BPSC 69th CCE Prelims General Studies · Question 88 of 144

Correct — C, Narayani. The Gandak of Bihar and the Narayani of Nepal are the same river under two names. UNESCO's World Heritage description of Chitwan National Park uses both in a single line — the park's "core area lies between the Narayani (Gandak) and Rapti rivers to the north" — and again calls it "the Narayani (Gandaki) river, the third-largest river in Nepal, which originates in the high Himalayas and drains into the Bay of Bengal." India-WRIS, the Central Water Commission's basin wiki, traces the same water from the upstream end: the Gandak, "known as Kalie or Krishna Gandaki in the upper reaches", rises in the glaciers of southern Tibet at 7,620 m near the Tibet–Nepal border south-east of Dhaulagiri, gathers the Mayangadi, Bari and Trisuli, and "debouches into the plains of West Champaran district of Bihar at Triveni (Valmikinagar)". From there it runs south, forms the Uttar Pradesh–Bihar boundary for about 45 km, crosses Bihar and "finally joins the River Ganga opposite Patna". Its catchment totals 45,731 sq km — 5,687 sq km in Tibet, 30,882 in Nepal, 1,874 in Uttar Pradesh and 7,288 in Bihar — with roughly 380 km of course in Tibet and Nepal and 250 km in India. So the river carries three names down one continuous channel: Kali or Krishna Gandaki in the mountains, Narayani or Gandaki across the Nepal terai, and Gandak from Valmikinagar onwards. Naming it Narayani is naming the same river, which is exactly what the stem asks. Two further lines from the same Commission page close the door on the most tempting wrong answer. First, it defines the Gandak basin's own limits: "bounded on north by the Himalayas. On the south by the River Ganga, On the east by the Burhi Gandak Basin and on the west by the Ghagra Basin." A river cannot be bounded on the east by itself, so the Commission is stating in its own words that the Burhi Gandak is a neighbour, not an alias — and the Burhi Gandak page returns the compliment, describing that basin as bounded "on the west by the Gandak Basin". Second, the Commission's Ganga page lists "the Yamuna, the Ramganga, the Ghaghra, the Gandak, the Burhi Gandak, the Kosi, the Mahananda and the Sone" as eight separate principal tributaries, with the Gandak and the Burhi Gandak counted twice over as different rivers. Two more details worth carrying from the Gandak page: the catchment is trapezoidal in shape up to Triveni, and the source lies at about 29°18′ north — the far side of the Himalayan crest from Bihar, which is why the Gandak is a snow-fed river with a high-altitude regime while every one of the three distractors starts far lower down.

• (a)Burhi Gandak — A genuinely different river that merely shares part of the name. India-WRIS records that the Burhi Gandak rises from a spring of the Someshwar hills in West Champaran district at only 300 m and at about 27°29′ north — not in Tibet at 7,620 m — and is "known as Sikrchana in its upper reaches". It picks up the Masan, Harbora, Tilawe, Siriswa, Koria, Pasaha, Tiar and Hahwa, all with catchments in those same Someshwar hills, becomes the Burhi Gandak only after the Tiar joins it, enters Muzaffarpur, passes Darbhanga district near Pusa, crosses the Samastipur–Mansi line at the Rusera railway bridge, takes in the Bainty Balan in Khagaria and falls into the Ganga about 7 km east of Khagaria. Total length 579 km; catchment 12,180 sq km, of which 10,370 lie in Bihar and 1,810 in Nepal — against the Gandak's 45,731 sq km, so it is under a third the size. Decisively, the Commission maintains a separate Burhi Gandak basin and places it immediately east of the Gandak basin, and lists both as distinct principal tributaries of the Ganga.
• (b)Mahananda — A separate north-bank tributary of the Ganga much further east — the Commission's own framing is that "after the river Gandak and the river Kosi meeting with the mighty river Ganga from the north, Mahananda, the most important tributary also meeting the river Ganga from the north", which places three distinct rivers in one sentence. India-WRIS describes the Mahananda as two streams: the right channel rises in the Nepal Himalaya, crosses Bihar, outfalls into the Ganga opposite Rajmahal and "is locally named as river Fulahar"; the left channel rises downhill at Darjeeling and runs about 400 km through Darjeeling, West Dinajpur and Malda into Bangladesh, reaching the Ganga near Godagarighat opposite Lalgola in Murshidabad. Average rainfall over that catchment is about 1,400 mm with 80% of it in four to five months, and the two channels merge in peak monsoon to waterlog Purnea and Katihar. So the Mahananda does have an alternative name — but it is Fulahar, not Narayani, and its basin never touches the Gandak's.
• (d)Punpun — The Punpun approaches the Ganga from the opposite bank, which makes it the easiest option to eliminate once you notice it. It rises in Palamu district of Jharkhand on the Chota Nagpur plateau and flows through Chatra, Gaya, Aurangabad, Jehanabad and Patna districts to meet the Ganga south-east of Patna. It has no Himalayan headwaters, no Nepali catchment and no snowmelt regime — it is fed only by monsoon rain on the plateau, so it can run near-dry in summer, the exact opposite of the Gandak, which carries Himalayan snowmelt through the lean season and meets the Ganga on the other side of the same city. North-bank and south-bank rivers are the first division of Bihar's drainage; a north-bank river cannot have a south-bank alias.

