BPSC 71st CCE Prelims General Studies · Question 107 of 150

Correct — C, Godavari river basin. The Godavari drains 3,12,812 sq km and runs 1,465 km from Brahmagiri hill at Trimbakeshwar in Nashik district, Maharashtra, at about 920 m, right across the peninsula to the Bay of Bengal — India's second longest river after the Ganga. Its basin lies in Maharashtra, Telangana, Andhra Pradesh, Chhattisgarh, Madhya Pradesh, Odisha, Karnataka and Puducherry (Yanam), with Maharashtra taking by far the largest share at about half, fed from the left by the Purna, Pranahita, Indravati and Sabari and from the right by the Pravara, Manjira and Manair, and it fans out into a delta at the Dhavaleshwaram barrage near Rajamahendravaram, splitting into the Gautami and Vasishta Godavari. Against the other three options this is not a close contest: Mahanadi roughly 1.3–1.4 lakh sq km depending on the source, Narmada 98,796 sq km, Kaveri 81,155 sq km. The Commission's own published remark on this question reads that the Godavari basin 'is the largest river basin in peninsular India and second largest after Ganga Basin in India'. The first half of that is unambiguous and is the fact worth memorising — no peninsular basin comes near the Godavari, which is why it is called the Dakshina Ganga. Be precise about the second half, though. The Ganga basin covers about 8.61 lakh sq km inside India, and the Indian portion of the Indus basin is reckoned at roughly 3.21 lakh sq km — marginally more than the Godavari's 3,12,812 — so the Commission's own remark calls it 'the largest river basin in peninsular India and second largest after Ganga Basin in India', and that is the sense the paper intends; on drainage area within India the Indus basin's Indian portion is larger than the Godavari's, so a ranking that counts it would put the Godavari third. The key is unaffected because the Indus is not on the option list: among the four rivers actually printed, the Godavari's basin is more than twice the next largest.

• (a)Mahanadi river basin — The nearest rival on the list and the reason the question is not trivial: the Mahanadi is 900 km long, rises at Nagri-Sihawa in Dhamtari district, Chhattisgarh at about 890 m, drains mainly Chhattisgarh and Odisha, and carries the Hirakud dam. But its basin is roughly 1.3–1.4 lakh sq km — well under half the Godavari's 3,12,812.
• (b)Narmada river basin — Tempting because the Narmada owns a different superlative — it is the largest WEST-flowing river of peninsular India, 1,312 km from Narmada Kund on the Amarkantak plateau in Anuppur district, Madhya Pradesh, to the Gulf of Khambhat. Its basin is only 98,796 sq km, because it runs in a narrow rift valley penned between the Vindhyas and the Satpuras and gathers almost no long tributaries.
• (d)Kaveri river basin — The smallest of the four. The Kaveri is about 800 km long from Talakaveri in the Brahmagiri hills of Kodagu district, Karnataka, at 1,341 m, and its basin is 81,155 sq km — roughly a quarter of the Godavari's. Its constant presence in inter-State water-dispute headlines gives it a prominence that has nothing to do with basin size.

A river basin, or catchment, is the entire area of land whose surface runoff drains into one river and its tributaries, bounded by a water divide along the ridge lines. So basin size is set by lateral reach — how far a river's tributaries stretch sideways — not by the length of the trunk stream. India's drainage divides into two very different families. The Himalayan rivers are snow-and-glacier fed, perennial, and carve huge alluvial basins across the northern plains; the peninsular rivers are rain-fed and seasonal, flow over old hard rock in mature, shallow valleys, and are largely fixed in their courses. The peninsula's water divide is the Western Ghats, which run close to and parallel with the west coast, so the great majority of peninsular drainage is forced eastward across the full width of the plateau into the Bay of Bengal. The Godavari, Krishna, Mahanadi and Kaveri are all products of that geometry; the Narmada and Tapi are the exceptions, running west down fault-bounded rift valleys.

