Which group of rivers is known for flooding parts of the northern plains annually while enriching the soil for agriculture?

Correct Option

The correct option is

The Ghaghara, Gandak, and Kosi

Explanation

The drainage system of the Northern Plains consists primarily of the Ganga river system and its tributaries. These tributaries are classified based on their origin: those rising from the Himalayas and those rising from the Peninsular uplands. The Himalayan rivers are perennial, carry heavy sediment loads, and are prone to frequent course changes and flooding.

Option Analysis

• The Chambal, Betwa, and Son is Incorrect: The Chambal, Betwa, and Son originate from the Peninsular uplands (Malwa Plateau and Amarkantak hills). These are rain-fed rivers with shorter courses and lower water volumes compared to Himalayan rivers. While they are part of the Ganga basin, they are not the primary drivers of the extensive annual flooding and silt deposition associated with the Northern Plains' agricultural renewal.
• The Ghaghara, Gandak, and Kosi is Correct: The Ghaghara, Gandak, and Kosi originate in the Nepal Himalayas. Due to heavy rainfall in their catchment areas and steep gradients, they carry immense volumes of water and silt. These rivers are notorious for flooding parts of the Northern Plains (particularly in Uttar Pradesh and Bihar) every year. However, these floods perform a critical ecological function by depositing fresh alluvium (silt), which renews soil fertility and supports intensive agriculture in the region.
• The Narmada and Tapi is Incorrect: The Narmada and Tapi are major west-flowing rivers of Peninsular India. They flow through rift valleys and drain into the Arabian Sea, having no connection to the Northern Plains.
• The Godavari and Krishna is Incorrect: The Godavari and Krishna are the principal east-flowing rivers of the Peninsular Plateau. They drain the Deccan region and form deltas on the eastern coast, distinct from the Northern Plains.

Key Takeaway: The Himalayan tributaries of the Ganga (Ghaghara, Gandak, and Kosi) are characterized by perennial flow and heavy silt loads, causing annual floods that enrich the Northern Plains with fertile alluvial soil.