Himalayan rivers routinely change names along their course, because each stretch was named by the people living beside it rather than by a surveyor working end to end. The Gandaki system is the classic case: it rises as the Kali Gandaki in the high Himalaya, cutting the gorge between Dhaulagiri and Annapurna that is often called the deepest in the world; below the hills the Kali Gandaki and the Trishuli merge and the combined river becomes the Narayani, Nepal's third-largest; and at Triveni, where it debouches onto the plain at Valmikinagar in West Champaran, India calls it the Gandak. The same habit produces Tsangpo–Siang–Brahmaputra–Jamuna and Bhagirathi–Ganga–Padma. For Bihar the Gandak matters twice over: it is one of the four great north-bank rivers that carry Nepal's monsoon runoff onto a near-flat plain, and it forms the western edge of Valmiki Tiger Reserve before running down to the Ganga opposite Patna. The scale of that transfer is the point — 45,731 sq km of catchment, of which only 7,288 sq km lie in Bihar and 30,882 sq km in Nepal, so more than two-thirds of the water Bihar has to absorb is generated outside India, on slopes Bihar cannot manage. The Gandak Barrage at Valmikinagar, on the former Bhainsalotan site, completed in 1968 and 739 m long, is the single structure through which that whole system is regulated, and it is a joint India–Nepal work. The naming, in other words, is not a curiosity: the reason the river has a Nepali name at all is the reason Bihar's flood problem is a foreign-policy problem.

Read the option list before reaching for a fact, because it is built out of one alias and three whole rivers. Burhi Gandak, Mahananda and Punpun are all separate named rivers of Bihar in their own right — every one of them appears in the Central Water Commission's own tributary lists alongside the Gandak — so if any of the three were the answer, the Commission's basin documents would be contradicting themselves. Narayani is the only name in the set that is not the title of a distinct Indian river, and it is the only one that belongs to Nepal. That single observation is the discriminator. The trap is (a): 'Burhi' means old, so 'Burhi Gandak' sounds like an older or alternative name for the same water, when in fact it is a much smaller river with its own source in the Someshwar hills and its own alias, Sikrahna. Note too that each distractor has a real second name of its own — Burhi Gandak is the Sikrchana or Sikrahna upstream, the Mahananda's Bihar channel is the Fulahar — so the question rewards knowing which alias attaches to which river, not merely that aliases exist. If you want a single line of proof rather than a chain of reasoning, use the Central Water Commission's basin boundaries: the Gandak basin is bounded on the east by the Burhi Gandak basin and on the west by the Ghagra basin. A basin cannot border itself, so that one sentence eliminates (a) outright, and the Commission's separate treatment of the Mahananda and the south-bank Punpun does the same for (b) and (d). A last discriminator by elevation, if names fail you entirely: the Gandak's source is at 7,620 m, the Burhi Gandak's at 300 m, and the Punpun's on a plateau — three orders of landscape apart, so they cannot be the same water under different names.

