I'll be damned if I'm the only internet movie-guy NOT getting a traffic boost for reporting non-news about TDKR. Everything after this jump almost-definitely ISN'T a "spoiler," but proceed with whatever caution you like anyway.
SuperHeroHype has some paperwork suggesting that there will be a big on-location action shoot for the film in Los Angeles that will include "simulated flood sequences" among other mass-destruction, suggesting that the poster/teaser motif of a destroyed city is meant to be taken literally.
To the degree that anything in a Christopher Nolan Batman movie can be said to suggest anything familiar to comic fans, this will certainly remind some people of "No Man's Land" - an in-continuity miniseries in which an earthquake cut Gotham City off from the mainland U.S. Such a sequence on film would definitely require flooding FX to show how the ocean fills-in the space between the land-masses, so... is this something?