Quote Originally Posted by HandsomeRob View Post
http://en.wikipedia.org/wiki/Stream_capture
Stream Capture (also known as Stream Piracy) is pretty sweet.

-Rob
Extremely relevant example: the artificially-postponed capture of the Mississippi River by the Atchafalaya. http://en.wikipedia.org/wiki/Old_Riv...trol_Structure

Would make for a pretty decent story in a fantasy setting too; a terrible disaster as a major port dries up. Or else an excuse for extensive ruins of that major port, decades/centuries after the fact.