-built on Mississippi delta
-sediment builds up in delta-fans out as new, low-elevation land
-causes location of river to change over time, resulting in marshy, loose land (natural buffer against waves/storm surge)
-city works against this change to lock river in place (and further development)
-creates new problems: lack of new material, no river flow to wetlands
-causes New Orleans to sink!
-natural wetland buffer is easily overwhelmed! (with no material, 30+ miles lost in Katrina can't be replaced)