Geography
India: Location and Physiography
Coastal Plains and Islands
Western and Eastern coastal plains, lagoons and deltas, and the Andaman–Nicobar and Lakshadweep islands for CGPSC Prelims and Mains GS-III.
Prerequisites
- The Peninsular Plateau — the Western and Eastern Ghats that border these plains.
- India: Location and Extent — coastline length and the channels between the islands.
The Hook: Where Does the Mahanadi Go?
Connect
The Mahanadi (महानदी) rises at Sihawa in Dhamtari district, waters the Chhattisgarh plain, and then leaves the state. Its journey ends on the Utkal coast of Odisha, where it builds a delta into the Bay of Bengal. Meanwhile, iron ore from Bailadila travels by rail to Visakhapatnam port on the same eastern coast. Chhattisgarh has no coast, yet its rivers and minerals end up there.
Why is the east coast wide and full of deltas while the west coast is narrow and full of backwaters? And why are the Andaman Islands mountains while Lakshadweep is coral? This page answers both.
Why it matters: Prelims asks about coastal names in order, lagoons and lakes, island facts (volcanoes, capitals, channels). Mains GS-III asks to compare the two coasts, and about ports, the blue economy and coastal hazards.
The Coastal Plains: Overview
The peninsula is fringed by narrow coastal strips between the Ghats and the sea: the Western Coastal Plain along the Arabian Sea and the Eastern Coastal Plain along the Bay of Bengal.
Western Coastal Plain (north to south)
| Section | Stretch | Features |
|---|---|---|
| Kachchh and Kathiawar | Gujarat | Rann of Kachchh (salt marsh); Gulf of Kachchh and Gulf of Khambhat with high tides |
| Konkan coast | Mumbai to Goa | Rocky, with cliffs and small bays |
| Kannad (Canara) coast | Goa to Mangaluru | Narrow; rivers rush down from the Ghats (Jog Falls on the Sharavathi is inland of this coast) |
| Malabar coast | Mangaluru to Kanyakumari | Wider; kayals (backwaters) and lagoons; Vembanad Lake, India’s longest lake |
Eastern Coastal Plain (north to south)
| Section | Stretch | Features |
|---|---|---|
| Utkal plain | Odisha | Mahanadi delta; Chilika Lake |
| Northern Circars | Broadly the Andhra coast | Godavari and Krishna deltas; Kolleru Lake between them |
| Coromandel coast | Tamil Nadu | Kaveri delta; Pulicat Lake (on the Andhra–Tamil Nadu border) |
Western vs Eastern Coastal Plain
| Point | Western Coastal Plain | Eastern Coastal Plain |
|---|---|---|
| Width | Narrow (except Gujarat) | Wider |
| Nature | Submergent coast (part of the land sank; old Dwarka is believed to lie under the sea) | Emergent coast (land has risen or the sea has retreated) |
| Rivers | Short, swift rivers; estuaries, no big deltas (Narmada, Tapi form estuaries) | Long rivers form large deltas (Mahanadi, Godavari, Krishna, Kaveri) |
| Ports | Many natural harbours with deep water: Mumbai, JNPA, Deendayal (Kandla), Mormugao, New Mangalore, Kochi | Fewer natural harbours; Visakhapatnam is natural (land-locked harbour); others such as Chennai and Paradip are artificial or improved |
| Continental shelf | Narrower near Kerala, wider off Gujarat–Maharashtra (Mumbai High oil field) | Wider, especially near deltas (Krishna–Godavari basin gas) |
| Lakes | Kayals (backwaters), Vembanad, Ashtamudi | Lagoons: Chilika, Pulicat; freshwater Kolleru |
| Rainfall | Heavy from the south-west monsoon | Rain from both monsoons; Tamil Nadu gets most rain in winter (north-east monsoon); cyclone-prone |
Lakes and lagoons to know
| Lake | State | Fact |
|---|---|---|
| Chilika | Odisha | Largest brackish-water coastal lagoon in India; one of India’s first two Ramsar sites (1981); Irrawaddy dolphins |
| Pulicat | Andhra Pradesh–Tamil Nadu | Second-largest brackish lagoon; separated from the sea by the barrier island of Sriharikota (ISRO launch centre) |
| Kolleru | Andhra Pradesh | Freshwater lake between the Godavari and Krishna deltas |
| Vembanad | Kerala | Longest lake in India; Kerala’s largest; Kochi port at its sea mouth |
Coastal wetlands and wildlife
- Mangroves: Sundarbans (West Bengal), Bhitarkanika (Odisha), Pichavaram (Tamil Nadu), Godavari–Krishna mangroves.
