"floods and droughts are common in India" - why?

Answer 1

India has dry and wet monsoonal seasons. During winter(or dry) monsoon, a northeast wind flow from the Himalayas predominates and India receives little or no rainfall for months at a time. During summer(wet) monsoon, winds shift from the southwest bringing humid tropical air into the region causing torrential rainfalls.

Answer 2

Monsoon season creates floods.

Lack of water supply to fields, dry air (except during monsoons, obviously) and the fact that part of the country is naturally very dry and free of rain are all contributors.