical Module) is one of the largest civil engineering endeavours in the world.

The design consists of 78 yellow mobile caissons or gates stationed at three different inlets. When the tide reaches 43 in. (109 cm) (which happens around four times a year), the gates rise above the water’s surface and protect the lagoon from flooding. When the tide dips, the gates fill with water and lower back in place.

The total barrier spans 1 mi (1.6 km) and weighs around 300 tons (272 tonnes). In 2020, the Mose protected Venice twice from flooding.

In 2007 the United States Army Corps of Engineers started construction of an ambitious project that aimed to prevent storm surges from flooding New Orleans by 2011. The IHNC Lake Borgne Surge Barrier on the confluence of these waterways is the largest in the United States.

It protects the city from the Gulf of Mexico from flooding the area. The new Seabrook floodgate prevents a storm surge from entering from Lake Ponchartrain. The GIWW West Closure Complex closes the Gulf Intracoastal Waterway to protect the west side of the city.

This complex is unique in that it contains the world’s largest pumping station, necessary to pump out rainwater that is discharged in the protected side of the canal during a hurricane. In December 2008, the Corps held a groundbreaking ceremony to mark the start of test pile driving.

Construction of the barrier’s flood wall began on May 9, 2009. On October 21, 2009 the last of the 1,271 main piles was driven. On August 29, 2012 (the seventh anniversary of Hurricane Katrina), the barrier was utilized for the first time, to protect the city from Hurricane Isaac. By June 2013, all major construction had been completed.

The Saint Petersburg Dam, is a 16 mi (25 km) complex of dams for flood control near Saint Petersburg, Russia. The complex is intended to protect Saint Petersburg from storm surges by separating the Neva Bay from the rest of the Gulf of Finland. Construction of the complex started in 1978 and became one of the longest construction projects in Russia, completed in 2011.

Discover Solution 160: flygskam

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