- Olive Ridley turtles nest in huge numbers (arribada) on Odisha beaches such as Gahirmatha and Rushikulya.
The Islands
India has two island groups with very different origins.
Andaman and Nicobar Islands (Bay of Bengal)
| Point | Detail |
|---|---|
| Number | 836 islands, of which 31 are inhabited (UT administration figures) |
| Origin | Tectonic: the islands are the elevated parts of a submarine mountain range, a continuation of the Arakan Yoma of Myanmar |
| Division | Andaman group (north) and Nicobar group (south), separated by the Ten Degree Channel |
| Capital | Sri Vijaya Puram (renamed from Port Blair in September 2024), on South Andaman |
| Highest peak | Saddle Peak (about 737 m), North Andaman |
| Nicobar high point | Mount Thuillier (about 642 m), Great Nicobar |
| Volcanoes | Barren Island: India’s only active volcano; Narcondam: a dormant volcano |
| Southernmost point of India | Indira Point, Great Nicobar |
| Climate and vegetation | Equatorial type; rain from both monsoons; dense evergreen forest |
| People | Indigenous groups including the Jarawa, Onge, Great Andamanese, Sentinelese (Andamans) and Shompen and Nicobarese (Nicobars) |
Lakshadweep (Arabian Sea)
| Point | Detail |
|---|---|
| Number | 36 islands; 10 inhabited |
| Origin | Coral: atolls and reefs built on submarine ridges |
| Area | About 32 km² (the smallest UT by area) |
| Name | Formerly Laccadive, Minicoy and Amindivi Islands; renamed Lakshadweep in 1973 |
| Capital | Kavaratti |
| Largest island | Andrott (about 4.9 km²) |
| Southernmost | Minicoy, separated from the main group by the Nine Degree Channel and from the Maldives by the Eight Degree Channel |
| Other | Pitti island: an uninhabited bird sanctuary |
Other islands
- Offshore islands: Elephanta (Mumbai harbour), Diu, Pamban (Rameswaram), Sriharikota (launch site), Dr A.P.J. Abdul Kalam Island (formerly Wheeler Island, Odisha; missile test range).
- River islands: Majuli in the Brahmaputra, India’s largest river island (see Northern Plains).
Significance (for Mains)
- Ports and trade: about 95% of India’s trade by volume moves by sea (government estimates); port-led development under the Sagarmala Programme.
- Blue economy: fisheries, offshore oil and gas (Mumbai High, Krishna–Godavari), salt (Gujarat), tourism.
- Agriculture: deltas are rice bowls (Kaveri, Godavari–Krishna); coconut and spices on the Malabar coast.
- Strategic: Andaman and Nicobar overlooks the Strait of Malacca; India’s only tri-service command is at Sri Vijaya Puram.
- Hazards: east-coast cyclones (Odisha 1999, Phailin 2013, Fani 2019), the 2004 tsunami, coastal erosion and sea-level rise. Odisha’s zero-casualty approach to cyclone evacuation is a model.
- Chhattisgarh link: landlocked, the state relies on Visakhapatnam and Paradip for exports; the Bailadila ore moves to Visakhapatnam by the Kirandul–Kottavalasa rail line.
