Riverine island
Also called: River island · Topic: Structure and Physiography of India: Himalayas, Plains, Peninsula, Coasts and Islands · NCERT: Class 11, Ch 2 "Structure and Physiography"; Class 11, Ch 6 "Natural Hazards and Disasters: Causes, Consequences and Management"
Meaning
A riverine island (river island) is land surrounded on all sides by river channels. It forms in wide, braided rivers, which split into many channels around bars of deposited sand and silt. As the river keeps dropping sediment, some bars grow big enough to hold villages and farms. These islands keep changing, because floods add new land in some places and wash it away in others.
Example
Majuli, in the Brahmaputra in Assam, is often called the world's largest river island. It is a centre of Vaishnavite satras (monasteries) and became a district in 2016. Erosion has shrunk it from about 1,250 sq km to roughly 350-500 sq km (the current figure needs checking).
Don't confuse with
- Delta: this is a fan of new land built where a river meets the sea, such as the Ganga-Brahmaputra delta (the Sundarbans). A riverine island forms inside the river's course, far from the sea.
Related concepts
- Indo-Ganga-Brahmaputra plain
- Bhabar
- Tarai
- Bhangar
- Khadar
- Piedmont alluvial plains
- Majuli
- Ganga-Brahmaputra delta