Photo credit: Peter Cassier on Flickr

Excessive rain is the most common cause of flooding, but other natural events also play a role. Storm tidal surges, for instance, can lead to coastal inundation.

As climate change takes hold, more flooding events are likely. These may result from more intensive rainfall, but there could be other equally devastating causes.

Of mounting concern in South Asia is the increasing variability of monsoon rains, which could affect the food security of millions of people.