Memory Tricks
West coast north to south: 'Kachchh Kids Kan Make (it)'
Kachchh–Kathiawar → Konkan → Kannad → Malabar. Three Ks and an M.
East coast north to south: 'U-N-C' (You Need Coconut)
Utkal (Odisha) → Northern Circars (Andhra) → Coromandel (Tamil Nadu).
Islands: 'Andaman = Mountain, Lakshadweep = Coral'
Bay of Bengal islands are big, high and volcanic/tectonic; Arabian Sea islands are small, flat and coral.
Don’t Confuse
| This | vs | That |
|---|---|---|
| Chilika — brackish lagoon, Odisha | vs | Kolleru — freshwater lake, Andhra Pradesh |
| Pulicat — lagoon behind Sriharikota | vs | Vembanad — Kerala backwater, longest lake |
| Barren Island — active volcano | vs | Narcondam — dormant volcano |
| Konkan — Mumbai to Goa | vs | Malabar — Mangaluru to Kanyakumari |
| Ten Degree Channel — Andaman/Nicobar | vs | Nine Degree Channel — Minicoy/Lakshadweep |
| Kavaratti — capital of Lakshadweep | vs | Andrott — largest island of Lakshadweep |
Common Mistakes
MCQ traps
- “The western coast is an emergent coast with large deltas.” False. It is a submergent coast with estuaries; deltas are on the east coast.
- “Kolleru is a brackish lagoon.” False. It is a freshwater lake.
- “Lakshadweep is of volcanic origin.” False. It is coral. The Andaman and Nicobar Islands are of tectonic (submarine mountain) origin.
- “Narcondam is India’s only active volcano.” False. Barren Island is.
- “Port Blair” as the current capital name. Since September 2024 the capital is officially Sri Vijaya Puram; recognise both names.
Practice
All questions below are original practice questions written in CGPSC style. They are not previous-year questions.
Level 1: Foundation
- The stretch of the western coast between Mumbai and Goa is called the ______ coast.
- India’s only active volcano is on ______ Island.
- The capital of Lakshadweep is ______.
Answers
- Konkan.
- Barren Island (Andaman Sea).
- Kavaratti.
Level 2: Prelims MCQs
Q1. Consider the following statements:
- The Eastern Coastal Plain is wider than the Western Coastal Plain.
- Kolleru Lake lies between the deltas of the Godavari and the Krishna.
- Lakshadweep islands are of volcanic origin.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 2 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer and explanation
(b) 1 and 2 only. The east coast is wider because of large river deltas. Kolleru is a freshwater lake between the Godavari and Krishna deltas. Lakshadweep is made of coral atolls, so statement 3 is wrong.
Q2. Match List I (Lake) with List II (State):
| List I | List II |
|---|---|
| A. Chilika | 1. Kerala |
| B. Vembanad | 2. Odisha |
| C. Kolleru | 3. Andhra Pradesh–Tamil Nadu |
| D. Pulicat | 4. Andhra Pradesh |
- (a) A-2, B-1, C-3, D-4
- (b) A-2, B-1, C-4, D-3
- (c) A-1, B-2, C-4, D-3
- (d) A-2, B-4, C-1, D-3
Answer and explanation
(b) A-2, B-1, C-4, D-3. Chilika is in Odisha, Vembanad in Kerala, Kolleru in Andhra Pradesh, and Pulicat straddles the Andhra Pradesh–Tamil Nadu border behind Sriharikota.
Q3. Arrange the following coasts from north to south:
- Malabar 2. Konkan 3. Kannad 4. Kathiawar
- (a) 4, 3, 2, 1
- (b) 2, 4, 3, 1
- (c) 4, 2, 3, 1
- (d) 4, 2, 1, 3
Answer and explanation
(c) 4, 2, 3, 1. Kathiawar (Gujarat) → Konkan (Mumbai–Goa) → Kannad (Goa–Mangaluru) → Malabar (Mangaluru–Kanyakumari).
