Kosi
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Overview
The Kosi is a left-bank Himalayan tributary of the Ganga that flows from Nepal into Bihar. It carries heavy silt from the Himalaya, which makes it flood often and shift its course, so it is called the "Sorrow of Bihar".
It is a standard case study in disaster management: after the Kosi floods, Bihar's recovery used owner-driven housing with World Bank support.
Geography and key facts
- Flows from Nepal into Bihar
- "Sorrow of Bihar": floods and shifting course
- Carries heavy Himalayan silt
- Left-bank tributary of the Ganga
Why it matters for UPSC
Asked on the Himalayan rivers that join the Ganga below Prayagraj (2024) and a river map question (1997); also a GS3 disaster-management example.
Note for UPSC
The "Sorrow of Bihar", known for floods and shifting course.
Prelims asks about tributaries, the states a river flows through, its basin and the projects on it, so trace the course on the map.
Asked in PYQs
- UPSC Prelims 2024 · Q6With reference to the Himalayan rivers joining the Ganga downstream of Prayagraj from West to East, which one of the following sequences is correct ?…
- UPSC Prelims 1997 · Q76In the map shown in the given figure, rivers labelled as 1, 2, 3 and 4 are respectively…
Questions from our Prelims bank whose text names Kosi.
Key facts
- Type
- River
- State / UT
- Bihar
- River system
- Himalayan
- Basin
- Ganga
- Extent on map
- 25.4°–26.9°N, 86.4°–87.3°E
- Asked in Prelims
- 2 questions · 2024, 1997
From the Map Explorer data; positions are for orientation.
In the lessons
- Physical Features and Drainage of India
- Major Hazards and Good Practices
- Drainage Systems of India: Himalayan and Peninsular Rivers
- Geomorphic Processes and Landforms
- Hydro-meteorological Disasters: Floods, Cyclones, Droughts, Heatwaves and Cloudbursts
- The Harappan (Indus Valley) Civilisation (map lesson)