RAS question
The Kosi River is known as the 'Sorrow of Bihar' because:
Correct answer: (A) It frequently changes course causing devastating floods.
The Kosi River is known as the Sorrow of Bihar because it frequently shifts course and causes devastating floods.
Explanation
The Kosi is a major tributary of the Ganga, formed by the Sun Kosi, Arun Kosi and Tamur Kosi, with its headstreams in the Himalayan region of Nepal and Tibet. India-WRIS, Ganga Basin describes the river as notorious for frequent and disastrous floods and for shifting its courses, explicitly linking this to its name, the Sorrow of Bihar. Heavy silt brought from the Himalayas makes the river unstable, so it has shifted laterally, including westward movement over the last 200 years. Flood-control works such as the Kosi Barrage at Birpur, built in 1963, reflect how central flood management is to understanding this river.
Why the other options are wrong
- (B) Salinity is not the stated reason for the Kosi's nickname; the phrase is tied to floods and shifting courses.
- (C) Pollution may be a general river-management issue, but it is not the reason here or in India-WRIS, Ganga Basin for calling the Kosi the Sorrow of Bihar.
- (D) The nickname is not based on the river drying up in summer; it is based on its flood-prone, course-shifting behaviour.
Concept
This tests drainage-system geomorphology, especially Himalayan rivers with high silt load, unstable channels and flood plains. It recurs in RAS because river behaviour links physical geography with disaster management and irrigation works.