Chapter 3: Indian Physiography
India’s physiography is diverse, shaped by tectonic movements and erosional-depositional processes. It can be divided into six major physiographic divisions:
1. The Northern and Northeastern Mountains
Includes: Himalayas, Trans-Himalayas, Purvanchal Hills
- Formation: Formed by the collision of Indian and Eurasian plates (convergent boundary).
- Divisions of Himalayas:
- Trans-Himalayas: Karakoram, Ladakh, Zaskar
- Greater Himalayas (Himadri): Highest peaks (Mt. Everest, Kanchenjunga), snow-covered
- Lesser Himalayas (Himachal): Hill stations like Shimla, Mussoorie
- Shiwalik: Foothills, recent origin, forested
- Important Passes: Zoji La, Shipki La, Nathu La, Bomdi La
Purvanchal Hills: Extension of Eastern Himalayas
- Located in Nagaland, Manipur, Mizoram, Tripura
- Include hills like Patkai, Mizo, Naga
Mains Relevance: Discuss Himalayan formation, landslides, seismic activity.
2. The Northern Plains
Formed by: Alluvium deposits from Indus, Ganga, Brahmaputra
Features:
- Flat, fertile, densely populated
- Three sections:
- Punjab Plains (Indus)
- Ganga Plains (Uttarakhand to Bengal)
- Brahmaputra Plains (Assam)
Subdivisions:
- Bhabar: Pebbly, porous belt at the foot of Himalayas
- Terai: Marshy area south of Bhabar, rich in wildlife
- Bangar: Old alluvium
- Khadar: New alluvium, more fertile
Prelims Note: Questions often ask about Bhabar–Terai differences.
3. Peninsular Plateau
Oldest landmass, composed of igneous and metamorphic rocks
Divided into:
- Central Highlands:
- Malwa Plateau, Bundelkhand, Baghelkhand
- Rivers: Chambal, Betwa, Son (flowing northward)
- Deccan Plateau:
- Between Western and Eastern Ghats
- Includes Maharashtra, Karnataka, Andhra
- Rivers: Godavari, Krishna, Mahanadi (east-flowing); Narmada, Tapi (west-flowing)
Important Features:
- Western Ghats: Steep, block mountains, heavy rainfall
- Eastern Ghats: Discontinuous, dissected by rivers
- Chotanagpur Plateau: Mineral-rich region (Jharkhand, Odisha)
4. Indian Desert (Thar Desert)
Location: NW Rajasthan
- Sandy soil, low rainfall (<150 mm), high evaporation
- Features: Dunes, salt lakes (Sambhar), dry rivers (Luni)
5. Coastal Plains
Western Coastal Plains:
- Narrow, from Gujarat to Kerala
- Divided into Konkan, Kannad, Malabar
Eastern Coastal Plains:
- Wide, deltaic
- Divided into Northern Circars, Coromandel
- Important deltas: Godavari, Krishna, Mahanadi
Backwaters/Lagoons: Vembanad (Kerala), Chilika (Odisha)
6. Islands
Andaman and Nicobar Islands:
- Bay of Bengal, volcanic origin, Barren Island (active volcano)
Lakshadweep Islands:
- Arabian Sea, coral atolls and reefs
- Headquarters: Kavaratti
Key Prelims & Mains Points
- Oldest Mountains: Aravalli Range (fold mountains)
- Youngest Mountains: Himalayas
- Block Mountains: Vindhya, Satpura
- Volcanic Hills: Rajmahal Hills
- Important Plateaus: Deccan, Malwa, Chotanagpur
- Physiographic Contribution:
- Himalayas: Barrier, source of rivers, biodiversity
- Plains: Agriculture, dense population
- Plateau: Minerals, irrigation
- Coasts: Ports, fishing, trade
Chapter 4: Indian Drainage System
India’s drainage system is the network of rivers, lakes, and other water bodies that drain surface water into the seas. The Indian drainage system can be broadly classified into two main types: Himalayan (perennial) rivers and Peninsular (seasonal) rivers.
4.1 Major River Systems of India
Himalayan Rivers
- Characteristics: Originating from the snow-covered mountains, these rivers are perennial — they flow throughout the year and carry large volumes of water.
- Examples:
- Indus: Originates in Tibet, enters India through Jammu & Kashmir, and flows into Pakistan. Major tributaries include Jhelum, Chenab, Ravi, Beas, and Sutlej.
- Ganga: Originates from Gangotri Glacier in Uttarakhand. Its major tributaries include Yamuna, Ghaghara, Gandak, Kosi, and Son. The Ganga is considered the lifeline of India, supporting a significant portion of India’s population.
- Brahmaputra: Originates in Tibet as the Tsangpo River. After crossing into India through Arunachal Pradesh, it flows into Bangladesh, where it merges with the Ganga.
