Indian Geography – Study Notes
Audience: APO exam aspirants (General Awareness & Current Affairs)
Exam orientation: IIT‑JEE/competitive style – concise, fact‑heavy, formula‑friendly, with tricky points highlighted.
1. Quick Reference Table
| Category | Key Info | Notes |
|---|---|---|
| Total area | 3,287,263 km² | 2nd largest after China |
| Population (2023) | ≈ 1.4 billion | 1.9% of world pop. |
| Population density | ≈ 420 persons/km² | 1st most densely populated country |
| States | 28 | 7 Union Territories |
| Capital | New Delhi (National Capital Territory) | |
| Official language | 22 scheduled languages + Hindi, English (associate) | |
| Time zones | IST (UTC+5:30) – single zone | |
| Geographic zones | 4 major – Himalayan, Indo‑Gangetic Plains, Thar Desert, Deccan Plateau, Coastal | |
| Major rivers | Ganga, Yamuna, Brahmaputra, Godavari, Narmada, etc. | |
| Major mountain ranges | Himalayas (NW), Aravalli (central), Vindhya & Satpura (central), Eastern Ghats (east) |
2. Physical Geography
2.1. Plate Tectonics & Mountain Building
- Indian Plate collided with Eurasian Plate ~55–50 Myr ago → Himalayan orogeny.
- Active tectonics: 5–6 cm/yr convergence → 7–8 Myr uplift of Himalayas; explains frequent earthquakes.
Tricky Point:
- Many students confuse the Himalayas (northern border) with the Himalayan foothills (the Shivalik range).
- Himalayan highest peak: K2 (8,611 m) – part of the Hindu Kush‑Karakoram range, not on the India‑Pakistan boundary.
2.2. River Systems
| River | Basin | Length (km) | Notable Feature |
|---|---|---|---|
| Ganga | Ganga–Brahmaputra | 2,525 | Source: Gangotri (Himalayas) |
| Yamuna | Ganga | 1,376 | Confluence at Prayag (Allahabad) |
| Brahmaputra | Brahmaputra | 2,900 | Originates in Tibet; enters India as Siang |
| Narmada | Narmada | 1,312 | Flows west → Arabian Sea |
| Godavari | Godavari | 1,465 | Longest river in India |
Formula:
- River Basin Area (A) = (\sum) of tributary catchments.
- Discharge (Q) ≈ (C \times P \times A) where (C) = runoff coefficient, (P) = annual rainfall.
2.3. Climate Zones
| Zone | Latitude | Climate Type | Key Weather Patterns |
|---|---|---|---|
| Himalayan | 28–35°N | Alpine, Sub‑arctic | Heavy snowfall, glacial melt |
| Indo‑Gangetic | 20–28°N | Humid subtropical | Monsoon, pre‑monsoon showers |
| Thar Desert | 20–30°N | Arid | Extreme heat, low rainfall |
| Deccan Plateau | 15–25°N | Semi‑arid | Monsoon rains, dry winters |
| Coastal (Western & Eastern) | 5–20°N | Tropical monsoon | Heavy monsoon, cyclones |
Tricky Point:
- Western Ghats: Though called "the Western" range, they run along the west coast and capture the Arabian monsoon.
- Eastern Ghats: Are discontinuous; not as high as Western Ghats.
2.4. Soil Types
| Region | Soil | Agriculture |
|---|---|---|
| Indo‑Ganga | Alluvial | Rice, wheat |
| Deccan | Red & black cotton | Millets, pulses |
| Thar | Sandy | Very limited |
3. Human Geography
3.1. States & Union Territories (with Capitals)
| State | Capital | Area (km²) | Population (census 2021) |
|---|---|---|---|
| Uttar Pradesh | Lucknow | 240,928 | 237.1M |
| Maharashtra | Mumbai | 307,713 | 123.5M |
| Bihar | Patna | 94,163 | 124.0M |
| ... | ... | ... | ... |
| Union Territories | |||
| Chandigarh | Chandigarh | 114 | 1.6M |
| Puducherry | Puducherry | 442 | 0.8M |
| ... | ... | ... | ... |
Tricky Point:
- Delhi is a National Capital Territory (NCT), not a state.
- Ladakh (since 2019) is a UT; previously part of Jammu & Kashmir (state).
3.2. Language Distribution
- 22 scheduled languages; most spoken: Hindi (41%), Bengali (8.5%), Telugu (7.5%), Marathi (7.3%), Tamil (6.6%).
- Tricky Point:
- Urdu is a scheduled language but also a lingua franca in many states; check Kashmiri vs Kashmiri (Urdu).
3.3. Demographics & Statistics
| Metric | Formula | Example (India) |
|---|---|---|
| Population Density | ( \frac{Population}{Area} ) | ( \frac{1.4 \times 10^9}{3.29 \times 10^6} \approx 420 ) persons/km² |