the canals are connected to ponchatrain
Which is part of the New Orleans basin, which my original reading on the subject said was massively innundated by the huge storm system Katrina dragged in with her. Ponchatrain was already escaping its banks and flooding NOLA by other pathways when the Levees broke.
Now I must say, The original claims were that the innundated pnchatrain was the cause for the failed levee, but some of the sources from the 5th on are saying "a combination of torrential rains and storm surge" led to the failure. Time may tell on this one, but my otriginal reading on the topic indicated that the record rainfall katrina brought broke the Levees.
However, the point remains moot in any cas WRT my original post on the issue.
DL