Question

how are floods plains formed

Answer 1

flood plains are formed when the Himalayan river gets over flooded and have floods it comes with thick layer of alluvial replenishing plains every year... this plains are also known as KHADAR 

Answer 2

Answer:

At times the river overflows its banks. This leads to the flooding of the neighbouring areas. As it floods, it deposits layers of fine soil and other material called sediments along its banks. This leads to the formation of a flat fertile flood plain.