Question about the flood walls

[BeFree]

We have heard that the flood walls on top of the levees began to fail as the water spilled over the top, eroding away the base of the floodwalls, leading to erosion of the levees.

So, why wasn't there a series of gates built into the flood walls? Gates could have been opened thereby keeping water from ever over topping the flood walls.

These relief gates would have saved the integrity of the levees. Yes, a minor flood would have occured, but the main height of the levees would have been sustained leading to the saving of New Orleans.

[skids]

1. Gates at the end of the canals...

... I think were part of one of the proposals that was totally ignored.

[rfkrfk]

2. gates {that don't exist} would need to be closed, to prevent the flood

the 17th St. canal is currently wide open to lake Ponchartrain.
I don't know about the other canal floodwall that failed.

The Lake is/was three feet above sea level,I think.
Parts of the city is twenty feet below sea level.

[Kolesar]

3. So, by your proposal,they could have "tapped off" one foot of Ponchartrain

...and drained it into the streets of New Orleans. After the hurricane swell was gone, Ponchartrain would have started to drain back into the Gulf for a few days. That would have probably caused three feet of water on the streets, instead of ten or more, which is what they got with the three breaches.

Do I follow you correctly?

[BeFree]

5. Yes, you got the idea

Instead of ten feet of water, they would have had three. And the levees would have stood solid - for the most part.

Almost every damn has a gate with a concrete spillway. Those gates allow excess water to be safely routed around a dam. The flood walls, indeed, the entire levee system is a dam. They should have had relef gates built into it at decent intervals.

[phantom power]

4. It makes me wonder if they could have been encased in cement.

I assume that a relatively thin layer of cement could have prevented erosion, even if the waters topped the levy. It would still wash over, the levies themselves would remain intact.