Your plan would flood my neighborhood next to City Park.

The broken canal walls were built in the last 10-15 years--not in the 30s. They failed because they are concrete walls built on top of a shorter dirt levee. The storm surge topped the concrete walls and ate out the dirt below causing the walls to collapse. Had there been more funding to create category 5 height walls perhaps they would have never failed.

Bayou St. John (along bottom in satellite picture) is capped off from the lake by a huge lock and is thus never a threat from flooding. The areas surrounding Bayou St. John flooded because of other levee breaches in the area.

Compartmentalizing the city with internal flood walls would be a better idea that might prevent one or two breaches from inundating the city. There was also a plan proposed to build a giant sea wall along I-10 near Slidell that would prevent storm surges from entering the lake. This might have prevented the storm surge from topping the levees along the canals.