Levees and Flood Control Devices

[woutero]

In january 1995 high water levels in the rivers Waal and Rhine lead to a near failure of the Dike Ring 43 (see map above). 250.000 people were evacuated. Fortunately the dike did not break. Since then, river dikes have been strengthened.

The most populous dike ring is number 14, with about 4,5 million inhabitants. There is no evacuation plan, because the infrastructure is insufficient for handling that many people. However, probably not all land within the dike ring would flood, and especially in cities, there are often higher grounds to be found.

[diablo234]

Construction of the Seabrook Floodgate in New Orleans. This is to keep the waters of Lake Pontchartrain out of the Industrial Canal.

image hosted on flickr

Seabrook Floodgate Complex by USACEpublicaffairs, on Flickr

The rebuilt 17th street canal in New Orleans. The breech in the levees from Hurricane Katrina took place here.

image hosted on flickr

New and improved 17th St canal by ianqui, on Flickr

This is what the floodwall looked like before Katrina.


This is what the floodwall looked like after it was breeched by the storm surge.



A memorial plaque at the location of the floodwall breach.


An Elevation Map of New Orleans.

[Slagathor]

Originally Posted by diablo234

The River Walk in San Antonio was actually built with flood control in mind after a disastorous flood in 1921. Instead of building over the river they decided to make it a public space and added several locks as well in addition to several channels in case the water level gets to be too high. Now it has become a tourist attraction in it's own right.

http://upload.wikimedia.org/wikipedi...iverwalk20.jpg

http://upload.wikimedia.org/wikipedi...ridge_2009.jpg

http://upload.wikimedia.org/wikipedi...an_Antonio.jpg

http://farm3.static.flickr.com/2207/...356d84bb11.jpg

That's extraordinarily pretty.

[diablo234]

Originally Posted by Slagathor

That's extraordinarily pretty.

Yeah it's a pretty nice asset to the city not to mention a huge tourism drawl. And to think that city leaders talked about paving over the river back in the 1930's.

[woutero]

Here are some more pics of dutch flood control.

The already mentioned Maeslantkering, protecting Rotterdam from ocean storms:

Closed:


Opened:


Oosterscheldekering (closing off Oosterschelde from the North Sea when closed):




Afsluitdijk:


Some of the older ways to keep our feet dry:

Traditional: wind mill (many still in use as backup):


Industrial revolution: Steam powered pumps:


Modern water pump (Gemaal) to pump rainwater out of the polder into higher level water (Boezem):


Schematich image of a polder:

[woutero]

And here is another interesting one: The Balgstuw, closing the mouth of the river IJssel off from the IJsselmeer, protecting the low lying areas around Kampen and Zwolle from water accumulation through storms from the west.

It is a big inflatable balloon that normally rests under water, but can be pumped up when needed:

[erka]

Another interesting Dutch defense line is the so called "slaperdijk" (sleeper dike). It is an inland dike, which once was the main defense dike but became obsolete when newer and higher dikes were built more outlandish.

Those inland dikes (sometimes centuries old) were not torn down but remained in place as a second line of defense. So when a Deltadike breaks, the old dikes can hold the flood or slow the flood down, giving more time to evacuate or rescue people.

Example:



In this case, the road can be shut with logs that are kept in reserve in the dike.

There are thousands of sleeper dikes.

[diablo234]

As an additional defense from storm surge, New Orleans is planning to revitalize and restore wetlands.

Cypress swamp near Lower 9th Ward will be restored as hurricane defense

Published: Thursday, November 10, 2011, 9:00 PM Updated: Thursday, November 10, 2011, 9:05 PM
By Mark Schleifstein, The Times-Picayune
http://www.nola.com/environment/inde...wer_9th_w.html

Local leaders announced Thursday the beginning of a project to restore a key area of cypress swampland near the Lower 9th Ward, an effort they called essential to protecting the metro area in the event of another major hurricane.

