This map script uses various manipulations of Perlin noise to create landforms, and generates climate based on a simplified model of geostrophic and monsoon wind patterns. Rivers are generated along accurate drainage paths governed by the elevation map used to create the landforms.
For more info and screeshots, see this thread:
http://forums.civfanatics.com/showthread.php?t=399952
For more info and screeshots, see this thread:
http://forums.civfanatics.com/showthread.php?t=399952