What sould Have Been Done in Louisiana

Build a new navigation channel from the Gulf into the Mississippi, about 40 miles south of New Orleans, so ships don't have to enter the river at its three southernmost tips 30 miles further away. For decades the corps has dredged shipping channels along those final miles to keep them navigable, creating underwater chutes that propel river sediment out into the deep ocean. The dredging could then be stopped, the river mouth would fill in naturally, and sediment would again spill to the barrier islands, lengthening and widening them. Some planners also propose a modern port at the new access point that would replace those along the river that are too shallow to handle the huge new ships now being built worldwide.

Erect huge seagates across the pair of narrow straits that connect the eastern edge of Lake Pontchartrain, which lies north of the city, to the gulf. Now, any hurricane that blows in from the south will push a wall of water through these straits into the huge lake, which in turn will threaten to overflow into the city. That is what has filled the bowl that is New Orleans this week. But seagates at the straits can stop the wall of water from flowing in. The Netherlands has built similar gates to hold back the turbulent North Sea and they work splendidly.

Mark Freshetti from Scientific American