Dive summary:

• A research team led by a co-developer of the computer model relied on by Louisiana state government, the U.S. Army Corps of Engineers and the Federal Emergency Management Agency concluded that levees on the west side of the Mississippi in a stretch called the Lower Plaquemines actually raise storm surges upriver in New Orleans.
• The way the levee system was designed, the earthen walls catch storm surges that are being blown across the river by the predominant easterly winds of hurricanes and turn them up the river.
• The team proposed lowering the levees so the surge can move across and, instead, building ring levees around the small towns in the area and connecting them by bridges, something like the Florida keys.

From the article:

"This study clearly shows that the man-built west bank levees on the lower Mississippi River enhance the capture of storm surge by the river," [Joannes] Westerink said. ...