What is the main reason for the formation of river islands in the Brahmaputra plain?

Braided flow and deposition

The Brahmaputra flows through a broad plain and carries a large quantity of sand, silt, and other sediments. Its channel often divides into several smaller channels and later joins again. Such a river pattern is called a braided channel. When the river’s speed decreases or its flow changes, the sediments are deposited between the channels. These deposited materials can gradually rise above the water and form temporary or permanent river islands.

Therefore, choice D is correct: braided flow and deposition. Desert winds, cooling lava, and sea-wave erosion do not explain the formation of islands in the Brahmaputra plain. The important sequence is that the river carries sediment, divides into several channels, deposits material, and leaves sedimentary bars or islands between the channels. This is why the Brahmaputra is especially known for river islands in its plain.

This is a Class 9 Geography question. Chapter: Physical Features of India. Topic: The Northern Plains.