By Allison Flynn
Bernhard Lehner is a hydrographer whose work is about to go global. Fusing the fields of hydrology and cartography, he has created a one-of-a-kind map of the world鈥檚 rivers that is included as a pull-out in the April 2010 鈥淔resh Water鈥� Issue of National Geographic, the iconic magazine that鈥檚 read in 32 [...]