when the Levee breaks

[Krill]

The whole reason the Dutch built that system of levees was because of a storm in the Northsea that broke the previous system of levees and killed thaosands.

It would suprise me if it was not rated to withstand a strong North Sea storm.

[germanos]

Originally posted by Berzerker
Lets see how those other systems stand up to a Cat 4 hurricane

I'm not fully confident on the exact specs of the dikes build, but the whole system is designed to prevent the events of 1953, which was a rare combination of 'spring-tide' (exeptional high-water) and a very strong North-western storm that pushes the water even higher up due to the bottle-neck that the English Channel creates in such an event.

It's true that the last barrier was only finished in 1998, but the question is whether this is due to lack of urgency or due to the high quality of the stuff required to make it fail-save for an event expected to occur once in 10,000 years.
One should also be aware that the program protects the full delta of the rine/meuse rivers (and to an extend the scheldt river as well)

For those interested, here's a link:

http://www.deltawerken.com/Deltaworks/23.html

and the last piece that was finished in 1998 (a surge barrier in the 'Nieuwe Waterweg', the entrance to one of the biggest and busiest ports of the world):

http://www.keringhuis.nl/

[chequita guevara]

Originally posted by Berzerker
Lets see how those other systems stand up to a Cat 4 hurricane

What Cat 4? NOLA didn't experience a Cat4, the tip of the Mississippi River did . . . maybe. After analyzing the wind data, they downgraded Katrina's intensity to a Cat 3 at landfall in LA and a Cat 2 when it hit the Mississippi coast. NOLA itself experienced 65 mph winds on the ground, 9mph below hurricane strength, a tropical storm.

What happened is that storm surge was channeled up through the river into the canal with such force that it overtopped the levee and eroded the base. It then failed. This is what flooded the Eastern part of the city.

Later, after the storm had passed, water flowing into Lake Ponchetrain built up up high enough that the two other levees which failed did so from water pressure alone. They weren't overtopped, the bases simply gave way. This is what destroyed the rest of the city.

The NOLA levees were underdesigned. They couldn't even handle what they were officially designed designed to handle. If they had driven the foundations deeper the levees would have held. Nine hundred people paid for that with their lives.

[chequita guevara]

Originally posted by DanS
AFAIK, they haven't built their metropolises on sand, either.

Venice is built on mud.

[Kuciwalker]

Venice is on the Mediterranean sea too. Not the Atlantic.

[chequita guevara]

NOLA isn't on the Atlantic. I am. NOLA is on the Gulf of Mexico. Venice also has a unique geography that makes it particularly vulnerable to flooding (aside from being built on muddy marsh islands which long ago subsided). The Adriatic is a narrow body of water so spring tides and storms easily flood the city as water from the Mediterranian pours in to the Adriatic.

[molly bloom]

Originally posted by Kuciwalker
Venice is on the Mediterranean sea too. Not the Atlantic.

Or as it's known to fastidious Eurocoms, the Adriatic Sea.

[QUOTE] To make matters worse, Venice has been sinking over the centuries, due to the natural settling of lagoon sediments and the indiscriminate pumping of freshwater from a deep aquifer beneath the city.

Sixteen hundred years ago, around the time of Venice's founding, the Adriatic's standard sea level was almost six feet below what it is today. For a millennium and a half, Venetians were able to cope with the problems associated with living in a water-dominated environment. As late as 1900, for example, water at extreme high tide covered St. Mark's Square only seven times a year.

[QUOTE]

http://www.pbs.org/wgbh/nova/venice/solutions.html

[Kuciwalker]

Originally posted by molly bloom
Or as it's known to fastidious Eurocoms, the Adriatic Sea.

Is the distinction meaningful when we're talking about weather patterns?

[molly bloom]

Originally posted by Kuciwalker


Is the distinction meaningful when we're talking about weather patterns?

So you think the weather in the North Atlantic off Ireland is the same as the weather in the Caribbean or the Gulf of Mexico ?

[Whoha]

Not anyone's fault but the states that the squandered the money given to them for that purpose. Heres an image of Galveston's sea wall.

[JohnT]

Which, again, was put in place after being devastated by a couple of storms.

[Dis]

how many hurricanes hit London, Venice, and the Netherlands again?

[JohnT]

Did you not even read the thread?

The dikes talked about in the OP were put in place because of a storm. Whether or not it was a "hurricane" was irrelevant - thousands of sq miles were flooded and almost 2,000 people lost their lives.

My point is, making things better after the fact is a very human trait, American or European.

[Dis]

that doesn't answer my question. The answer was 0 by the way.

[Apocalypse]

Originally posted by JohnT
Which, again, was put in place after being devastated by a couple of storms.

I think "devastated" is kinda lightening the situation a bit