I did read John McPhee's great article Atchafalaya on attempts to keep the Mississippi river from doing what it wants to do, which is shift course entirely, several hundred miles upstream from New Orleans.
The river goes through New Orleans like an elevated highway. Jackson Square, in the French Quarter, is on high ground with respect to the rest of New Orleans, but even from the benches of Jackson Square one looks up across the levee at the hulls of passing ships. Their keels are higher than the AstroTurf in the Superdome, and if somehow the ships could turn and move at river level into the city and into the stadium they would hover above the playing field like blimps.If ever an article called for extensive maps and diagrams, this is it. Unfortunatly it doesn't have them. McPhee is good at describing complex geographies in words, but still. It would be a neat project to have the web collectively generate a visual annotation. Here's my contribution (well, somebody else's, I'm just linking to it). More pictures at the link.
Update: A detailed map of the Old River Control Structure, which figures prominently in the McPhee article and is what is supposed to keep the Mississippi on its present course, but is hampered by the fact that it's kind of hard to push a big river around when it doesn't feel like cooperating.