A quick and reliable route to the answer is to rank the four by length, which you almost certainly know: Godavari 1,465 km, Narmada 1,312 km, Mahanadi 900 km, Kaveri about 800 km. That puts the Godavari first and gets you the mark. But do not generalise the shortcut, because it fails on the very next pair — the Narmada is 400 km longer than the Mahanadi yet has the smaller basin (98,796 sq km against roughly 1.3–1.4 lakh), for the simple reason that a rift-valley river hemmed in by two ranges has nowhere to grow sideways. The real discriminator for the Godavari is lateral reach: it is the only peninsular river whose tributaries push north-east into Chhattisgarh and Odisha (Indravati, Sabari) while others run back west into Maharashtra (Purna, Pranahita) and south into Telangana and Karnataka (Manjira). That sprawl across five States is what makes the basin 3.13 lakh sq km. The last discipline is with the phrase 'second largest in India' itself — safe here only because the Indus is absent from the options.

• Godavari: length 1,465 km, basin 3,12,812 sq km; India's second longest river after the Ganga; rises on Brahmagiri hill at Trimbakeshwar, Nashik district, Maharashtra, at about 920 m; known as the Dakshina Ganga
• Godavari basin States, all eight of them: Maharashtra (about 48.7%, much the largest), Andhra Pradesh and Telangana together, Chhattisgarh, Madhya Pradesh, Odisha, Karnataka and the Yanam enclave of Puducherry. A five-State list circulates widely and drops Madhya Pradesh and Karnataka; its percentages sum to only about 88%, which is the giveaway
• The comparison the question turns on: Godavari 3,12,812 sq km against Mahanadi roughly 1.3–1.4 lakh sq km, Narmada 98,796 sq km and Kaveri 81,155 sq km
• The ranking caveat: the Ganga basin covers about 8.61 lakh sq km within India and the Indian portion of the Indus basin about 3.21 lakh sq km, so standard references call the Godavari India's third largest basin — it is, however, unambiguously the largest basin of peninsular India, and the Commission's key stands because the Indus is not an option
• Godavari tributaries and delta: left bank Purna, Pranahita, Indravati and Sabari; right bank Pravara, Manjira and Manair; the delta starts at the Dhavaleshwaram barrage near Rajamahendravaram, where the river splits into the Gautami Godavari and the Vasishta Godavari

• Treating 'second largest river basin in India' as an unqualified ranking — it is the Commission's phrasing and it is right for peninsular India and on the usual reckoning; counting the Indus basin's Indian portion (about 3.21 lakh sq km) would put the Godavari third, and the key holds because the Indus is not among the options
• Using river length as a proxy for basin area — the Narmada is 1,312 km against the Mahanadi's 900 km, yet its basin (98,796 sq km) is the smaller of the two
• Confusing the Narmada's real superlative, largest west-flowing peninsular river, with the Godavari's, largest peninsular basin

BPSC asks the superlative outright and lets the option list carry the difficulty — three peninsular basins that are all comfortably smaller, so a single remembered ranking clears it. UPSC prefers to make you assemble the basin rather than recall its rank: in 2015 it asked which of Vamsadhara, Indravati, Pranahita and Pennar are Godavari tributaries, and in 2003 it asked four peninsular rivers to be ordered by length.

• practice — not a real PYQ

  Arrange the following river basins in descending order of drainage area: 1. Narmada 2. Godavari 3. Kaveri 4. Mahanadi Select the correct answer using the code given below:

  • (a)2, 1, 4, 3
  • (b)2, 4, 1, 3
  • (c)4, 2, 1, 3
  • (d)2, 4, 3, 1

  Answer(b) 2, 4, 1, 3 — Godavari 3,12,812 sq km, Mahanadi roughly 1.3–1.4 lakh sq km, Narmada 98,796 sq km, Kaveri 81,155 sq km. The pair that decides the question is Mahanadi against Narmada: the Narmada is the longer river at 1,312 km against 900 km, but a rift-valley river hemmed between the Vindhyas and Satpuras has no room for long tributaries, so its basin is the smaller of the two.

• practice — not a real PYQ

  Which is the largest west-flowing river of peninsular India?

  • (a)Tapi
  • (b)Narmada
  • (c)Mahi
  • (d)Periyar

  Answer(b) Narmada — 1,312 km from Narmada Kund on the Amarkantak plateau, draining 98,796 sq km westward through a rift valley into the Gulf of Khambhat. The Tapi is the second west-flowing river and runs a parallel rift south of the Satpuras; the Mahi is far smaller; and the Periyar is a short Kerala river of the Western Ghats.