BPSC 70th CCE Re-exam Prelims General Studies · Question 78 of 142

Correct — A, Kosi. The epithet is old, standard, and earned by a set of physical facts that no other Bihar river matches. The Kosi rises in Tibet and Nepal, gathers as the Sapta Kosi from the Sun Kosi, the Arun Kosi and the Tamur Kosi — the Arun's catchment containing Everest and Kanchenjunga — and drops abruptly on to the flat north Bihar plain carrying one of the heaviest silt loads of any river in the world. Unable to carry that load once the gradient goes, it dumps it, raising its own bed, and then finds a new line across the deposit. The result is one of the largest alluvial fans on earth and a river that has occupied at least twelve channels; a widely quoted figure puts the lateral shift at more than 120 km over 250 years, though a review of twenty-eight historical maps from 1760 to 1960 found the movement oscillating rather than a simple march in one direction, so the shift is better described as restless than as one-way. Its floods have inundated on the order of 21,000 sq km. The Kosi Project after the disastrous floods of 1954 built a barrage at Bhimnagar and long embankments to pin the river down, while the high dam proposed at Barakshetra in Nepal was never built — and on 18 August 2008 the eastern embankment breached at Kusaha, sending the river back into an old channel and causing the catastrophic Bihar flood of that year. That is what the phrase 'Sorrow of Bihar' records.

• (b)Ganga — Bihar's main stem, and it does flood — it bisects the state from Buxar to Bhagalpur and its own overtopping affects the diara lands along it. But the Ganga is not a wandering river in Bihar: its channel is broadly stable, its floods are seasonal rather than catastrophic reorganisations of the landscape, and no standard usage attaches this epithet to it. A trunk river is the reference line against which a tributary's misbehaviour is measured.
• (c)Gandak — The strongest wrong answer, because the Gandak is genuinely a serious flood river of north Bihar — it too comes off the Nepal Himalaya, it too carries heavy silt, and the Gandak Project's barrage at Valmiki Nagar and its Tribeni, Eastern and Western canals exist for exactly that reason. But it has not migrated across the plain in the way the Kosi has, and the sorrow epithet has never been attached to it in standard usage.
• (d)Son — The Son is a south-bank tributary, rising at Amarkantak on the Maikal range and flowing across the peninsular edge to join the Ganga above Patna. Being largely rain-fed and running over harder ground, it has a comparatively stable course, and its dry-season flow is thin. Its association in Bihar is with irrigation — the Sone barrage at Dehri and the Sone canal system — not with disaster.

The 'sorrow of' epithets belong to a small family of rivers that share one mechanism: a heavy sediment load delivered on to a flat plain, so that the river builds up its own bed until it stands above the surrounding country and then breaks out. The Hwang Ho, the Yellow River, is the Sorrow of China for precisely this reason and is the original of the phrase. The Damodar is the Sorrow of Bengal, and was the object of India's first great multipurpose river valley project, the Damodar Valley Corporation of 1948, modelled on the Tennessee Valley Authority. The Kosi is Bihar's. The engineering response has everywhere been the same and has everywhere had the same limitation: embankments confine the river and stop the flood, but they also stop the silt from spreading, so the bed inside the embankments keeps rising and the consequences of an eventual breach get worse over time. That is the structural argument behind the Kusaha breach of 2008, and it is why flood management on the Kosi is now framed around drainage, spill channels and the Kosi-Mechi link rather than embankments alone.

Two routes lead to the answer and both are worth having. The first is straight recall of the epithet family — Hwang Ho for China, Damodar for Bengal, Kosi for Bihar — because these are conventions, not deductions. The second is physical and survives even if the phrase has gone: ask which of the four rivers is a Himalayan tributary that reaches Bihar with an enormous silt load and no gradient left to carry it. The Ganga is the trunk, not a tributary. The Son comes from the peninsular south and is rain-fed. That leaves the Kosi and the Gandak, both north-bank Himalayan rivers, and between them the Kosi is the one with the megafan and the recorded channel migration. It is also worth being precise about a claim you will meet often: the Kosi's westward shift of about 120 km is repeated everywhere, but the map evidence shows oscillation rather than a steady one-way march, so state it as a range of wandering rather than as a directed migration.

• The Kosi is formed in Nepal from the Sun Kosi, Arun Kosi and Tamur Kosi; the Arun's catchment includes Mount Everest and Kanchenjunga. Its floods have inundated on the order of 21,000 sq km.
• Its alluvial megafan is among the largest in the world, built from at least twelve former channels; a review of twenty-eight maps from 1760 to 1960 shows the shifting to be oscillating rather than a simple east-to-west march.
• The Kosi Project, launched after the 1954 floods, built the barrage at Bhimnagar and long embankments; the high dam proposed at Barakshetra in Nepal was never built.
• On 18 August 2008 the eastern Kosi embankment breached at Kusaha, causing the catastrophic Bihar flood of that year.
• The companion epithets: the Damodar is the Sorrow of Bengal, tackled by the Damodar Valley Corporation from 1948, and the Hwang Ho is the Sorrow of China.

• Choosing the Gandak because it also floods. Flooding is common to several north Bihar rivers; the epithet belongs to the one that rebuilds its own course across a megafan.
• Repeating 'the Kosi has shifted 120 km westward' as a settled fact. The map record shows oscillation, so describe the shifting as restless rather than one-directional.
• Treating embankments as a solution. They stop the spread of silt as well as of water, so the bed inside them rises and a breach becomes more damaging with time — the story of Kusaha in 2008.

BPSC asks river epithets and river facts in the plainest possible form and returns to Bihar's rivers in every edition — the 69th CCE asked for the Gandak's other name and for the river the Triveni Canal is built on. UPSC does not ask epithets; it asks the geomorphology behind them, such as which east-flowing river occupies a rift valley, or how a river's load and gradient shape its channel.

• practice — not a real PYQ

  The Kosi embankment breach that caused the catastrophic Bihar flood of 2008 occurred at

  • (a)Bhimnagar
  • (b)Kusaha
  • (c)Kursela
  • (d)Barakshetra

  Answer(b) Kusaha — the eastern embankment breached there on 18 August 2008. Bhimnagar is the barrage site, Kursela is near the Ganga confluence, and Barakshetra in Nepal is where the proposed high dam was never built.

• practice — not a real PYQ

  Which river is called the 'Sorrow of Bengal' ?

  • (a)Hooghly
  • (b)Mahananda
  • (c)Damodar
  • (d)Teesta

  Answer(c) Damodar — silt-laden and prone to catastrophic flooding, which is why the Damodar Valley Corporation was created in 1948 as India's first multipurpose river valley project.