Physical Features of India

Overview

Physical Features of India is a foundational topic in Social Studies for Assam TET Paper II. It covers the major landforms—mountains, plains, plateaus—along with the river systems and climatic patterns that shape the subcontinent. This topic forms the basis for understanding agriculture, population distribution, natural resources, and regional diversity across India.

For the Assam TET, expect direct questions on identification of physical divisions, characteristics of major rivers, and climate types. Questions often link physical geography to human activities—why certain regions are densely populated, why floods affect Assam, or why the Deccan is mineral-rich. Mastering this topic also helps with the Geography of Assam section, as Assam's landforms and rivers are part of the broader Indian physiographic framework.

Students must build a clear mental map of India's six physiographic divisions and understand how relief, drainage, and climate interact to create India's geographic diversity.

Key Concepts

• **Six Major Physiographic Divisions**: India is divided into the Himalayan Mountains, Northern Plains, Peninsular Plateau, Coastal Plains, Islands, and the Thar Desert—each with distinct formation, soil, and economic significance.

• **Himalayan Formation**: The Himalayas are young fold mountains formed by the collision of the Indian Plate and Eurasian Plate about 50 million years ago. They are still rising and experience frequent earthquakes.

• **Three Parallel Ranges of Himalayas**: From north to south—Himadri (Greater Himalayas, permanently snow-covered), Himachal (Lesser Himalayas, includes hill stations), and Shiwaliks (Outer Himalayas, youngest and most fragile).

• **Northern Plains as Alluvial Formation**: Formed by depositional work of Indus, Ganga, and Brahmaputra rivers. Divided into Bhabar (pebble zone), Terai (marshy), Bhangar (older alluvium), and Khadar (newer alluvium, fertile flood plains).

• **Peninsular Plateau as Ancient Landmass**: Part of the Gondwana landmass, one of the oldest and most stable land blocks. Divided into Central Highlands (north of Narmada) and Deccan Plateau (south of Narmada).

• **Drainage Divide**: The Western Ghats act as a water divide—rivers flowing east (Godavari, Krishna, Kaveri) drain into Bay of Bengal; rivers flowing west (Narmada, Tapi) drain into Arabian Sea.

• **Monsoon as Unifying Climate Factor**: India's climate is dominated by the monsoon system. The southwest monsoon (June–September) brings 75% of annual rainfall; the northeast monsoon affects Tamil Nadu in winter.

• **Continental Nature of Indian Climate**: Large size creates temperature extremes—Rajasthan exceeds 50°C in summer while Ladakh drops below -40°C in winter.

Formulas / Key Facts

| Feature | Key Fact | |---------|----------| | Highest peak in India | Kangchenjunga (8586 m) in Sikkim | | Longest river in India | Ganga (2525 km) | | Largest river by volume | Brahmaputra | | Highest plateau | Ladakh Plateau (average 5000 m) | | Oldest mountain range | Aravalli Range | | Western Ghats average height | 900–1600 m | | Eastern Ghats average height | 600 m | | Chilika Lake location | Odisha coast (largest coastal lagoon) | | Area of Northern Plains | About 7 lakh sq km | | Monsoon onset in India | Kerala coast, around 1st June |

**River Systems**:

• Himalayan rivers: Perennial (snow-fed + rain-fed) — Ganga, Yamuna, Brahmaputra
• Peninsular rivers: Seasonal (rain-fed only) — Godavari, Krishna, Kaveri, Mahanadi
• West-flowing rivers: Narmada, Tapi (flow through rift valleys)

Worked Examples

**Example 1**: Why are the Northern Plains densely populated?

*Step-by-step*: 1. The Northern Plains are formed by alluvial deposits from Himalayan rivers 2. Alluvial soil is extremely fertile, supporting intensive agriculture 3. Flat terrain allows easy construction of roads, railways, and canals 4. Perennial rivers provide year-round water for irrigation 5. Moderate climate supports multiple cropping seasons

*Answer*: Fertile alluvial soil, flat terrain, perennial water supply, and good transport connectivity make the Northern Plains ideal for agriculture and settlement, leading to high population density.

**Example 2**: Differentiate between Western Ghats and Eastern Ghats.

| Aspect | Western Ghats | Eastern Ghats | |--------|---------------|---------------| | Continuity | Continuous chain | Discontinuous, broken by rivers | | Average height | 900–1600 m | 600 m | | Highest peak | Anai Mudi (2695 m) | Mahendragiri (1501 m) | | Rainfall | Heavy (windward side) | Moderate | | Rivers | Source of peninsular rivers | Cut through by Godavari, Krishna, Kaveri |

**Example 3**: Explain why Assam experiences severe floods annually.

*Step-by-step*: 1. Brahmaputra carries enormous water volume from Himalayan snowmelt and monsoon rains 2. The river flows through a narrow valley between hills 3. Heavy monsoon rainfall (200–400 cm annually) in catchment areas 4. Deforestation in upper catchment increases runoff 5. Flat terrain of Brahmaputra valley prevents quick drainage 6. River carries heavy silt load, raising riverbed levels

*Answer*: The combination of high water volume, narrow valley, heavy monsoon rainfall, and flat terrain causes the Brahmaputra to overflow its banks, resulting in annual floods in Assam.

Common Mistakes

• **Confusing Himadri with Himachal**: Students mix up the three Himalayan ranges. Remember: Himadri is highest (Greater), Himachal is middle (Lesser, has hill stations like Shimla), Shiwaliks are lowest (Outer, most eroded).

• **Calling all Peninsular rivers seasonal**: While most peninsular rivers are seasonal, the Godavari and Krishna have some tributaries that maintain flow. The key distinction is snow-fed (perennial) versus rain-fed (seasonal).

• **Thinking Western Ghats are higher because they receive more rain**: Western Ghats receive more rain because they are on the windward side of the southwest monsoon, not because of height. Eastern Ghats are in rain shadow.

• **Placing Narmada and Tapi as north-flowing**: Narmada and Tapi flow westward through rift valleys into the Arabian Sea. They are exceptions among peninsular rivers, which mostly flow eastward.

• **Assuming monsoon arrives uniformly**: The monsoon advances gradually—Kerala by June 1, reaches Assam by June 5–7, and covers entire India by mid-July. This phased advance is frequently tested.

Quick Reference

• **6 Physiographic Divisions**: Himalayas, Northern Plains, Peninsular Plateau, Coastal Plains, Islands, Thar Desert

• **3 Himalayan Ranges (N→S)**: Himadri → Himachal → Shiwaliks

• **4 Plains Zones (N→S)**: Bhabar → Terai → Bhangar → Khadar

• **Major East-flowing Rivers**: Mahanadi, Godavari, Krishna, Kaveri

• **Major West-flowing Rivers**: Narmada, Tapi (through rift valleys)

• **Monsoon Branches**: Arabian Sea branch (western India) and Bay of Bengal branch (eastern India, including Assam)