Complete Geography Notes for UPSC, PSC, SSC (Part-2): Oceanography & Biogeography

Chapter 3: Oceanography

3.1 Introduction to Oceanography

Oceanography studies the physical, chemical, and biological aspects of oceans, which cover ~71% of Earth’s surface. For UPSC, focus on ocean currents, marine ecosystems, and their impact on India’s climate and economy.

UPSC Relevance: Questions often link oceanography to monsoons, fisheries, and maritime boundaries.

3.2 Structure of the Ocean Floor

• Continental Shelf: Shallow, gently sloping (0–200 m depth), rich in marine life (e.g., India’s western shelf supports fisheries).
• Continental Slope: Steep drop to the ocean basin (200–3,000 m).
• Abyssal Plain: Flat, deep ocean floor (~3,000–6,000 m), covered with sediments.
• Mid-Oceanic Ridges: Underwater mountain ranges (e.g., Mid-Indian Ridge).
• Trenches: Deepest parts (e.g., Mariana Trench, ~11,000 m).
• Seamounts and Guyots: Volcanic peaks, often flat-topped (guyots).

Prelims MCQ Trend: Match ocean features with examples (e.g., Mariana Trench = Pacific Ocean).
Mains Angle: “Discuss the role of continental shelves in India’s marine economy.”

3.3 Ocean Currents

Ocean currents are large-scale water movements driven by wind, temperature, salinity, and Earth’s rotation (Coriolis effect).

• Types:
  • Surface Currents: Driven by winds (e.g., monsoon currents in the Indian Ocean).
  • Deep Currents: Driven by density differences (thermohaline circulation).
• Major Currents:
  • Warm Currents: Gulf Stream (Atlantic), Kuroshio (Pacific).
  • Cold Currents: Labrador Current (Atlantic), Oyashio (Pacific).
  • Indian Ocean Currents: Southwest Monsoon Current (summer), Northeast Monsoon Current (winter).
• Impact on India:
  • Southwest Monsoon Current brings moisture, driving India’s monsoon.
  • Somali Current (upwelling) supports fisheries off India’s west coast.

Prelims Alert: Identify currents affecting India’s climate (e.g., Southwest Monsoon Current).
Mains Task: “Analyze the role of ocean currents in shaping India’s monsoon system.”

3.4 Tides and Waves

• Tides: Periodic rise and fall of sea levels due to gravitational pull (Moon and Sun).
  • Spring Tides: High tides during full/new moon.
  • Neap Tides: Moderate tides during quarter moons.
  • India’s Key Tidal Ports: Kandla, Mumbai (high tidal range).
• Waves: Wind-driven surface disturbances; tsunamis caused by underwater earthquakes (e.g., 2004 Indian Ocean Tsunami).
• UPSC Angle: “How do tides influence India’s coastal economy?” (e.g., fishing, ports).

3.5 Marine Ecosystems

• Coral Reefs: Calcium carbonate structures, supporting biodiversity (e.g., Andaman & Nicobar, Lakshadweep).
  • Great Barrier Reef: World’s largest (Australia).
  • India’s Coral Reefs: Gulf of Mannar, Lakshadweep (threatened by bleaching).
• Mangroves: Coastal forests (e.g., Sundarbans, West Bengal), protect against erosion and storms.
• Upwelling Zones: Nutrient-rich waters (e.g., Malabar Coast), boosting fisheries.

Prelims Favorite: Match ecosystems with locations (e.g., Sundarbans = mangroves).
Mains Angle: “Discuss the ecological and economic significance of India’s mangroves and coral reefs.”

3.6 Ocean Resources

• Fisheries: India ranks 3rd globally in fish production; major species include sardines, mackerel.
• Minerals: Polymetallic nodules (manganese, nickel) in the Indian Ocean.
• Energy: Tidal energy (Gulf of Kutch), offshore wind potential.
• UPSC Relevance: “Evaluate the potential of ocean resources for India’s blue economy.”

