Flood barrier
A flood barrier, surge barrier of storm surge barrier is a specific type of floodgate, designed to prevent a storm surge or spring tide from flooding the protected area behind the barrier. A surge barrier is almost always part of a larger flood protection system consisting of floodwalls, levees (also known as dykes) and other constructions and natural geographical features.
Surge barriers allow water to pass under normal circumstances, but when a (storm) surge is expected the barrier can be closed. The means of closing can consist of various forms of gates.
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[edit] Flood barriers around the world
[edit] Delta Works
The Delta Works in the Netherlands is the largest flood protection project in the world. This project consists of a number of surge barriers, the Oosterscheldekering being the largest surge barrier in the world, 9 kilometres (5.6 mi) long. Other examples include the Maeslantkering, Haringvlietdam and the Hartelkering.
[edit] Thames Barrier
The Thames Barrier is the world's second largest movable flood barrier (after the Oosterscheldekering) and is located downstream of central London. Its purpose is to prevent London from being flooded by exceptionally high tides and storm surges moving up from the North Sea. It needs to be raised (closed) only during high tide; at ebb tide it can be lowered to release the water that backs up behind it.
[edit] New Orleans
In 2005, with the approach of Hurricane Katrina, a storm surge funneled by the confluence of the Gulf Intracoastal Waterway and Mississippi River Gulf Outlet levees created multiple breaches in the Industrial Canal's concrete floodwalls, resulting in catastrophic flooding. The situation was worsened when a storm surge from Lake Ponchartrain entered the canal from the other side. In 2009 the United States Army Corps of Engineers started construction of an ambitious project that aims to prevent storm surges from flooding the city by 2011. The IHNC Lake Borgne Surge Barrier on the confluence of these waterways[1] will be the largest in the United States. The new Seabrook floodgate will prevent a storm surge from entering from Lake Ponchartrain. The GIWW West Closure Complex will close 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.[2]
[edit] Eider Barrage
The Eider Barrage is located at the mouth of the river Eider near Tönning on Germany’s North Sea coast. Its main purpose is protection from storm surges by the North Seas. It is Germany’s largest coastal protection structure.