Peninsular Rivers
- Characteristics: These rivers are seasonal, and most of them flow eastward, emptying into the Bay of Bengal. They have fixed courses and are shorter and more mature compared to the Himalayan rivers.
- Examples:
- Godavari: Originates in Trimbakeshwar, Maharashtra, and flows southeastward into Andhra Pradesh. It is the second longest river in India.
- Krishna: Originates in the Western Ghats, flows eastward across Maharashtra, Karnataka, and Andhra Pradesh.
- Mahanadi: Originates in Chhattisgarh, flows into the Bay of Bengal.
- Narmada: Originates from the Amarkantak Plateau in Madhya Pradesh and flows westward into the Arabian Sea. It is one of the few west-flowing rivers in India.
- Tapi: Originates from Satpura Range in Madhya Pradesh and flows towards the west into the Arabian Sea.
- Kaveri: Originates in the Western Ghats, and flows through Karnataka and Tamil Nadu, reaching the Bay of Bengal.
4.2 Characteristics of River Systems
Himalayan Rivers:
- Perennial flow due to glacier melt.
- Larger catchment areas and more sediment transport.
- Examples: Indus, Ganga, Brahmaputra.
Peninsular Rivers:
- Seasonal flow, primarily dependent on the monsoon.
- Shorter courses, and are mature rivers.
- Drainage Pattern: Mostly trellis and radial.
4.3 Drainage Basins and Watersheds
- A drainage basin is an area from which all surface runoff flows into a common outlet (river, lake, etc.).
- Watersheds: Smaller drainage areas within a basin.
- India’s major river basins:
- Indus Basin (Western India)
- Ganga Basin (Northern India)
- Godavari Basin (Central India)
- Krishna Basin (Southern India)
- Mahanadi Basin (Eastern India)
4.4 Important Features of India’s River System
- Deltaic Regions:
- Sundarbans Delta (formed by the Ganga-Brahmaputra) in West Bengal. This delta is the largest in the world and is famous for its mangroves and tigers.
- Godavari Delta (Andhra Pradesh)
- Krishna Delta (Andhra Pradesh)
- Mahanadi Delta (Orissa)
- Estuaries:
- Where rivers meet the sea, they create a unique blend of saltwater and freshwater ecosystems.
- Examples: Narmada Estuary, Tapi Estuary
4.5 River Water Distribution
- Western India (Rivers flowing towards Arabian Sea):
- Narmada, Tapi, Mahi, Sabarmati.
- Eastern India (Rivers flowing towards Bay of Bengal):
- Ganga, Brahmaputra, Godavari, Krishna, Mahanadi.
4.6 River Linkage Project
The National River Linking Project (NRLP) aims to connect India’s major rivers to provide equitable water distribution across the country and to prevent floods and droughts. The inter-linking of rivers will improve irrigation and drinking water supply.
Major Proposals:
- Linking of Ganga and Kaveri
- Linking of Brahmaputra with Ganga
- Linking of Ken and Betwa
4.7 Major Dams and Irrigation Projects
- Bhakra Nangal Dam: Located on the Sutlej River, it is one of India’s oldest and most important multi-purpose dams.
- Tehri Dam: Built on the Bhagirathi River in Uttarakhand, providing hydroelectric power and irrigation.
- Hirakud Dam: Located on the Mahanadi River in Odisha, one of the longest dams in the world.
- Sardar Sarovar Dam: Located on the Narmada River, it is a major source of water for irrigation and drinking.
4.8 Rivers and Flooding in India
- Flooding is a recurring problem, especially in the Ganga-Brahmaputra Basin during monsoons.
- The Himalayan Rivers bring heavy rainfall and meltwater from glaciers, leading to flooding.
- Flood management strategies include embankments, river training, dams, and flood forecasting.
4.9 Important Lakes in India
- Wular Lake (Jammu & Kashmir) – Largest freshwater lake in India.
- Sambhar Lake (Rajasthan) – Saltwater lake, India’s largest inland saltwater lake.
- Chilika Lake (Odisha) – Largest coastal lagoon in India, famous for migratory birds.
- Vembanad Lake (Kerala) – Largest lake in Kerala.
4.10 Map-based Questions
For UPSC, PSC, and SSC, it’s essential to focus on rivers, dams, deltas, and drainage systems on maps. This is crucial for both Prelims and Mains.
- Rivers: Mark the flow and tributaries of Ganga, Indus, Brahmaputra, Godavari, Krishna, etc.
- Dams: Know locations of Bhakra Nangal, Tehri, Hirakud, Sardar Sarovar, Narmada.
- Delicacies: Learn major deltaic regions like Sundarbans, Godavari, Krishna, etc.