Chapter 4: Biogeography

4.1 Introduction to Biogeography

Biogeography studies the distribution of plants and animals, critical for understanding India’s biodiversity and conservation strategies.

UPSC Relevance: Questions focus on biodiversity hotspots, national parks, and climate change impacts.

4.2 Biogeographic Zones of India

India is divided into 10 biogeographic zones (per Wildlife Institute of India):

1. Trans-Himalayan: Ladakh, cold desert (snow leopards).
2. Himalayan: Western and Eastern Himalayas (red panda, Himalayan tahr).
3. Desert: Thar, Kutch (Indian bustard).
4. Semi-Arid: Punjab, Gujarat (blackbuck).
5. Western Ghats: Biodiversity hotspot (lion-tailed macaque).
6. Deccan Peninsula: Central India (chital, sambar).
7. Gangetic Plain: Fertile plains (Gangetic dolphin).
8. Northeast India: Biodiversity hotspot (one-horned rhinoceros).
9. Coastal Region: Mangroves, coral reefs (olive ridley turtles).
10. Islands: Andaman & Nicobar, Lakshadweep (dugong).

Prelims Pick: Match zones with species (e.g., Western Ghats = Nilgiri tahr).
Mains Task: “Explain India’s biogeographic diversity and its conservation challenges.”

4.3 Biodiversity Hotspots in India

India has four global biodiversity hotspots:

• Western Ghats: ~7,400 plant species, 139 mammals (e.g., Nilgiri langur).
• Eastern Himalayas: High endemism (e.g., red panda).
• Indo-Burma: Includes Northeast India (e.g., hoolock gibbon).
• Sundaland: Andaman & Nicobar Islands (e.g., Nicobar megapode).

UPSC Angle: “Why are the Western Ghats and Eastern Himalayas critical for global biodiversity?”

4.4 National Parks and Wildlife Sanctuaries

• Key National Parks:
  • Jim Corbett (Uttarakhand): First national park, tigers.
  • Kaziranga (Assam): One-horned rhinoceros.
  • Sundarbans (West Bengal): Royal Bengal tiger, mangroves.
  • Silent Valley (Kerala): Lion-tailed macaque.
• Biosphere Reserves: 18 in India (e.g., Nilgiri, Sundarbans, Nokrek).
• Conservation Programs:
  • Project Tiger: Launched 1973, ~50 tiger reserves.
  • Project Elephant: Protects elephant corridors.
  • Crocodile Conservation: For gharial, mugger.

Prelims Alert: Match national parks with states or species.
Mains Angle: “Discuss the role of biosphere reserves in balancing conservation and development.”

4.5 Forests and Vegetation Types

• Tropical Evergreen: Western Ghats, Northeast (~2,000 mm rainfall, ebony, mahogany).
• Tropical Deciduous: Central India, Eastern Ghats (moist/dry, teak, sal).
• Thorn Forests: Rajasthan, Gujarat (acacia, low rainfall).
• Mangrove Forests: Sundarbans, Bhitarkanika (tidal, sundari trees).
• Montane Forests: Himalayas (coniferous at higher altitudes, oak/chestnut lower).

India’s Forest Cover: ~24.6% of land area (India State of Forest Report 2021), Madhya Pradesh leads (~77,700 sq.km).

Prelims Favorite: Match vegetation with rainfall/region.
Mains Task: “Analyze the impact of deforestation on India’s biodiversity and climate.”

4.6 Climate Change and Biodiversity

• Threats:
  • Habitat loss (deforestation, urbanization).
  • Species extinction (e.g., cheetah extinct in India).
  • Coral bleaching (Gulf of Mannar, Lakshadweep).
• Adaptation Measures:
  • National Action Plan on Climate Change (NAPCC): Eight missions, including Green India Mission.
  • Protected Areas: 106 national parks, 567 wildlife sanctuaries (2024 data).

UPSC Relevance: “Evaluate the impact of climate change on India’s biodiversity hotspots.”