Nearly a third of India is suffering from chronic water shortages, and making up for it with "the world's largest groundwater mining operation," according to experts.

A band of land stretching across northern India, at the foot of the Himalayan Mountains, is one of the most heavily populated and intensely irrigated regions in the world. The area is chronically short of water. But the region still has a limited supply of it in underground aquifers, according to water resources expert Shama Perveen of Columbia University.

According to a new study by Perveen and her colleagues, Upmanu Lall and Naresh Devineni, some parts of India are using groundwater three times faster than it’s being replenished.

The team's new analysis draws on a 100-year