Q4. Which of the following pairs is correctly matched?
- (a) Saddle Peak — Great Nicobar
- (b) Ten Degree Channel — between Minicoy and the Maldives
- (c) Andrott — largest island of Lakshadweep
- (d) Narcondam — active volcano
Answer and explanation
(c). Andrott (about 4.9 km²) is the largest Lakshadweep island. Saddle Peak is in North Andaman; the Ten Degree Channel separates Andaman from Nicobar (the Eight Degree Channel separates Minicoy from the Maldives); Narcondam is dormant, while Barren Island is active.
Level 3: Mains Answer Writing
Q1. (150–200 words) Compare the Western and Eastern Coastal Plains of India. How do their differences affect ports and agriculture?
Model answer outline
- Intro: Narrow plains between the Ghats and the sea; western along the Arabian Sea, eastern along the Bay of Bengal.
- Comparison: width (narrow vs wide); submergent vs emergent; estuaries vs deltas; kayals vs lagoons (Chilika, Pulicat); rainfall (south-west monsoon vs both monsoons, cyclones).
- Ports: west has deep natural harbours (Mumbai, Mormugao, Kochi); east has fewer natural harbours, but Visakhapatnam and Paradip serve the mineral belt.
- Agriculture: eastern deltas are rice bowls (Kaveri, Godavari–Krishna, Mahanadi); western coast has coconut, spices, cashew.
- Chhattisgarh angle: The Mahanadi from Sihawa builds the Odisha delta; Bailadila ore is exported through Visakhapatnam.
- Conclusion: Both coasts are central to the blue economy; the east needs cyclone resilience, the west needs erosion and wetland protection.
Q2. (60 words) Why are the Andaman and Nicobar Islands strategically important for India?
Model answer outline
- Located near the Strait of Malacca, a key sea lane for trade and energy.
- Host India’s only tri-service command (Sri Vijaya Puram).
- Extend India’s Exclusive Economic Zone and surveillance in the Bay of Bengal and Andaman Sea.
- Gateway for the Act East policy towards South-East Asia.
Quick Revision Table
| Fact | Detail |
|---|---|
| West coast (N→S) | Kachchh–Kathiawar, Konkan, Kannad, Malabar |
| East coast (N→S) | Utkal, Northern Circars, Coromandel |
| West vs East | Narrow, submergent, estuaries vs wide, emergent, deltas |
| Chilika | Largest brackish lagoon; Ramsar site 1981; Odisha |
| Kolleru | Freshwater; between Godavari and Krishna deltas |
| Pulicat | Behind Sriharikota |
| Vembanad | Longest lake in India; Kerala |
| Andaman and Nicobar | 836 islands, 31 inhabited; tectonic; capital Sri Vijaya Puram (from 2024) |
| Barren / Narcondam | Active / dormant volcano |
| Saddle Peak | About 737 m, North Andaman |
| Lakshadweep | 36 islands, 10 inhabited; coral; Kavaratti; Andrott largest |
Key Takeaways
Key Takeaways
- West coast: narrow, submergent, estuaries and natural harbours. East coast: wide, emergent, deltas and lagoons.
- Learn both coasts north to south: Kachchh–Konkan–Kannad–Malabar and Utkal–Northern Circars–Coromandel.
- Andaman and Nicobar are tectonic and mountainous; Lakshadweep is coral.
- Barren Island is India’s only active volcano.
- Chhattisgarh is landlocked, but its rivers (Mahanadi) and minerals (Bailadila) end on the east coast.
What’s Next
- India: Location and Physiography — Quick Revision — the whole chapter on one page
- Climate and the Indian Monsoon — cyclones and the two monsoons
- Industries and Transport — ports and coastal shipping
- Chhattisgarh: Drainage and Rivers — the Mahanadi from Sihawa
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