• UNESCO's Chitwan National Park listing names the river twice as "Narayani (Gandak)" and "Narayani (Gandaki)", and calls it the third-largest river in Nepal
• India-WRIS: the Gandak is "known as Kalie or Krishna Gandaki in the upper reaches", rises in southern Tibet at 7,620 m south-east of Dhaulagiri, and enters the plains at Triveni (Valmikinagar) in West Champaran district
• It forms the Uttar Pradesh–Bihar boundary for about 45 km and joins the Ganga opposite Patna; catchment 45,731 sq km — 5,687 in Tibet, 30,882 in Nepal, 1,874 in Uttar Pradesh, 7,288 in Bihar; about 380 km of course in Tibet and Nepal, 250 km in India
• The Burhi Gandak is a different river: it rises from a Someshwar hills spring in West Champaran at 300 m, is called Sikrahna in its upper reaches, runs 579 km with a 12,180 sq km catchment and joins the Ganga about 7 km east of Khagaria
• The Central Water Commission's Ganga page lists the Yamuna, Ramganga, Ghaghra, Gandak, Burhi Gandak, Kosi, Mahananda and Sone as separate principal tributaries — the Gandak and Burhi Gandak are not one river
• The Mahananda's Bihar channel is locally the Fulahar and joins the Ganga opposite Rajmahal; the other channel rises at Darjeeling, runs about 400 km and reaches the Ganga near Godagarighat in Bangladesh; the Punpun rises in Palamu district, Jharkhand, and reaches the Ganga from the south bank near Patna
• India-WRIS on the Gandak basin: "bounded on north by the Himalayas. On the south by the River Ganga, On the east by the Burhi Gandak Basin and on the west by the Ghagra Basin" — the single sentence that proves the Burhi Gandak is a neighbouring river, not an alias
• Burhi Gandak detail: source at about 27°29′ N in the Someshwar hills; tributaries Masan, Harbora, Tilawe, Siriswa, Koria, Pasaha, Tiar and Hahwa; the name changes from Sikrchana to Burhi Gandak only below the Tiar confluence; basin districts West Champaran, Muzaffarpur, Samastipur and Khagaria
• Only 7,288 of the Gandak's 45,731 sq km of catchment lie in Bihar and 30,882 sq km lie in Nepal, which is why the Gandak Barrage at Valmikinagar (the former Bhainsalotan site, completed 1968, 739 m long) is a joint India–Nepal structure

• Reading 'Burhi Gandak' as an older name for the Gandak; it is a smaller, separate river whose own upstream name is the Sikrahna
• Assuming a Nepali river name and an Indian one must belong to different rivers — Narayani, Gandaki and Gandak are the same water
• Mixing up the Gandak with the Ghaghra: both rise in Nepal and both join the Ganga in Bihar, but the Ghaghra meets it near Chhapra and the Gandak opposite Patna

BPSC asks the Bihar river map as bare name-recall — the other name of a river, the district a river rises in, the river a barrage sits on — and builds the option list from other real Bihar rivers so that a half-memory cannot survive. The 69th paper alone does this twice, asking the Gandak's other name here and the river behind the Triveni canal two questions later. UPSC asks the same knowledge as a relationship: which river is a tributary of which, whether two rivers share a source, whether a named river actually reaches the sea on its own. The preparation that covers both is a one-line basin profile per Bihar river — source, alias, states crossed, confluence point — which is exactly the structure the Central Water Commission's basin pages already use.

• practice — not a real PYQ

  The Gandak river enters the plains of Bihar at which place in West Champaran district?

  • (a)Valmikinagar (Triveni)
  • (b)Bagaha
  • (c)Sonepur
  • (d)Barauni

  Answer(a) Valmikinagar (Triveni) — the Central Water Commission records that the Gandak debouches onto the plains at Triveni, Valmikinagar, where two more tributaries join it.

• practice — not a real PYQ

  The Burhi Gandak river is known by which other name in its upper reaches?

  • (a)Narayani
  • (b)Sikrahna
  • (c)Fulahar
  • (d)Trishuli

  Answer(b) Sikrahna — India-WRIS records that the stream rising in the Someshwar hills is called Sikrahna and becomes the Burhi Gandak after the Tiar joins it. Narayani belongs to the Gandak, Fulahar to the Mahananda's Bihar channel.