http://gillesleblanc.wordpress.com/2013/01/09/creating-a-random-2d-game-world-map-part-2-adding-rivers-and-lakes/
http://www.cs.sjsu.edu/~teoh/research/papers/isvc08.pdf
http://procworld.blogspot.com/2013/10/water-bodies.html
http://procworld.blogspot.com/2014/01/leveling-lakes.html
