Policies needed to protect natural 'water towers'

In a unique study, scientists have assessed and ranked the importance of Earth's great "water towers". These are the 78 mountainous regions that are able to generate and then store vast quantities of water, delivering it in a controlled way to major populations living downstream. The Dutch-led team finds the Indus basin in Asia - fed by sections of the Himalayan, Karakoram, Hindu-Kush, and Ladakh ranges - to have the most important storage unit on the planet. Its water, produced at high elevation from rain and snow, and draining from lakes and glaciers, supports more than 200 million people settled across parts of Afghanistan, China, India and Pakistan. Study leader Prof Walter Immerzeel from Utrecht University spoke with our science correspondent Jonathan Amos.

Image by Brittany Mumma/National Geographic

More here: 1.9 billion people rely on natural 'water towers'