香蕉视频

For Bernhard Lehner, an assistant professor in the geography department at 香蕉视频, it seemed a daunting task: to design a detailed digital map of the world鈥檚 rivers. But seven years and thousands of computer hours later, Lehner finally has a finished product: a global map detailing the world鈥檚 rivers, which has been posted online courtesy of National Geographic.