News Earth

What leads rivers to suddenly change course?

Two factors work together to prime a river for a sudden diversion

Structures and trees are inundated in flood waters.

In 2008, the Kosi River breached its embankment in northern India, shifting course by more than 100 kilometers and displacing millions of people.

Manpreet Romana/AFP

By Nikk Ogasa

Shifting is in a river’s nature. But when a river breaks free of its channel and carves a new path across the landscape, devastating floods may descend upon communities with little to no warning.

For decades, researchers have struggled to explain exactly how river channels become primed for such sudden diversions, or avulsions.