"Four breaches occurred on the IHNC (Inner Harbor Navigation Canal) during Hurricane Katrina, on the morning of August 29th. Two of the breaches occurred on the east bank between the Florida Avenue Bridge and the North Claiborne Avenue Bridge adjacent to the 9th Ward, and two on the west bank just north of the intersection of France Road and Florida Avenue (Figure 1). Three of the breaches involved failures of floodwalls on levees, and one involved failure of a levee. All of the IHNC floodwalls and levees were overtopped on August 29th. The peak storm surge elevation in the IHNC was 14.2 ft1 at 9:00 AM, about 1.7 ft above the tops of the floodwalls and levees. The reaches where the floodwalls and levees did not collapse have therefore survived water loading considerably higher than the design loading. Water flowing over the I-walls when they were overtopped eroded trenches on the protected side of the walls as it cascaded onto the levee fill. Soil that was providing support for the walls eroded away, making the walls less stable."
New Orleans Hurricane Protection Projects Data: https://ipet.wes.army.mil/