Most of NO north of the Miss. River is divided into 3 sections of levees. The largest one is the west and central city, bordered on the east by the Industrial/Navigation Canal. The smallest is to the east of the Industrial/Navigation Canal that runs north/south and south of the Intercoastal Canal that runs east/west and ends at the Ind. Canal. The 3rd is to the northeast, east of the Ind. Canal and north of the Intercoastal Canal. Each has its own set of levees, forming their own bowl. So a breach/overtopping in one won't affect the others (though the conditions that cause such might.)
Here are zoomable topo maps:
http://terraserver-usa.com/
enter 'New Orleans' 'LA', but unfortunately the map edge cuts in the middle of the east and northeast sides. To see east of there, enter 'Slidell' 'LA', which is northeast and across the lake, and then you can zoom out and follow the I-10 freeway to the south/southwest to the northeast portion of New Orleans.