Swinging shovels full of dirt, New Orleans Mayor Mitch Landrieu and St. Bernard Parish President Craig Taffaro said the eventual restoration of the 30,000-acre triangle of the once-vibrant Central Wetlands will be part of the several lines of defense that will keep the area safe from storm surge.

The first phase, which will restore 2,300 acres, will cost $10 million and will be paid for by the federal Coastal Impact Assistance Program, which is financed by offshore oil revenue. Another $30 million will be made available to expand the effort in the next few years.

“This is one of those bright spots where governments join together, crossing parish lines in Louisiana, and do something good for the public, good for the future of all of our communities,” Taffaro said.

“It really sends a message to the rest of America that its critically important that we rebuild all of Louisiana, all of New Orleans, all of St. Bernard because we all have common threats,” Landrieu said.

In 1956, before the completion of the Mississippi River Gulf Outlet, the Central Wetlands contained about 8,000 acres of swamp, 7,600 acres of freshwater marsh, 4,000 acres of brackish and salt marsh, and more than 1,000 acres of forest. The MR-GO cut through several natural ridges in St. Bernard Parish, funneling salt water into the area, where it killed cypress and freshwater marshes. By 1978, only 28 acres of forest remained.

The project’s first phase involves raising the soil level in two patches of the sunken triangle so that bald cypress trees and freshwater wetland plants can survive. The triangle is formed by the 40-Arpent Levee and the levee adjacent to the Mississippi River-Gulf Outlet and Gulf Intracoastal Waterway that follows the historic path of Bayou Bienvenue.

..........

[diablo234]

Work on the Lake Borgne storm surge barrier just outside of New Orleans is nearly complete.


http://www.nola.com/environment/inde...terway_at.html

2011: New hurricane protection system is built
Published: Monday, January 23, 2012




An $8 billion re-engineered levee system came on line for hurricane season, six years after its predecessor failed miserably to protect the area from Hurricane Katrina. A chastened Army Corps of Engineers admitted that design, construction and maintenance flaws caused the old system to fail.

The Corps of Engineers worked feverishly to meet a 2011 congressional deadline to have a new, stronger system in place to protect the area from a 100-year storm.

***

The keys to the new system are two new structures designed to keep the east and west banks protected from storm surge. The Lake Borgne Surge Barrier, also called The Great Wall of Louisiana, is a nearly two-mile-long, 26-foot-high barrier to prevent the kind of flooding that ravaged the Lower 9th Ward. The West Closure Complex in Belle Chasse will prevent the Harvey Canal from inundating the West Bank. Giant pumps are used to get rainwater runoff past the barrier.

[...]

[diablo234]

LDP West Closure Complex

image hosted on flickr

26photo by Team New Orleans, US Army Corps of Engineers, on Flickr

image hosted on flickr

23photo by Team New Orleans, US Army Corps of Engineers, on Flickr

image hosted on flickr

11photo by Team New Orleans, US Army Corps of Engineers, on Flickr

image hosted on flickr

IMG_0988 by Team New Orleans, US Army Corps of Engineers, on Flickr

image hosted on flickr

10.28.11 ASABE WCC tour by Team New Orleans, US Army Corps of Engineers, on Flickr

[diablo234]

The Fox Point Hurricane Barrier in Providence, Rhode Island.

The Fox Point Hurricane Barrier is a 3,000-foot (910 m) long tidal flood barrier spanning the Providence River in Providence, Rhode Island, located 750 feet (230 m) upstream from Fox Point. It was constructed between 1960 and 1966 to protect the low-lying downtown area of the city from damaging storm surge and floods associated with hurricanes and other major storm events.

The Fox Point Hurricane Barrier consists of five main parts: river gates, rock and earthen dikes along each shore, vehicular gates along each shore where roads pass through the dikes, canal gates at the west end of the barrier associated with the nearby electric power station, and a pumping station to control the flow of water.

http://en.wikipedia.org/wiki/Fox_Poi...ricane_Barrier

[duozhuchen]

General sea ladder is to consider how the design height of it?