Indian Geography – Study Notes (IIT‑JEE / Competitive Exams)
Why Indian Geography?
In the Indian competitive exams (IIT‑JEE, UPSC, NTS, BITSAT, etc.) a solid grasp of geography is essential to answer questions on physical features, climate, resources, demographics, and recent policy initiatives. The following notes combine concise facts, derivations, and “tricky points” that often trip candidates.
1. Quick Facts – The Landscape of India
| Feature | Data | Notes |
|---|---|---|
| Total area | 3 287 226 km² | 1.27 % of Earth’s land mass |
| Population (2024) | ~1.43 billion | 18.5 % of world pop |
| Population density | ~435 people/km² | Varies from 3800 in Kerala to <1 in Arunachal |
| Coastline | 7 516 km | 5 % of world’s coastline |
| Official languages | 22 | 19 scheduled, 3 non‑scheduled |
| Major rivers | Ganga, Yamuna, Brahmaputra, Indus, Godavari, Krishna, etc. | 7 of 11 longest rivers in Asia |
| Major mountain ranges | Himalayas, Vindhya, Satpura, Aravalli, Deccan Plateau, etc. | 4 major physiographic zones |
2. Physical Geography
2.1. Physiographic Zones
| Zone | Key Features | Altitude (approx.) | Major Rivers |
|---|---|---|---|
| Himalayas | Highest peaks, glaciers, alpine climate | 8 848 m (K2) | Ganga, Yamuna, Brahmaputra |
| Aravalli Range | Ancient, eroded, mostly low | 600–1 400 m | None major |
| Vindhya & Satpura | Plateaus, rolling hills | 300–900 m | Narmada, Tapti |
| Deccan Plateau | Extensive basaltic plateau | 300–1 800 m | Krishna, Godavari |
| Coastal Plains | Low-lying, alluvial | <200 m | Ganga, Brahmaputra (banking) |
| Thar Desert | Arid, sand dunes | <200 m | Little (Rann of Kutch) |
Tricky Point:
- Himalayas are part of the Indian Subcontinent but not the Indian Peninsula.
- Aravalli is the oldest mountain range in India; its age (~2.5 Ga) is crucial in explaining the scarcity of major rivers.
2.2. Climate Zones (Köppen)
| Zone | Description | Typical Temp | Precipitation |
|---|---|---|---|
| Humid Subtropical (Cwa, Cwb) | North & Central India | 5–35 °C | 800–1 800 mm |
| Tropical Monsoon (Am) | South India | 20–35 °C | 1 800–5 000 mm |
| Arid (BSh, BWh) | Thar Desert | 20–40 °C | 200–650 mm |
| Cold Desert (BWk) | Saurashtra, parts of Rajasthan | −5–25 °C | <200 mm |
Derivation Example:
- Mean Annual Precipitation (MAP) of a region = (Sum of monthly precipitations) / 12.
Used to classify climate types.
2.3. Hydrology
- River Basins:
- Ganga‑Brahmaputra Basin – ~1 200 km long, 10 % of India’s area.
- Indus Basin (in Pakistan) – 1 200 km long, flows through India’s NW.
- Narmada–Tapti Basin – longest basin in peninsular India (~1 600 km).
Tricky Point:
- Indus River originates in the Himalayas but flows west of the Indo‑Gangetic plain – rarely considered a “major Indian river” by Indian sources.
2.4. Natural Resources
| Resource | Distribution | Notes |
|---|---|---|
| Coal | Eastern (Jharia), Western (Kolkata) | 70 % of world’s coal reserves |
| Oil & Gas | Offshore (Bay of Bengal, Arabian Sea) | 22 % of India’s oil reserve |
| Minerals | Iron ore (Bihar), Bauxite (Karnataka), Copper (Gujarat) | 2nd largest bauxite producer worldwide |
| Forests |